Equine Nutrition and Feeding Management Flashcards
1
Q
how is a horse classified in terms of its digesstive tract and feeding style
A
non-ruminant, hindgut-fermenting herbivore
2
Q
list and describe the function of the 2 functional divisions of the horse digestive tract
A
- foregut: enzymatic digestion
- hindgut: microbial digestion
3
Q
what 4 parts make up the foregut?
A
- mouth
- esophagus
- stomach
- small intestine
4
Q
what does the foregut of horses function similarly to?
A
the digestive tract of monogastrics
5
Q
what 2 parts make up the hindgut?
A
- large intestine (composed of the cecum, large colon, and small colon)
- rectum
6
Q
what function as a large fermentative vat for horses?
A
the cecum and the large colon
7
Q
what happens in the cecum and large colon that make a large fermentative vat? (2)
A
- microbes aid digestion
- microbes break fown nutrients that would otherwise be unavailable to the horse
8
Q
what are the 5 functions of the mouth?
A
- prehension
- mastication
- saliva production
- minimal digestion
- swallowing
9
Q
how much salive do horse produce per day?
A
about 10 gallons per day
10
Q
what does saliva do?
A
softens food and helps form a feed bolus to pass down the esophagus
11
Q
how is minimal digestion accomplished in the mouth?
A
saliva contains some, but limited amylase to begin some digestion
12
Q
what does it mean if a horse chokes? compare to human
A
a bolus of food is stuck in the esophagus, can massage to clear; in humans we choke when food is stuck in our trachea
13
Q
what is done if horses have poor dental conformation?
A
float the teeth: file them down because teeth grinding side to side can cause sharp points to form on the molars
14
Q
what are 5 signs of poor dental conformation?
A
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)
15
Q
what does hypsodont mean literally? then apply to horses
A
high crowns; teeth continue to emerge from gum line over life
16
Q
describe horse teeth (2)
A
- flat surfaces for grinding fiber
- enamel covers entire length from crown to below gum line
17
Q
what does the esophagus do and how?
A
moves food bolus to stomach by peristalsis
18
Q
what does the diameter and tone of the musculature and angle of entrance into the stomach of the esophagus result in?
A
- make it difficult for the horse to expel gas through eructation of vomiting
- predisposes horse to ruptures, distension, and colic
19
Q
what does the cardiac sphincter do?
A
controls the movement of food from the esophagus to the stomach
20
Q
what is a common site of ulcers if acidic materal touches it and why?
A
the margo plicatus, the border between the glandular and nonglandular stomach; if acidic material touches the unprotected nonglandular area= ulcers
21
Q
how large is the horse stomach and what percentage of the total volume of the digestive tract does it take up?
A
3-4 gallons; about 8% of total volume of GI tract
22
Q
describe the flow of ingesta through the horse GI system and why it is this way
A
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
23
Q
what is gastric emptying dependent upon in horses? explain what happens with large meals
A
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)
24
Q
describe a horse’s sense of satiety and what this relates to in their eating style naturally
A
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
25
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)
26
what is the main site of digestion and absorption in horses?
the small intestine
27
what can the small intestine digest and absorb (6)
1. most sugars
2. amino aicds
3. lipids
4. fat-soluble vitamins
5. some water-soluble vitamins
6. minerals
28
what percent of the GI tract is taken up by the small intestine?
30% of GI tract
29
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)
30
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
31
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)
32
what 2 things affect rate of flow of ingesta?
1. feed intake level
2. physical form of feed
33
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
34
on average, how long does it take for feedstuffs to pass through the entire small intestine?
65-70 minutes
35
what are advantages of feeding pellets? (3)
1. less dust
2. uniform composition
3. easier to feed
36
what MUST be in a horse's diet for proper GI tract function?
roughage!
