Cattle - Nutrition and trace elements
Explain the use of milk quality analysis to assess diet in dairy herds
Butterfat and protein levels in the milk are measured on a herd basis (via the bulk tank - usually weekly) or an individual animal basis (via milk recording - usually monthly). Butterfat levels reflect rumen health and the levels of effective long fibre in the diet, whilst milk protein levels primarily reflect longterm energy status of the cows. On an individual animal basis, the Fat : Protein ratio can be used: high fat/low protein indicates issues with excessive NEB, whereas low fat/normal protein is indicative of issues with subacute rumen acidosis (SARA). However it should be noted that there are other influences on milk quality such as dilution/concentration effects from milk production, genetics etc., and so assessing nutrition on milk quality alone is not possible.
50% of the milk fat is synthesised from?
Butyrate and acetate
What is the major transport protein for copper?
Caeruloplasmin
List the macronutrients of the ruminant
Calcium Magnesium Phosphorous Potassium Sodium Chloride Sulphur
Which gases is produced during fermentation?
Carbon dioxide (40%) Methane (40%) Hydrogen (5%)
What are the roles of selenium and Vitamin E?
Cellular anti-oxidants - they protect cells against damage by lipid peroxidases and free radicals
How do one typically classify feeds on the basis of neutral detergent fibre content?
Cellulosic - contain high levels of plant cell wall material Non-cellulosic
Explain how genetics influence milk quality
Channel Island breeds (especially Jersey) have higher milk quality, with Ayrshires having intermediate quality and Holsteins relatively poor quality.
Explain the use of faecal examination to asses the diet on a dairy farm
Closer examination of the faeces (washing through using a sieve) may reveal the presence of undigested long fibre, food material such as cereal grains or mucus casts (indicating gut damage). These signs would usually be seen as being indicative of poor rumen health or SARA
Explain how inclusion in compound feeds can be used to treat cobalt deficiency
Cobalt is frequently added to concentrate rations for feeding to cattle and sheep.
Explain how liver vitamin B12 level can aid your diagnosis of cobalt deficiency
Cobalt is poorly stored in the body, although liver Vitamin B12 will provide a guide to limited continuous body storage. Samples are taken either via liver biopsy or post-mortem, and can be used to determine flock cobalt status. Animal variation is not as pronounced as blood levels, and so 3 - 5 samples per group are needed. Liver cobalt levels can also be analysed, although Vitamin B12 is preferred.
Why must injectable compounds use Vitamin B12 and not cobalt to be effective in treating cobalt deficiency?
Cobalt will not enter the rumen in sufficient levels (where the cobalt is required)
What is the prevalence of cobalt deficiency?
Common in weaned lambs Extremely rare in supplemented animals.
What is the relationship between selenium and vitamin E?
Complimentary, but independant roles.
What are the three purchase options you have for concentrates?
Compound feeds Blends Raw materials/straights
What are the two forms of nutritional muscular dystrophy/white muscle disease?
Congenital Delayed
What are the two forms of swayback seen in sheep?
Congenital Delayed
What do you need to consider when taking blood sampling for metabolic profiling?
Consider times when the cows are potentially under periods of metabolic and nutritional stress, therefore try to identify such issues before they impact productivity.
Explain how dry cow management can increase milk protein
Controlling body condition score in the dry period to ensure minimise NEB. Provision of extra DUP in the dry cow ration may also help.
List the trace elements of the ruminant
Copper Cobalt Selenium Iodine Iron Zinc Manganese
What are the rules for metabolic blood profiling?
Correct timing of test Cow selection; early lactation group Mid lactation group Dry cows Group size Cow selection Use of background information
Explain the treatment regime of intra-ruminal boluses to treat selenium deficiency
Cosecure, also contains copper and cobalt; Tracesure™ and Agrimin™ are other suppliers) provide slow release of selenium for 6-12 months.
What are the main factors influencing dry matter intake?
Cow factors Food factors Management factors
List some different metabolic profiles seen in farm animal practice
Cow side testing - single biochemical metabolites Larger scale panels to assess multiple parameters.
What are some common problems in terms of selecting animals for metabolic profiling?
Cows that have been calved for more than 3 weeks in the early lactation group. If cows have been incorrectly fed, they may have adjusted their milk yields accordingly, and so all biochemical parameters may be within the normal range. Inclusion of too many cows that are not representative of the herd. Given a free choice, herdsman will often include "problem" or "odd" cows which can lead to a misleading interpretation of the results Cows with long standing health or reproductive problems seldom give abnormal biochemical results, as the underlying cause has occurred weeks previously. Sampling immediately before or after a major management or nutritional change
What biochemical indicators of muscle damage can be used to diagnose WMD?
Creatine kinase (CK) AST
What do you need to remember about selenium in regards to the pregnant animal?
Cross the placenta Concentrated in the colostrum together with vitamin E
What is the equation used for calculating DMI?
DMI = 2.5% of liveweight (kg) plus 10% of milk yield (kg/day)
How does stage of pregnancy affect DMI?
DMI decreases in late pregnancy
How is vitamin E levels affected by storage and treatment methods?
Decline rapidly during long-term storage Destroyed by various treatment methods (e.g. addition of alkali)
Explain the transition period
Defined as the period from 3 weeks before calving to 3 weeks post calving. Feeding during this critical period is critical to the success of the subsequent lactation - a successful transition will lead to increased DM intakes, reduced disease problems and increased milk production during early lactation. Diseases such as ketosis, milk fever and LDA all have their origin in the nutrition during the transitional period. Thus this period should be viewed as "effectively the first month of lactation".
How do you diagnose selenium/vitamin E deficiency?
Diagnosis of WMD Soil and pasture levels of selenium Selenium levels in blood and liver Glutathione peroxidase (GSHPx) levels in blood Vitamin E levels in blood
Explain how fertility can be used to assess the diet on a farm
Diagnosis of conditions at the routine fertility visit such as endometritis, cystic ovarian disease, post-partum nutritional anoestrus or PD negative cows may all indicate underlying issues with nutrition worth investigating further.
How do you optimize rumen microbial protein synthesis?
Diet synchrony - ensuring optimal levels of both energy and protein in the rumen at the same time.
Explain how dietary levels can aid your diagnosis of copper deficiency
Dietary copper levels are useless, due to the effects of molybdenum, sulphur and iron. Some advocate the use of dietary molybdenum levels (levels above 2mg/kg DM) or copper:molybdenum ratio (mg:mg - ratios less than 1:1 indicate a high risk of problems), but these must be interpreted with extreme care.
How does dieatry deficiencies affect ERDP?
Diets deficient in ERDP may reduce DMI.
List the main food factors influencing DMI
Digestibility of foodstuff Concentrates Forages Dietary deficiencies Palatability
What clinical factors can you use to assess the diet on a dairy herd?
Disease Fertility
What are the two forms of oral compounds used to prevent/correct mineral deficiencies?
Drenches - on their own, or in combination with anthelmintic drenches Boluses - remain lodged in the GIT
What are the inputs you can analyze on a dairy farm?
Dry matter intakes Feed quality
When are free radicals and lipid peroxidases produced?
During normal cellular oxidative metabolism.
What happens in the depletion phase of insufficient mineral levels in the diet?
During this phase, there is a loss of mineral from storage sites (e.g. liver, bone). However, the levels in the transport system (usually bloodstream) are normal.
What is the source of ammonia from fermentation?
Effective Rumen Degradable Protein (ERDP)
Explain the use of globulin to assess protein status in the dairy cow
Elevated globulin levels indicate the presence of chronic inflammation (eg. metritis, mastitis, lameness, chronic suppurative pneumonia, liver fluke)
What is the benefit of correctly usage of metabolic profiling?
Enable the veterinarian to become involved in all aspects of dairy management practice and diet evaluation. Valuable objective piece of the jigsaw
What does microbial protein production depend on?
Energy content of the diet.
Explain how you would optimize dry matter intakes
Ensure optimum rumen health The TMR ration must be well-mixed (but not over-mixed!) and highly palatable. The ration should be provided truly ad-lib to the cows. This means that enough ration should be provided to the cows such that 5-10% of the ration is left over at the end of the day. This is then removed before fresh food is offered. Trough space should be adequate for all the cows to feed at once The ration must be pushed up on a regular basis to ensure that there is fresh, highly palatable feed in front of all of the cows at all times. Ensure excellent cow comfort Clean, fresh water should be available to the cows at all times. There is a direct correlation between DMI in the day before calving and at day 21 after calving (ie. the higher the DMI prior to calving, the higher the DMI in early lactation)
What is the significance of iodine?
