Animal nutrition #1

When to withhold water

1. Before and after surgery- don't want them to aspirate 2. Before and after extreme exercise- can cause vomiting 3. When animal is vomiting- can cause more and subsequent dehydration 4. House training- small animals often urinate soon after drinking

Protein quality

1. Biological value 2. digestibility

Nutrients made available in Rumen

1. Carbohydrates and volatile fatty acid-> both provide considerable amounts of energy ->these are liberated from the high fiberous feed which contains large amounts of cellulose--> the breaking up of the special beta bonds by the microbes yield simple sugar 2. All the amino acids needed to make protein-> bacteria can fix N onto carbohydrate molecules to produce these as a.a. 3. Large amounts of water soluble vitamins + vit K

Order for performing analytic procedures

1. Chemical- see if nutrients are in the feedstuff -if not, you move on -if there is, go to the microbiological -> biological procedure

5 steps to proximate analysis of feed

1. Dry matter 2. Crude protein 3. Ether extract 4. Ash content 5. Carbohydrates

Differences of ruminants

1. Esophageal groove 2. Rumination 3. Eructation

Classification of amino acids

1. Essential amino acids- those that must be supplied in diet since cant be synthesized at all or in needed amount 2. Non essential amino acids- also important but can be adequately synthsized in body; usually from essentail a.a. >Lysine and methionine

Sources of water

1. Free drinking water (springs, lakes, buckets) 2. Food- water content in food, amount can vary greatly 3. Metabolic water- break down of glucose (C6H12O6=>Energy+ CO2+ H2O) >Under most conditions this counts for only small amount of water. Water is a biproduct when breaking down >Important source of water for desert and hibernating animals

Mixed polysaccharides

1. Hemicellulose- lie between starch and cellulose> slightly digestable so some energy can be used but not lots 2. Pectins- used as a jelling agent for jams and jellies> little if any nutritional value 3. Gums- little if any nutritional value, highly indigestible

Functions of carbohydrates

1. Main sources of energy in most animal feeds -lipids supple remaining energy needs -possible to meet an animals energy needs with just lipids but has no practical purpose and more expensive 2. Important source of body heat for animal 3. Serves as building blocks for other nutrients> microbes can attach N to CHO=> CHON (a.a.) 4. Can be converted into fat; stored energy source

3 forms of digestion

1. Mechanical forces-> chewing/mixing 2. Chemical forces-> hydrochloric acid, bile, etc. 3. Enzyme activity

Classification of carbohydrates

1. Monosaccharides 2. Disaccharides 3. Polysaccharides -cellulose

Analysis of Feedstuffs

1. Most commonly used to design *properly balanced rations*. -need to know the nutrient content of the feed so you can match that with the animals nutrients needs -rations are carefully calculated 2. Determine the *proper time of harvest* -you will get the most money for a crop when it is at its nutritional peak

Why is the study of animal nutrition important?

1. Most expensive part of raising animals esp. livestock ranchers 2. Importnat for health and welfare -affects physical capabilities, disposition, susceptibility to disease, delay aging, etc.

Protein functions

1. Structural components for cells 2. plasma and blood proteins: -albumin; helps prevent the excessive movement of water from blood -Fibrinogen; blood clotting -hemoglobin; oxygen carrier of RBC 3. Enzyme formation- needed for most metabolic rxns 4. Hormones- peptide hormones; regulate and coordinate bodys activity 5. Immune antibodies- fight infection and disease 6. Energy source- following deamination of a.a.

Functions of water

1. Transportation- of waste products and nutrients vie blood plasma >each cell needs a supply of nutrients and also need to eliminate its metabolic wastes > GIT & UT to transport out of body 2. Participates in many necessary metabolic reactions 3. Thermoregulation- water has unique ability to store large amounts of heat and it also dissipate large amounts of heat 4. Help maintain the shape of the body cells for proper function 5. Lubricate joints and protects various body structures (CNS)

What water content varries based on

1. age 2. physical condition 3. performance 4. production

Water locations in the body

1. intracellular water 2. extracellular water 3. gastrointestinal & urinary tract

