Nutrition Flashcards
What affects nutrient availability?
Digestibility of diet, species differences in GI tract and metabolism, nutrient interactions in diet and husbandry factors - freshness of diet, storage and spoilage
Which nutrient requirement does fibre/fat increase?
Taurine
Which mineral availability does phytate reduce?
Zinc
Why do animal eat, and what is the exception?
To fulfil energy requirements, except in RUMINANTS on high fibre diets where stomach fill is important
What is the definition of a calorie?
Energy required to heat 1g of water from 15.5 degrees C to 16.5 degrees C
How do you measure the total energy in a food?
Kilojoules obtained after total combustion in a bomb calorimeter. Not all available to animal.
What is digestible energy?
Gross (total) energy minus faecal loss of energy as undigested fibre.
What is metabolisable energy?
Digestible energy minus urinary and methane loss
What is the metabolisable energy requirement (MER)?
Energy required by an inactive animal in thermoneutral conditions including the energy required to obtain and digest food
How does MER vary within species?
The higher the MER relative to body weight, the more energy needed - eg shrew has very high MER relative to body weight so must eat continually
How is MER calculated for dogs and cats?
For dogs - 100 x body weight ^ 0.75 kcal per day
For cats - 70 x weight kcal per day (a linear approximation because weight doesn’t vary much)
What is an overview of the diet of a herbivore?
Cellulose mainly. Dietary starch and glucose minimal so gluconeogenesis important
Overview of the diet of a carnivore?
Mostly protein. Starch and glucose minimal so gluconeogenesis important
Overview of the diet of an omnivore?
Significant starch and glucose. Stored as glycogen and fat. Gluconeogenesis only in fasting.
Which bond in cellulose can mammalian enzymes not break down?
Beta-1,4-glucose
Differences between ruminant and non-ruminant herbivores?
Non-ruminant herbivores have microbial fermentation in a modified large intestine. Cellulose digestion is less efficient. BUT there is some normal digestion further up the gut first so glucose can be absorbed before microbial fermentation.
Why is some bacterial breakdown of fibre in the large intestine important in omnivores?
Butyrate from colonic bacterial fermentation provides 50% of energy needs of colonic epithelial cells - may prevent colonic cancer
What is the difference in bacteria in the colon and small intestine?
In the colon gram negative and anaerobes dominate. In the small intestine, there is fewer bacteria which is mainly aerobic with fewer gram negatives
Differences between parts of ruminant stomach?
Microbial fermentation in rumen and reticulum. No secretory glands or enzymes in rumen, reticulum or omasum. Acid pH and enzymes in the abomasum.
Problems with rumination
Loses control of diet constituents, saccharides and starch broken down so adult ruminants can’t get glucose from diet. Starch escaping fermentation isn’t used because maltase activity is low and glucose absoption is poor.
Rumen volume
40 gallons
Rumen pH
6.8
Rumen temperature
38-40 degrees C
Which vitamins do rumen bacteria need?
Biotin and other B vitamins
What kind of bacteria are in the rumen?
Gram-negative anaerobes
Which vitamins do ruminal bacteria synthesize?
Vitamin K and most vitamin B requirements
What is the function of ruminal protozoa?
Metabolise cellulose and store it as a polysaccharide like starch. Feed on bacteria so if protozoa die then bacteria numbers increase. More sensitive to pH so die earlier in ruminal acidosis.
What age are ruminal microflora present from?
14 days after inoculation from older animal
What is the process of starch or cellulose metabolism in the rumen?
Starch/cellulose to short chain fatty acids then to glucose or ketones/fat
What is the process of protein and non-protein nitrogen metabolism in the rumen?
Firstly to microbial protein and then the host digests the microbes and absorbs the amino acids
Why does a dairy cow need lots of glucose?
To make lactose
Why are lots of methane, hydrogen and short chain fatty acids produced during microbial metabolism?
Because oxidation of carbohydrates and proteins must be accompanied by a reduction so there are reduced waste products
What fraction of ruminant calorie intakes is supplied by short chain fatty acids?
2/3
What are the main short chain fatty acids in microbial metabolism?
Acetate, propionate, butyrate and some valerate and isovalerate.
What is propionate used for?
Into liver and muscles to make glucose
Why do ruminants use glucose not fatty acids?
For nutrition of cells with no mitochondria or lacking oxygen supply, can’t use ketone bodies in brain, need lactose and glycerol for milk triglycerides, can be stored as glycogen, source of fructose for sperm, used for TCA cycle intermediates
What percentage of total body glucose is used for milk production at peak lactation?
85%
For the first how many weeks of lactation is there a negative energy balance?
Six
Which short chain fatty acid are used to make glucose?
Propionate and gluconeogenic amino acids
What is the fate of acetate and butyrate in a ruminant?
Converted to acetyl CoA and oxidised to make ketone bodies or fatty acids (ketogenic or lipogenic BUT NOT gluconeogenic)
What percentage of its glucose does a sheep get from propionate? And what percentage from gluconeogenic amino acids? Lactate? Glycerol?
40% and 35%, 15%, 10%
In a fasting ruminant what happens to propionate and where does the animal get the extra glucose from?
Propionate production decreases and more glucose is gained from glycerol and amino acids
Which factors affect nutrients intake?
Amount of diet fed and the availability of nutrients in the diet
Proportion of propionate converted to lactate during passage through ruminal wall
1/5
When is hepatic gluconeogenesis maximal in ruminants? How is this different in man and dogs?