Essential constituent of the thyroid hormones, particularly T3.
Explain iodine defiency brought on by environmental factors
Factors that increase the basal metabolic rate (BMR) of animals, such as low environmental temperatures, will increase thyroid hormone production.
What is the impact of BCS on DMI?
Fat cows (over condition score 4) have reduced appetites
How would you treat/prevent SARA?
Feed a suitable transitional diet for 3-4 weeks prior to calving Increase the amount of effective long fibre in the ration. Increase DMI to ensure ingestion of sufficient forage Avoid sudden increases in concentrate feeding, especially after calving Review of feeding strategies. This particularly applies when large quantities of concentrates (over 4kg) are fed at one time (so called "slug" feeding). Reduce sorting of long fibre by cows - by feeding quality long roughages Improve cow comfort
What is roughage/forage?
Feeds for ruminants that are derived from plants, and which contain a significant amount of cellulose.
Why is cobalt deficiency extremely rare in supplemented animals?
Feedstuff tend to have higher levels of cobalt.
Which animals should be targeted for metabolic profiling?
First cows in the group to experience new dietary or management conditions.
How can you increase milk protein?
Forage changes Concentrate changes Dry cow management
Explain the use of glutathione peroxidase (GSHPx) levels in blood as a diagnostic tool for selenium/vitamin E deficiency
GSHPx is a selenium-containing enzyme, and is the standard biochemical test for selenium deficiency. As erythrocyte GSHPx levels depend on selenium levels during erythropoeisis and RBCs live for several months, blood GSHPx levels reflect long-term selenium status (2-4 months).
Explain how intercurrent disease influence absorption of dietary copper
Gastrointestinal parasitism can markedly affect copper absorption.
What does optimum productivity of a dairy herd depend on?
Genetic potential of cows Nutrition Digestion Management Cow environment Health
What are the clinical signs of iodine deficiency?
Goitre. The classical sign of iodine deficiency is thyroid enlargement, due to compensatory mechanisms invoked by the lack of thyroid hormone production. The enlargement may not always be clinically obvious, but can be detected by histopathology in these marginal cases. Goitre is usually seen in the newborn animal Stillbirths or birth of weak calves/lambs. Calves and lambs born to iodine-deficient dams may be stillborn, with goitre and areas of alopecia and subcutaneous oedema (myxoedema). Weak calves/lambs are unwilling to suck, and associated perinatal mortality is high Fertility. The role of iodine in infertility is controversial, with poor reproductive performance in sheep and cattle being implicated. Poor production. Loss of appetite with poor milk yield, and poor wool production in sheep has been associated with iodine deficiency in cattle.
Explain secondary iodine deficiency
Goitrogens act by disruption of iodine metabolism, and there are two main types.
What is the link between pasture levels of selenium and clinical disease?
Good correlation between low soil selenium, low pasture selenium and clinical disease.
What is the cheapest and most readily available forage in the UK?
Grass
List some other types of forage than grass
Grass silage Hay Straw Other types of silage - maize or whole crop
Which plants are high in vitamin E?
Green pastures Relatively low in root crops
What is one of the major problems with feeding cows in a dairy farm?
Group feeding of cows
What is primary/simple mineral deficiency?
Here the levels of the mineral in the diet are inadequate
What happens in the dysfunction phase of insufficient mineral levels in the diet?
Here, the low levels of mineral lead to a decline in the concentrations or functions of enzymes involved in metabolism, and thus body function is impaired. The animal still appears clinically normal.
What does the fatty acid concentration in the diet vary upon?
High levels of fibre in the ration (cellulose and hemi-cellulose) lead to a higher proportion of acetate High levels of concentrate feeding (starch and sugars) - lead to a higher proportion of propionate.
What are the groups most farmers split their herd into?
High, mid and low yielders or Early, mid and late lacation.
How do you diagnose mineral deficiencies?
History Clinical examination - usually unrewarding unless advanced clinical signs Soil/pasture content - soil content may not be equivalent to pasture content, or uptake Characteristic disease/pathology - some deficiencies lead to characteristic changes (eg. white muscle disease in selenium deficiency), but may not be apparent. Animal samples to collect; What samples to collect? Which animals to sample? What to analyse the samples for? How many samples to collect? How to interpret the results? Controlled supplementation trials
How can you prevent copper deficiencies in subsequent years?
House sheep during last 6-8 weeks of pregnancy Provision of supplementary feeding during late pregnancy Copper supplementation of sheep in early pregnancy (using one method only
Other than assessing diet, what can metabolic profiling be good at?
Identify problems before they cause problems such as lost milk production, poor health etc.
When is the only time you should give sheep copper supplementation?
If clinical disease has been previously diagnosed, and hypocuprosis has been confirmed.
What are the clinical signs of cobalt deficiency?
Ill-thrift. This is the predominant clinical sign seen in lambs, with reduced appetite and failure to reach target growth rates. Severely affected animals are pot-bellied, empty, emaciated and listless. In the UK, this condition is commonly termed "pine" Conjunctivitis. Low-grade conjunctivitis with a watery ocular discharge and tear staining Anaemia. This is usually only seen in terminal stages, but pale mucus membranes may also be observed. Ovine White Liver Disease (OWLD). This is due to fatty infiltration of the liver in cobalt deficient lambs, and may result in signs of liver failure and death. Increased perinatal lamb mortality. This is often associated with higher stillbirth rates, poor suckling and reduced colostrum intakes in cobalt-deficient ewes Increased susceptibility to infection, especially PGE Infertility. Has been recorded, although it is debatable as to whether this is a primary problem, or a consequence of cobalt deficient animals with severely compromised metabolism
What is the consequence of too low rumen pH (below 6)?
Impaired digestion of fibre and may result in ruminal acidosis.
What is the importance of microbial cells as an end product of fermentation?
Important source of protein for the cow
How has farmers responded to the strains put on the diary cows to produce higher yields of milk?
In order to meet these increased energy demands and avoid prolonged NEB in early lactation, the energy density of the ration has increased with the use of high levels of concentrate feeding/maize silage. These contain increased quantities of rapidly fermentable carbohydrates that result in acid production in the rumen and a consequent fall in rumen pH below the optimum range of 6 - 7.
Explain the use of urea/urea-N to assess protein status in the dairy cow
In ruminants, this is used to measure short term intakes of Effective Rumen Degradable protein (ERDP) from the diet, utilisation of ERDP in the rumen, and the balance of rumen energy (FME) and ERDP in the rumen. Therefore low urea-N values would indicate poor short term intakes of ERDP from the diet - either because the diet was low in ERDP, or Dry Matter intakes were poor. Conversely high urea-N values would indicate that either ERDP intakes are high (when grazing grass for example), or there is not enough FME in the diet to enable the rumen microbes to convert ERDP into microbial protein in the rumen.
What are the clinical signs of cobalt deficiency in cattle?
In severe circumstances, ill-thrift has been observed.
Explain the use of superoxide dismutase (SOD) as a diagnostic tool for copper deficiency
In theory, analysis of erythrocyte or liver SOD would give a better diagnosis of deficiency and dysfunction states, but is expensive.
What happens in the deficiency phase of insufficient mineral levels in the diet?
In this phase, the levels in the transport system decline.
What are the risk factors for developing SARA?
Inadequate effective long fibre in the ration Excessive levels of concentrate feeding, particularly starch and sugars. Poor nutritional management Poor cow comfort
What direct methods to prevent/correct mineral deficiencies are there?
Inclusion in compound feeds Free-access minerals Medication of water supply Oral compounds Injectable compounds
Explain how you could use inclusion in compound feeds to treat copper deficiency
Inclusion of copper in concentrate feeds for sheep is banned in the UK (however, there will be low levels of copper in most concentrate feeds). Copper may be included in concentrates fed to cattle (up to a limit of 35mg/kg).
How would out-of-parlour feeders affect DMI?
Increase feed intakes by 5-10%
Explain how concentrate changes can increase milk protein
Increased levels of concentrate feeding will supply more energy to the cow. Feeding of bypass starch (maize grains and by-products) will increase milk protein The previous points to try and increase levels of energy in the diet will only work as long as ruminal acidosis does not develop (SARA will inhibit rumen function) Increasing levels of DUP will also increase milk protein production, but only if dietary protein is limiting.
Explain how increasing the amount of effective long fibre in the ration influences butterfat levels
Increases butterfat levels Long fibre may be added to the TMR by the inclusion of 0.5kg chopped straw/cow/day or 2-3kg good quality hay or haylage.
