Term
| How are horses unique from other herbivores? |
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Definition
| They are non-ruminant herbivores |
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Term
| How does the stomach structure of the horse allow for greater agility than a cow? |
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Definition
| No rumen, very heavy ponderous stomach, lack of heavy stomach allows greater agility |
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Term
| Which has more nutritional efficiency, a horse or a cow? Why? |
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Definition
| Cow. A horse's caecum and colon are past the small intestine and the small intestine is the site of nutrient uptake and thus the fermentation occurs too late. Won't receive as many nutrients from fibrous material |
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Term
| How does the microbial activity of horses compare to that of ruminants? |
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Definition
| Lower-->therefore it is between ruminant and monogastric in nutrient utilization |
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Term
| How long does it take feed to move through a horse's GI tract? |
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Definition
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Term
| Why does a relatively small stomach cause problems for horses? |
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Definition
| Nibble under natural circumstances but in a confined setting eating meals can overload the stomach |
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Term
| How does the mouth structure contribute to horse digestion? |
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Definition
| Lips are strong, mobile, sensitive and prehensile which is important for digestion. Teeth on both upper and lower incisors which permit close grazing. Lower jaw is narrower than upper jaw so lateral grinding is limited. |
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Term
| Describe the salivary glands of the horse. |
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Definition
| Parotid secretes 90% of equine saliva. Sublingual and submaxillary glands are much smaller. Saliva contains bicarbonate buffers and lubricates the feed. Contains amylase which begins carb digestion |
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Term
| Compare the bovine stomach to the equine stomach. |
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Definition
| Bovine is 10 times greater capacity. The horse stomach empties about 3x faster. |
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Term
| Contents of the equine stomach? |
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Definition
| small microbial population-->some fermentation-->some VFAs-->can be an issue for horses with stress-->acid; digestion facilitated by gastric HCl which allows hydrolysis by pepsin; gastric lipase |
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Term
| Describe the structure of the small intestine and accessory organs |
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Definition
| SI is 30% of equine digestive tract. No gallbladder-bile directly from bile duct. Majority of absorption in duodenum and jejunem. |
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Term
| What percentage of the GI tract does the large intestine account for? |
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Definition
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Term
| Which has the larger large intestine a cow or a horse? |
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Definition
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Term
| What potential energy could VFAs synthesized in the caecum provide the horse with? |
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Definition
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Term
| Which animals require the most supplementation of water soluble vitamins? Why? |
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Definition
| Young and elderly. Bacterial population is in low supply |
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Term
| What happens to undigested dietary protein? |
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Definition
| Degraded to ammonia in the large intestine and carbon backbone becomes VFAs |
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Term
| Amino acid absorption in the large intestine? |
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Definition
| microbial aa of little significance-->very little active transport of aa's in large intestine |
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Term
| Why is high quality dietary protein required for horses to meet essential amino acid requirements? |
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Definition
| Less able to improve amino acid profile of low quality diet protein due to microbes late in digestive tract |
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Term
| When does the horse's caecum become fully functional? |
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Definition
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Term
| Describe the process of protein digestion in horses? |
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Definition
| Begins in the stomach with pepsin, small intestine is site of digestion of most protein absorbed by active transport, aa synthesized by microbial action are absorbed from the cecum and large intestine-->largely by diffusion |
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Term
| What amino acid promotes growth in young horses? Is this essential in the foal diet? |
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Definition
| Lysine. Yes-->low caecal development |
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Term
| Describe carb digestion in the horse. |
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Definition
| Digested and absorbed in the small intestine. Soluble carbs are metabolized to VFAs acetate, propionate and butyrate. Insoluble are metabolized to VFAs. Types of protozoa differ greatly from ruminants. |
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Term
| Describe lipid digestion in the horse. |
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Definition
| No gallbladder, but high fat is still well tolerated. Fatty acids absorbed in the small intestine. Fatty acid composition of body fat mimics that of dietary fat-->very little change to them. |
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Term
| Describe mineral digestion in the horse. |
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Definition
| Large intestine is major site of phosphorus absorption. Calcium is absorbed mainly in proximal small intestine. This is the reason dietary phosphorus reduces calcium absorption but not the opposite. |
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Term
| Likely causes of protein deficiency in horses? |
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Definition
