Roughage
high fiber feedstuffs (≥ 18% crude fiber)
Grass forage
higher in hemicellulose and NDF
Legume forage
higher in protein, calcium, pectin, lignin, vitamin E, & beta-carotene
Early to Mid-Maturity Hay
lots of leaves, fine stems, few seed heads growing horses, lactating mares, hard keepers
Mid-Maturity
lots of leaves, small + soft seed heads performance horses, pregnant mares
Mid to Late-Maturity
stemmy hays, lots of mature seed heads recreational-use horses, easy keepers, ponies
Early to Late maturity nutrient content
Decrease in: NSC, protein, minerals, DE, digestibility Increase in: hemicellulose, cellulose, lignin
Advantages of processed forage
less sorting, less waste, reduce gut fill - more can be eaten, less storage space, minimal dust, less chewing (for bad teeth)
Disadvantages of processed forage
eaten faster, boredom, wood chewing, may increase choke chances, may cost more, difficult to evaluate without lab
Minimum amount of forage needed? Ideal level?
minimum amount = 1.5% BW ideal = 90-100% of diet is forage
High-fiber alternatives to forage
beet pulp (highly digestible), hulls (less digestible)
Cereal Grains
high in starch; low in sugar, fiber, and fat
Grains vs forage
Grains have higher DE, higher starch, lower fiber
Processing grains
alters physical form of grain and improves digestion EXCEPT for oats
Grain byproducts
nutrient composition similar to roughages, all grain byproducts are high in phosphorus
Rice bran
high in fat (other brans are not)
High fat feedstuffs
vegetable oils, flaxseed, heat-processed soybeans
Vegetable oil
provides fat, does not provide any other nutrients
High protein feedstuffs
skim milk, soybean meal, cottonseed meal, whey, whole soybeans
Why is fat and fiber added to commercial feeds over starch?
high starch can cause a digestive upset
Fat-added feed
≥5% crude fat
Fiber-added feed
≥12% crude fiber
Fat and Fiber-added feed
≥5% crude fat and ≥12% crude fiber
Concentrates
needed when forage-only diet does not meet nutrient requirements (ex. growing horses, late gestation mares, lactating mares, moderate to heavy exercise, fed low quality forages)
Maximum amt of daily concentrate intake
< 50% total DM intake/day; 0.5% BW per meal
Complete feed
complete feeds combine roughage + fortified concentrate and are only food source; ≥18% crude fiber
Must add minerals
salt, electrolytes
What vitamins and minerals are made by horse or microbes?
vitamin E, vitamin A; calcium, phosphorous, magnesium, sodium, chloride, potassium, zinc, manganese, copper, selenium
What vitamins and minerals must be supplemented?
vitamin D, C, K; cobalt, chromium, fluorine, iodine, iron, sulfur
Options to supplement vitamins/minerals
mineral blocks, premix vitamin/mineral, ration balancer
When would vitamins/minerals needed to be supplemented?
forage only diet, unfortified grains, insufficient amt of fortified feed
What are dietary sources of energy? And what is their immediately available form?
Starch and sugar = blood glucose, fiber = propionate, acetate, fat = fatty acids, protein = some glucose/acetate
Stored forms of dietary energy
starch/sugar = liver/muscle glycogen + triglycerides, fiber = same as sugar/starch, fat = triglycerides, protein = not stored
How does exercise affect which energy sources are used?
Endurance = mostly fat, some carbs Middle distance = mostly carbs, some fat Sprint = carbs Combo = carbs and fat
Nutrient requirements most affected by exercise
Energy, water, electrolytes, vitamin E
Expected DM intake and hay:concentrate needed for horses in work
Light = 2% BW (70-80% forage, 20-30% grain) Moderate = 2.25% BW (50-70% forage, 30-50% grain) Heavy/intense = 2.5% BW (40-50% forage, 50-60% grain)
What is lost in sweat? What affects it?
electrolytes; increased heat + humidity, increased exercise duration
What are some electrolyte replacement strategies?
Replace them as they are lost, add to water, salt, top dress feed, oral paste; horses cannot store electrolytes
What are benefits of adding fat to diet?
decreased excitability, decreased dust, energy source, shiny coat
Is a high protein diet harmful to most horses? What happens to excess protein?
not generally harmful as long as adequate water is supplied; BUT will increase ammonia excretion which is bad for respiratory system in stalled horse
What happens when horse eats grain meal? How long do effects last? How does it impact fuel availability?
Insulin increases with blood glucose, decrease in fat mobilization for 4 hours; puts body in storage mode and reduces fuel available to muscle
What happens when horse eats large hay meal? How long do these effects last?
decreased blood volume, increased gut fill and weight; lasts about 4 hours
How would a large hay meal affect exercise? How does this change with a small hay meal?
gut will compete with muscles for blood and increased body weight negatively affects exercise; small hay meal reduces this effect
What is a good pre-exercise feeding strategy?
Small grain and hay meals with continuous hay intake; decreases risk of colic and negative effects on fuel availability
What is a good post-exercise feeding strategy?
replenish muscle glycogen with starch, do NOT feed until body temp drops below 102, use good quality hay + small grain meal 60-90mins after exercise, then grain again 2-3hrs later
Difference between RER and PSSM
RER - defective calcium regulation PSSM - excess of abnormal muscle glycogen
How does high NSC trigger RER and PSSM?
RER - indirect effect - excitable behavior PSSM - direct effect - glycogen synthesis
How should RER/PSSM horses be fed?
RER - low to moderate NSC with added fat concentrate, low NSC hay/pasture PSSM - low NSC with added fat concentrate, low NSC hay/pasture
How is nutrition connected to sporadic vs chronic tying up?
Sporadic - deficient in electrolytes, vitamin E, selenium Chronic - high starch/sugar
How does nutrition affect reproductive performance?
deficient DE and protein can result in messed up fertility and pregnancy loss
How does body condition affect reproductive performance in broodmares?
thin = lower pregnancy rate, low milk production obese = low milk production, risk of metabolic disease
What is the ideal body condition score for broodmares? Why?
BCS 6-7; she will need fat stores for weaning and lactating
What type of mare would the practice of "flushing" going into the breeding season be most effective?
may help improve fertility in thin mares
When is the most opportune time to improve the body condition of a broodmare? Why?
in early gestation; her nutrient requirements are similar maintenance which will allow her to put on weight
How much weight gain is needed to move up 1 BCS level?
20kg
How many extra Mcal DE are needed for 1kg of weight gain?
20Mcal DE
Maximum safe weight gain in mature horses
0.5kg/day
How does gestation and lactation affect the mare's requirements?
all nutrients affected by lactation; DE increase 90%, protein increase 45%, minerals increase 25%(TM)-200%(Ca + P)
How does stage of pregnancy or lactation affect how we feed mares?
early gestation = forage usually sufficient, concentrate only needed if mare needs to gain weight late gestation = forage 70-80% diet, concentrate 20-30% lactation = forage 50-60% diet, concentrate 40-50%
How should we manage mares consuming tall fescue? Why?
remove mares from infected fescue 30 days before foaling and mow pastures; fescue can increase length of gestation, stillborn foals, retained placenta
How should you handle the mare's diet around the time of weaning? Why?
feed normally up to weaning; post-weaning gradually reduce concentrate
What is the ideal body condition score for stallions? Why?
BCS 5-6; need energy stores for breeding season
What affects stallion's requirements?
temperament and psychological response to breeding
How should stallions be fed during non-breeding and breeding seasons?
non-breeding = "high" maintenance, 90-100% forage and 0-10% concentrate breeding = light work, 70-80% forage and 20-30% concentrate