How does milk yield affect DMI?
Increasing levels of milk production stimulate appetite
What strains are put on dairy cows in the "near" dry period?
Increasing nutrient demands from the foetus and increasing requirements for the initiation of milk production - all combined with a reduction in DMI.
How can you alter butterfat levels?
Increasing the amount of effective long fibre in the ration High levels of concentrate feeding Sodium bicarbonate administration Inclusion of saturated fats
What are the two methods used to prevent and correct mineral deficiencies?
Indirect methods Direct methods
Explain the treatment regime of short-term supplementation for cobalt deficiency
Injection of 1 - 2 mg Vitamin B12 will raise serum and liver Vitamin B12 levels for up to a month. Repeated dosing may be necessary for fattening lambs in the autumn
How is DMI influenced by stage of lactation?
Intakes are depressed by 2-3kg in freshly calved cows
How does digestability of foodstuff affect DMI?
Intakes will increase as the digestibility of the feed increases (the "D" value)
How do you subdivide concentrates?
Into their primary contents
Explain use of long-term supplementation (injection) as a treatment/prevention option for iodine deficiency
Intramuscular injections of iodised poppy-seed oil (Lopiodol) provide adequate supplementation for up to 2 years. The dose is 1ml for ewes and 4ml for adult cattle. It is currently unavailable in the UK
Explain the use of iodine levels as a diagnostic tool for iodine deficiency
Iodine concentrations in the thyroid gland will decrease markedly.
Explain the use of soil and pasture iodine levels to diagnose iodine deficiency
Iodine deficient areas are usually known, but the role of goitrogens in many cases means that soil and pasture levels are not particularly useful.
Explain use of inclusion in compound feeds as a treatment/prevention option for iodine deficiency
Iodine is frequently added to concentrate rations for feeding to cattle and sheep. Kelp seaweed is a good source of iodine.
Explain how iron influence absorption of dietary copper
Iron can inhibit copper uptake either directly by the formation of insoluble compounds with copper, or via combination with sulphides to form FeS which then binds copper. Iron contamination of forages commonly occurs via soil contamination
Explain how controlled supplementation trials can aid your diagnosis of cobalt deficiency
It is often necessary to perform such trials, where half the group are supplementation and half the group are not, and the growth rates of the two groups are then compared.
Why is it helpful to subdivde concentrate feeds?
Judging how to supplement and balance a ration
Should farmers aim for feed that is high in NDF to stimulate rumination?
Just because it have a high NDF does not mean it will stimulate rumination.
What should you do to ensure optimal rumen function and digestion of forage?
Keep rumen pH between 6.5 - 7 Ensure optimum cow comfort and health ==> good rumination Sufficient protein (ERDP) for the rumen microbes Avoid sudden dietary changes and/or excessive quantities of fermentable energy
Who can assess the food quality?
Laboratories - analyse forage/concentrate
What is a big problem with the single TMR feeding?
Late lactation cows become fat, leading to overfat dry cows at calving with further reduced DMI
Explain how high levels of concentrate feeding will influence butterfat levels
Lead to increased propionate production and decreased acetate production in the rumen, leading to a fall in butterfat levels
Explain how AST can be used as a diagnostic tool for diagnosing WMD
Levels may be raised during liver damage, so this is non-specific. However, levels remain raised for 7-14 days following muscle damage.
Explain how indicators of metabolic dysfunction can aid your diagnosis of cobalt deficiency
Levels of both serum Methylmalonic Acid (MMA) and urine Formiminoglutamic Acid (FIGLU) are increased during cobalt deficiency, as both of these metabolites build up due to impaired metabolism. However cost and problems with the laboratory analysis currently preclude their use on a commercial basis.
What is secondary/conditioned mineral deficiencies?
Levels of mineral in the diet are normal, but there are other factors that limit its availability to the animal.
What is the major storage organ for copper_
Liver - containing 70% of body copper reserves
Explain the use of liver copper levels as a diagnostic tool for copper deficiency
Liver samples give an estimation of body copper reserves, and can be used to monitor copper supplementation. 3-4 liver samples should be taken.
What physical form is essential to stimulation of rumination?
Long fibres - 2.5 - 10cm long
What are the clinical signs of SARA?
Loose faeces, with excessive faecal soiling of hindquarters. Closer examination of the faeces may reveal fibrin casts, undigested cereal grains and long fibres Cows swishing their tails (when there are no flies), due to gut and/or urine irritation Reduction in milk butterfat. Reduction in milk yield, with cows not milking to expectation. Reduction in DMI Individual animals variable go "off their food" with consequent reduction in milk yield Cows "spilling their cud" whilst ruminating Increased incidence of nutritional-related diseases, such as NEB/acetonaemia, LDAs, poor fertility, lameness and other peri-parturient diseases (eg. mastitis).
What is hypocuprosis?
Low concentrations of copper in the liver, blood or other tissues.
Explain primary deficiency of iodine
Low iodine content in the soil occurs predominantly in the west of the UK (associated with high rainfall).
What must the daily routine of a cow consist of to make sure its adequate digestion of food?
Lying down for 12 - 14 hours Eating for 3-4 hours Drinking for 1 hour Consuming 10-20 meals Spending up to 10 hours ruminating Producing 100-150 litres of saliva, containing 3.5kg bicarbonate Chew, crush and fragment forage using 30 - 50,000 jaw movements
What can you use to assess mineral status in the dairy cow?
Magnesium Phosphate Calcium
How do you calculate energy requirements of a dairy cow?
Maintenance Lactation Pregnancy Liveweight change
What are the two categories of essential mineral required for ruminant life?
Major/macronutrient Trace/micronutrient
Explain compound feeds for cattle
Manufactured by feed companies (e.g. pellets)
Explain how disease can be used to assess the diet on a dairy farm
Many clinical diseases have their origins in nutritional management, including "transition cow diseases" such as LDAs (target less than 1% per annum), clinical ketosis (target less than 1%), metritis (target less than 3%), milk fever (target less than 5%) and retained foetal membranes (less than 8%). However although monitoring disease incidence can give an indication as to nutritional problems, ideally we would like to prevent these diseases occurring.
Explain how forage changes can increase milk protein
Maximising DMI during early lactation to minimise the extent of any NEB Use a mixture of forages/TMR to stimulate intakes and energy supply. Feed higher levels of maize silage (contains more starch and energy)
When may application of mineral fertilizers to pasture not work?
May not work if factors leading to secondary deficiencies are still present, then fertilizers may have little effect.
What can you use to measure the rate of digestion, and thus DMI in cattle?
Measure neutral detergent fibre (NDF) which is the plant cell wall material lignin, cellulose and hemicellulose
Explain the use of protein as a measure of mineral status
Measurement of blood calcium is only of value if measured within 48 hours of calving for the assessment of hypocalcaemia. However even the value of this is debatable, as most cows will suffer a drop in blood calcium levels around calving. It is likely that the depth and extent of low calcium levels around calving determines the development of clinical milk fever
What is the consequence if the protection by selenium and Vitamin E fails?
Membrane damage and then tissue necrosis
On a forage-based ration at normal milk yeilds, where does the majority of the protein come from to produce milk proteins?
Microbial protein
What are the two components of metabolisable protein (MP)?
Microbial protein (synthesised from ERDP and NPN) Bypass protein (Digestible undegradable)
Which animals may it be worth treating for swayback?
Mildly affected lambs to stop progression of the disease using very small doses of copper (orally or injectable) All remaining pregnant ewes should be given copper (either by injection or bolus). All surviving lambs born out of pregnant ewes that have not been given copper should be dosed to prevent cases of delayed swayback.
Why is cobalt deficiency rare in suckling animals?
Milk contains high concentrations of Vitamin B12, therefore unless the mother is deficient they wont be either.
What production outputs can you measure in a cow herd?
Milk production Milk quality
Since most protein is obtained from microbial protein, which depends on energy content of the diet, how can this help you?
Milk protein nearly always reflects long-term energy status.
Explain how age affects milk quality
Milk quality tend to decrease as the animal gets older, due to a dilution effect.
List the main management factors affecting DMI
Mixed forages TMR diet Out-of-parlour feeders Frequency of presentation of food Restriction of access to food Water Cow comfort
Explain how molybdenum influence absorption of dietary copper
Molybdenum reacts with sulphur in the rumen to form thiomolybdates, that irreversibly bind copper and prevent its absorption. Molybdenum levels in the pasture are affected by soil content (some areas are known to have high molybdenum levels), pasture improvement via liming (high soil pH values encourage molybdenum uptake) and stage of maturity (molybdenum levels increase later in the grazing season)
What is the prevalence of secondary copper deficiency?
