Animal Nutriton Exam 2
Is there a valid reason for not allowing an animal unlimited access to water?
An exception to this occurs when animals have been water deprived or over heated. Such animals may over consume if allowed water ad libitum. In this case it is better to restrict intake over a period of several hours and allow the animals limited water at intervals until they have rehydrated.
1. What are the factors that affect nutrient utilization from a given feedstuff?
Animal's age, species, physiological state, and type of GI tract
Why do rabbits practice cecotrophy?
Animals that practice cecotrophy eat the contents of the cecum directly from the anus and digest it after it has been fermented in the cecum. this allows them to obtain digest bacterial protein
What types of diets are usually fed to animals in a growth trial?
Animals used in a growth experiment usually are fed the test diet concurrently with similar animals fed a standard (or basal) diet of known nutrient quality that allows normal growth.
Generally speaking, how much water do animals need per quantity of dry feed consumed?
Animals will consume 2-5kg of water for every kg of dry feed consumed.
Describe the extent of postgastric fermentation in the ruminant.
Approximately 5-15% ·of the total digestion of feedstuffs by the ruminant occurs in the large intestine and cecum. -VFAs will be produced and absorbed from the fermentation. -This is poorly quantitated.
Why is it difficult to delineate the water requirements of an animal?
Because numerous dietary and environmental factors affect water absorption and excretion and because water is so important in regulation of body temperature.
In a growth trial, how can we deal with the fact that growth is a variable biological parameter?
Biological variation can be removed by using full- or half-siblings or animals of similar genetic background.
How does the water consumption of birds compare to mammals?
Birds require less water.
What is the composition of the gas coming off a ruminant fermentation?
CO2 65% CH4 25% N2 7% SOME O2, H2, H2S
Define carnivore, omnivore, and herbivore.
Carnivores are flesh-eating animals. Omnivores consume both animal and vegetable matter. Herbivores eat vegetable-based foods exclusively.
What is the "normal" ratio of water consumption to dry matter consumption for cattle? Sheep? Why do cattle need more?
Cattle: 4:1 Sheep: 3:1 Cattle require more water because they are not as efficient at conserving water.
What are the common names of the four ruminant stomachs?
Common names are: -"paunch" for the rumen -'honeycomb" and "hardware stomach" for the reticulum -"manyplies" and "stockman's bible" for the omasum -"true stomach" for the abomasum.
What is the effect of salt consumption on water consumption and excretion?
Consumption of salt increase consumption and excretion of water.
Describe eructation and the consequences if a ruminant is unable to eructate.
Contractions of the upper sacs of the rumen force the gas forward and down. The esophagus then dilates and allows the gas to escape. Much of the gas goes into the trachea and lungs. This provides a muffling effect (burping gas) -Bloat is a common problem in ruminants ifgas cannot escape the rumen.
Define deglutition.
Defined as the reflex passing of food and water (or anything else) from the mouth to the stomach via the esophagus.
Why use digestibility by difference? (Note to Students: Don't get bogged down with any more of this--it's graduate student level.)
It is desirable to evaluate the digestibility of a feedstuff when fed in a mixture with one or more other feeds.
How does one account for the fact that apparent digestibility of a protein in a feed is influenced by the level of protein in a feed?
The apparent digestibility of protein in a feed is influenced by the level of protein in feed. This is so because the amount of endogenous protein tends to be constant, so at a high-protein intake the endogenous fraction represents a smaller percentage of the total nitrogen excretion.
How does the body prevent itself from having large changes in temperature?
The body has a great capacity to store heat, which prevents any sudden change in body temperature.
What are the major anatomical differences in the avian and the pig? Describe each along with its function.
The digestive organs of fowl are similar to other monogastrics except for the lack of teeth and the presence of the gizzard and the crop. birds have no soft palate absence of teeth poorly developed salivary glands salivary amylase little value, little to no digestion here
Why do different animals use very different kinds of feeds?
The digestive system determines what the animal can successfully use. The more complicated the feed the more complicated the digestion tract must be.
What happens to water consumption in relation to water need on lush pastures?
The water content of the feed consumed affects total water intake. This results in consumption of more water than needed when forage is very lush with a high water content.
How long does it take feed to get through the ruminant tract?
The rate or time of passage of ingesta through the ruminant digestive tract is relatively slow. -10 days to get the last material through
What is the function of the horse small intestine?
The small intestine is much the same as the pig, except the horse has no gall bladder Continue digestion and nutrient absorption.
Why do we use the term "apparent digestibility" instead of simply "digestibility"?
The term apparent digestibility takes into account both the unabsorbed feed residues and the components of the feces that are of endogenous origin.
Is the water in feed an important contributor to livestock water needs? If so, how important?
The water content of feedstuffs consumed is highly variable. In forage, it may range from a low of 5-7% in mature plants and hays to as high as 90% in lush young vegetation. Precipitation and dew on ingested feed may account for a very substantial amount of water consumption.