After a meal when most propionate reaches the liver in the portal blood. Gluconeogenesis reduced after a meal in man and dogs due to increased insulin which inhibits gluconeogenesis.
What stimulates insulin release in ruminants?
Propionate, butyrate, isovalerate and valerate
Why is it better for less glucose to be derived from gluconeogenic amino acids in ruminants?
Important for making structural body proteins
How does increased roughage (cellulose) affect acetate and propionate?
Increased acetate, decreased propionate
How does increased concentrates affect propionate, butyrate and acetate levels?
Increased propionate and butyrate, decreased acetate
How does heating/cooking the ration affect propionate production?
Increases it
What percentages acetate, propionate and butyrate does the average dairy cow produce?
60-70, 15-20, 10-15
How is lactic acidosis caused?
Too much concentrate feed, increased lactic acid production, drop in pH, buffering capacity exceeded, desirable microflora inhibited and protozoa die so lactate producer grow favoured.
Effects of lactic acidosis
Damage to rumen wall causing bacterial infection, bacteraemia, liver abscesses, general acidosis of blood, water pulled into rumen by osmosis so hypovolaemia (reduced circulating volume), death
Which form of lactate accumulates during lactic acidosis
D forms as metabolised much more slowly than L
Why isn’t propionate fed directly to high yielding dairy cows?
Would inhibit propionate-producing microbes in rumen favouring acetate and butyrate producers causing severe propionate shortage if cow goes off food, stimulates insulin release which suppresses fatty acid release so milk fat concentration lowered, depresses appetite, unpalatable
What is the fate of triglycerides, phospholipids and cholesterol esters in the rumen?
Hydrolysed to glycerol and galactose which are fermented to short-chain fatty acids
What are the main lipogenic short chain fatty acids generated by microbial fermentation and which is the most important?
Acetate and butyrate, acetate is the most important
What do ruminal microflora do to dietary unsaturated fatty acids?
Hydrogenate them to saturated fatty acids
How does a high dietary content of unsaturated fatty acids affect microflora?
Depresses them
How does increased dietary fat affect propionate production?
Increases it
Where does most fatty acid and triacylglycerol synthesis occur in the non-lactating ruminant? What about a lactating ruminant?
Adipose tissue and mammary gland when lactating
What is the main source of absorbable amino acids for a ruminant?
Microbial protein from digestion of microbes further down the gut
How much protein does host ruminant “make” per 100g ingested organic matter?
12g
How do ruminants use non-protein nitrogen
Microbial ureases break it down to ammonia, then used to make microbial protein
Why don’t ruminants have any dietary requirement for essential amino acids?
All made by microflora as long as building blocks eg sulphur provided in diet
Why do high-yielding dairy cows require essential amino acids?
Their demand for amino acids is so high
What is the fate of most dietary nitrogen in ruminants?
Degraded by microbes by hydrolysis and deamination producing ammonia and carbon skeletons
What happens if energy is surplus in the rumen?
Microbial growth not limited, microbial cell growth increases with ruminal ammonia concentration
Which ammonia concentrations are dangerous to the host?
Above 4.5mmol/l
What happens the rumen ammonia concentration if carbohydrate or another essential component is lacking from the diet?
Ammonia concentration will rise
What percentage of ammonia produced in the rumen is incorporated into microbial protein?
90%
How is ammonia “recycled” in ruminants?
Ammonia absorbed into blood and converted to urea, urea either diffuses back in or is secreted into saliva. Then ureases break it back down to ammonia.
How is recycling of ammonia in ruminants useful?
Can metabolise more bicarbonate via CO2 which is helpful for acid-base balance as they have an excess of bicarbonate.
Why do ruminants have an excess of bicarbonate?
Plants contains lots of organic acids metabolised to bicarbonate.
What is an “escape protein” or “rumen undegradable protein”
Less soluble in rumen and resistant to microbial degradation. Pass unchanged to small intestine where they are digested similarly to man and dogs
Where are the enzymes most important for protein digestion in the small intestine produced?
Pancreas
In which area of the intestine does highest amino acid uptake occur in cows, and why is this further down than in dogs and man?
Mid to lower ileum because acid abomasal digesta is neutralised slowly and pancreatic enzymes are neutralised slowly
What % of dietary protein is nitrogen and what % is non-protein nitrogen?
85% true protein, 15% non-protein nitrogen
What % of dietary nitrogen is recycled into the rumen?
12%
What % of dietary protein is escape protein?
40%
What % of dietary non-protein nitrogen and recycled nitrogen is degraded by microbes?
100%
What % of amino acids available for absorption in the small intestine come from microbial nitrogen?
60-80%
What % of amino acids used to make milk proteins come from microbes?
65%
What % of microbial nitrogen is true protein usable by the host?
80%
What % of microbial true protein is digested and absorbed in host’s small intestine?
80%
What happens if an essential amino acid is missing from the escape proteins in the ruminant diet?
The others aren’t stored and are simply deaminated or broken down until the missing one is eaten
What percentage escape proteins are there in casein, barley, soybean meal, corn, brewer’s grains and fish meal?
10,20,30,40,50,60
How does increasing quantity of escape proteins affect wool growth, body growth and milk production?
Increases
What are the essential amino acids for ruminants?
Methionine, lysine, valine, isoleucine, leucine, histidine, threonine, phenylalanine, tryptophan and arginine
Why are lysine and methionine particularly important for ruminants?
Levels usually low in plants and lack is rate-limiting for growth and milk production
How does feeding escape proteins allow non-protein nitrogen to be included in the diet without risking ammonia toxicity?
