Equine Nutrition and Feeding Management Flashcards
how is a horse classified in terms of its digesstive tract and feeding style
non-ruminant, hindgut-fermenting herbivore
list and describe the function of the 2 functional divisions of the horse digestive tract
- foregut: enzymatic digestion
- hindgut: microbial digestion
what 4 parts make up the foregut?
- mouth
- esophagus
- stomach
- small intestine
what does the foregut of horses function similarly to?
the digestive tract of monogastrics
what 2 parts make up the hindgut?
- large intestine (composed of the cecum, large colon, and small colon)
- rectum
what function as a large fermentative vat for horses?
the cecum and the large colon
what happens in the cecum and large colon that make a large fermentative vat? (2)
- microbes aid digestion
- microbes break fown nutrients that would otherwise be unavailable to the horse
what are the 5 functions of the mouth?
- prehension
- mastication
- saliva production
- minimal digestion
- swallowing
how much salive do horse produce per day?
about 10 gallons per day
what does saliva do?
softens food and helps form a feed bolus to pass down the esophagus
how is minimal digestion accomplished in the mouth?
saliva contains some, but limited amylase to begin some digestion
what does it mean if a horse chokes? compare to human
a bolus of food is stuck in the esophagus, can massage to clear; in humans we choke when food is stuck in our trachea
what is done if horses have poor dental conformation?
float the teeth: file them down because teeth grinding side to side can cause sharp points to form on the molars
what are 5 signs of poor dental conformation?
excessive loss of feed (dribbling on the ground while eating)
2. positioning head sideways while chewing
3. untrhiftiness
4. whole grains or long hay in feces (indicated didn;t chew as efficiently)
5. quidding hay (drroling or spitting out, can’t keep in mouth)
what does hypsodont mean literally? then apply to horses
high crowns; teeth continue to emerge from gum line over life
describe horse teeth (2)
- flat surfaces for grinding fiber
- enamel covers entire length from crown to below gum line
what does the esophagus do and how?
moves food bolus to stomach by peristalsis
what does the diameter and tone of the musculature and angle of entrance into the stomach of the esophagus result in?
- make it difficult for the horse to expel gas through eructation of vomiting
- predisposes horse to ruptures, distension, and colic
what does the cardiac sphincter do?
controls the movement of food from the esophagus to the stomach
what is a common site of ulcers if acidic materal touches it and why?
the margo plicatus, the border between the glandular and nonglandular stomach; if acidic material touches the unprotected nonglandular area= ulcers
how large is the horse stomach and what percentage of the total volume of the digestive tract does it take up?
3-4 gallons; about 8% of total volume of GI tract
describe the flow of ingesta through the horse GI system and why it is this way
the stomach is small because horses are designed to eat constantly, little meals, so flow of ingesta is relatively fast to support the wander and graze eating style
what is gastric emptying dependent upon in horses? explain what happens with large meals
gastric emptying is dependent upon volume; so large meals pass more quikcly than feed eaten at slow, continuous volumes (as in grazing); this means that with large meals there is not full foregut digestion before ingesta moves to the hindgut (no good)
describe a horse’s sense of satiety and what this relates to in their eating style naturally
horses have a limited sense of satiety, this is to help them meet their caloric needs by grazing high fiber forages for many hours without becoming full
describe the potential repercussions of a horse’s limited sense of satiety
if a horse is given or has access to a lot of grain, it will overeat the good stuff bc it won’t feel full and that’s real bad for digestion (decreased absorption)
what is the main site of digestion and absorption in horses?
the small intestine
what can the small intestine digest and absorb (6)
- most sugars
- amino aicds
- lipids
- fat-soluble vitamins
- some water-soluble vitamins
- minerals
what percent of the GI tract is taken up by the small intestine?
30% of GI tract
do horses have a gall bladder? if not what happens instead?
no; bile salts are instead secreted continuously through the bile duct from the liver directly into the small intestine (because eat constantly; don’t need to store bile, always need it)
what is used in horses for digestibility trials? explain?
fecal and urine collection bags are strapped to the horse; males are commonly used because it is easier to separate urine and feces, but horses don’t like them so you must acclimate them to the bags first
since the feed intake level influences the rate of flow of digesta, describe the rate of passage of frequent, small meals
moderate and steady (the goal)
what 2 things affect rate of flow of ingesta?