Water losses

1. urine 2. feces 3. vaporization 4. sweating

Rumen

1st chamber. A large hollow muscular pouch that fills the whole left side of the abdomen >Adult cows average capacity is 50 gallons >Rumen is basically a large fermentation vat -1tsp of rumen contents contains about 25-50 billion microorganisms (bacteria, protozoans, yeast, fungi, etc.) >As a result of this extensive pregastric digestion a lot of nutrients are available >These nutrients are used by the microbes to grow more microbes and then they in turn digest by the animal

5. Carbohydrates

2 forms 1. crude fiber 2. nitrogen free extract

Pyloric gland region (s)

2 types of glands located here: 1. mucus 2. Proteolytic enzymes -these break down proteins

Reticulum

2nd chamber and is the smallest. >Located at base of esophagus >Directs ingesta to various parts of the digestive tract >Has muscular walls (look like honey combs) and responsible for regurgitation of cud up esophagus

Fundus gland region (s)

3 different glands produced: 1. Mucus- protection 2. Hydrochloric acid- breaks down connective tissue 3. Gastric enzymes

Other functions

3. fats/lipids serve as important component in the structure of plasma membrane 4. carriers of fat soluble vitamins 5. maintain healthy skin and hair coat 6. contribute to palatability 7. form adipose tissue- protection and insulation 8. Myelin and nervous tissue formation- very important in early brain development 9. affects reproductive capabilities, too fat or too thin can be problem

Omasum

3rd chamber. Has a lot of internal folds to increase the surface area-> cud gets in folds and is further broken down >Main function is to reduce the particle size and some water absorption >Reduce volume of contents to facilitate passage from there on

Stomach

4 chambers in a cows stomach 1. Rumen 2. Reticulum 3. Omasum 4. Abomasum

Polysaccharides

4 or more sugar molecules a. Starch- a stored form of energy in plants, long term storage >major component in livestock rations >highly digestable energy source >alpha links b. Glycogen- (animal starch) formed in animal by the liver from excess glucose->can be converted back to glucose when needed >principle component of plant cell walls, very abundant fibrous feeds >Chemical structure is identical to stratch except the individual molecules are connected by beta links c. mixed polysaccharides

Abomasum

4th chamber. "True or glandular stomach" >Corresponds closely to monogastrics >where active role in digestion starts Up to now pregastric digestion has occurred. From this point on, animal takes active role in digestion -From here rest is similar to simple monogastric

Nutrients

6 basic groups A food component or a group of food components of the same chemical composition that's absorbed through the intestinal tract and aids in the support of life

Functions of fats

9

Eructation (belching)

A byproduct of fermentation is considerable gas production-> CO2 +CH4 >Produce a lot of this so they need to eliminate it

Supplements

A feed or a mixture of feeds which is added to another feed to improve its nutritional balance. -It is usually high in a specific nutrient (protein, energy, etc.)

Ration

A fixed daily allowance of feed or a mixture of feeds that are supplied to an animal on a daily basis

Digestive tract

All of the structures from the mouth to the anus -Only system that is not completely sterile

Omnivore

Animal which eats both plants and animal tissue

Carnivore

Animal which primarily eats animal tissue

Herbivores

Animal which primarily eats plants

Metabolic conversions

Animals have limited ability to store energy as glucose-> excess glucose converted into glycogen in the liver ->this glycogen then stored in liver & muscles until needed ->when glucose levels are low, glycogen gets converted back into glucose >process helps maintain fairly content blood glucose levels >glycogen storage is limited->when ingested carbohydrates exceed capacity= gets converted into fat, for long term storage

Feedstuff

Any product of natural origin or artificially prepared that has nutritional value -easier to ask what isn't? (glass, plastic)

Cecum (LI)

Area below where small and large intestines meet >size varies on species: small in carnivores, large in herbivores >In simple monogastrics, it tends to be small and undeveloped (almost non-functional)

Basal feed

Base Concentrated sources of *energy* that are especially high in starches and sugars (corn, barley, wheat, outs)

Protein

Basic structural material for formation of all cells and body tissue >highest concentration of protein in body is muscle tissue and other soft tissue >also present in significant amounts in bone, horn, hooves, feathers, and hair >requirements greatest in young growing animals because produce more cells than are replaced

Non protein nitrogen

Because of the mocroorganisms, ruminants can utilize NPN to synthesize a.a./ proteins >when fed urea (NPN source) along with fermentable carbohydrates the microbes can synthsize a.a. at reduced cost -->high levels of urea can be toxic, best to supply no more than 1/3 of nitrogen need from urea