What is the relative quality of the protein manufactured in the rumen?
Their quality is similar to soybean meal, which is an excellent quality feedstuff.
What is the advantage to doing a balance trial rather than just a digestion trial?
Balance trials are similar to digestion trials but provide information on utilization of nutrients after absorption from the GI tract. The intent is to get an accurate measure of total intake and total excretion in order to determine whether there is a net retention or loss of the nutrient in question
How is water's thermal conductivity useful in dissipating body heat?
It is important in the dissipation of heat from deeply situated areas of the body as many animals dissipated internal and absorbed heat by evaporation of body water.
Why must there be a preliminary period in a conventional digestion trial?
It is needed to void the GI tract residues of pretest feed and to allow adaptation of the animal to the diet.
Why is the pig used as a model for human nutrition?
Its digestive system is similar anatomically and functionally to that of humans.
Why do similar animals digest a given diet to different events?
1. mastication of forages 2. absorptive capacity based on the specificity of a wide variety of specialized transport systems present in the intestinal epithelium 3. other unrecognized factors
What is the point of a "weigh-suckle-weigh"?
milk production is estimated indirectly by measuring gain of the young or weighing them before and after suckling
What is the advantage of a paired feeding experiment?
Eliminates differences in animal performance related to voluntary intake of feed.
What is the purpose of saliva in the horse?
Secretion of saliva is stimulated by the mechanical action of feed on the mucus membrane of the inner cheeks. -The saliva of the horse has no enzymes.
Describe one·(or more) situations where a perfectly normal animal might not need to drink water.
Sheep will seldom drink water when the forage moisture is 65-70% or higher
What is the role of the stomach in digestion?
Significant chemical, enzymatic, and mechanical digestion is accomplished in the glandular stomach. In addition to digestion, the stomach has another important function. This function is food storage. -The storage capacity allows the animal to eat at a much faster rate than if digestion had to occur at the same pace the food was consumed.
How does stomach capacity affect digestibility?
Studies with sheep have demonstrated, even in animals of the same breed, sex, and age, that there may be considerable difference in stomach capacity, which in turn affects eating rate, amount eaten, and passage rate through the GI tract.
How do these factors affect how much water is required? Young vs. Adult Activity (nervousness)
Young animals generally require more water per unit of body weight than adults.Activity increases requirements. Nervous animals will likely conserve more water.
What is the point of fitting a cow with a rumen cannula?
allows sampling of contents and infusion of known quantities of substances at known rates directly into the rumen
Name the nutrients produced as a result of rumen fermentation.
energy, vitamin K, and B-vitamins
How can you treat/prevent bloat?
-Appropriate feeding strategies can help avoid but not totally prevent the problem. Examples include mixing pastures with no more than 50% legumes, limiting grazing oflegumes, feeding hay before turning animals out to pasture, and not grazing rain- or dew-saturated pastures. -Treatments include feed additives such as poloxalene (Bloatguard), which is expensive but effective, It is an anti-foaming agent that must be ingested at 12-hour intervals to be effective. -For short-term situations you can feed two to three ounces of laundry detergent per day. The detergent breaks down the foam by changing the surface tension so the foam disintegrates. -In emergency situations, use a trocar and cannula, which is a device used to puncture the rumen and release the gas.
How does digestion occur in the avian? What are the differences between a chicken and a pig?
-Esophagus. The esophagus is that portion of the digestive tract connecting the mouth and the stomach or proventriculus. The first section connects the mouth to the crop. -Crop: It functions as a food storage organ and moistening reservoir. -Proventriculus: It is the site of gastric juice production (HCl and pepsin) and has a pH of 4. -Gizzard or ventriculus. A highly specialized grinding organ. It is very muscular. The gizzard normally contains grit to aid in the grinding of feed to smaller particles. -Small intestine. Functions in digestion and absorption of feed and nutrients just as in other monogastrics. -Ceca: Some fiber digestion (perhaps as much as 18% of total fiber) and water-soluble vitamin synthesis occurs in the ceca by bacteria. This is less than most mammals. -Large intestine: The main site of water absorption (not digestion). Vitamin K synthesis and absorption does occur here in the chicken. -Cloaca. The common orifice for waste elimination (feces and urine), copulation, and egg laying in females.
What does pancreatic juice do? Include a description of the function of each enzyme.
-Pancreatic juice contains the really important, very potent digestive (hydrolyzing) enzymes. --Trypsin, chymotrypsih, carboxypeptidase, and aminopeptidase, all of which digest proteins. --Intestinal lipase, which breaks fats into fatty acids and glycerol. --Amylase that is specific for starch. --Other enzymes that work on dipeptides, disaccharides, etc.
What are the three portions of the small intestine and what are the functions of each?