More common than primary
Explain how clinical signs can aid you in diagnosis of copper deficiency
Most clinical signs are non-specific, except for cases of swayback (submit brain and spinal cord to look for characteristic histopathology lesions).
Is it possible to measure dry matter intakes in grazing cows?
No
Does metabolic profiling replace BCS, milk quality and the other assessments of diets on the dairy herd?
No, they should be used together.
There is also another substance that ruminants can utilise to synthesise microbial protein, what is this?
Non-protein nitrogen (NPN), e.g. urea.
What are the rules for metabolic blood profiling in terms of cow selection?
Not an individual animal test, should not select "atypical" cows (e.g. very high yielding, very low yielding, disease problems etc.)
How quickly does milk protein respond to dietary changes?
Notoriously slow
How will frequency of presentation of food affect DMI?
Novelty value will also increase intakes
What are the clinical signs of selenium/vitamin E deficiency?
Nutritional muscular dystrophy (also called White Muscle Disease (WMD) Ill-thrift. This is usually observed as poor growth rates and ill-thrift in growing calves and lambs. Deficiency syndromes may also occur in adults (eg. poor milk production in dairy cattle), possibly due to secondary effects on thyroid hormone function. Fertility. In cattle, the role of selenium in fertility disorders remains controversial. In sheep, selenium deficiency has been associated with increased embryonic mortality Impaired immune function. Selenium/Vitamin E deficiency can lead to increased susceptibility to disease, in particular mastitis in dairy cows and mortality in lambs. Retained foetal membranes. In cattle, RFM has been associated with selenium/ Vitamin E deficiency (amongst other causes of RFM)
How can you use the fact that milk butterfat and milk protein is affected by nutrition to your advantage?
Nutritional problems can be identified by examination of milk quality.
Explain the use of cow comfort to asses the diet on a dairy farm
Observing cows when undisturbed gives a clear indication of cow comfort and welfare. Useful parameters to look at include feed bunk access (can all of the cows eat at once when fresh food is put out?), Cow Comfort Index (CCI: defined as the number of cows in cubicles that are lying down, divided by the number of cows that are lying and standing in cubicles: should be over 85%), Stall Standing Index (measures the proportion of cows in contact with a cubicle that are standing [inverse of CCI]: should be under 15%.) and Stall Usage Index (defined as proportion of cows within a pen that are lying down divided by the cows within a pen who are not actively feeding: should be over 75%). Cow cleanliness and hock scores may also give an indication of farm management, housing and cow comfort.
Explain the use of rumen fill to asses the diet on a dairy farm
Observing the left side of the cow in the rumen sublumber fossa gives an assessment of feed intake, ration composition, and the rate of passage of feed through the rumen. The appearance of the "danger triangle" (an empty rumen) would suggest that the cow has not eaten, and so may have/about to get a clinical disease problem such as an LDA.
How does concentrate affect DMI?
Offering concentrate foods with forage to cows can lead to 3 possible outcomes: supplementation, substitution or complementation.
When does clinical signs of copper deficiency occur?
Only occur after exhaustion of liver stores, followed by decreases in blood copper concentrations and then a fall in copper levels at the essential tissue siutes
What is a concern with dry matter intake analysis?
Only possible on a group rather than individual animal basis.
What is the main aim for protein requirements for a diary cow?
Optimise rumen microbial protein synthesis
What are your direct methods to treat/prevent cobalt deficiency?
Oral compounds; Oral drenching with cobalt sulphate Intra-ruminal boluses Injectable compounds; Short-term supplementation Long-term supplementation Inclusion in compound feeds Free-access minerals Medication of water supply
What are your direct methods of treatment for copper deficiencies?
Oral compounds; oral copper sulphate copper oxide needles Intra-ruminal boluses Injecatbale compounds Inclusion in compound feeds Free-access minerals Medication of water supply
Explain the treatment regime of oral sodium selenate to treat selenium deficiency
Oral dosing using 0.1 mg/kg sodium selenate will provide adequate supplementation for 1-3 months (frequently incorporated into drenches).
Explain oral drenching with cobalt sulphate as a treatment regime for cobalt deficiency
Oral dosing using 7 mg cobalt per week will prevent deficiency. However it must be repeated weekly due to lack of storage. Cobalt is often added to worm drenches, but the levels provided are often insufficient
Explain use of oral iodine salts as a treatment/prevention option for iodine deficiency
Oral dosing using potassium iodide may be performed, but is relatively short-acting. Iodine poisoning is a potential risk
Explain the treatment regime of oral copper sulphate to treat copper deficiency
Oral dosing with copper sulphate (1g per ewe in 30ml water) eight and four weeks prior to lambing is traditionally used to prevent swayback.
What are your main treatment options for iodine deficiency?
Oral iodine salts Intra-ruminal boluses Painting of 5% tincture of iodine on the flank skin-fold once a week in cattle Long-term supplementation (injection) Inclusion in compound feeds Free-access minerals Medication of water supply Application of iodine fertilizers to pasture Minimising effects of goitrogens.
What are your methods of preventing/treating selenium deficiency?
Oral sodium selenate Intra-ruminal boluses Short-term supplementation (injection) Long-term supplementation (injection) Inclusion in compound feeds Free-access minerals Medication of water supply Application of selenium fertilizer to pasture
What are some ways you can make dry matter intake anaylsis a bit easier?
Out of parlour feeders/robotic milking systems
Traditionally the focus has been on dietary inputs, what should we instead focus on?
Outputs, i.e. what effect the diet is having on the cows.
Explain how inadequate effective long fibre in the ration can predispose to SARA
Overall lack of fibre (concentrate:forage DM ratio greater than 60:40) Lack of effective long fibre (short chop length, overmixing of TMR rations) Cow chooses not to eat fibre (sorting of ration, poor/no mixing of TMR)
How do you calculate overall lactation yield?
Peak yield x 200 = overall lactation yield (ie. an 8,000 litre cow would be expected to peak at 40 litres per day)
What do you need to remember about farm animal metabolic profiling testing?
Perform the least expensive test that gives the most information. Example: calcium in healthy cows vs. downer cows.
What is critical to stimulation of rumination?
Physical form of the food
What synthesizes vitamin E?
Plants
Explain the use of vitamin E levels in blood to diagnose selenium/vitamin E deficiency
Plasma alfa-tocopherol levels below 1 μmol/l indicate a significant risk of WMD, even if selenium status is adequate
Explain how iodine levels in blood, urine and milk can be used as a diagnostic tool for iodine deficiency
Plasma inorganic iodine (PII) measures current daily iodine intake (short-term), and is thus susceptible to changes in feed intakes/inappetance etc. Iodine levels in milk and urine reflect dietary intakes. The normal range for plasma inorganic iodine in cattle is 105-287 ng/ml
What are some commonly encountered problems involving dairy cow nutrition?
Poor milk quality Milk butterfat Milk protein Subacute ruminal acidosis
Explain how poor nutritional management can predispose to SARA
Poor/non-existent transitional diet, with sudden changes in diet, especially at calving Variable DMI - empty troughs, inadequate trough space Feeding strategies - "slug" feeding of concentrates in parlour
What is a concern you must remember about selenium?
Potentially toxic - care to prevent over-supplementation
Since sheep have higher requirements for cobalt, what can we make of this?
Predominantly a disease affecting weaned lambs during the summer and autumn.
How would you asses herd to diagnose SARA?
Presence of NEB/subclinical ketosis in early lactation. Milk production (actual vs. predicted/expected) Milk quality - especially milk butterfat levels Rumination. At least 60% of the cows should be chewing their cud whilst resting. Cow comfort. Incidence of disease (eg. lameness, LDAs), fertility records etc.
Is cobalt deficiency usually primary or secondary?
Primary
What are the forms of iodine deficiency encountered?
Primary deficiency Secondary deficiency due to goitrogens Deficiencies of other trace elements Environmental factors
What are the two forms of mineral deficiencies?
Primary/simple Secondary/conditioned
Why is managing high yielding dairy cows at grass difficult?
Problems with intake constraints - especially a problem with freshly calved cows.
What is important to remember about swayback in sheep?
Progressive disease Pathology is irreversible.
What is the major precursor for glucose?
Propionate
What two metabolic processes is vitamin B12 required for in the ruminant?