Not degraded by ruminal microbes so aren’t a source of ammonia
Which cheap nitrogen sources in the ruminant diet can result in ammonia toxicity?
Highly degradable protein with little escape protein eg casein, large amounts of non-protein nitrogen eg urea, ammonia itself eg ammoniated molasses
Why does excess ammonia cause neurological signs?
Readily crosses blood-brain barrier and brain has no cycle to detoxify it
Why does urea cause blood alkalosis?
Binds H+ ions
How does alkalosis cause tetany?
Increased calcium binding to plasma proteins so reducing plasma ionised calcium
What is the most abundant constituent of all mammalian milks?
Water
Which lipids do ruminant milks contain?
Triacylglycerol, diglyceride, cholesterol, free fatty acids, phospholipids, monoglycerides
How does the lipid content of non-ruminant milk compare to ruminants?
Increased sterols and sterol esters, reduced triacylglycerols
How many carbons do most fatty acids in ruminant milk have?
16-18
How many carbons in the fatty acids of herbivores are more common than other animals?
4-14
At least how many different fatty acids are there in cow’s milk?
437
What is the major protein constituent of milk?
Caseins
What pH range does casein have low solubility at?
4-5
What are the amino acid components of casein?
Serine-bound phosphate, high proline content, few or no cysteines,
How are caseins present as an important source of minerals in the milk?
Micellar complexes with calcium and inorganic phosphates?
Why is low cysteine in casein not a problem?
Can be synthesised from methionine, high concentration in whey proteins
What are non-casein proteins in milk called?
Wheys
Which kinds of species have many whey proteins and which have few?
Carnivores many, rodents few
In cows which whey proteins are present?
Beta-lactoglobulin, alpha-lactalbumin, protease-peptones, traces of serum albumin and immumoglobulins
What is the predominant carbohydrate in most milks?
Lactose
Which monosaccharides make up lactose?
Glucose and galactose
Which salts are found in milk?
Sodium, potassium, calcium, magnesium, phosphate, chloride, citrate
Which is the only hormone rabbits need to maintain milk production?
Prolactin
Which hormones do cows sheep and goats need to maintain milk production?
Prolactin, growth hormone, thyroxine, parathyroid hormone, corticosteroids and oxytocin
When do lipid synthesis and lactose synthesis for milk commence?
Lipid synthesis before lactation, lactose synthesis at parturition
Where are fatty acids for milk extracted/produced?
Either extracted from blood or made from acetate and malonyl CoA
What can be the primer molecule in milk fatty acid production instead of acetyl CoA in cows?
Butyryl CoA or propionate
What % of nitrogenous compounds in milk are synthesised de novo in the mammary gland from amino acids in the blood?
92%
How is there net conversion of essential to non-essential amino acids in secretory cells for milk protein synthesis?
Mammary gland selectively takes up too many essential amino acids and too few non-essential
What is the mammary gland the only source of?
Lactose
What is the pathway of lactose production in the mammary gland?
Glucose to UDP-galactose in the cytoplasm and then UDP-galactose and glucose to lactose in the golgi by lactose synthetase
What proportion of the total substrates taken up by the bovine mammary gland is glucose?
400g/kg
What is glucose used to make in the bovine mammary gland?
Lactose and glycerol
What % of total body glucose usage does the mammary gland account for at peak lactation?
85%
What are the consequences of glucose shortage during lactation?
Body fat mobilisation to supply glycerol for gluconeogenesis and also fatty acids which can’t be used to make glucose
What happens to the fatty acids mobilised during glucose shortage during lactation?
Diverted to liver, either stored or converted to ketone bodies
What are the problems with fatty acid storage or conversion to ketone bodies during glucose shortage during lactation?
Fatty liver syndrome, ketoacidosis
What are the signs of ketosis?
Depression, loss of appetite, fall in milk yield, neurological signs and death
Why can ketosis result in death?
Ruminant brain poorly adapted to using them for energy
How is pregnancy toxaemia in ewes different to ketosis in cows?
Occurs in late pregnancy when ewe is under greatest energy and glucose demand but food supply is least (late winter)
What is the equine equivalent of pregnancy toxaemia and ketosis and how is it different?
Hyperlipidaemia - last third of pregnancy or lactation, don’t become ketotic but have elevated blood triglycerides
Why kind of pony is hyperlipidaemia most frequent in?
Shetland
What is the feline equivalent of equine hyperlipidaemia?
Hyperlipaemia
Which ketone body is not a ketone?
Hydroxybutyrate
How do ketone bodies have an advantage over long chain fatty acids as a fuel?
Don’t need albumin for transport, easily cross membranes, can be carried in higher concentrations in blood and interstitium
Which vital muscles can use ketone bodies during starvation?
Heart, diaphragm, gut and myometrium
Which dietary deficiency causes dam or kitten coat to change from black to brown?
Tyrosine or phenylalanine
Do foods for older dogs have higher or lower energy content?
Reduced
Why do large breed dogs fed fish and rice often lose weight?
Low dietary fat
Which animals need and don’t need vitamin C?
Dogs and cats don’t, guinea pigs, bats, birds and fish do
What is the intermediate between glucose and L-ascorbate?
Glucuronate
What are some functions of vitamin C?
Collagen synthesis, bile acid formation, enhances absorption of iron from gut, antioxidant
How does hepatic rate of vitamin C synthesis in dogs and cats compare to other animals?
Half
Why might you supplement vitamin C in very stressed dogs?