37
what marks the beginning of the hindgut? describe it
the cecum; a smooth muscular pouch that contracts to churn feed
38
how does ingesta pass from the small intestine to the cecum?
through the ileocecal valve
39
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
40
what are the 3 parts of the cecum? describe
apex: pointy end at beginning
body: curly Q
base: the end of the cecum
41
what happens to ingesta in the cecum? how?
mixing, churning (smooth muscle contraction), and microbial fermentation (via bacterial, protozoal,and fungal populations)
42
how does ingesta exit the cecum?
through the cecocolic orifice into the right ventral large colon
43
how large is the large colon? (2)
1. 40-50% total capacity of the GI tract
2. approx 20 gallon capacity
44
what happens in the large colon?
finer particles continue to break down and decrease in size, plus some additional microbial digestion
45
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
46
what happens at the end of the large colon?
it narrows into a short section called the transverse colon
47
what are the 3 parts of the cecum? describe
apex: pointy end at beginning
body: curly cue
base: the end of the cecum
48
what happens in the small colon? (2)
1. finals site of water absorption
2. formation of fecal balls
49
describe what happens to the dry matter content of ingesta as it passes from large intestine to rectum?
dry matter content increases
50
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
51
what is grain overload?
when horses eat too much grain, causing rapid passage of starch to cecum and colon
52
what happens to the microbial populations in horses due to grain overload? what is the result of this?
1. 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
2. starch-fermenting organisms proliferate
3. endotoxemia results
53
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
54
related to feed, when does water intake increase? (2)
1. as feed intake increases to support activity or lactation, water intake also increases
2. if fed a low digestible, poor quality ration, water intake will also increase
55
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
56
is energy a nutrient?
no; it is a requirement
57
what is energy?
the capacity to do work
58
how is the energy content of feed measured?
calories
59
what are food calories?
the amount of energy produced by cellular metabolism of that food inside an animal
60
what nutrients provide energy?
CARBS AND FATS and protein if needed
61
how do we feed horses for energy? (3)
1. grains
2. forages
3. supplements
62
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
63
how is energy supplemented?
fat supplements such as corn oils (more later)
64
how are calories describe in horse nutrition? what does this represent?
in mega calories (Mcal) 1Mcal is 1,000 kcal
65
how man kcal per gram from CHO, fat, protein
CHO: 4 kcal/gram
fat: 9kcal/gram
protein: 4kcal/gram
66
what are the 2 groups of carbohydrates based on plant physiology?
1. NSC (nonstructural CHO): stored within plant cells
2. structural CHO: support plant walls
67
what do grains provide in the diet?
hydrolyzable CHOs in the form of simple sugars, disaccharides, and starch absorbed in the small intestine
68
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
69
what are VFAs?
volatile fatty acids, absorbed from strach and important sources of calories
70
what are the major products of fiber digestion?
the VFAs acetate!!! and butyrate (proprionate)
71
what is so important about acetate?
it is a direct energy source
72
what happens as increasing proportions of starch are left undigested in the small intestine?
proprionate increases
73
what is the result of large amounts of starch in the hindgut? (3) what is this also called?
grain overload again
1. prediposes horse to colic
2. gaseous products of microbial digestion
3. abnormal changes in gut pH and fluid balance
74
what influences the amount of starch bypassing the SI to the hindgut? (3)
1. intake level (increased rate of passage means increased starch in hindgut)
2. abrupt diet changes
3. small particle size from ground feed (also increase rate of passage)
75
what are the 5 results of overeating grain?
1. microbial imbalance
2. excessive acid
3. damage to membranes of hindgut
4. colic
5. laminitis
76
what is the recommendation for feeding for energy? (2)
1. split starch feeds into 2 meals when grain levels are greater than 0.5% of BW per day
2. 5-6lbs of grain as the upper limit for an 1100lb horse
77
what is a source of fermentable CHOs (fiber) for horses? why are these important? (2)
hay and pasture
1. critical for integrity of microbiome
2. contain fructose, soluble and insoluble fibers, hemicellulose, cellulose, and lignin
78
what percent of their body weight should horses be eating daily?
2-2.5%
79
compare the digestibility of mature stemmy feedstuff to immature leafy stuffs
mature stemmy: inefficiently digested
immature leafy: efficiently digested
80
what nutrient makes up 2-3% of grains?
fat
81
what is commonly added to grian mixes, and at what percentage, for what kind of horses?
fat at 8-12% for older horses who struggle holding weight as GI efficiency decreases and they lose teeth
82
what is a safer source of energy than CHO/starch and is 2.25x more energy dense than CHOs
fat
83
what is the issue with feeding fat for energy
horses don't always like it because it isn't as palatable and you have to be careful that it doesn't go rancid
84
what is a common fat supplement for horses and why?
corn oil; it is palatable
85
what is the result of too much oil in feed?
it can coat the Gi tract, resulting in greasy stools and decreasing absorption
86
what are 6 benefits of added fat to a diet?