Propionate metabolism (adenosylcobalamin) One-carbon metabolism (methylcobalamin)
What are the precursor for milk proteins?
Proteins obtained from body reserves and from dietary protein (both microbial protein and DUP)
Explain blends feed for cattle
Purchased mixture of unmilled raw materials
How would you asses ration to diagnose SARA?
Quantity and quality of effective long fibre, visual assessment of ration in front of cows, use of Penn State Forage Particle Separator.
What is the prevalence of primary cobber deficiency?
Rare
What is the prevalence of cobalt deficiency in cattle?
Rare - due to the lower cobalt requirements.
Explain straight feed for cattle
Raw materials which are fed as a part of a TMR
Explain the measurement of NEFA to assess energy balance in the cow
Released during fat mobilisation, NEFA is regarded as a direct measure of fat mobilisation, and by extension an indirect measure of fatty liver. Note that BHB and NEFA measure different stages of energy metabolism in the animal, and so it is not uncommon to have animals with low BHB and high NEFA levels, or vice versa
Explain the effect administration of sodium bicarbonate will have on butterfat levels
Rumen pH may be altered by the addition of sodium bicarbonate to buffer the rumen, and raise acetate production. The quantities required are high (250 - 500g/cow/day), and there are problems with palatability.
What is a problem with high concentrate to forage DM ratio?
Ruminal acidosis
Explain the use of rumination activity to asses the diet on a dairy farm
Rumination activity gives an indication of rumen health, stress and cow comfort. As a guide, 60% of cows that are lying down should be ruminating, and cows should chew each cud over 60 times. There are now automated systems such as neck collars that will record rumination activity.
Explain the treatment regime of inclusion in compound feeds to treat selenium deficiency
Selenium and vitamin E is frequently added to concentrate rations for feeding to cattle and sheep
Explain iodine deficiency brought on by deficiency of other trace elements
Selenium is required for the conversion of T4 to active T3, and thus selenium deficiency may lead to secondary iodine deficiency states
How can selenium levels in blood and liver be used as a diagnostic test for selenium/vitamin E deficiency?
Selenium levels in the blood are dependant on current daily intake of selenium, and blood selenium levels thus measure short-term intakes. Liver samples may be useful to determine the need for supplementation. However, selenium analyses are expensive and so rarely performed.
How can you diagnose WMD?
Selenium status Biochemical indicators of muscle damage Post-mortem findings
Explain how presence of goitre can aid your diagnosis of iodine deficiency
Severe goitre is readily diagnosed on clinical examination and post-mortem. However, less severe cases may be difficult to distinguish, and thyroid weight and fresh thyroid weight:body weight ratio can useful in these cases
Does sheep or cattle have higher requirements?
Sheep
Which animal is highly susceptible to copper poisoning?
Sheep - especially certain breeds.
Explain how genetics influence absorption of dietary copper
Sheep in particular show marked breed differences in the ability to absorb copper. Texels are able to absorb and retain relatively high levels of copper (and are thus more susceptible to copper toxicity), whereas Blackface sheep are relatively poor at absorbing copper (and are thus more susceptible to deficiency).
What is the major products of fermentation?
Short chain fatty acids - acetate, butyrate and propionate.
Explain the "far-off" dry period
Should be viewed as a period to allow the cow to recuperate after calving, and get her into the correct body condition score at calving of 2.5 - 3.0. Overfat cows should be slimmed on low quality rations (strawbased diets), whereas thin cows should be fed to gain body condition.
How do you diagnose copper deficiency?
Signs of clinical disease Dietary levels Plasma/serum copper levels Liver copper levels Superoxide dismutase (SOD) Response to treatment Caeruloplasmin:copper ratios - controversial
What is a current trend in feeding dairy cattle?
Single TMR
List some other deficiencies encountered in UK ruminants
Skeletal abnormalities associated with calcium, phosphorous and Vitamin D deficiencies Sodium deficiency Vitamin A deficiency
Explain the treatment regime of short term supplementation to treat selenium deficiency
Sodium selenate or selenite may be given by injection, usually combined with Vitamin E (eg. Dystosel, Vitesel). This will provide adequate selenium supplementation for up to 3 months.
How do you diagnose iodine deficiency?
Soil and pasture iodine levels Goitre Thyroid histopathology Thyroid iodine levels Iodine levels in blood, urine and milk Thyroid hormone levels Controlled supplementation trials
How do you diagnose cobalt deficiency?
Soil and pasture levels of cobalt Serum Vitamin B12 levels Liver Vitamin B12 levels Indicators of metabolic dysfunction Post-mortem diagnosis of OWLD - PM sign non-specific Controlled supplementation trials
Explain pasture properties that can affect cobalt available to ruminants
Soils vary widely in their cobalt content, and large areas of the UK and worldwide have recorded problems with cobalt deficiency. It is usually a primary deficiency, although uptake by plants is mixed, and manganese can reduce plant cobalt uptake. Heavy liming used for pasture improvement may also reduce cobalt uptake by plants. Generally cobalt uptake by plants is poor during rapid pasture growth and in mature pasture, and so deficiency is mainly seen in the summer and autumn. Soil contamination tends to increase cobalt uptake, as soil tends to have higher cobalt levels than pasture.
Why is fibre essential in a diary cows diet?
Source of energy Promote rumination Form the rumen mat to ensure optimum digestion of feeds Stimulate butterfat production
Explain the "third midday meal" method
Split the concentrate feed into three meals a day
What is the prevalence of iodine deficiency in the UK?
Sporadic occurrence
Explain the use of out-of-parlour feeders
Spread the concentrate load out throughout the day (usually in 10-12 small feeds) Enables tight control, but is expensive
What are the factors that influence milk quality?
Stage of lactation Age Genetics Disease Nutrition
What are some other names for subacute ruminal acidosis (SARA)?
Subclinical acidosis Low milk fat syndrome
Explain the treatment regime of long term supplementation to treat selenium deficiency
Subcutaneous injections of barium selenate (Deposel Injection) provide adequate supplementation for 9-12 months
Explain the treatment regime of long-term supplementation for cobalt deficiency
Subcutaneous injections of long-acting Vitamin B12 (SMARTShot) provide adequate supplementation for 3 - 6 months. This product is only available overseas (New Zealand), but can be imported under licence to the UK.
What are the clinical signs of delayed WMD affecting cardiac muscles?
Sudden death
Explain the reason for the single TMR feeding
Suggested that the cows will regulate their DMI in relation to requirements - thus high yielding cows will eat more than predicted to meet their needs.
What are the factors influencing absorption of dietary copper?
Sulphur Molybdenum Iron Other elements Differences between feedstuffs Intercurrent disease Genetics
Explain how sulphur influence absorption of dietary copper
Sulphur is converted to sulphides in the rumen by rumen flora, which then reacts with copper to form insoluble copper sulphide (CuS).
How can you use the fact that selenium crosses the placenta to your advantage?
Supplement the dam's with selenium and vitamin E in late pregnancy will help to ensure good supplies to the newborn calf/lamb.
How do you treat/prevent vitamin E deficiency?
Supplementation with Vitamin E may be given using selenium combinations (as detailed above) or Tocovite tablets. Treatment may be needed at weekly intervals (watch for selenium toxicity if giving combined selenium/Vitamin E preparations).
What are the two limiting factors to supply of microbial crude protein from the rumen?
Supply of ERDP - in which case microbial protein production is equal to ERDP Supply of energy to the microbes (FME)
What are the clinical signs of copper deficiency seen in sheep?
Swayback (also called enzootic ataxia). This disease is less common now, and is due to severe copper deficiency of pregnant ewes in mid to late gestation. It is usually associated with mild winters, and can also affect goats and deer (but not calves). The disease is progressive Depigmentation. Discolouration of the fleece in dark coloured sheep may be observed. Defective keratinisation. Loss of wool crimp, distortion of the wool fibres and reduction in wool quality may be seen - described as "stringy" or "steely" wool Bone defects. Osteoporosis and spontaneous fractures may rarely occur in sheep Susceptibility to infection Other disorders. Although described, anaemia and ill-thrift are rarely seen in sheep.
Explain how thyroid hormone levels can be used as a diagnostic tool for iodine deficiency
T4 levels reflect the thyroid and iodine status of the animal, and thus are useful in the diagnosis of deficiency. Care must be taken in interpretation of values, as there is natural variation in T4 levels according to stage of lactation (levels are much lower in early lactation), season etc. T4 levels will be high in cases of iodine deficiency secondary to thiouracil goitrogens, as they prevent the conversion of T4 to T3
What should you keep in mind when assessing BCS, milk quality and fertility?