Vitamin C concentration decreases in stress
Where do cats obtain glucose?
Gluconeogenesis from protein
What is the % protein requirements of dogs and cats?
Cats 20-30% and dogs 18%
How does the activity of hepatic nitrogen catabolising enzymes in cats compare to the activity in dogs?
Increased activity
Why do cats go into negative nitrogen balance during insufficient protein intake? What is a consequence?
Can’t down-regulate enzymes, will break down body protein
Why have cats lost the ability to down-regulate enzymes?
Lack of selection pressure, diet always contains lots of protein
Which nitrogen catabolising enzyme activity is increased in cats compared to dogs and rats?
Alanine aminotransferase and glutamate dehydrogenase
Which amino acid can be used an a precursor in cats during an alternative hepatic gluconeogenic pathway?
Serine
Which amino acid requirement is higher in cats than man or dogs?
Arginine
How long can rats survive in nitrogen balance without arginine?
A short period
What is the pathway if arginine in the urea cycle?
Arginie to citrulline to ornithine to arginosuccinic acid to arginine
Why do cats fed arginine-free diets show signs of increased blood ammonia?
Depletion of urea cycle intermediates - can break down protein but not excrete urea
Why two enzymes involved in ornithine synthesis in cats have low activity?
Pyrroline-5-carboxylate synthase and ornithine aminotransferase
What are some possible reasons for increase cysteine and methionine requirement in cats?
Sulphur-containing amino acid called felinine excreted in urine, may be a sink for cholesterol (proved wrong) so maybe needed to make keratin for fur
What % amino acids absorbed by cats are used to make fur?
30%
Which amino acid is taurine made from?
Cysteine
What can taurine deficiency cause?
Poor reproductive performance, poor growth, dilated cardiomyopathy, retinal degeneration
How much taurine is needed to prevent retinal degeneration in cats?
500mg/kg taurine
How much taurine is needed to prevent dilated cardiomyopathy in cats?
1000-1500mg/kg in dried food and 2200-2500mg/kg in canned food
Why do cats have high taurine requirement?
Reduced ability to synthesise it from cysteine, conjugation of bile acids solely with taurine
Why do cats have reduced ability to synthesise taurine?
Low activity of cysteine dioxygenase and cysteinesulphinate decarboxylase
Which amino acids do cats, humans, rabbits and rats use to conjugate bile acids?
Cats taurine, humans taurine and glycine, rabbits glycine, rats taurine but can switch to glyco-conjugation if it’s limiting
Why is there a constant drain on taurine in cats?
Conjugation and bile acids and subsequent loss from intestines, any excess excreted in urine
Why are there different taurine requirements in dry and canned food?
Canned diets have higher fibre so more bacteria growth which split taurine from bile acids, also higher fat content stimulates bile secretion
What are the functions of taurine?
Regulates calcium flux across membranes, osmoregulation, neuromodulation
How does cow’s milk compare to meat or cats milk as a taurine source?
300x less
Why shouldn’t cats drink milk?
Undigested lactose causes osmotic diarrhoea
Why dietary requirement do cats share with mosquitos and turbot fish?
Need arachidonic acid
What are the functions of essential fatty acids?
Prostaglandin and leukotriene synthesis, maintenance of skin and coat condition and membrane function
What are signs of essential fatty acid deficiency in cats?
Hair loss, poor wound healing, anaemia and reduced fertility
Why is linoleic acid an essential fatty acid?
Mammals can’t add another double bond on the methyl side of oleic acid
How is linoleic acid converted to arachidonic acid in dogs and man?
Linoleic acid to alpha-linoleic acid to dihomo-alpha-linoleic acid to arachidonic acid
How are retinol and retinal formed?
Retinol preformed in foods of animal origin or in bacteria, retinal made from beta-carotenes in intestinal mucosa
What is beta-carotene with respect to retinal?
Two molecules of retinal joined at aldehyde end
Why enzyme can dogs and man use to convert beta-carotene to retinaldehyde?
Beta-carotene-dioxygenase
Why do cats need preformed vitamin A, not just beta-carotene?
Don’t have beta-carotene dioxygenase
What is vitamin A used for?
To make visual pigment, rhodopsin, for skin and bone development, immunity and reproduction
What is a cause and problem of vitamin A toxicity in cats?
Too much liver or cod liver oil causes hypervitaminosis A causing cartilage calcification between neck vertebrae
What is nicotinic acid important for?
Metabolic pathways for hydrogen transfer ie NAD and NADP.
In man and dogs, what is nicotinic acid formed from?
Tryptophan
In man and dogs, what % of tryotophan in converted to nicotinic acid?
1%
How does the nicotinic acid requirement of cats compare the that of dogs? Why?
4 x higher in cats because they have high activity of picolinic carboxylase so lots of glutamate and no nicotinic acid to protect against toxic effects of high tryptophan
What does deficiency of nicotinic acid cause?
Pellagra - severe mucosal and intestinal ulceration causing dehydration and death
What are some signs that cats are less able to cope with high carbohydrates?
Glucokinase activity low in feline liver, pancreatic amylase has 3x less activity than dogs, intestinal amylase stimulated less by dietary starch, cats fed high protein can maintain blood glucose level better when starved than if they’d been fed high carbs
What are signs of cobalt deficiency?
Progressive loss of appetite, weight and production, anaemia, weakness and pica - can’t make B vitamins
What are signs of copper deficiency?
Poor coat, loss of condition, reproductive problems
What are signs of iodine deficiency?