1. increased caloric density
2. imporved body condition score
3. improved absorption of fat-soluble vitamins
4. glossy coat
5. efficient fuel for aerobic performance (prolonged exercise)
6. management of certain diseases
87
describe what disease added fat to a diet can help manage and how?
can help manage polysaccharide storage myopathy, which is an issue with glycogen storage and usage; a high fat diet can counteract effects of the disease
88
what do we determine how much to feed horses based on? (2)
1. weight
2. activity
89
for a 500kg (1100lb) horse, give energy requirements for maintenance, late gestation, lactation, and intense work
maintenance: 16.7Mcal/day DE
late gestation (11 months): 21.4 Mcal/day DE
lactation (1st two months): 31.7Mcal/day DE
intense work: 34.5Mcal/day DE
90
give the energy requirement of 12 month yearling
18.8Mcal/day DE
91
what is DE?
digestible energy
92
what does protein supply and why is this important?
supplies amino acids, which are the greatest component of most body tissues and aid in developing and maintaining lean body tissue
93
how is protein absorbed in the small intestine? how is it absorbed in the hindgut?
small intestine: absorbed as amino acids and small peptides
hindgut: absorbed as ammonia
94
do horses have requirements for crude protein? if not, what do they require?
no; have requirements for amino acids
95
what are essential amino acids?
those that must be consumed because the body cannot synthesize them
96
how are essential amino acids absorbed?
intact because the horse cannot synthesize them
97
what is meant by quality protein?
contains more essential amino acids in the right ratio
98
what are the 10 essential amino acids?
PVT TIM HALL
99
what is meant by a limiting amino acid?
large concentrations of these amino acids are needed, but the body is usually deficient in these amino acids
100
what are the first three limiting amino acids in horses?
1. lysine
2. threonine
3. methionine
101
what is ideal protein?
a fantasy goal where dietary amino acids are provided in adequate amounts as well as in proper ratios to each other
102
how is protein digested in horses?
digested to amino acids in the foregut and then absorbed in the small intestine
103
what happens to the proteins that pass to the hindgut?
they contribute to the gut microbiome since they are not absorbed and produce ammonia instead
104
give the protein requirements of an 1100lb horse for maintenance, intense work, lactation, and for 4 month old weanling
maintenance: 630g or approx 8% of diet on a dry matter basis
intense work: 1,004g, approx 13%
lactation: 1,530g, approx 13.5%
weanling: 669g, approx 14.5%
105
why does a weanling need more protein than a mature horse on a maintenance diet? can you feed them more protein to push for faster growth?
they are growing and laying down muscle; can feed more protein to a certain extent for faster growth, but don't overdo because this stresses the bones and the horse will be unhealthy down the line
106
if you are feeding protein to a horse on an intense work diet, when would you want to provide/supplement protein? why?
AFTER exercise; to rebuild/regenerate damaged muscle tissue
107
describe dietary mineral research in horses
limited compared to other species
108
in terms of minerals in horses, what ratio do we care about?
Calcium: phosphorous
109
what is the ratio at which Ca:P is fed?
2:1
110
what are the functions of calcium? (5)
1. bone formation
2. muscular activity
3. cell membrane function
4. blood clotting
5. enzyme activation
111
in what 2 groups of horses is calcium hella important?
1. growing horses
2. lactating mares
112
what are the functions of phosphorous (4)?
1. bone formation
2. ATP, ADP- energy transfer
3. phospholipids in cell membranes
4. synthesis of DNA and RNA
113
what is big head disease?
too much phosphorous relative to calcium disrupts bone development
114
what are the 4 fat soluble vitamins?
A D E K
115
how are most vitamin needs met in horses?
through quality hay and pasture; shouldn't really have to supplement
116
what vitamin is most commonly supplemented in horses?
vitamin A
117
what is the biologically active form of vitamin A? what is the pro-vitamin
retinol is bioactive; beta-carotene is the pro-vitamin that is converted to beta-carotene
118
what are the functions of vitamin A? (3)
1. night vision
2. growth
3. reproduction
119
why does vitamin Ahave the greatest potential for toxicity?
it can be stored for up to 6 months in the liver and adipose tissue
120
what is moon blindness?
a deficiency in vision in low light due to a vitamin A deficiency
121
what is the active form of vitamin D?