Tend to give historical information. Fertility can be affected by nutrition for the last 2-3 months.
What is metabolic profile blood testing?
Term used to indicate blood, milk or urine sampling of animals for the biochemical assessment of metabolic status and nutrition.
Which animal is the diet usually formulated towards?
The average animal
Explain how to make buffer feeding work
The buffer feed needs to be highly nutritious to ensure good intakes of energy. Thus forages frequently used are maize silage, wholecrop silage and good quality grass silage The buffer must be palatable - fresh food should be fed daily, and wastage cleared away Cows require to be confined with access to buffer only, so they eat the buffe The timing must be correct to allow access to fresh grazing. Intakes of grass are higher in the evening due to the higher DM and sugar content of grass
How should you manage a dairy cow in the "near" dry period?
The cows should be in the correct body condition score of 2.5 - 3.0 at calving. Fat cows at calving have depressed DMI, and thus rapidly lose body condition during early lactation leading to subsequent health and fertility problems. Body condition score should only be altered during the "far-off" dry period. Provide 24 hour access to fresh, high quality forages of the type that the cows will receive in early lactation. The cows should be fed 2-3 kg of concentrates per day during this period. It will act to: Increase the energy density of the ration as DMI falls (thus maintaining energy intakes). Allows acclimatisation of the rumen microbes to the post-calving diet Promotes growth of the rumen papillae leading to an increase in the surface area of the rumen lining and thus rapid absorption of VFAs in the early lactation period. Maximise DMI to reduce the extent and duration of the drop in DMI at calving. Cows that eat more prior to calving, eat more after calving. Provide sufficient palatable long fibre to stimulate good rumination. Ensure adequate supplies of protein - both ERDP and DUP. Magnesium supplementation and/or DCAB manipulation to prevent milk fever
How can you split the dry period?
The first month of the dry period (the "far-off dry period) - 2-1 months prior to calving The transition period - 3 weeks before calving to 3 weeks post calving
There is often said to be 4 different diets found on a farm, what are they?
The formulated diet - what the nutritionist think is being fed The deliver diet - the diet that is put in front of the cows The eaten diet - the diet that the cows actually eat The used diet - the diet that the cows digest, and utilise for milk production, growth, immune system function, reproduction etc.
Explain how the requirements for cows have changed over the years
The increase in individual cow milk yields in the last 20 years has meant that the energy requirements for lactation have increased dramatically
Explain how stage of lactation influence milk quality
The lactose concentration in milk tends to be stable, whereas the butterfat and protein content tend to decrease as milk yield increases. This is purely due to a dilution effect, and may cause marked variation in milk quality in a block calving herd.
What is a concern with the traditional method of feeding cows ad-lib forage in trough and concentrate twice daily in the parlour?
The maximum amount of concentrate that a cow can eat during milking is limited to 4-5kg plus the risk of ruminal pH fluctuation.
What are the rules for metabolic blood profiling in terms of group size?
The numbers of cows to sample for the detection of 10 - 15% level of subclinical ketosis at 75 - 95% CI is between 5 - 12 cows per group (minimum group size is 5 cows). Stage of production is the critical selection criteria, especially in relatively small herds.
What is the one benefit and one downside with using free-access minerals to prevent/correct mineral deficiencies?
The provision of minerals as blocks, licks and troughs is very convenient, but there is a large variation in consumption.
Explain genetic selection to prevent/correct mineral deficiencies?
There may be a marked genetic difference between individuals and between breeds in mineral absorption (eg. copper in sheep).
Explain thiouracil as a goitrogen leading to secondary iodine deficiency
These act by disrupting the iodination of thyroid hormones and prevent the conversion of inactive T4 to active T3. These compounds are found in brassica seeds (eg. some older varieties of oil-seed rape).
Explain thiocyanate as a goitrogen leading to secondary iodine deficiency
These act by impairing iodine uptake in the thyroid via competitive inhibition, and thus their effects can be overcome by additional iodine. These compounds are found in brassicas and legumes (eg. white clover).
Explain the treatment regime of copper oxide needles for treatment of copper deficiencies
These are given orally in a capsule, and then lodge in the abomasum to give slow-release of copper over a period of 2-3 months. E.g. Copprite
Explain the use of plasma/serum copper levels as a diagnostic tool for copper deficiency
These are suitable for the diagnosis of clinical disease, but not for the estimation of body copper reserves. A group of 7-10 samples should be taken.
Explain the treatment regime of intra-ruminal boluses for treatment of copper deficiency
These boluses provide slow release of copper for up to 6 months. Eg. Cosecure, also contains cobalt and selenium, Tracesure™ and Agrimin™ are other suppliers
Explain how free-access minerals can be used to treat/prevent selenium deficiency
These can be provided as blocks or licks, usually containing salt to improve palatability. Intakes are very variable.
Explain how free-access minerals can be used to treat cobalt deficiency
These can be provided as blocks or licks, usually containing salt to improve palatability. Intakes are very variable
Explain use of free-access minerals as a treatment/prevention option for iodine deficiency
These can be provided as blocks or licks, usually containing salt to improve palatability. Intakes are very variable, but may be sufficient and cost-effective in extensive systems
What happens in the disease phase of insufficient mineral levels in the diet?
These changes in metabolism lead to detectable clinical abnormalities.
Explain the treatment regime of injecatable compounds for treatment of copper deficiency
These vary in respect to: speed of absorption from the injection site, duration of activity, degree of tissue reaction, retention of satisfactory levels in the liver, and safety margin and risk of toxicity (especially if overdose given).
Ruminants have poor absorption of copper, how have they developed to deal with this?
They are designed to cope with the constant risk of copper deficiency.
Why are animals with a functioning rumen more susceptible to cobalt deficiency?
They need glucose to be manufactured via propionate.
Why are pre-ruminant Vitamin B12 requirements low?
They rely on glucose as their main energy source.
What are the two main types goitrogens leading to iodine deficiency?
Thiocyanate Thiouracil
Explain use of minimizing effects of goitrogens as a treatment/prevention option for iodine deficiency
Thiocyanate. These may be overcome by the use of additional iodine. Thiouracil. The effects of these cannot be overcome by the provision of excess iodine, and thus feeding should be avoided in late pregnancy. Rapeseed meals are usually treated to eliminate goitrogens prior to feeding
What methods are used to try to avoid the concentrate slug feeding?
Third midday meal Out-of-parlour feeders Total mixed Ration/complete diet feeding
Explain the measurement of BHB to assess energy balance in the cow
This is a stable ketone body that can be measured in blood, urine or milk. It can be measured cow-side using urine/milk dipsticks or hand-held ketone testing meters. Regarded as the "gold standard" for the assessment of energy balance, it is a reflection of the partial metabolism of fatty acids during fat mobilisation. Values greater than 3.0 mmol/l would be indicative of pregnancy toxaemia (beef cows and sheep in late pregnancy) or clinical ketosis levels between 0.8 or 1.0 - 3.0 mmol/l would be indicative of subclinical ketosis
Explain how creatine kinase can be used as a diagnostic tool for diagnosing WMD
This is released soon after the onset of muscle damage, but levels decline rapidly after a few days. Levels over 5,000 IU/ml indicate severe muscle damage (normal range < 200 IU/ml). Problems arise with the interpretation of milder rises in CK (500-1,500 IU/ml), which can occur after handling, transport, IM injections etc.
Explain the use of measuring rumen pH in diagnosing SARA
This is required for the definitive diagnosis of SARA. The pH of a sample of rumen fluid (taken via stomach tube or rumenocentesis) taken from 12 cows is measured using a pH meter or indicator papers. SARA is defined by the presence of a rumen pH of less than or equal to 5.5 in at least 30% of the animals sampled.
How does congenital WMD present?
This is seen as stillbirths, or the birth of weak calves/lambs that fail to thrive and suckle and usually die within a few days.
What is the use of inclusion of minerals in compound feed to prevent/correct mineral deficiencies?
This is the most reliable method of ensuring adequate intakes of minerals, but may not be economic in some circumstances (eg. hill grazing).
How does delayed WMD present?
This is usually seen in calves or lambs at 1-4 months of age. Signs are usually precipitated by exercise (eg. turnout in the spring) or stress (such as handling, bad weather). Clinical signs vary according to which muscles are affected
Which animals is response to treatment a possible diagnostic tool for copper deficiency?
This may be attempted in cattle, but should not be done in sheep due to risks of copper toxicity.
When may minimising factors that interfere with mineral uptake be usable?