Weakness in new-borns, stillbirths
What are signs of manganese deficiency?
Infertility, poor growth, poor hair coat
What are signs of zinc deficiency?
Parakeratosis, alopecia, poor condition
What are signs of selenium deficiency?
Muscular dystrophy (white muscle disease)
Where is vitamin A stored?
The liver
What are two precursors of retinol found in plant matter?
Carotenoids, xanthophylls
What destroys vitamin A and what encourages this?
Oxidation - light, moisture and air
What is vitamin A used for and what can deficiency cause?
Vision (rhodopsin) and epithelial integrity, deficiency causes night blindness and rough scaly skin
Excess of which vitamins is toxic?
D and A
What are three forms of vitamin D?
Ergocalciferol, cholecalciferol, calcitriol
What is the main form of vitamin E?
Alpha-tocopherol
Why is a regular supply of vitamin E required?
Not stored in the body
What % vitamin E is lost during haymaking?
90%
What can vitamin E or selenium deficiency cause?
Nutritional myopathy - white muscle disease in calves, stiff lamb disease, cardiac myopathy (mulberry heart disease) in pigs
Why is vitamin K deficiency rare?
Found in most green foods
What does menadione form?
Prothrombin
What is sweet clover disease?
Dicoumarol is anti-vitamin K, causes petechiation, haemorrhage, anaemia
What can vitamin B deficiency cause?
Poor growth and nerve problems
Why are primary vitamin B deficiencies not seen?
All members of the complex are formed by rumen and colon microbes
Where is thiaminase gained/produced?
Can be present in diet or produced by rumen bacteria during acidosis
What is a result of thiaminase deficiency?
Cerebrocortical necrosis in lambs
What does cobalt deficiency cause?
Vitamin B12 requires cyancobalamin and intrinsic factor from stomach pylorus so deficiency causes pernicious anaemia
What does milk fever cause?
Muscle hyoerexcitability then paralysis of all muscle types
What can cause hypocalcaemia?
Calcium depletion or excess plasma protein binding in alkalosis
What causes hypercalcaemia and what can it result in?
Excess PTH causes metastatic calcification
What can cytochrome oxidase deficiency interfere with?
Pigmentation of hair, fur and wool
What is “swayback”?
Poor myelination in lambs
What is goitre?
Neck swelling as thyroid gland increases in volume
How does goitrin affect thyroxine production?
Interferes with iodination of tyrosine
What are some poisonous plants?
Yew (taxol inhibits microtubules), ragwort (alkaloid causes cirrhosis of the liver), buttercup (causes buccal ulcers)
What does zinc deficiency cause?
Parakeratosis (abnormal scaly skin) in pigs
What is a “teart pasture”?
High molybdenum which in the presence of sulphur forms thiomolybdenate which chelates copper and reduces its absorption
What parts of the world are sodium-deficient pastures common in?
Africa, Australia
What does selenium deficiency cause?
Myopathy
How can potassium deficiency occur?
Diuretics (iatrogenically)
What can potassium deficiency cause? Excess?
Deficiency = hyperpolarisation of excitable cells, excess = hyperpolarises, affects heart
What can excess alfalfa cause?
Too much potassium causes hyperkalaemic periodic paralysis on mutated sodium channels
How is hypomagnaesic tetany different to calcium deficiency?
Doesn’t progress to flacidity
When does acute lack of magnesium occur?
Following turnout onto succulent pastures
When does chronic lack of magnesium occur?
Following acute stress imposed on low intake
Which mineral do high N/K fertilisers interfere with the uptake of?
Calcium
What is an advantage of growing lucerne, alfalfa and clover?
Legumes, fix nitrogen, don’t require NO3- fertiliser
Which kind of grass accumulates tryptophan?
Rapidly growing grass after it’s been cut
What is a problem with legumes?
Foam stabilisers prevent eructation and result in accumulation of rumen gases - bloat, pressure on diaphragm, can’t breathe
What problem does gossypol from cottonseed cause?
Causes damage to red cells in heart
What is “tedding”?
Cutting grass into small pieces so it dries faster
What bacteria can mouldy hay contain?
Actinomycetes (farmers lungs), aspergillus (mycotic abortion), listeria (listeriosis - abscesses and abortion)
Why can concentrates cause bloat?
Excessive fermentable carbohydrates
What is the ideal Ca:P ratio?
2:1
Which vitamin are fat soluble and which are water soluble?
Fat - ADEK, water - BC
What causes goose-stepping in pigs?
Pantothenic acid deficiency
What causes curly toe deficiency in poultry?
Riboflavin, B2 deficiency
What is thiamine B1 a cofactor for?
Pyruvate dehydrogenase
What are menadione and phylloquinone needed for?
Prothrombin synthesis
What species does dicoumarol in clover particularly affect?
Cattle
What % gross energy is lost as rumen gases?
8%
What is skimmed milk denatured with?
Oil
Which animals are fed reconstituted skimmed milk?
Pigs and calves
Why should animals be weaned off artificial milk replacer ASAP?
Reduces diarrhoea and cost of feeding
What are milk pellets and which species are they fed to?
Dried skimmed milk, for pigs weaned young
What is the normal DM content of dried grass?
15-35%
Why is fresh grass of limited value for dairy cows in the winter?
Low protein and digestibility
What is DM of silage if you can squeeze water from it, if you can squeeze water with force, if you can only just squeeze water out, if you can’t squeeze water out?
20%, 20-25%, 25-30%, 30-40%
What is the usual DM content of haylage?
