16: Life cycle nutrition of reproductive and aged horses Flashcards
Describe the estrous cycle of a broodmare. What is it influenced by?
Cycle from March to October, estrous cycle = 22 days
Influenced by photoperiod, nutrition, physiological condition, environmental temperature
Slide 5
BCS horses
Typical gestation length in horses? What is very important?
Typically 335-345 days
Body condition score very important (BCS >5 = reserves)
Gestation in winter conception. Protein and energy requirements in gestation
Winter conception has longer gestation period (due to photoperiod)
Protein and energy requirements not completely determined
Benefits of optimum body condition score in broodmare
- increased fertility
- increased milk yield
- increased health
- shorter follicular phase in estrous (increase # of cycles)
- shorter winter anestrous
Low BCS in broodmares leads to…
Longer anestrous bc of decreased hormone levels
Ideal BW gain during gestation
12-15% above normal BW
Energy is required for what during pregnancy?
- Maintenance of dam
- Deposition of fetal and placental tissue
- Hypertrophy of the uterus
- Mammary development
- Maintenance of additional tissues mentioned above
Timing of fetal and non-fetal accretion during gestation
Greatly increases after day 150 (non-fetal tissue accretion from day 150-330 = ~45 g/d)
Most fetal tissues accumulated in last 60 days of gestation
Why do pregnant mares have added maintenance requirements?
Additional weight from both fetal and non-fetal tissues + non-fetal tissue is more metabolically active
Composition of each unit of gain during pregnancy
Each unit is ~20% protein, 3% lipid
Water is 3x protein composition
Also skeletal tissue
When do the energy requirements change for mares during pregnancy?
Met by DE of maintenance for first 5 months
Then increase exponentially until end of pregnancy:
- 5-8 months = increase DE by 11%
- 11 months = increase DE by 28%
Main recommendation about energy requirement during pregnancy
Do not allow for accretion of body stores (in the mare *if she is at an ideal BCS)
Mares with BCS <5 require additional energy
Mares with BCS <5 suffer from
- delayed estrous (longer time to rebreed)
- reduced conception
- embryonic death
Protein requirement during pregnancy? Deficiency?
Requirements have received little research
>2.8 g CP/kg BW/d eliminate problems related to hormonal status (linear relationship btw protein and progesterone)
<2.0 g CP/kg BW/d = protein deficiency:
- can cause weight loss
- early fetal loss
- slower start to ovulation
Slide 14
Confused
Protein requirement in first four months of gestation? Afterwards?
Conception to 4 months = average CP requirement (not a lot of protein tissue gain)
5th month to parturition = correct for kg fetal fain
Minerals with increased requirements during gestation? When?
During late gestation: change in nutrient requirement bc of increasing fetal growth
Calcium, phosphorus, magnesium, potassium
Vitamin requirements in late gestation
Increase vitamin A and E to 2x maintenance
Feed/energy intake before and after parturition
Feed intake should reduce 24h before birth: provide good quality hay, low energy cereal and bran (insoluble fiber to reduce constipation)
After parturition, energy and protein needs must be met: feed bran mash first (insoluble fiber), second feeding should contain cereal and protein (for milk production)
Feeding a mare up to 10 days postpartum
Restrict concentrate feeding (do not overfeed starch or sugar): avoids excess milk secretion and GI disturbances in foal
After 10 days, want to stimulate milk production
Slide 18
Composition of mare’s milk
How does milk production vary postpartum? Yield is influenced by…
First few weeks 5-15 kg milk/day, peaks in months 2 and 3 at 10-20 kg milk/d, at month 5 reduced to 5-10 kg/d
Yield influenced by:
- feed consumption during late gestation
- feed quality
- water availability
- nutrient and energy intake
- breed, age, stage of lactation, twins?
Mares produce how much of their body weight in milk?
1.9-3.9%
How does DE maintenance requirement change throughout lactation
75% increase in months 1-2, down to 55% increase in months 5-6
Protein quality and lactation? Low CP intake?
Milk production is sensitive to protein quality
Low CP intake with poor quality leads to
- decreased weight
- decreased milk production
PTH, bone density and demand for Ca during lactation
- increase in PTH = decrease in ionized Ca 3d prepartum to 2d postpartum
- mares lose bone density during first 12 weeks of lactation
- requirement highest in first 3 months of lactation, follows trend in milk production (decreases in later stages of lactation)
Nutrition of breeding stallions
- same seasonal breeding cycles: photoperiod affects concentration of hormones in blood
- require increased E during breeding season
- generally, E requirement greater than mares or geldings
- limited research on true DE requirement
- requirement changes based on activity, temperature, etc
Nutrient requirements in aged horses? Physical signs of aging
Challenge to define nutrient requirements; little knowledge of age-related changes to metabolism
There are age-related diseases and large metabolic change
Physical signs:
- chronically low BCS
- loss of muscle mass
- “sway” back appearance (minerals?)
- gray coat
- dental disease
How to address dental abnormalities in aged horses
- alter physical form of ration to increase digestibility
- feed haylage or chopped hay
- soak hay or hay cubes in water
- supplement oil to increase energy density
Energy, protein and other nutrient requirements in aged horses
Energy: MER relationship to age undefined in horses, MER typically lower in older animals (less activity, less protein mass)
Protein: suggested decline with aging (lower CP digestibility). Requirement undetermined.
Other nutrients: requirements uninvestigated
What is cushing’s disease? Clinical signs?
Pituitary pars intermedia dysfunction: loss of dopaminergic inhibition
Clinical signs:
- increase adrenocorticotropin (ACTH)
- increase pro-opiomelanocortin peptides
- increase in cortisol (despite no stresses)
Symptoms of cushing’s disease
- hypertrichosis (excess hair growth)
- sweating
- muscle wasting
- risk of laminitis
- insulin resistance
Addressing cushing’s disease through nutrition
Risk of laminitis and insulin resistance are both partially controlled by diet
With insulin resistance, feed less starch, reduce concentrate and provide forage
Slides 27,28
Cushing’s
What is equine metabolic disease? Symptoms? Etiology? Possible treatment?
Obese, high adiposity
Symptoms are hyperinsulinemia (insulin resistance) and laminitis
Etiology is unknown. Likely genetic, also partly tied to diet
Treat by feeding more forage, less starches/sugars
What is laminitis? Causes?
Inflammation of laminae causing distal phalanx to ‘detach’ from inner hoof
Causes:
- sepsis/endotoxemia
- toxins
- obesity
- trauma
- diet: fructans and dietary digestible CHOs (starch and sugar)
How many laminitis cases are diet related? What might be a management issue in Alberta?
Pasture associated laminitis = >46% of cases
Grain overload = >7% of cases
> 50% of cases are diet related and therefore preventable
Grazing management is important
In AB, half the year there is no grazing whatsoever. Need to feed forages and concentrates high in starch/sugar