-The duodenum is the first part. --It extends from the pylorus of the stomach to the beginning of the jejunum. In most species it is in the form of a loop and is often referred to as the "duodenal loop." It is generally only about one footlong. --Bile and pancreatic secretions enter the small intestine here. --This is the main site of food breakdown in the small intestine. -The jejunum is the second and longest part. Digestion continues here but its major job is absorption of the end products of digestion. It is several feet long. -The ileum is the third part. Its major job is to form the connection to the large intestine but absorption also is accomplished by the ileum.
What does bile do?
-The first is a detergent action that helps solubilize and emulsify fats. (A major benefit of this process is that it increases the surface area of the fat so lipase can digest it. At the same time it allows the fat to come into contact with the lipase, which is water soluble.) -The second way bile helps is by forming a complex with fatty acids (products of fat digestion), which is easily absorbed. Thus, bile aids in absorption and digestion.
How does diet affect VFA concentrations in the rumen?
-The type of feed (forage versus grain) affects the type of microbial species and the concentration of each species. -Rumen fluid from cattle on grain diets will have concentrations of 100-120 mmol VFAs and a pH of 5.5 -6.0. - On forage diets the VFA concentrations are lower; 60-80 mmol VFAs and a pH of 6,5-7.0.
Describe in detail what happens in the large intestine and the cecum of the horse.
-There is bacterial breakdown of cellulose and other carbohydrates producing VFAs (acetic, propionic, butyric). Absorption ofVFAs does occur from the cecum. The horse on a forage diet will receive the majority of its energy from the large intestine. -Bacterial synthesis of water-soluble vitamins occurs and they are absorbed from the large intestine, though in limited amounts. -Bacterial synthesis of protein occurs but the horse is not able to absorb this product because of the lack of enzymes and absorptive mechanisms. Because this protein is not subject to the action of the digestive juices, the horse doesn't benefit much, if any, from the protein unless it practices coprophagy. Horses on a poor diet will consume their own feces. -The cecum is the primary area of water reabsorption from intestinal contents, although more is absorbed from the colon. -The large intestine is usually expanded with fibrous material. This is another source of digestive tract disorder in the horse. Impaction of the large intestine may easily occur and can be fatal.
Define digestion. What are the three major methods (mechanisms) of digestion? Describe them.
-digestion is the preparation of food for absorption. it is over when nutrients from the feed are in an absorbable form. -physical or mechanical action: chewing, muscular and mechanical action of the digestive tract -chemical action: hydrochloric acid is used in the stomach for the chemical breakdown of food and bile that is used in small intestine to help digest fats -enzymes that break down the chemical bonds in food by the addition of a water molecule: some produced by GI tract, some by microorganisms (these are most important in ruminants and cecal fermenters), enzymes act as biological catalysts, many enzymes in the digestive system are needed for speedy digestion of carbohydrates, lipids, and proteins
What are the components of saliva?
-water (major constituent) -electrolytes (mostly Na and K with some Mg and Cl) -proteins (mucin, lysozyme, salivary amylase) -lipase
What are the advantages of growth trials?
1. allow for the accumulation of relatively large amounts of data at reasonable costs 2. the animals usually can be maintained under conditions that are similar to normal environmental situations 3. the measurements are easily obtained4. the results are a reflection of a fundamental biological response, yet can be applied directly to commercial production systems
What are the advantages of using laboratory animals as models for farm animals in nutrition studies?
1. Contribute to knowledge of nutritional requirements and interrelationships in farm animals. 2. The numbers of animals and housing facilities needed to obtain meaningful information is often so large as to become economically prohibitive. 3. the shorter life cycle of smaller animals offers the opportunity to obtain data covering several generations per year.
What are all the sources of water to an animal?
1. Drinking water 2. Water in feed 3. Metabolic water 4. Water from body reactions 5. Water in tissues catabolized for energy.
Describe the methods of water loss from the body in detail, but no greater detail than the course guide.
1. Expired H2O, which exits with the air from the lungs as water vapor. Air is 90% saturated when exhaled.2. Vaporization from the skin. This happens two ways:A. Diffusion. Blood vessels dilate, bring blood closer to the surface of the skin. H2O diffuses across.B. Sweating from sweat glands. (perspiration)3. Feces. Some species have very wet, loose feces.4. Urine. Urine volume is greatly influenced by the species' form of nitrogen excretion. Urea requires a good deal of water for excretion. Uric acid requires very little water.
List four problems with using external markers. (Note to Students: Don't get bogged down with anymore of this -it's graduate student level.)
1. Irregular excretion 2. Incomplete recovery 3. Rare earth elements 4. Extensive processes
Give nine reasons we might conduct feeding trials other than to measure growth or digestion.