50%
What horses in particular should be given haylage?
Respiratory problems - “broken wind”
What colour straw is best?
Shiny dark gold
What stock can you feed grass feed to?
All
Why is grass meal only used in limited circumstances?
Expensive, some vitamins lost
What is the major nutrient for which soya bean meal is purchased?
Protein
What is the oil content of soya bean meal?
1%
Why do you toast soya bean meal?
To inactivate trypsin inhibitor
What are the major anti-nutritive or toxic factors in soya bean meal?
Contains anticoagulant, cysteine and methionine are sub-optimal, contains allergic goitrogenic
What is the main nutrient provided by fish meal?
Protein - lysine methionine tryptophan
What livestock would you feed fish meal to?
Young simple stomached animals
What colour is good quality fish meal and why?
Light brown because if it is dark brown then it’s been overheated and there’s too much acid-detergent insoluble nitrogen
What does micronised mean?
Microwaved and rolled
Where are rumen-protected lysine and methionine released?
Abomasum
How do you feed rumen-protected lysine and methionine?
In concentrates, not silage because it would be degraded in rumen
What are limiting amino acids in cats, cattle, poultry and pigs?
Taurine in cats, methionine in cattle for horn, methionine in poultry for feathers, lysine in pigs for muscle growth
What amino acids are present in high or low concentrations in beans and peas?
High in lysine, low in cysteine and methionine
How are beans and peas processed before feeding to dairy cows?
Cracked, kibbled, coarsely ground
How are beans and peas fed to horses?
Micronised
Which grains have the highest and lowest energy content?
Highest is maize, lowest is oats
Which species are fed oats and how are they prepared?
Horses and ruminants, fed bruised or crushed
What are the disadvantages of using maize in livestock rations?
Poor quality protein, low in tryptophan, lysine or methionine
How are potatoes fed to crops?
Cooked for pigs and poultry, raw for cattle
What is protein degradability of by-products?
Variable depending on heating, usually between that of fishmeal (40%) and silage (85%)
How do you store wet brewers grains?
Ensiled
What stock is sugar beet pulp fed to?
Not pigs or poultry, good for sheep and dairy cows
What is fibre content of sugar beet pulp like?
High fibre like grass and silage
How should sugar beet pulp be fed to horses?
Soaked because it swells up
What does proximate analysis measure?
Moisture, ash, crude protein, ether extract, crude fibre, nitrogen-free extract, dry matter, gross energy, carbohydrate
What is the biological value (BV)?
Proportion of food protein used to synthesize body tissue and compounds
What is neutral detergent fibre?
Residue after extraction with boiling neutral solutions of EDTA and sodium lauryl sulphate
What is modified acid detergent fibre?
Residue after extraction with acids
How do you work out crude protein from nitrogen content?
Multiply by 6.25
What proportion of a protein’s mass comes from nitrogen?
1/6
Which reaction is used to measure nitrogen?
Biuret
Why is the crude fibre measurement not useful for a herbivore diet?
They can get nutrients from it
What is another term for carbohydrates?
Nitrogen free extractive
What % metabolisable energy is lost in urine in monogastrics?
4-8%
What % metabolisable energy is lost in urine and methane in ruminants?
8 and 12%
How many years ago were dogs domesticated?
40,000
When is puberty in a dog?
6-10/12 months
How long is anoestrus in dogs?
3 months
How long is metoestrus in dogs?
2 months
How long is pro-oestrus in dogs?
1-2 weeks
How long is oestrus in dogs?
9 days
When is the neonatal period in dogs?
0-14 days
When is the transitional period in dogs?
14-21 days
When is the socialisation period in dogs?
3-10 weeks
When is the “juvenile” period in dogs?
10 weeks to 6 months
When is the socialisation period in cats?
2-7 weeks
What is a forage feedstuff?
Grass and conservation products
What is a total mixed ration?
Grass and conservation products plus concentrates
What moisture content does hay go from and to?
65-85% to 15%
What % water and dry matter should silage be?
70% water, 30% dry matter
What length is grass for silage cut to?
2-4cm
What does silage analysis include?
pH, dry matter, protein, fibre, digestible organic matter, energy, residual sugars
How much of the total nitrogen should be true protein?
Above 75%
What is a good indicator of secondary fermentation?
Ammonia
What is a problem with too much fibre in ruminants?
Reduces appetite
How can you measure fibre?
Neutral detergent fibre, acid detergent fibre and modified acid detergent fibre
What is the ideal digestible organic matter value?
450-800g per kg dry matter
What is a usual energy value per kg dry matter for ruminants?
10-12 MJ
What proportion of the metabolisable energy should be fermentable in ruminants?
Greater than 70%
What are some examples of volatile fatty acids?
Acetic, propionic, butyric
What % of fermentation acids should be volatile fatty acids?
Less than 20%
What are residual soluble carbohydrates used for?
Energy for rumen microflora
What may reduce residual sugar levels in feed?
Wilted crops or adding acid when ensiling
What is a normal value for residual soluble carbohydrates per kg dry matter?
Greater than 100g
Which fat-soluble vitamins can be stored?
ADEK (all of them)
Which is the only water soluble vitamin that can be stored?
B12
How do ruminants and horses meet B vitamin requirements?
Microbial synthesis
Where is vitamin A found?
Liver, egg yolk, milk fat
Is vitamin A present in vegetable material?
No but carotenoid precursors are
Which part of the plant are carotenoids found in?