1,25-dihydroxycholecalciferol (D3)
122
how do horses get vitamin D?
through sun cured hay and exposure to sunlight
123
when might vitamin D be supplemented?
if horses have limited access to fresh forage
124
what is the function of vitamin D?
calcium homeostasis
125
what is the most biologically potent form of Vitamin E?
alpha-tocopherol
126
what is the function of vitamin E?
antioxidant; scavenges for and removed free radicals
127
what is the name of vitamin K?
phylloquinone
128
what is different about vitamin K in horses?
it is synthesized by the microbes in their cecum and colon, so it is not routinely added to diets
129
what is vitamin K important for? (2)
1. blood clotting
2. vascular health
130
what are 2 water soluble vitamins?
B and C
131
how do horses get their B vitamins? regular and then for exercising horses
microbes produce regularly, but may supplement for exercising horses
132
what is the role of B vitamins?
catalysts for energetic pathways
133
how is vitamin C synthesized in horses?
from glucose
134
what is vitamin C important for? (2)
1. antioxidant
2. collagen synthesis
135
what is the common syaying for feeding forages? what does it mean?
forages first; should make up 50-100% of diet
136
what is the MINIMUM level of forage you should be feeding?
0.75% of body weight
137
what does incorporating long stem forage into rations do? (3)
1. increases particle size of ingesta to slow passage rate
2. increases dry matter intake to stimulate water intake (dehydration can lead to colic)
3. reduces incidence of tail hcewing, wood chewing, and coprophagy
138
what is important to consider when buying hay?
the nutritional value in relation to the cost and the kind of hay
139
how do you want hay to look for horses?
leafy, green, not old or coarse or musty
140
what are the 5 aspects of hay evaluation and which is most important?
1. plant maturity (most imporant!)
2. leafiness
3. color
4. odor
5. softness
141
what are 3 types of forages?
1. warm season grasses
2. cool season grasses
3. legumes
142
what are 3 warm season grasses? which of these is the best and most used for horses?
1. bermuda grass: the best and most used
2. bahia grass
3. crabgrass
143
what are 3 types of cool season grasses?
1. orchard grass
2. kentucky bluegrass
3. fescue
144
which of the 3 types of forages is the most nutritious and palatable and highest in protein?
legumes
145
what are 3 kinds of legumes?
1. alfalfa
2. white clover
3. birdsfoot trefoil
146
what is called the queen of the forages?
alfalfa
147
what is the big issue with alfalfa?
blister beetles
148
where are blister beetles found? do you only have to worry about them in these regions? why or why not?
central and southwest US, but since hay is shipped, you always have to look out for it with alfalfa
149
what is found in blister beetles and what does it cause in horses (3)?
cantharidin- a potent chemical irritant that causes
1. nephritis
2. cystitis
3. ulceration of oral, esophageal, and gastric mucosa
150
what 4 clinical signs are observed in horses who have eaten alfalfa infested with blister beetles?
1. colic
2. salivation
3. frequent urination
4. sham drinking (dunking head in water to relieve irritation)
151
how is illness due to eating alfalfa infested with blister beetles treated?
give fluids to flush out the toxin, mineral oil to coat the GI tract, and activated charcoal to bind up and remove the toxin
152
when are blister beetles in alfalfa observed?
at baling time while the hay is drying, the beetles swarm
153
what 3 grasses are bad for grazing horses and why?
1. sorghum
2. sudangrass
3. johnson grass
all have the potential for prussic acid, which interferes with oxygen transferring ability and can be lethal
154
what is a FANTASTIC grass for grazing? but what is the issue?
kentucky 31 tall fescue; was planted all over the US since it was so good but it can be infected with endophyte fungus
155
what is the most widely grown cultivated cool season pasture grass in the US? why?
tall fescue because it is such a hardy grass
156
why is tall fescue so hardy? (5 characteristics) and then say the reason for these characteristics
1. easily established
2. tolerates close grazing
3. stands up to heavy traffic
4. survives drought conditions better than most cool season grasses
5. resistant to insects, disease, and weed competition
so hardy due to symbiotic relationship with the endophyte fungus
157
where is the endophyte fungus found and what does it do?