- feed intake level
- physical form of feed
describe how pellets pass through a horse GI tract as opposed to textured grain mixes combined with hay
pellets pass more quickly bc more digestible than grain mxed combined with hay
on average, how long does it take for feedstuffs to pass through the entire small intestine?
65-70 minutes
what are advantages of feeding pellets? (3)
- less dust
- uniform composition
- easier to feed
what MUST be in a horse’s diet for proper GI tract function?
roughage!
what marks the beginning of the hindgut? describe it
the cecum; a smooth muscular pouch that contracts to churn feed
how does ingesta pass from the small intestine to the cecum?
through the ileocecal valve
where is the cecum located? how big is it?
a the junction of the ileum and the large colon; on the right side of the horse’s abdomen; has an 8-9 gallon capacity
what are the 3 parts of the cecum? describe
apex: pointy end at beginning
body: curly Q
base: the end of the cecum
what happens to ingesta in the cecum? how?
mixing, churning (smooth muscle contraction), and microbial fermentation (via bacterial, protozoal,and fungal populations)
how does ingesta exit the cecum?
through the cecocolic orifice into the right ventral large colon
how large is the large colon? (2)
- 40-50% total capacity of the GI tract
- approx 20 gallon capacity
what happens in the large colon?
finer particles continue to break down and decrease in size, plus some additional microbial digestion
what is the most common site of impaction colic and is located in the large colon? what is this important for?
the pelvic flexure; important for separating fiber particle size
what happens at the end of the large colon?
it narrows into a short section called the transverse colon
what are the 3 parts of the cecum? describe
apex: pointy end at beginning
body: curly cue
base: the end of the cecum
what happens in the small colon? (2)
- finals site of water absorption
- formation of fecal balls
describe what happens to the dry matter content of ingesta as it passes from large intestine to rectum?
dry matter content increases
take us through the cecum, large colon, and small colon (A-I)
A: ileum/ileocecal valve
B: cecum
C: R ventral colon
D: L ventral colon
E: pelvic flexure
F: L dorsal colon
G: R dorsal colon
H: transverse colon
I: small colon
what is grain overload?
when horses eat too much grain, causing rapid passage of starch to cecum and colon
what happens to the microbial populations in horses due to grain overload? what is the result of this?
- there is a rapid increase in the number of lactic-acid producing bacteria, which causes pH to drop from 7 to 4 in 12-24 hours
- starch-fermenting organisms proliferate
- endotoxemia results
what is the range of the daily minimum requirement of water for horses and what does this depend on (2)
5-20 gallons, depends on
1. environment
2. physiological state
related to feed, when does water intake increase? (2)
- as feed intake increases to support activity or lactation, water intake also increases
- if fed a low digestible, poor quality ration, water intake will also increase
what MUST horses have regarding water? what must you be aware of regarding water?
must have free access to clean, palatable water, but watch the mineral content
is energy a nutrient?
no; it is a requirement
what is energy?
the capacity to do work
how is the energy content of feed measured?
calories
what are food calories?
the amount of energy produced by cellular metabolism of that food inside an animal
what nutrients provide energy?
CARBS AND FATS and protein if needed
how do we feed horses for energy? (3)
- grains
- forages
- supplements
do you want to use protein as a main source of energy? why or why not?
no! urea and amoonia are byproducts of protein metabolism and can cause health issues if inhaled, protein is expensive to feed, and heat is also a byproduct of protein metabolism
how is energy supplemented?
fat supplements such as corn oils (more later)
how are calories describe in horse nutrition? what does this represent?
in mega calories (Mcal) 1Mcal is 1,000 kcal
how man kcal per gram from CHO, fat, protein
CHO: 4 kcal/gram
fat: 9kcal/gram
protein: 4kcal/gram
what are the 2 groups of carbohydrates based on plant physiology?
- NSC (nonstructural CHO): stored within plant cells
- structural CHO: support plant walls
what do grains provide in the diet?
hydrolyzable CHOs in the form of simple sugars, disaccharides, and starch absorbed in the small intestine
where does starch go during digestion? give ideal and then bad news bears
ideally: digested in small inestine;
but if rate of passage is increases or abrubt diet change, bypasses to the hindgut where it is digested by microbes and absorbed as VFAs
what are VFAs?
volatile fatty acids, absorbed from strach and important sources of calories
what are the major products of fiber digestion?
the VFAs acetate!!! and butyrate (proprionate)