Green parts
Which is the only vegetable concentrate to contain carotenoids?
Yellow maize
What time of year is vitamin A deficiency common?
End of winter
Which species can’t form vitamin A from beta carotene so needs preformed vitamin A?
Cats
What disease do cats get if they eat too much liver?
Cervical spondylitis
In which conditions is vitamin A unstable?
Heat, light, water, metals
What % vitamin A per month is lost in food stored properly?
10%
What is vitamin D2 called?
Ergocalciferol
What is vitamin D3 called?
Cholecalciferol
Which animal tissues contain vitamin D?
Fish liver oils, eggs and colostrum
What is vitamin D formed from under UV light?
Dihydrocholesterol
Which species can’t produce vitamin D?
Dogs
Which species needs vitamin D3?
Poultry, some primates
What does excess vitamin D cause? What about deficiency?
Metastatic calcification, rickets
Which vitamin E compound is the most active?
Alpha tocopherol
Under what concentrate storage conditions is vitamin E lost?
Wet
Where is vitamin E deficiency often seen?
Calves on whole milk
Which foods is vitamin K found in?
Green foods, egg yolk and fish meal
What is vitamin K available synthetically as?
Menadione
Which feedstuff does not contain B1 thiamin?
White flour
What might B1 deficiencies be caused by?
Plants or bacteria producing thiaminase
What conditions is B1 deficiency seen in?
Bracken poisoning, cerebrocortical necrosis, Chastek’s paralysis
Where is B2 riboflavin found?
Yeast, liver, milk esp whey and green leafy crops
Why is B2 deficiency not seen in adult ruminants?
Made in the rumen
What does B2 deficiency cause in chicks?
Clubbed down and curly toes paralysis
In which foodstuff in nicotinamide found in bound form?
Cereals
What can the body synthesise nicotinamide from?
Tryptophan
What disease does nicotinamide deficiency cause in poultry?
Chondridystrophy
Why is more B6 pyridoxine needed in high protein diets?
Has role in protein metabolism
For which species is there not enough pantothenic acid in cereals?
Pigs, poultry, cats or dogs
What does pantothenic acid deficiency cause in pigs?
Goose stepping
What does pantothenic acid deficiency cause in dogs?
Premature greying
What can folic acid deficiency cause?
Anaemia or neural tube defects
Which feeds are poor in biotin?
Wheat and barley
What does biotin deficiency cause in poultry?
Fatty liver and kidney syndrome
What does biotin deficiency cause in pigs and horses?
Foot lesions
Where is B12 cyanocobalamin found?
Foods of animal origin
What do B12 deficiencies in poultry cause?
Poor egg hatchability, poor growth, skin and feathering
What is needed to synthesise choline in a deficit?
Folic acid, B12 and methionine
Other than acetylcholine, what is choline needed for?
Methyl group transfer as betaine
What does choline deficiency cause in poultry?
Chondrodystrophy
What are some trace minerals?
Iron, iodine, copper, manganese, zinc, cobalt, selenium, molybdenum and chromin
Which feedstuffs have low calcium levels?
Cereals grains and meat
What % of phosphorus is found in bones and teeth?
80
Why do oilseeds and cereal grains have poor phosphate availability to ruminants?
Bound as phylates
What does phosphorus deficiency cause?
PICA, poor growth, reproduction, milk yield, stiff joints and muscle weakness
Why does phosphorus deficiency cause rickets in young birds?
Phytate binding
What does excess phosphorus cause in horses?
Bran disease - “big head”
What is Ca:P ratio in laying hens?
6:1 or greater
What % of magnesium is in skeleton?
70%
Are magnesium levels high or low in milk?
Low
What does magnesium deficiency cause in cows fed on whole milk?
Tetany
What is “grass staggers”
Lush spring grass - low Mg, high Na and K
What can excess magnesium cause in poultry?
Constipation
How can potassium be lost from the body?
Vomiting, chronic kidney failure
What can excess potassium interfere with?
Mg absorption
What can molasses high in potassium cause in poultry?
Loose droppings
What can dietary SO4 be used for?
Cartilage
What does NaCl deficiency cause in poultry?
Poor performance, cannibalism, egg eating
What can improve palatability in ruminant diets?
Salt
What % of iron is complexed in protein?
90%
Is milk a good or bad source of iron and copper?
Bad
If mothers are iron-deficient, where do puppies get their iron from?
Stores in liver
What lowers Fe absorption in laying hens?
High Ca
How available is cereal Fe to poultry?
Not very
What causes veal to be pale?
Low Fe
What can copper deficiency cause?
Poor fertility in cattle and sheep, diarrhoea, loss of hair pigmentation and wool crimp, anaemia, and “swayback” in lambs (poor myelination if spinal cord)
Why does a teart pasture cause copper deficiency?
Forms complex in gut
What is used as a growth promoter in pigs?
Copper
Why might sheep get copper poisoning from a concentrate diet?
Orchid sprays may contaminate
Which dog breed is susceptible to copper poisoning?
Bedlington terrier
What happens during copper poisoning?
Accumulates in liver, causes haemolytic crisis, increased liver enzymes give early warning
Which type of stomachs need preformed B12?
Monogastrics
What is cobalt deficiency called and what are some symptoms?
Listlessness, unthriftyness, lack of oestrus in ewes, poor conception in cattle
What can B12 deficiency take a long time to develop?
Body stores it
Why is B12 deficiency treated with an injection in ruminants?
Not well absorbed through ruminant gut
What can iodine deficiency cause?