What understanding is required for nutrition

Biology, chemistry, and math

Hepatic portal system (SI)

Blood is re-routed to the liver -here some nutrients are further metabolized and where detoxification of harmful chemicals occurs >from liver blood goes to vena cava and then back to heart

Digestion

Break down of feed particles into suitable products for absorption 3 forms

Regurgitation

Bringing up undigested material from the stomach to the mouth -it can be voluntary and is a more mild form of vomiting

2. Crude protein

CP is not actual protein, based on the knowledge that protein contains 16% N Kjeldahl procedure: determine how much nitrogen is in feed -grams of nitrogen X 6.25 Downside: you can get nitrogen from things in the feed other than protein--> Non protein nitrogen (NPN) almost all feeds have some of this. ex) actual protein= CP - NPN

Bloat

Caused when the esophagus becomes blocked >Can be caused by froth from certain fermenting feeds >Thus gas can't be expelled and the animal begins to swell up >Immediate treatment needed->medications to break up blockage. May require surgery if these don't work >Don't feed apples or potatoes, don't chew well at first

3 general procedures used to analyze feeds

Chemical, biological, microbiological

2.e.Rectum (LI)

Compaction of feces and temporary storage

Microbiological procedure

Compromise between chemical and biological procedures -Partially answers the availability of nutrients -not as time consuming, not very expensive -certain bacteria are isolated and grow in the presence of specific nutrients such as glucose, a.a., certain lipids, etc. -Feed samples then added to these individual bacterial colonies in petri dishes and incubated for 48hrs, bacterial growth rates are then examined -Usually followed up by a biological procedure Downside: just because microorganisms can digest and utilize nutrients in the feed does not mean another animal cal

2.e. Cecum and large colon (LI)

Contains large number of microorganisms which ferments feed (roughages and cellulose in fibrous feeds) -Produces carbohydrates and volatile fatty acids which are good sources of energy >Issue: location- it is after the small intestines= minimal absorption of nutrients occurs most of nutrients produced just pass out in feces

Bomb calorimeter

Determines the amount of gross energy or calories in a feed -box filled with water with another box (heavier) inside it containing your food item--> take the temp of the water before and after the test to see how much it increased after burning sample in pure oxygen -1Kcal= the amount of heat necessary to raise the temp of 1 liter of water 1C

1. Dry matter

Everything in the feed except water= if dry matter is 90% the moisture matter would be 10% -determine by heating the feed to 100-105C, just above boiling point until weight loss stops (getting rid of water) -weigh sample before and after to determine the difference Downside: Could lose more than just water, like soluble vitamins -Freeze drying works better, It is more accurate but also more expensive

Structure of protein

Extremely large molecules composed of small molecules called a.a.->20+ a.a. found in feeds >a.a. linked together by special chemical bond known as a peptide bond

Supply energy

Fats are broken down into fatty acids and glycerol which serve as concentrated sources of energy >all energy in diet can be provided by carbohydrates, so no specific fat requirement for energy >but fats have other functions that can only be done by consuming fats

Saturated fatty acids

Fatty acid chains are said to be saturated when each C in the chain has 2 H atoms attached to it (except terminal C) ->fats from most animal tissues tend to be saturated

Concentrate

Feed or mixture of feeds which supplies the *primary nutrients* and provides less than 18% crude fiber -Usually specific feeds (corn, meat, barley)

4. Ash content

Feed sample is put in furnace and burned for 2hrs at 600C -what is left behind is the total mineral content -does not tell you specifically what minerals are in it, this value is needed later on in the process

Roughage

Feeds high in fiber but low in useful energy -Bulky feeds (hay, silage)

Disaccharides

Formed from 2 monosaccharides with loss of water molecule (C12H22O11) a. Sucrose- table sugar->compound of glucose and fructose b. Maltose- malt sugar-> compound of 2 glucose molecules c. Lactose- milk sugar-> compound of glucose and golactose (only found in mammals)

Water

Generally the cheapest and most abundant nutrient >Unfortunately it can be the most ignored-> if you deprive an animal of any nutrients they will die, but lack of water will cause them to die sooner >Water content varies based on: age, physical condition, performance, and production >An animals body water content can vary from about 70% in newborns to about 50% in adults >Level of body fat is inversely proportional water content--> higher the water content= the lower the fat content and vice versa