1. It provides information about the rates of disposition of fats, protein, and bone. 2. It measures the quality and quantity of the milk that is produced. 3. It measures the effects of the diet on egg production in birds. 4. It measures the effects of diet on the endurance or speed of horses. 5. It helps measure the nutrient utilization of animals at a maintained level. 6. It helps determine the effect of a particular nutrient in a diet to compare it to a response from the animal due to a toxic substance. 7. It helps determine the effect that iodine deficiency on the goiter incidence in young lambs. 8. With cows in the winter, it helps determine the likelihood of urea toxicity when there is poor quality fed. 9. It helps determine the vitamin A requirements for sperm production in roosters.
This particular question requires synthesis of material from the whole lesson. In addition, you will need material found in the last section of this text chapter "Water Quality." Presume that your cattle herd is not drinking much water. Itis your job to discover why. Develop a step-by-step plan for troubleshooting the problem. Describe what steps you would take at each point in your plan if you found a positive response to your solution and what steps you would take if you found a negative response to your solution. .Number and list your steps. Make it easy for me to read.
1. My first step would be to evaluate the set up that the cattle are in. a. I would look to see how many places there are for the cattle to get water. A possible issue could be the fact that there are not enough sources of water for the herd to get water. I would also evaluate the status of the water in the containers. When the water is polluted or low quality, the herd is likely to stop drinking as much water and eating as much feed. b. If there are not enough places for the cattle, then I would put out more sources of water. If water quality is the issue, then I would test the water regularly 2. My second step would be to evaluate the food that the cattle are eating. a. Water quality affects the feed consumption in cattle. Lower water quality cause lower water consumption and in turn feed consumption. Depending on the source of feed, the amount of water consumption varies. b. A potential solution would be to swap the current feed with a feed that has a higher water content to allow for more water absorption. I would also look for a feed with a higher water quality. c. I would measure the amount of feed consumed to see if the cattle are eating more of the higher water quality food. 3. Finally, I would have the cattle evaluated. To ensure there aren't any internal issues going on. a. I would take them have their GI tracts evaluated. i. I would check to see if their intestines are absorbing the water properly. ii. I would have them looked ate for an infection. I would look for a bacterial, viral, or fungal infection. If there is an infection, then I would have the cattle treated for the issue and monitor their condition.
What are the components of urine?
1. Nitrogen compounds. (Urea is excreted in mammals. Uric acid is excreted in birds. This requires much less water from the body to excrete.) 2. Sulfurous metabolites. 3. Minerals: Cl, K, P, Na. 4. Water. The kidney is a major regulatory mechanism for keeping the body appropriately hydrated.
I fed a mouse 40g of protein. I collected 30g of protein in its feces for the corresponding time period. What is the apparent digestibility of the protein?
1. Nutrient intake (40g) - Nutrient in feces (30g) = 10g 2. 10g/ Nutrient intake (40g) = 0.25g 3. 0.25g x 100 = 25%
Why is the horse prone to stomach disorders?
1. The horse has a smaller stomach than other species. Horses should be fed small portions of ration several times daily if possible. At a bare minimum, two times daily feeding is desirable. 2. The horse stomach is also unique in that it. does not have extensive muscular activity compared to other species. The feed tends to arrange itself in layers because of this.
Presume you are changing your lifestyle to become a desert nomad. You have the opportunity to develop a new animal for your use that is more water efficient. (It cannot be an existing animal.) List the characteristics of this animal. (Number and list the characteristics. Make it easy for me to read.) Note to student: The intent of this question is to allow you a vehicle to demonstrate your knowledge of this chapter, especially water loss and water requirements. Be sure you incorporate solid information about water into your answer and do not "invent" strategies that do not exist.
1. This animal would require low level of proteins. This is because it takes a lot of water for the excretion of proteins. 2. The animal's diet would consist largely of carbohydrates. Carbohydrates provide more net metabolic water than fats or proteins. 3. The animal should have a very efficient kidney in order to be able to reabsorb water and prevent the loss of water in urine. There should be minimal water loss due to waste. 4. This animal would hibernate because animal that hibernate can live off of metabolic and performed water. 5. The animal would avoid salty food. Eating salty foods requires the animal to drink more water. 6. The animal would have a calm demeanor. When an animal because nervous, it will consume more water. The animal should have marginal area for evaporation to help limit the amount of water that is lost to evaporation.
Describe how an animal defecates.
1. This reflex is stimulated by the pressure of feces in the rectum. 2. This reflex is assisted by parasympathetic nervous signals that intensify the peristaltic waves of the large intestines. 3. Many animals also use the Valsalva maneuver. They breathe deeply, close the glottis, and then flex the abdominal muscles. This puts pressure on the fecal contents and helps expel them.
What are the methods used to estimate endogenous excretion of nitrogen?
1. feeding a nitrogen-free diet and determining the amount of nitrogen in the feces 2. feeding several levels of the nutrient (nitrogen) and calculating the fecal level by regression analysis to a zero intake of the nutrient 3. feeding a completely digestible protein
What are the properties of water that allow it to have a marked affect on temperature regulation?