Weak, deformed young, anoestrus, retained placenta or abortion
How do you prevent goitregenic foods causing a problem?
Provide extra iodine
In which feedstuffs is manganese levels low?
Maize, animal proteins, some pastures
What can manganese deficiency cause?
Infertility in dairy cows, calves with knuckled joints, poor hatchability and deformities in poultry
What disease can poultry get from a high-maize diet?
Chondrodystrophy
What can zinc deficiency cause?
Poor spermatogenesis and infertility in males
What’s the relationship between molybdenum and copper?
Low molybdenum levels cause copper toxicity, high molybdenum levels cause copper deficiency
What is selenium needed for?
To produce glutathione and glutathione peroxidase and other selenoproteins
Is selenium deficiency in pastures common?
Yes
What does selenium deficiency cause?
Myopathy in 6-18 month cattle at turn out and retained placenta
What does excess selenium cause?
Blind staggers, alkali disease
What fluorine levels will cause toxicity?
20ppm
What are some non-cellulosic feeds?
Good clover, grains, molasses, beet, turnips
How does the NDF content affect the acetate:propionate ratio and how does this affect milk fat content?
The lower the NDF, the lower the ratio and the greater the likelihood of reduced milk fat content
What can overfeeding of non-cellulosic feeds cause?
Acidosis and rumen stasis (“feedlot bloat”)
Why are non-cellulosic feeds essential for high milk fat content?
Spare breakdown of amino acids for energy in the liver during early lactation so they can be used for milk protein synthesis
What effect do non-cellulosic feeds have on the diet of a dairy cow?
Boost total feed intake, increase energy, increase protein, rectify specific nutrient deficiencies
What effects do cellulosic feeds have on the diet of a dairy cow?
Stimulation rumination and saliva production, produce acetic acid, buffer rumen acidity, reduce feed intake and weight gain, encourage weight loss, reduce feed costs
What are cereal grains?
Concentrated feeds where the main component is starch
What % dry matter are cereal grains?
86-90%
If dry matter is low in cereal grains, how must you store it?
Wet, preserved with propionic acid or caustic soda but this causes vitamin E destruction
Which part of the grain has proteins and lipids?
Embryo/germ
What are the layers in grain?
Starch endosperm surrounded by husk, oats and barley have an additional outer hull with an inner and outer pale
What are the main oils in cereals?
Unsaturated - linoleic and oleic
Which vitamins do cereals contain
No A or D, some beta carotene in yellow maize. Some vitamin E unless wet storage. B vitamins good except B12, B2 and biotin. Niacin present but bound in monogastrics.
What is the principal cereal for horses?
Oats with some barley and fluked maize
What is the principal cereal for pigs and ruminants?
Barley
What is the principal cereal for poultry? What about the USA?
Wheat, maize
What is the problem with wheat containing high gluten?
Dough formation/digestion disturbance in pigs and horses
What’s a problem with feeding wheat as a meal/mash to poultry?
Beaks become sticky
What % wheat meal is added to pelleted compound feeds so the gluten can bind it together?
15%
What are some hot and cold processes for cereals?
Steam flaking, micronisation are hot and grinding, rolling are cold
Why might propionic acid be added to high moisture grains?
Mould inhibitor
Why is some cereal processing necessary for cattle?
Whole grains can get into abomasum so any grains not cracked when eaten won’t be ruminated
Which part of the grain does cereal processing damage?
Seed coat
Why is slow starch release a good thing in ruminants?
Protects rumen from low pH
For how long after NaOH treatment should you not use whole grain?
7 days
What is the nutritional value of oat hulls?
None - fibrous filler
What is brewers/distillers grain?
Insoluble residue after starch to maltose
What is wheat bran?
Husk and adherent endosperm
What is middlings?
More endosperm, less husk
What is wheatfeed?
Bran + middlings
What % flour and wheatfeed is wheat?
72% flour, 28% bran and middlings
What is the main energy source in roots?
Sucrose
What are turnips high in?
Non-protein nitrogen
Why is sugar beet not usually used?
Poor Ca:P ratio
What is the % DM in molasses?
70-75%
Why are molasses not used in poultry?
High in potassium, causes wet litter
What causes gastroenteritis in potatoes?
Alkaloid solanine
What may cause problems in manioc?
Cyanogenetic glucosides
How much more protein do peas and bean have than cereal?
2.5%
How long must peas and beans be stored for? Why?
3 months, may cause digestive disturbances
Why does oilseed processing involve heat?
Inactivates trypsin inhibitors
What are oilseeds low in?
Calcium, vitamin E
Up to what % protein concentrates are used in monogastrics to make up amino acid deficiencies?
10
What may go rancid in fish meal?
Unsaturated fats
What are the only ruminants where fish meal is used?
Young or high yield dairy cows
What is there high risk of in meat and bone meal?
Salmonella
What is the maximum % of meat and bone meal which should be used?
2.5-5%
What are milk products deficient in?
Fe, Mg, vitamins D and E
Why can’t poultry digest lactose?
Fermented in caeca
Which species can have sour milk and how can you preserve it?
Pigs, formalin
Does barley or whey have better residual protein quality?
Whey
What is whey pimento rich in?
Lactose and minerals
What’s the rumen and reticulum volume?
130 litres
How much water does a dairy cow need per day?
60-100 litres
Do cows eat more when particle size is larger or smaller?
Smaller
At what dry matter content is cattle moisture intake highest?
45-55%
When is the only time camelids need concentrate feed?
Pregnancy and lactation