Non- carbohydrate sources

Glucose can also be formed from non carbohydrate sources ->both lipids and amino acids can also be metabolized for energy ->only occurs when carbohydrates not available -->more involved process and creates additional waste products which must then be excreted

Metabolism of carbohydrates

Glucose must first be broken down by glycolysis into pyruvate-> pyruvate then enters krebs cycle (citric acid cycle) End result = CO2, water, energy in form of ATP, heat

Special analytic method

Gross energy -bomb calorimeter

1.b. Esophagus

Hallow muscular tube which transports the ingesta from mouth to stomach >Does this thru *peristalsis*- involuntary rhythmic, muscular contractions that move ingesta thru entire digestive tract -Esophagus does not contribute to the digestive process, only for transportation

Mouth

Have no upper incisors->instead they have a dental pad which is a thick wad of tissue which comes in contact with the lower incisors >Produce large amounts of saliva (about 12gal. a day)

2. Post-gastic Fermenters

Horse, rabbit, guinea pig, etc. Fermentation occurs after the stomach >Consume large amounts of roughages

2.a. Mouth

Horses have both upper and lower incisors to clip off grass that it eats >Upper jaw is wider so chew side to side= can cause teeth to sharpen so need to have them floated or filed >Saliva does not contain amylase >Produce large amounts of saliva (about 10gal a day)

2.e. Large intestine

Includes 60% capacity of the entire gastrointestinal tract 4 regions: 1. Cecum and large colon 2. small colon 3. Rectum

1.a. Mouth

Ingestion of feed occurs >Tongue- aids in prehension, mixing of ingesta and forming the bolus for swallowing >Teeth- for prehension and mastication >Salivary glands- secrete saliva (3 components) 1. water-> moisten the feed 2. Mucin-Lubrication, aids in swallowing 3. Bicarbonate salts-> help buffer the pH of the stomach 4. Amylase-> initiates carbohydrate break down

Colon (LI)

Largest part Major function is water absorption >many microorganisms that produce some nutrients, especially some water soluble vitamins

2.c. Stomach

Less muscular activity, not as much churning= could settle in layers, lead to colic >Relatively small stomach= need to eat frequently

Carbohydrates

Main source of energy in most feeds> most abundant >All carbohydrates contain elements C,H, and O -> always 2:1 ration of H to O= CH2O >Plants are the source of nearly all carbohydrates via process of photosynthesis: CO2+H20+ Solar energy--> C6H1206+O2

3.b. Esophagus

Many birds have a widening of the esophagus known as the crop

Essential to fatty acids

Many but main 3 are considered essential because they MUST be supplied in diet >Only can be supplied from unsaturated fats >Linoleic and linolenic acids can't be synthsized by animal tissue thus must be supplied in diet >Archidonic acid- can be synthesized from linoleic acid by most animals -->cats are the exception; specifically need this in diet >Alpha-linolenic acid- also known as omega-3, recently shown to be dietary necessity >The specific functions of essential fatty acids not totally clear but known to be vital for synthesis of--> Prostaglandins- hormone like substance needed by the body

Cellulose

Molecules simular to starch except glucose >connected by beta links >microorganisms are only thing that can break them

Catalytic action

Molecules that speed up metabolic reactions

Biological procedure

More accurate, very good at telling you the availability of nutrients -takes a long time, very expensive -These procedures involve providing the feed to animals using a test group and a control group

Chemical

Most commonly used method, quickest, cheapest, and least accurate. -Uses a variety of caustic acids and bases to break the feed into their basic chemical compounds -Does not tell you the availability of the nutrients

Gastrointestinal & urinary tract

Moves materials through these systems for eliminating these waste Urinary to make urine >Amount varies according to species and diet

Protein digestion

Must be broken down in the GIT into a.a. for absorption ->exception; first 24-48hrs of life -whole portein (maternal antibodies) can avoid breakdown and be absorbed directly into blood stream

Feces

Need some water to have bowel movements. Varies in different species Monogastrics- usually get rid of more water in urine than feces Ruminants usually get rid of more in feces rather than urine

3.a. Mouth

No teeth= no real mastication >Has a tongue to push back and saliva contains amylase

Supplementary effect

Obtained when 2 or more protein sources are combines so they compliment one another