1. high specific heat= accumulation of heat 2. high thermal conductivity= ready transfer of heat 3. high latent heat of vaporization= loss of large amounts of heat on vaporization
What are the functions of saliva? Reduce the functions to one-word answers. You should find eight of these.
1. moistening and lubrication of food to facilitate chewing and swallowing (most irreplaceable salivary function.) 2. dissolves small portions of food allowing it to come into contact with taste buds and give food its taste. Saliva may also stimulate the taste nerves. 3. washing action of saliva cleanses the mouth and prevents the decay of leftover food particles. They are washed out and swallowed after eating. 4. Lysozyme supplies a disinfectant action by killing bacteria that would otherwise damage the mucus lining of the mouth and cause tooth decay. Dogs and some other carnivores have especially large amounts of lysozyme. 5. The ruminant relies on saliva for its buffering action. Saliva contains bicarbonates (Na+ and K+) that buffer rumen acids, especially the volatile fatty acids. The VFAs would soon damage the rumen wall if they weren't buffered. 6. Saliva provides readily available nutrients for rumen microorganisms. (nitrogen, phosphorous, and sodium) 7. The antifrothing property of saliva helps prevent bloat from being a daily occurrence. It prevents a stable foam from forming that would interfere with eructation. 8. Saliva also has an excretory function. (secretes mercury (Hg) and lead (Pb))
What is the relative volume of each compartment in the ruminant "stomach"?
1. rumen 80% 2. reticulum 5% 3. omasum 7-8% 4. abomasum 8-9%
How many calories are lost from the body by evaporating five grams of water? Is this efficient?
2900 Calories of heat are lost by evaporating 5g of water. This an efficient use of water.
How many animals per diet do I need for a digestion trial?
4 to 6 animals per treatment
How long is the collection period in a conventional digestion trial?
4-10 days following the preliminary adjustment period
What is the associative effect in digestibility data?
A common phenomenon observed with digestibility data is that mixtures of feedstuffs do not always give results that would be predicts from digestibility values of the individual components of the mixture.
What is the relationship between dry matter consumption and water consumption as Jong as the animal is not in heat stress?
A good linear relationship exists between dry matter consumption and water consumption.
How much saliva does the horse produce?
A mature horse may secrete up to 10 gallons per day (40 liters).
Describe the importance of water to life.
Absence of water causes death faster than absence of any other nutrient. Water is the nutrient required in the largest amount by man and animals
What are the advantages of using purified diets?
Allow one to make quantitative changes in the concentration of a single nutrient without greatly affecting the concentration of other nutrients in the diet.
Compare the water needs of a desert rat to that of producing livestock.
Desert rat don't require drinking water except in rare situationsProducing livestock require copies amounts of water when producing at a high-level, especially when they are heat-stressed.
What types of factors determine the relative importance of these to a specific animal?
Diet, habitat, and ability to conserve body water.
Why is feed efficiency a useful estimate of nutrient adequacy of a test diet?
Diets that promote a high rate of gain will usually result in a greater efficiency than diets that do not allow rapid gain. (High rate of gain results in higher efficiency, rapidly gaining animals uses less food for maintenance so more of it is used for gain)
Why have purified diets not solved completely the dietary essentiality of all trace minerals?
Even highly purified inorganic element sources may contain trace amounts of contaminating elements. (minimizes that presence of unknown constituents presents in natural feedstuff that might affect the utilization of or requirement for the nutrients under study.)
Describe how heat stress can affect water needs for animals. Give a concrete example (bottom of left-hand column, text p. 67).
Feed consumption is apt to decrease and water consumption is increased greatly. More gallons of water per pound of feed in cattle at 100F. (Winter consumption is 19L and summer is 31L)
What is feed efficiency?
Feed required per unit of weight gain or weight gain per unit of feed
Explain the digestion of a bite of mixed feed in a cow and a pig. Do this in a stepwise progression beginning with prehension and ending in defecation. At each step compare and contrast what is happening in each species. Point out what organ the feed is in. Outline, narrative, or table form is acceptable.