| Feed grains and by-products are often deficient to certain AAs. High cost of protein supplements in horse feeds |
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Term
| Major body store of essential amino acids? |
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Definition
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Term
| Results of long term protein deficiency? |
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Definition
| Poor growth in young, muscle wasting in adults, immunosuppresion |
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Term
| Most labile pool of amino acids? |
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Definition
| Blood proteins-->mobilized in a fasted state |
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Term
| Common protein sources in equine feeds? |
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Definition
| Soybean meal, distillers dried grains, protein in grains such as corn, wheat and oats, protein in hay |
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Term
| Define essential amino acids |
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Definition
| Those which cannot be synthesized by the horse or cannot be synthesized in adequate amounts |
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Term
| Dietary essential amino acids for horses? |
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Definition
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Term
| Examples of amino acids that are only essential at certain development stages |
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Definition
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Term
| Why is lysine an important essential amino acid? |
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Definition
| For optimal growth. Because it is key to formation of cross-linkages in structural proteins |
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Term
| Lysine requirement for weanling horses? |
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Definition
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Term
| Lysine requirement for yearling? |
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Definition
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Term
| What dietary lysine supports maximal growth of thoroughbred and Quarter Horse foals? |
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Definition
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Term
| Lysine requirement range? |
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Definition
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Term
| Why does N balance improve during constant exercise intensity? |
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Definition
| Reduced urinary N loss resulting from improved N retention and increased muscle mass |
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Term
| What percentage of lysine uptake occurs in the equine distal jejunum? |
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Definition
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Term
| Which feedstuffs are richest in lysine? |
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Definition
| fish meal, dried brewers' yeast, soybean meal, dried skim milk |
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Term
| Adequate dietary cystine reduces the _______ requirement |
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Definition
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Term
| Adequate dietary tyrosine reduces the _______ requirement |
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Definition
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Term
| Waste product of amino acid catabolism? Energy cost? |
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Definition
| Urea, energy intensive process |
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Term
| How was methionine proven to be an essential amino acid in horses? |
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Definition
| Feeding supplemental dietary methionine in mares shows increased blood concentrations of methionine and other essential AA |
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Term
| What determines the first limiting amino acid? |
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Definition
| Deficiency of any one that will limit protein synthesis |
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Term
| What is the second limiting amino acid for yearling horses? |
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Definition
| Threonine-->low amounts show reduced feed intake and weight gain |
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Term
| What AAs smay increase equine aerobic work capacity? |
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Definition
| Leucine, isoleucine, valine and glutamine |
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Term
| What about branched chain amino acid catabolism is unique? |
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Definition
| Initial deamination takes place in muscle |
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Term
| What amino acid traps amino groups and carries them to the liver for urea synthesis? |
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Definition
| Alanine (Glucose-alanine cycle) |
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Term
| Which branched chain AA promotes nitrogen retention? |
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Definition
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Term
| How does leucine affect muscle protein synthesis? |
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Definition
| It promotes the loading of amino acids onto tRNA |
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Term
| How does leucine affect muscle protein degradation? |
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Definition
| A metabolite formed during the degradation of the C side chain of leucine alters pH in lysosomes which reduces activity of the acid cathepsins, catabolic enzymes that degrade proteins |
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Term
| How is protein for an energy source for horses? |
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Definition
| Inefficient and expensive |
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Term
| Results of being fed excess protein? |
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Definition
| Increased sweating and high pulse and respiration rates. Increased times to finish races |
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Term
| Results of feeding 130% of protein? 24%? 20%? 10, 13, 16, 19%? Overall? |
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Definition
| Increased urinary excretion of calcium and phosphorus. No adverse effects. No adverse effects? Increased growth rates over 112 days. Overall: Small excess gives no harm but excess provides no benefits |
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Term
| High fibre diets lead to higher ___________ levels |
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Definition
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