Extracellular water

Occurs in the spaces between the cells Includes-> tissue fluid, blood plasma, lymph & cerebrospinal fluid

Proximate analysis of feed

One of the first procedures developed to analyze feed. -Chemical procedure -Tells you what is present and the amount, but not the availability -It is the basis for the terminology that we use today

Enzyme

Organic compound capable of catalytic action. Primarily composed of proteins -Every metabolic reaction requires enzymes

Esophageal groove

Passageway from the bottom of the esophagus to the omasum >Bypasses the rumen an reticulum >only in young ruminants because they only consume milk >Disappears when the animal begins eating food, completely gone around 45days

Lipids

Potent source of energy >1g of fat yields 9.45Kcal energy-> 2.25x more energy that either a gram of carbohydrates or protein >Insoluble in water but soluble in organic solvents like ether

Cardiac gland region (s)

Primarily produces mucus which protects the stomach from digesting itself

2.e. Small colon (LI)

Primary function is water absorption

Rumination

Process in which the animal almost constantly regurgitates a feed bolus->sending it up to esophagus to masticate ingesta more thoroughly >Usually done while laying down->may spend 8-14hrs a day in this activity

Prehension

Process of taking food and water into the mouth

3.c. Proventriculus (glandular stomach)

Produces significant digestive materials >No storage capacity so ingesta moves right thru (14sec)

Mastication

Reduction of feed particle size which is generally achieved through chewing

Biological value

Refers to balance of a.a. in relation to animals need >depending on the proteins that have to be synthesized, certain a. . will be needed in greater quantities than others First limiting a.a.--> One that is present in a feed in the least amount in relation to need >good quality protein do not have any significant limiting a.a. >protein sources with highest BV tend to come from animal sources >protein sources from cereal grains and other plant sources tend to have much lower BV due to reduced levels of needed a.a. >nitrogen has to be extreted in the form of UREA-> overtime can stress kidneys; remaining part can used for energy

3. Ether extract

Refers to lipid or fat content in a feed -Here they use ether to get the fat out of the food -Grind up a feed sample-> let it soak for 4hrs in ether-> filter it then evaporate ether and you are left with lipids -Ether extract will not be pure lipids, but it will be mostly lipids

Jejunum and ileum (SI)

Remainder of small intestines >Main function is nutrient absorption >Contains villi= greatly increase the surface area for absorption 2 major structures: 1. Lacteal- each villi contains this> absorbs fats and lipids and takes lipids to the lymph system 2. Capillaries- other nutrient absorption, they contain arterioles (bring blood in) and venules (take blood away) >the venules don't carry blood directly back to heart, vie vena cava Instead the blood goes thru-->Hepatic portal system

Defecation

Removal of indigestible wastes (feces)

Excretion

Removal of metabolic wastes

Urine

Removes metabolic wastes through kidneys >amount of water lost depends on species >desert animals like cats can really concentrate their urine while animals like cows have dilute urine

Sweating

Requires sweat glands. Minor because most have small distribution >only animals with large abundance of sweat glands are humans and horses >4x more effective at dissipating heat than vaporization

2.b. Esophagus

Same except it is longer- 50 to 60ft long on left side of neck >Only one way peristalsis= regurgitation almost impossible

Protein deficiency

Shortage of protein in a ration- one of more common nutrienal deficiencies->thus because most feed high in energy are low in protein, also protein sources tend to be more expensive Symptoms: reduced growth rate, anemia, infertility and fat accumulation in liver.

2.d. Small intestines

Similar in structure and function to a pig, however: >Horses don't have a gallbladder >Produces bile from the liver >Horses cannot tolerate high fat diets

3.e. Small intestines

Similar to simple monogastrics 2 differences: produce one less digestive enzyme and one digestive hormone

Digestive tracts of monogastrics

Single chambered stomach -Primarily fed concentrates which are high in protein and energy and low in fiber (grains, animal tissue) -can utilize fibrous feeds but only to a limited extent 3 types 1. simple monogastric 2. post-gastric fermenters 3. Avian digestive system

3.h. Cloaca (vent)

Single opening for the elimination of feces and urine >Only opening for the reproductive system

Monosaccharides

Single sugar molecule (C6H12O6) a. Glucose- only carb that can used directly by cells for energy b. Fructose- a simple sugar found in fresh fruits and other sources like honey. sweetest of the sugars c. Ribose- important for RNA d. Galactose- derived from lactose (disaccharides)