For both cows and pigs, digestion begins with prehension, the process of grabbing food and bringing it to the mouth. The next step is mastication. For pigs eating plant material, they chew fully to allow enzymes from their saliva to get to the food. For cows, they form a bolus and swallow. By doing this, the food isn't chewed very much. Later, the cow will regurgitate the food and chew it fully. The bolus will go down the esophagus when the animal swallows. For both pigs and cows, this process is the same due to a neural reflex. When the food gets to the back of the mouth, it will start to go down the esophagus and peristaltic waves will help move the food down. With pigs, the food goes into the stomach and a valve prevents the food from be able to come back up. With cows, the food goes into the reticulum. The food is then moved into the rumen and fermentation happens due to microorganisms. Through the fermentation, the caw is able to turn fibrous food into an energy source. Then, the food is moved into the omasum, which helps reduce the size of the food. For cows, two-thirds of the energy is absorbed into the forestomach. The cow then regurgitates and eats the material again. The food enters the abomasum and the fermentation occurs, creating a lot of gas. The abomasum in cows and the glandular stomach in pigs contain gastric juice. For both cows and pigs, mechanism digestion happens. Mechanical digestion occurs through the churning, contractions, and physically breaks down the food material. Next comes chemical digestion which happens when HCL is secreted in the stomach. HCL denatures the proteins in the food and enzymes come in to aid with digestion. For pigs, the stomach serves as a storage space for food. Then, the food moves into the small intestine. For both animals, the small intestines have structures that help increase surface area to help break down food and absorb the food. Pancreatic secretions aid with digestion and the nutrients are absorbed through the epithelium. They then pass into the circulatory or lymphatic systems where the nutrients can be moved throughout the body. The leftover material is then moved into the large intestine which has three parts: colon, cecum, and rectum. The large intestine absorbs, water, electrolytes, vitamins, and minerals. For cows, VFAs are produced and used for energy. The final step for both animals is defecation. The internal and external sphincters in the rectum relax and let the material leave the body. Micturition also occurs for both animals. This is urination that removes more waste products.
Describe the nylon bag technique in ruminants. What is its value? When is it most useful?
For the nylon bag technique, the feedstuff is placed into a nylon bag and is suspended in the rumen of an animal with a rumen fistula. The bags are removed after a predetermined time and the loss of material from the bag would be evaluated. It is useful because it determines the difference between the feedstuff but doesn't give values that are similar with those from live animal digestive tracts. It is most useful when it comes to studying rumen digestion of grains than the in vitro method.
Why is forage utilization enhanced by feeding adequate nitrogen to the ruminant?
Forage utilization is enhanced by adequate ruminal N because of what is called a positive associative effect. --This is when one feed increases the utilization of a second feed.
How does protein intake affect water intake?
High levels of protein increase water intake because of greater urinary excretion of excess protein as urea.
Why don't hibernating animals need to drink water?
In hibernating animals, metabolic and preformed water is apparently adequate to supply total body needs to sustain normal functions.
How does fat consumption affect water intake?
Increased fat intake may increase water intake
How does feed intake above maintenance affect digestibility in ruminants?
Increased feed intake above maintenance tends to depress digestibility.
What are ionophores?. What do they do and what is the outcome of feeding them?
Ionophores are feed additives that alter ruminal metabolism by favoring propionic acid-producing species. -The outcome is increased propionate, and decreased acetate as well as decreased methane and lactate.
Define mastication. How do different animals accomplish this?
Mastication or chewing involves the vertical movements of the jaw to crush the food particles between the teeth. This is a mechanical process. -Carnivores masticate only to the extent needed to reduce the size of meat so it can be swallowed. -Herbivores need thorough chewing of their feed (mostly forage) to allow bacterial enzymes access to cellulose by increasing feed surface area. --Ruminants first form a bolus and then swallow and don't chew much at all. ---Later they regurgitate the feed and thoroughly chew it. ---The cow needs 4,700jaw movements per day to eat grain, 10,500 to eat forage, and 26,400jaw movements per day for rumination. ---Horses must chew thoroughly before swallowing because the food goes directly into the glandular stomach for digestion to begin. They don't regurgitate.
What are some common lab animals used in nutrition studies?
Mice, rats, guinea pigs, and other mammals. Birds such as Japanese quail. A variety of reptiles and fish.
What do bacteria do in the gut of a monogastric herbivore?
Microorganisms break down cellulose in the cecum and large intestines, much as it is done in the rumen. The VFAs produced are absorbed and used as an energy source much as happens in the ruminant.
Why do you think that dairy cows drink so much more water than beef cows? (Use your common sense -the answer is not in the book.)
Milk is mostly water, so to produced a lot a milk, a cow must ingest a lot of water.
How does milk production affect water consumption in cattle?
Milk production increases water consumption.
2. Define growth in both a narrow and a broad sense.
Narrow: the constructive or assimilatory synthesis of one substance at the expense of another (nutrient) that undergoes dissimilation. Broad: an increase in body weight resulting from assimilation by body tissues of ingested tissues.
Why is weight gain not always a precise estimate of diet utilization?
One animal may deposit more lean muscle mass and its penmate may deposit more fat, which has a much higher energy content. (an equal increase in body weight does not necessarily indicate equal growth of body tissues)
Compare and contrast the end products of protein and carbohydrate digestion between the pig and the cow. (This is an exercise to determine if you understand the predominantly enzymatic digestion of the pig compared to the microbial digestion of the ruminant that is then followed by enzymatic digestion.)
