Nutrition and Feed
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biological value of a protein
high biological value - contains the essential AA required by in a proportion similar to that required by the consumer low biological value - one or more essential AA are scarce limiting AA - AA in shortest supply in relation to need
ration formation
goal: to provide the animal w/ a balanced diet containing the nutrients required to meet its physiological needs needs include: -maintenance requirements + additional needs for: growth pregnancy lactation work etc. must consider: nutrient composition of feedstuffs -digestibility -palatability
diet
all feedstuffs being consumed including water
ration
specific feeds being given in a 24hr period specific quantities
national research council
NRC Publishes: -nutrient requirement of domestic animals -nutrient contents of ration ingredients
physiological control of feed intake
energy and gut fill in energy density is too low then cant consume enough due to gut capacity
feedstuff components
water (moisture) protein fat carbohydrates vitamins minerals energy (calories)
proximate analysis
a general approximation of the feeds (or rations) content of major nutrient groups a chemical analysis
moisture content determination
dry the feed sample weight before - weight after = moisture content
kjeldahl
chemical analysis of total nitrogen in the sample
ether extraction
removes fat from the sample weight before - weight after = fat content
measure soluble carbohydrate and protein
boil in acid boil in alkali then left w/ crude fiber and ash
ash
minerals
measure soluble carbohydrates
nitrogen free extract (NFE) 100% - CP - fat - crude fiber - ash = NFE
calories in feed
bomb calorimeter carbs = 4kcal/g protein = 4kcal/g fat = 9kcal/g
gross energy
includes all energy in feed not all available to the animal bomb calorimeter test
digestible energy
how much energy does NOT end up in the feces = energy absorbed
metabolized energy
what is left after accounting for energy lost in feces, urine, and gases
net energy
left after losses in feces, urine, gases, and heat increment available for maintenance, growth, lactation, work, etc.
heat increment
energy lost in fermentation and in metabolic processes associated with work of digestion
digestibility trials
estimating feed value based on digestibility w/in the target animal biological analysis
apparent digestibility
digestion trial w/ animals consuming the test ration nutrient consumed - nutrient excreted in feces = nutrient digested and absorbed
nutrient digestibility %
(nutrient intake - nutrient in feces) x 100 nutrient intake
NRC 8 categories of feedstuffs
dry forages and roughage pasture range plats and green forages silages energy feeds protein supplements mineral supplements vitamin supplements non-nutritive additives