found between the plant cells of tall fescues and produces and alkaloid toxin
158
what is the name of the fungus found in tall fescue?
neotyphodium coenophialum
159
how is the endophyte fungus spread?
seed-borne only
160
describe the prevalence of the endophyte fungus
most KY31 tall fescue pasttures are infected to varying degress
161
is the alkaloid effect of endoohyte fungus destroyed or reduced by mkaing hay (cutting grass)?
nope
162
can the endophyte fungus be detected visually on tall fescue? how detected
no; must send pasture samples to a lab for testing
163
what can endophyte-infected tall fescue result in in broodmares? (7)
1. abortions around time of foaling
2. carrying 30-40 days longer than normal (prolonged gestation)
3. dystocia due to large foals (possible red bag foaling)
4. thickened placenta (leading to infection, laminitis, problems re-breeding)
5. agalactia
6. mare does not exhibit typical signs of foaling
7. large "dummy" foals
164
what specifically causes the repro issues observed with fescue toxicity?
the alkaloid resulting from the fungus mimics dopamine
165
give the mechanism of fescue toxicity causing repro issues (4)
1. the alkaloid resulting from fungus infections mimics dopamine and binds to dopamine receptors
2. excess dopamine has a suppressing effect on prolactin, which is essential to the final stages of pregnancy and birth
3. without the prolactin signal, the mare's body does not realize it is time to foal
4.dopamine inhibits ACTH secretion by binding with DA2 receptors on corticotrophs
166
describe normal ACTH during late pregnancy
1. adrenocorticotropic hormone, secreted by corticotrophs (cells in the anterior pituitary); fetal ACTH is released
2. which triggers fetal release of cortisol
3. the increase of fetal cortisol increases the mare's progesterone and decreases her estrogen in the last 30d of gestation
4. these hormonal changes are necessary for normal gestation duration and parturition
167
describe ACTH in mares eating infected tall fescue
1. extra dopaminergic activity at the DA2 sites due to ergovaline mimicking dopamine
2. mares have decreased progesterone and increased estrogen
3. the signal is not given for parturition to begin so pregnancy is prolonged
4. dopamine also affects milk production as the interaction with DA2 receptors inhibits secretion of prolactin
168
what does prolactin do?
stimulates milk production when released from the pituitary gland
169
describe what happens when prolactin is inhibited
1. decreased mammary gland development and agalactia
2. intensified by decreased progesterone since progesterone is needed for mammary tissue to develop
170
what are 3 feeding mamagement solutions to tall fescue toxicity
1. take mare off fescue AT LEAST 30d before foaling, with 3 months prior being ideal
2. feed mare alfalfa hay or other legume hay (highly palatable and nutritious) in a dry lot, or stick mare in pasture with forage other than TF
3. eliminate fescue and replant with another grass, but this is labor intensive as fescue is hard to remove
171
if you choose to eliminate fescue and replant with another grass, what are 3 options?
1. an endophyte-free fescue such as jessup (but isn't as hardy so is more difficult to grow up)
2. Max-Q: infected with the fungus for symbiotic benefits, but a nontoxic version of the fungus; very expensive
3. kentucky 32: endophyte-free, is as persistent as KY31
172
how can you dilute the effects of infested fescue?
supplement with grain and hay feeding, should decrease amount of fescue consumed, but horses with still graze the fescue so will still have issues
173
how do you treat a mare that has consumed infected tall fescue?
with domperidone, a DA2 dopamine receptor antagonist that seems to relieve the prolactin depressing effects of ergot alkaloids and can shorten gestation to normal length and allow more mammary development
174
what is the risk of treating a mare with domperidone?
you want to give it before the expected foal date, but you can't really know if the mare in infected and if you give it too early the mare could foal prematurely and the foal won;t be mature enough
175
what are dummy foals? (4)
1. result from abornmal birthing
2. also called neonatal maladjustment syndrome (NMS)
3. affects 1-2% of newborn foals
4. exhibit neuro abnormalities such as detached, disoriented, unresponsive, confused, have trouble nursing
176
what is the madigan squeeze technique (MST)?
creating pressure aorund the lungs and heart mimics normal birth canal and is believed to signal a dummy foal to transition from sleeping in womb to wakefulness