Pancreatic enzymes of pigs in the small intestine perform protein digestion that begins in the stomach with pepsin. Enzymes in the stomach break down the proteins into amino acids. For pigs, proteins are broken down into amino acids. For cows, the bacterium in the rumen breaks proteins into amino acids. Then, the amino acids are turned into ammonium ions. These ions are used to makes microbial proteins. These proteins continue to move through the system and are digested similarly to amino acids. Cows can also ferment the proteins and turn the carbohydrates into volatile fatty acids. These VFAs can be used for energy in the cow. For pigs, glucose is the main product of carbohydrate digestion. Pigs use the available carbohydrates for digestion. For cows, the available carbohydrates are used to make glucose. The bacteria in the rumen of cows digests the carbohydrates in similar ways to cellulose and starch. It is then used to makes VFA. The VFA go through the rumen wall and used for almost half of the cow's energy. In pigs, carbohydrate digestion yields glucose and energy. In cows, carbohydrate digestion yields VFAs and energy.
What is prehension?
Prehension is the first step of digestion. It is defined as the seizing and conveying of food to the mouth. Animals use a variety of methods to accomplish this. This is a mechanical process.
What kinds of microorganisms are found in the rumen?
Protozoa, yeast and phages (bacterial viruses)
What is metabolic water? What chemical component yields the most metabolic water upon hydrolysis? Which one supplies the most net metabolic water?
Results from the oxidation of organic components in the cells of the body. (water of oxidation) -Fat yields the most metabolic water per gram. -Carbohydrates supply more net metabolic water.This is due to the added respiration required with fat.
How does urea consumption affect urine volume?
Results in greater urine volume than an equivalent amount of N in the form of purified soy bean
What is bypass protein and what are the implications to production of feeding it?
Ruminal undegradable proteins (bypass or escape). Bypass protein is an animal or plant based protein source that resists degradation in the cow's rumen in order to pass into the lower GI tract and gives the cow essential amino acids. Bypass proteins are known to stimulate the voluntary feed intake, increase quality milk production and thereby improve economic status from dairy cow farming
What is salivation? What do you think dictates the amount of saliva that is produced by the various species?
Salivation includes secretion and mixing of saliva with food -The amount of saliva produced varies with several factors including species, diet, health, and others -Carnivores produce the smallest amounts of saliva of the three. An average dog produces about 200 ml/day. -Herbivores produce the largest amounts. --A horse can produce 40 liters/day. --A cow produces 60 liters/day (about 16 gallons/day). --A high producing dairy cow could manufacture from 120-200 liters/day and a sheep may make 10 liters/day
Explain why ruminants, cecal fermenters, and monogastrics have such different abilities for digesting forages.
The digestive system of the animal determines what feed the animal can use. With a more complicated feed, a more complicated digestive system is need. Monogastric animals have an uncomplicated stomach. They can't have to get their food from what they eat while ruminants and cecal fermenters are able to use cellulose into food sources. Some monogastrics are cecal fermenters and have cecal digestion. They have a hard time digesting fiber. Ruminants have multiples stomachs. In these stomachs, fermentation and other forms of digestion occur.
What is the esophageal groove and what does it do?
The esophageal groove (reticular groove), is a groove that can contract and form a tube that acts as a bypass of the rumen and empties into the omasum. -The function of this groove is to keep milk out of the young ruminant's undeveloped rumen. The milk can't be adequately digested in the immature rumen and will literally "rot." The calf will develop a severe case of diarrhea or scours due to proliferation of bacteria and production of toxins in the rumen.
Why is it good to have simulation techniques for rumen digestibility?
The high cost of digestion trials
Milk is mostly water. Why do nursing animals need even more water?
The high protein content of milk results in high obligatory urinary water loss.
What is the relative capacity of the horse stomach?
The horse has a smaller stomach than other species. It provides only 8% of the capacity of the tract.
Why doesn't the horse regurgitate?
The horse has only one-way peristaltic movements in the esophagus.
Explain the problem of getting an accurate weight on animals in a growth trial. Why is it a problem, in which animals is this the biggest problem, and how do we correct for it?
The live body weight of an animal does not only depend on the body tissue mass but also the water ingest that is within the GI tract. The amount that fills this varies between animals and is dependent on the ingesta mass. This ingesta mass can change due to a change in feed consumption, time of defecation/urination, and the interval after the consumption of food and water. Ruminates are the biggest problem because their GI tract capacity is much higher than a nonruminant. One way to fix this problem is to use the average of two or three consecutive daily weights.
How can an animal increase heat loss through the lungs? Can you think of an environmental situation in which evaporative cooling would not be a very efficient and one where it would be highly efficient?
The lungs have a large surface for evaporation of water. Humid environments would not allow for good evaporative cooling, while a dry environment would allow for good evaporative cooling.
Describe the anatomy of the ruminant tract.
The main function of the complex stomach of the ruminant is to allow the animal to use roughages (cellulose) as a source of energy. -The complex stomach is comprised of four compartments. Names used for the various stomach compartments are: rumen, reticulum, omasum, and abomasum.
What is the function of the rumen?
