Bioenergetics Flashcards
Typical DM intake?
1.5-2%
What happens to DM when energy requirements are increased?
Increase
How is dry matter calculated?
total weight - moisture
What is dietary energy?
driving force behind homeostasis
How can energy be provided in the diet?
- CHO
- complex vs. simple - fats
- oils - protein
- water, mineral, vitamins
Define 1 calorie (R)
heat required to raise the temperature of 1kg of water by 1 degree celsius
how many cals in 1 kcal?
1000
how many kcals in Mcals?
1000
how many joules in 1 cal?
4.184
how many kjoules in kcal?
4.184 kjoule
Explain what energy partitioning is
- energy losses from ingestion to excretion
- greater heat of fermentation in horses
- loss of C and O –> losing energy
Define digestible energy
energy intake - energy in feces/energy intake x 100
Net energy for maintenance
Basal metabolism
- minimum energy energy required to sustain life
- brain, tissue functioning, digestion (normal bodily functions)
Voluntary activity
- voluntary, conscious movement
- walking, foraging
Thermoregulation
- energy to maintain body temperature
- E.g. below LCT –> increase energy consumption = require more energy to maintain body heat
Net energy for production
- hair
- amount of energy dedicated to hair growth (difficult to quantify) - growth, reproduction, milk
- lactation, growing fetus
- foal = part of mares energy requirement (why peak lactation is so energy demanding) - activity
- fattening
What is the major source of dietary energy in horses?
CHO and fibre and lipid (present in forages)
- CHO make up the single largest component of the equine diet
- sugars/starches are readily digested by the horses, rapidly fermented if they reach cecum/colon
- fiber is poorly digested and slowly fermented in colon
Define energy balance
energy ingested - energy expended
Why is predicting energy requirements so challenging?
Drastic changes in energy requirements
- age
- reproductive status
- body condition (fatter = less energy per kg)
- activity level
- breed –> physiologic, metabolic, temperament differences (genetics)
- temperament (cribbing, pacing costly)
- health status (immune response is costly)
- environmental conditions (hot/col = increased energy)
Energy requirements/day for minimum working horse
30.3 kcal/kg BW
Energy requirements/day for average working horse
33.3 kcal/kg BW
Energy requirements/day for elevated working horse
36.3 kcal/kg BW
Calculating DE requirement in an average working horse
33.3kcal/kg x 450kg = 14,985