This may be feasible in certain circumstances (eg. soil contamination of forages will reduce copper absorption)
Explain the delayed form of swayback seen in sheep
This occurs in lambs 2-8 weeks of age. Signs are similar to the congenital form, but tend to be less severe. It may be precipitated by gathering or handling.
Explain the TMR/complete diet feeding
This system involves the mixture of all the separate ingredients of the ration (forages and concentrates) in a mixer wagon. The cows should therefore receive a mix of slowly and rapidly fermentable feeds (containing the correct balance of energy and protein) 24 hours a day, thus ensuring a stable rumen pH with minimal fluctuations throughout the day. DMI is maximised by up to 30%. In a "true" TMR system, the only food the cows are given is the TMR. However, many farms in the UK practise a "semi-TMR" or "hybrid TMR" where the cows receive a basic ration via the TMR, and are then fed additional concentrate in the parlour
Explain use of painting of 5% tincture of iodine on the flank as a treatment/prevention option for iodine deficiency
This was the traditional method, but is labour intensive and requires frequent handling.
Instead of reference ranges, what is used in metabolic profiling of farm animals?
Thresholds
Where is the majority of the iodine found in the body?
Thyroid (80%)
What is the gold standard of diagnosing iodine deficiency?
Thyroid histopathology
Which tissues are most susceptible to damage caused by failure of protection from selenium/vitamin E?
Tissues with the highest rates of oxidative metabolism, espcially muslces (skeletal, cardiac and respiratory muscle)
What affects milk butterfat and milk protein?
To a large extent nutrition
What is the principle of buffer feeding?
To ensure maximum DMI of good quality forage
Why is cobalt required by ruminants?
To produce vitamin B12 by the rumen micro-organisms
What is another name for Vitamin E?
Tocopherol
Explain the indirect method of application of cobalt fertilizers to pasture as a treatment option for cobalt deficiency
Treatment of pastures with cobalt sulphate can be effective for up to 3-4 years depending on application rate.
Explain use of application of iodine fertilizers as a treatment/prevention option for iodine deficiency
Treatment of pastures with iodine salts is relatively inefficient, due to poor uptake by herbage.
Explain the use of selenium fertilizers to treat/prevent selenium deficiency
Treatment of pastures with sodium or barium selenate (usually as slow-release granules) can be effective for up to 3 years.
When can inhibition of DM occur?
Troughs empty for any period of time - typically first thing in the morning Food not pushed up on a regular basis Insufficient trough space - allowing all the cows to feed at once will stimulate feed intakes due to competition Self-feed silage systems (at the clamp) will reduce intakes by 5-10% Use of electric fence at the silage face will reduce intakes by 5-10% Heifers competing with cows for available food will lead to depression of DMI in the heifers by 5-10%
Explain the congenital form of swayback seen in sheep
Typical signs include stillbirths, and the birth of weak lambs. Neurological signs are seen within a few days of birth and include ataxia, inability to stand, staggering gait and weakness of the hindlimbs ("swaying" gait). Affected lambs are usually bright and alert otherwise
How much of the cows total energy supply can the short chained fatty acid constitute?
Up to 75%
What can you measure to assess protein status in the cow?
Urea or urea-N Albumin Globulin
How would you asses cows to diagnose SARA?
Using rumen fill, faecal consistency and examination of faeces. (Dung from cases of SARA tends to have to long fibres, undigested grains or fibrin casts).
What are the clinical signs of copper deficiency in cattle?
Usually seen in growing animals after weaning (3-12 months of age) Depigmentation. Classically, this occurs as greying/brown of the coat in black cattle, especially around the ear margins and eyes (giving a "spectacle-eye" appearance). Defective keratinisation. This can lead to the formation of a thin, dry, sparse hair coat, with a "tatty" appearance (not to be confused with the normal shedding of winter coat). Bone defects. Widening of the epiphyses of the distal limb bones (especially metatarsal), and enlargement of the costochondral junctions Ill-thrift. Usually manifested as disappointing performance and growth rates Anaemia. This only occurs after prolonged and/or severe periods of deficiency. Other disorders. Cardiac hypertrophy leading to sudden death, impaired resistance to infection and immune system dysfunction has all been associated with copper deficiency. Diarrhoea. This is classically seen immediately after turnout onto pastures with high molybdenum concentrations (>15mg/kg DM), and is only associated with molybdenum excess ("teart pastures"). Signs include severe diarrhoea and weight loss. Infertility. The relationship between low copper and infertility is still controversial. Current evidence suggests that impaired fertility is associated with molybdenum excess. Swayback not seen in calves
Explain how disease affects milk quality
Various diseases can have major effects on milk quality, including mastitis and liver fluke (which can depress milk protein levels).
Explain how serum Vitamin B12 levels can aid your diagnosis of cobalt deficiency
Vitamin B12 concentrations in the blood are dependant on daily cobalt intakes, and serum Vitamin B12 levels thus measure short-term cobalt intakes. Values will rise within days of cobalt supplementation, and yarding of animals for more than 6 hours prior to sampling can artificially elevate serum Vitamin B12 levels (as will poor sample handling). Individual animal variation is high, and so at least 10 animals must be sampled to provide an accurate assessment of the group. Serum Vitamin B12 is therefore best used for the diagnosis of cobalt deficiency. Serum Vitamin B12 cannot be assessed accurately in cattle due to the presence of non-specific binding proteins which interfere with laboratory analysis (milk may be a better alternative in dairy cattle).
Explain one-carbon metabolism, with focus on Vit B12
Vitamin B12 is required for building carbon chains via methylation, and therefore the production of certain S-amino acids. This pathway also affects hepatic lipid metabolism, leading to Ovine White Liver Disease.
Explain the propionate metabolism, focused on Vit B12
Vitamin B12 is required for propionate production in the rumen and liver, and therefore glucose metabolism and energy balance.
What are the main end products of rumen fermentation?
Volatile fatty acids Ammonia Microbial cells Gas
In laymen's term, what is metabolic profiling trying to establish?
What the cow think of the diet in respect to energy, protein minerals and trace element status.
How does forages affect DMI?
When forages are fed to cattle, rumen fill constrains intake.
When do you need to feed other types of forage than grass?
When grass growth is inadequate
When are metabolic profiling most succsessful?
When used as an integral part of a planned preventative medicine programme.
What post mortem findings do you expect to find in an animal with WMD?
White necrotic lesions in the myocardium and skeletal muscles (classically the thigh, shoulder and diaphragm). Histopathology may be required to confirm the diagnosis.
How does mixed forages affect DMI?
Will increase intakes by around 5%
How quickly does butterfat respond to dietary changes?
Within days
Explain what other elements can influence absorption of dietary copper
Zin and cadmium have been rarely implicated
What are the clinical signs of delayed WMD affecting respiratory muscles?
respiratory distress, dyspnoea (often confused with pneumonia)
What are the rules for metabolic blood profiling in terms of cow selection, dry cows?
s (within 2 - 10 days of their predicted calving date, ideally not in the last 48 hours before calving). Cow condition and biochemical status in last 10 days prior to calving give valuable clues to potential problem areas (eg. too fat, negative energy balance, low magnesium status, ERDP shortage). Sampling two groups of dry cows for comparison ("far off" group at 60-30 days prior to calving, and "close up" group at 2 - 10 days precalving) can reinforce the need for management change, and permit remedial action to be taken.
What are the clinical signs of delayed WMD affecting skeletal muscles?
stiffness and discomfort (often confused with joint-ill), inability to stand, reluctance to move or get up, myoglobinuria.
What are the rules for metabolic blood profiling in terms of cow selection, early lactation group?
(10-20 days post calving). Although most high yielding dairy cows will almost inevitably be in energy deficit at this time, it is the extent and duration of the NEB that will indicate whether failure to attain peak milk production, metabolic disease or, in the longer term, adverse effects on milk quality and reproduction will result (ie. excessive NEB, over and above that which might be expected in high yielding dairy cows). If cows are sampled too long after calving (greater than 20 days), they may respond to underfeeding by dropping their milk yield and quality, and have normal biochemical parameters.
What are the rules for metabolic blood profiling in terms of cow selection, mid lactation group?
(80 - 150 days calved, ideally in the same feeding group as the early lactation group). These cows will have full potential DM intake, and are invaluable as a control group for comparison with the early lactation cows. It is important to monitor body condition at this stage. It is often possible to assess the contribution that can be obtained from the forage, and enable adjustments to be made to concentrate feeding levels to reduce feed costs.