The main function of the rumen is to act as a site of anaerobic bacterial fermentation.
What measurements do growth experiments usually include?
The measurement of absolute gain in body weight during a period of feeding a test diet.
What are the two stomach types in livestock? What is the subcategory listed under one of the types?
The monogastrics are one stomached (or simple-stomach) animals. Some monogastrics have a cecal digestion and are referred to as cecal fermenters. Thus, there are "pure" monogastrics and monogastrics with cecal fermentation. Ruminants have more than one stomach compartment where both fermentation and the other types of digestion take place.
What is the major anatomical difference in ruminants and nonruminants?
The most important difference between ruminants and monogastrics is the complex stomach of the ruminants
Why do nutrient requirements for growing animals change throughout the growing period?
The nutrient requirements for growing animals change throughout the growing period in direct response to the changing needs of the individual organs and organ systems making up the whole animal.
What are VFAs of importance in the rumen and what does the animal do with them?
These VFAs are absorbed through the rumen wall and supply about 50% of the energy requirement for the ruminant. --The VFAs formed include: acetic acid (C2), propionic acid (C3), butyric acid (C4), valeric acid (Cs), and lactic acid.
What are the two basic functions of water in the body?
These are aiding body metabolism and temperature regulation.
What is the usual way of determining true digestibility of nitrogen in ruminants?
True digestibility can be estimated by subtracting the amount of N appearing in the feces of an animal fed a low-protein diet from the amount of N appearing in the feces of an animal fed a test diet.
What are the problems with using internal indicators to calculate digestibility?
Use of lignin is plagued with problems of incomplete recovery and difficulty in analysis
What are the four important overall functions of water in body metabolism? Briefly describe them.
Water as a Solvent: Many of the biological functions of water are dependent on its property of acting as a solvent for a wide variety of compounds; many compounds ionize readily in water. Water as a Transport Medium: Serves as a medium for transportation of semisolid digestion the GI tract, for various solutes in blood, tissue fluids, cells, and secretions, and in excretions such as urine and sweat. Water as a Dilutent: Provides for dilution of cell contents and bodily fluids so that relatively free movement of chemicals may occur within the cells and in the fluids and GI tract. Water in Hydrolysis and Oxidation: In hydrolysis, water is a substrate in the reaction.In oxidation, water is a product of the reaction.
Where is water absorbed in the digestive tract? (This is the only piece of information I will hold you responsible for in this section)
Water is absorbed from most sections of the digestive tract in most species.
What portion of the body mass is water? Molecules?
Water makes up about 1/2 to 2/3 of body mass of adult animals and 90% of newborns. It accounts for more than 99% of the molecules in the body.
What is the function of the large intestine?
Water, electrolytes, vitamins, minerals, and volatile fatty acids (VFAs) are absorbed from this material with emphasis on water and electrolytes.
Describe symbiosis. How do ruminants and its microbes qualify for status as symbiotic partners?
a relationship between two different organisms, where both derive some benefit from the relationship. -The animal benefits because the microorganisms digest feeds it could not otherwise use and generate nutrients it needs. -The microorganisms benefit from the arrangement because the ruminal environment is maintained by the animal to support the microorganisms.
Describe the significance to the horse of being a cecal fermenter.
capable of using roughage because they have an active cecal bacterial population that digests fiber
What is the function of the reticulum? Omasum? Abomasum?
reticulum: site of microbial action, also acts as a pacemaker of rumen contractions. omasum: The function of the omasum is unclear. It probably is involved in water and VFA absorption. abomasum: The abomasum is equivalent to the true glandular stomach in monogastrics and has the same functions.
In order to determine changes in body composition during growth in beef cattle without grinding a whole carcass, what can we do?
the 9-10-11 rib cut has been shown to give a relatively accurate estimate of the total carcass for fat, protein, water, and ash (mineral) content.
Why must we feed horses their amino acids and we don't have to feed the cow any?
there is a good deal of microbial protein manufactured in the cecum, but the horse is not able to digest it. Even if it could it would probably be unable to absorb it. Therefore, essential amino acids must be fed to horses. Horses should receive better feed than cattle if we expect them to perform to their potential.
What is the point of digestion trials?
used to determine the proportion of the nutrients in a feed or diet that are absorbed from the GI tract
Why feed Megalac?
used to increase the fat in a ration -They remain unaltered by rumen fermentation and thus have no effect on fiber fermentation. -Using these can allow increases in the fat content of the ruminant diet up to 7" 8%. -Dairy nutritionists use protected fat to feed dairy cows. It increases the milk fat as well as helping with energy balance.
Why use the indicator method instead of a conventional digestion trial?
used when it is impossible or inconvenient to measure total feed intake or to collect total feces.
What is the relative importance of VFAs to the energy contribution of a ruminant animal?
volatile fatty acids (VFAs) are a major end product of ruminal fermentation. --Contribute 50-70% of energy for the animal