1.e. Large intestines

Size varies in different animals, shorter than small intestines but larger in diameter >Broken down into 3 regions 1. Cecum 2. Colon 3. Rectum

1.d. Small intestine

Small in diameter, but long in length; short as 12ft in canines and up to 65ft in swine 2 parts: 1. Duodenum 2. Jejunum an ileum

3.f. Ceca (plural)

Some fermentation occurs producing some water soluble vitamins >Water absorption, temp. storage

Digestibility of protein

Some proteins are easily digested others not Protein quality recieves much more attention when dealing with monogastric nutrition than runinants

Rectum (LI)

Some water absorption, but primarily a temporary storage area for feces >where it exits digestive system

Water consumption

Specific water requirements vary greatly for every animal due to many variables that affect water consumption 1. Genetics 2. Environmental temperatures- high (more water) vs. low 3. Dry matter consumption- drier feeds require increased water consumption vs wet feed 4. Dietary factors- diets high in protein and fats will increase need of water consumption -salt (NaCl) and other nutrients will increase thirst 5. Activity level- amount of energy expelled -lactation requires much more water Generally best way to give water is free choice.-> should be clean, palatable, and at desirable temperature

B. Nitrogen free extract (NFE)

Starches and sugars (the water soluble carbohydrates) -Determined *difference* , no chemical testing involved 100g feed- 10g H2O- 12g CP- 36g EE- 4g Ash- 15g CF= 23g NFE

1. Simple monogastric

Swine, dogs, cats, humans 5 parts

3.b. Crop

Temporary storage area and allows for some soaking and fermentation >seen in young birds

1.c. Stomach

Temporary storage area for ingesta -Length of time ingesta spends there will vary on species and type of feed> more watery= quicker it will move thru (carnivors may only spend few hours, omnivores may stay for up to 24hrs) Divided into 3 regions: 1. cardiac gland region 2. fundus gland region 3. pyloric gland region >Once the content leaves the stomach it is now *chyme*

A. Crude fiber

The fiber content in a feed -Determined by taking the ether extract residue and boiling it first in a weak acid then a weak base->gets rid of protein, starches, and sugars and leaves you with crude fiber and minerals -Weigh it then determine Ash content -Part destroyed by burning was crude fiber

Duodenum (SI)

The first 1-2ft-> most digestion occurs here 3 reasons: 1. produces many digestive materials in the walls for chyme breakdown 2. receives many pancreatic digestive materials 3. bile from the liver> for fat break down

Ruminant digestive systems

These animals are polygastric->3-4 chambered stomachs >Primarily consume high fibrous feeds (roughages) >Require a tremendously large number of microorganisms to break down their feed

3.d. Ventriculus (gizzard)

Thick, muscular organ with small stones and grit which the bird intentionally swallows >very efficient- grinding, enzymes, acidic breakdown >No digestive materials added nut much mastication occurs here

3. Avian digestive system

This system differs considerably in anatomy compared to other monogastrics

Balanced ration

Ties diet and ration together. A feed mixture for a specific animal that supplies all the nutrients in a proper amount and proportion for a 24hr period

Absorption

Transfer of substance from the intestinal tract into the blood and lymph systems through diffusion

Esophagus

Transportation; peristalsis in both directions

Structure of fats

Typical fat molecule is composed of a base unit-> glycerol >Attached to which can be 1, 2, or 3 fatty acids 1 fatty acid= monoglyceride 2 fatty acids= diglyceride 3 fatty acids= triglyceride

3.g. Large intestines

Very short, water absorption

Vaporization

Water lost during exhalation >usually not a lot of water loss unless temperatures and activity go up >primary way in which most animals dissipate their body heat. Can result in significant water loss when temperatures are fairly high

Diet

What an animal usually eats or drinks. Refers to specific types of feedstuff (corn, hay, pond water, floor sweepings)

Intracellular water

Within the cell; need it to function >Greatest amount of water >Found here especially in soft tissue

Unsaturated fatty acids

have double bonds which attach the C atoms in the chain-> saturated with H atoms ->It is in the presence of double bonds that "kink" the chains resulting in a more liquid condition substance ->fats from plants and fish are generally unsaturated and thus oils