Explain use of intra-ruminal boluses as a treatment/prevention option for iodine deficiency
(eg. Agrimin Iodine bolus for cattle). These boluses provide slow release of iodine for up to 6 months
Explain intra-ruminal boluses to treat cobalt deficiency
(eg. Cosecure, also contains copper and selenium; Tracesure™ and Agrimin™ are other suppliers) provide slow release of selenium for 6-12 months
What is urea-N?
(urea = urea-N X 2.14
What are the four phases that occur in the animal when fed insufficient minerals?
1. Depletion 2. Deficiency 3. Dysfunction 4. Disease
What is the occurence of clinical diseases causes by anti-oxidant deficiency related to?
1. Selenium status. 2. Supply of other dietary anti-oxidants (primarily Vitamin E). 3. Supply of dietary oxidants. The main ones are polyunsaturated fatty acids (PUFA), which are found in high levels in young, rapidly growing pastures (especially in the spring) 4. Generation of oxidants (eg. via exercise at turnout, infection, toxins).
Give an example of a dry matter intake for a high-yielding 700kg Holstein dry cow in late gestation
12-15kg DMI/day
What is the water requirements for a lactating dairy cow?
2-3 litres of water for every kg of milk produced.
Give an example of a dry matter intake for a high-yielding 700kg Holstein cow in mid lactation with peak DMI
25-30kg DMI/day
As a general rule of thumb, how much should DMI be in a cow?
3% of BW
What is the "near" dry period?
3-4 weeks prior to calving
How long does it take for the liver stores to be exhausted and clinical signs to develop in copper deficiency?
3-6 months.
Explain how inclusion of saturated hard fats will affect butterfat levels
40% of the butterfat in the milk does come from dietary fat. Inclusion of saturated "hard" fats will increase butterfat levels, provided their inclusion levels do not exceed 6%. However, unsaturated "soft" fats will actuallydecrease milk butterfat levels by depressing fibre digestion. Feeding of protected fats that bypass the rumen (such as Megalac and Energizer RP10) will also boost butterfat levels
What is the energy requirements for lactation?
5.0 MJ/kg milk at 4% butterfat and 3.4%
What is the magic number that should not be exceeded for concentrate to forage DM ratio?
60:40
What is the maintenance energy requirement for a Holstein cow?
70-80 MJ of ME/day
How big % of copper in the bloodstream is bound to caeruloplasmin?
80%
Explain the measurement of glucose to assess energy balance
A milking cow has a massive requirement for glucose due to the lactose content of milk: a high yielding cow requires over 4 kg of glucose per day, almost all of which must be synthesised de novo via gluconeogenesis in the liver. However due to the tight homeostatic control over blood glucose levels, measurement of blood glucose is considered to be not as reliable for the assessment of energy balance as BHB and NEFA. However it is of value as a short-term indicator of energy supply from the rumen, as well as the severity of excessive NEB (when the cow loses the ability to regulate blood glucose levels).
In a block calving herd, explain the metabolic profiling regime you could use
A sampling regime would include testing dry cows in the month before calving starts, and then repeat sampling every month during the calving period. Although grazed grass is often assumed to provide the majority of the energy and protein requirements of cows, grass growth and quality is often unpredictable and variable due to factors such as temperature, drought and rainfall, and assessment of nutrition in cows at grass is difficult. Blood testing in grazing cows can therefore help assess if grazing is supplying the needs of the cows. During the winter housing period, a blood test 2 - 3 weeks after cows have been eating full winter rations gives a good indication of the balance of the overall diet, allowing necessary adjustments to be made before expensive health and production problems arise. It is also valuable to blood test after any major management or feeding change, such as a change of silage pit or introduction of maize silage.
Explain the use of BCS to asses the diet on a dairy farm
A very valuable technique, especially when used to compare cows at different stages of lactation (for example the dry period and early lactation). Should be done routinely on all advisory or fertility visits. There are two measurements of interest 1) the actual BCS value at certain stages of the production cycle, especially at drying off and calving. Ideally BCS should be around 2.5 - 3.0, and remain at this target at all stages of the production cycle. 2) The contrast/change in BCS between groups of cows, especially in early lactation. A group loss of ≥ 0.75 unit of body condition score in early lactation has been shown to adversely affect fertility.
What is the major precursor for milk butterfat?
Acetate
When does milk start to decline, and by how much?
After 100 days, 8-10% per month.
Explain the use of albumin to assess protein status in the dairy cow
Albumin levels assess long term protein status, liver function and disease conditions causing hypoalbuminaemia (eg. Johne's Disease, liver fluke).
Explain the use of injectable compounds to prevent/control mineral deficiencies
All the animals receive a known amount of mineral at a certain time, to provide slow release over prolonged periods (depot injections)
Explain the use of faecal consistency to asses the diet on a dairy farm
Although a very basic parameter, it remains extremely useful and frequently overlooked. It is a reflection of the water content, fibre content and fibre digestion in the rumen. Cows with SARA will have loose or variable dung consistency. If the dung is very stiff, this indicates high levels of fibre in the diet, or that there is insufficient energy or protein in the diet for the rumen microbes to break down the fibre in the rumen.
Explain how soil and pasture levels of cobalt can aid your diagnosis of cobalt deficiency
Although cobalt deficiency is usually a primary deficiency, correlations between soil cobalt levels, pasture cobalt levels and animal cobalt status are poor. They cannot therefore be relied on to diagnose deficiency.
What are the causes of secondary copper deficiency?
Antagonism by sulphur, iron and molybdenum in the rumen - this means that between 90-99% of copper eaten by adult ruminants is passed through the gut unabsorbed
What is dry matter intake (DMI)?
Appetite or voluntary food intake (VFI)
What are your indirect methods of treating copper deficiencies?
Application of mineral fertilizer to pasture Minimising molybdenum and iron intakes - e.g. reducing soil intakes Genetic selection - use of selective breeding is theoretically possible in sheep.
Which indirect methods can be used to prevent/correct mineral deficiencies?
Application of mineral fertilizers to pasture Minimising factors that interfere with mineral uptake Genetic selection
When is peak milk yield?
Around 2 months of lactation
Explain the use of measuring milk production in terms of diet analysis
As the main source of income for most dairy farms, milk production is the parameter most closely evaluated by farmers and feed advisors. Both peak milk yield and persistency will affect lactation milk yields, and must be monitored on a regular basis
How can soil and pasture levels of selenium be used as a diagnostic test for selenium/vitamin E deficiency?
As there are good correlations between soil selenium, pasture selenium and animal selenium status, soil levels below 0.5 mg/kg selenium may lead to low pasture levels (less than 0.05 mg/kg DM in forages)
How do farmers tend to analyse dry matter intake?
Assess Fresh weight intakes, assumptions made to convert to dry matter intakes.
How do you diagnose SARA?
Assessment of ration Assessment of cows Herd assessment Rumen pH measurement
What are the rules for metabolic blood profiling in terms of use of background information?
At time of sampling it is essential to record: Cow identification, calving date, condition score, bodyweight (by weighband is the most accurate and usually the easiest method), milk yield and quality, lactation number and dietary information. Attempting to interpret biochemical data in isolation is futile, and can be extremely misleading
What are the rules for metabolic blood profiling in terms of correct timing of test?
Because of the biological variation associated with feeding, it is essential to allow 2-3 hours to elapse after the cow has had a major intake of concentrate feed (eg. sampling cows after they come out of the parlour). Likewise cows should not be sampled if they have been restricted with no access to feed for 2 - 3 hours. This is not as much of an issue on TMR systems as levels of concentrate feeding are spread throughout the day, and the cows should always have feed in front of them. It is also essential to wait until 2 weeks after a major dietary change before testing, as the rumen microflora takes time (7-10 days) to adjust to a new diet.
What can you use to assess the energy balance of the cow?
Beta-hydroxybutyrate (BHB) Non-esterified fatty acids (NEFA) Glucose
Explain the use of phosphate as a measure of mineral status
Blood phosphate levels reflect short-term intakes from the diet
What are some cow specific things you can use to analyse the diet in a dairy herd?
Body condition Faecal consistency Faecal examination Rumen fill Cow comfort Rumination activity
List the cow factors influencing dry matter intake
Body weight Milk yield Stage of lactation Stage of pregnancy Body condition score Cow comfort, health and disease Rumen health
Explain how differences between feedstuff influence absorption of dietary copper
Brassicas and cereals tend to be good sources of copper (especially for sheep), whereas root crops and grazing tends to be poor (especially in autumn and winter).
