15: Nutrient requirements of growing horses Flashcards
Foal development at birth
Skeleton is well developed at birth
- typically standing within 30 mins of birth
- can walk, trot, gallop within first 12 hours
Four nutritional phases during first 12 months of birth
- Nursing for first few weeks
- Incorporate solid feeds ~10 days postpartum
- Wean ~6 months of age
- continue rapid growth to 12 months of age
What is colostrum? Why is it required
Milk produced in the first day of lactation that is required in the first 24 hours after birth
Required for nutrients, antibodies and growth factors
What kind of placenta do horses have? Why does this affect the need for colostrum
Epitheliochorial
There are fetal and maternal membranes at the placenta interface; these structures prevent transfer of antibodies in utero
Slide 6
Absorption of immunoglobulins from colostrum
- Absorbed through small intestine epithelium (higher efficiency immediately post partum)
- Absorption efficiency declines at 12h +
- no longer absorbed >24 h
What happens in absence of maternal antibodies?
The foal will start to produce their own antibodies sooner, but there would be a period of no antibody protection
When do foals start nursing after birth? Frequency?
Within 1-2 hours
Nurse 10 times/h in first 24 hours
Consume 15% BW as milk in first 24 hours
Digestibility of milk? Supplies all nutritional needs for…
98%
For 6-8 weeks
Trend in nutrient composition of mares milk from week 1 to 12
Energy, protein and fat content of milk decreases slightly
Lactose increases
Slide 9, 10, 11
How do mature BW and height change during growth? In a foal, what is deposited first? What does this mean?
Foals growth first in height, and then in weight
Deposit bone, then muscle, then fat
= mineral nutrition is very important in early life bc of bone development
Weaning age and growth rate
Weaning age has little influence on growth rate; initial colostrum necessary for regular growth, weaning depends on management practices of farm
Feeding behaviours of foals by 21 weeks
Spend ~50% of day eating solid feed
- dams allow foals to eat grain (more likely to consume if confined to box stall)
- foals seek solid food sources for nutrient supply
What is creep feeding? Why use it?
Separate the feeding of the foal from the mare, providing nutrient-dense source of feed to foals (w high palatability)
- protect against mare taking food
- helps reduce weaning stress
- increases ADG and wither height
Voluntary intake of creep feed varies… Influenced by…
Between foals
Influenced by herd behaviour, creep feed placement, presence of other foals
Largest increase in foal height occurs when? Height reflects…
From 0-3 months of age
Height largely reflects linear growth of long bones (growth occurs at metaphyseal plate)
Slide 16, 17
Examples of long bones
Metatarsal
Metacarpal
Maintenance energy is…
the amount of E needed to prevent a change in body total energy
Energy required during growth for…
DE required for kg of gain varies with…
Energy for maintenance + growth
Varies with rate of gain, gender, breed, feed, thermal challenges
Why does the amount of energy required for 1kg gain increase with age?
More fat is deposited than protein
Adipose tissue is more energy dense, but 1g weighs the same as 1g protein
Slide 20,21
Look
Growing horses are sensitive to… Limiting aa in horses?
Protein quality (amino acid profile and digestibility of a protein)
Lysine is first limiting, threonine is also limiting
When is efficiency of use of dietary protein the highest? What happens to it?
4-6 months it is 50% (most accelerated rate of growth/most efficient protein deposition)
Decreases to 30% at 12+ months bc more protein is needed per kg of BW gain
Why do growing foals require calcium? Deficiency?
For skeletal growth; 16 g deposited per kg gain
Deficiency can lead to osteopenia; insufficient Ca deposition in skeletal tissue
- creates enlarged joints and crooked long bones
Phosphorus deficiency? Excess?
Deficiency can lead to rickets-like changes
Excess reduces Ca uptake (can lead to nutritional secondary hyperparathyroidism)
What is nutritional secondary hyperparathyroidism? Symptoms?
Metabolic bone disease associated with Ca:P (bone demineralization)
Shifting lameness, tenderness of joints, reluctance to move, stiff, stilted gait
“Big Head”
Difficulty chewing = weight loss
Sustained secretion of PTH
There is inadequate dietary Ca during nutritional secondary hyperparathyroidism due to… Ca:P ratio in growing horses?
- Low to deficient dietary calcium (large cereal diets, mature grass hay)
- Excessive dietary P (supplementation of high P mineral, byproducts)
2:1 ideal ratio (higher than 1.4:1 in mature horses)
Nutritional management to treat NSH
- alter diet to provide increased available dietary Ca intake
- alter diet to reduce dietary P to appropriate Ca:P ratio
- early treatment = increase Ca:P ratio to 3-6:1
How to prevent NSH
- provide sufficient available Ca and P
- maintain dietary Ca:P of 1-2.5:1
- dietary Ca higher in legumes than grass hay
What is developmental orthopedic disease in growing horses? Prevalence?
Complex of musculoskeletal abnormalities including angular limb deformities, physitis and osteochondrosis
Occurs in as much as 80% of young horses (40% need corrective trimming, 8% need surgical correction)
How is DOD related to energy intake?
Too much rapidly digestible energy (starches, sugars) = uncontrolled rapid growth
Controlled energy nutrition is important in animals with long bones
Slides 28-30
DOD pics
DOD is divided into two causes:
- Idiopathic: causes are usually hereditary/genetic
- Acquired: associated with trauma or nutritional causes
DOD originates from… Can be brought on by… Mainly found in horses with…
Abnormalities of growth plates
Brought on by dietary mismanagement
Mainly found in horses with too high ADG (too much rapidly digestible energy)
Nutritional causes of DOD
- excessive energy intake
- high non-fiber CHOs diets (too much sugar and starch): increased insulin and insulin-like growth factor 1
Prevention of DOD
- Feed more fiber, less starch/sugar (less rapidly digestible E)
- Make sure foal stays on ideal growth curve
- Reduce glycemic index (slide 33)
Possible epigenetic factor related to DOD
Mares fed concentrates during gestation more likely to produce foals that are affected (incidence affected by maternal nutrition)
Other potential causes and prevention measures for DOD
Ca and P imbalance, inconsistent nutrition, confinement
Prevention:
- copper supplementation of dam may reduce DOD (supplementation in foals may help repair cartilage)
- voluntary exercise may be beneficial in reducing DOD
