animal sceince chapter 17
• What are maintenance requirements?
It's the basic food an animal needs daily just to stay alive and healthy, without gaining or losing weight.
This includes energy for breathing, keeping warm, and moving around a little.
• How does body size affect food needs?Larger animals need more total food each day because they have more body to maintain.
But smaller animals need more food for every pound of their body weight than larger animals.
Why? Because small animals lose heat faster (they have more skin surface compared to their body mass), so they need more energy to stay warm.
• Simple example:
Imagine a 500 lb animal needs 15 lb of food per day.
A 1000 lb animal (twice the size) won't need exactly 30 lb of food (which is twice as much).
Instead, it will need less than 30 lb but more than 15 lb.
This is because their energy needs don't simply double when their weight doubles; it's a bit less than that (it often scales by ).
Growth occurs when protein synthesis is in
excess of protein breakdown
• Majority of muscle is protein so young
growing animals have greater protein
requirements
• If young animals experience a restriction in
feed for a short time, they may experience
compensatory growth once nutrition
improves
• Compensatory growth is above average
growth rate
•Some look for this in feedlot animals
• Monogastrics need protein and certain
amino acids for growth
•Pigs usually supplemented with soybean
meal for amino acids
•Young ruminants must have adequate milk
along with roughage for maximum growth,
can’t achieve it on roughage alone
Young animals need adequate
calcium and phosphorus for bone
growth and salt (sodium)
• Combination of hay and grain
typically meets these needs
• Hay alone is usually deficient in
phosphorus
• High concentrate diets can be
deficient in calcium
• Finishing = complete once market weight is
achieved
• Fed high energy rations during last phase of
feeding program
•At this point optimal growth drops and excess
energy from feed is stored as fat, decreasing
marketability
• Gain during growth of lean tissue is less
costly then gain from fattening
•Producing a pound of fat takes 2.25 more
energy than a pound of protein
Two categories:
1. Gamete production
2. Fetal growth in uterus
•Energy requirements for gamete production
no greater than those need to maintain
healthy condition
• Nutrients for growing fetus much greater in
last trimester, when most of fetal growth takes
places
Milk production requires protein, minerals, vitamins
and energy
• Lactating dairy cows reach peak lactation 45-65
days post calving
• Feed intake doesn’t catch up with rising energy
requirements for 8-10 weeks
• Results in loss of body weight…don’t see very
many fat dairy cattle
Protein need is greater, milk is 3% protein
• Generally during peak milk production feed
can not compensate and cow utilizes body
protein
• Calcium and phosphorus imbalances can
lead to decreased lactation and even death
“milk fever”
• Dairy goats and sheep have similar
requirements
Dairy cows should be fed roughly 40:60
roughage to concentrate diet, just increasing
concentrates doesn’t work
• Nutrients requirements depends a lot on purpose of
production
• Boilers – need nutrients for growth (discussed earlier)
• Layers - need nutrients focused on eggs
• Layers are smaller and maintenance requirements are less
• These nutrients are needed in addition to maintenance, growth and
reproduction
•Poor quality of feed is usually limiting factor in wool production
• Wool fiber is primarily protein so…….make sure there is adequate
protein!
•Shearing removes insulation so may require increase in energy
requirements for heat loss
Animals used for work require large amounts of energy
• If energy in ration is not adequate, body fat will be used
until depleted then….
•Prolonged perspiration may require NaCl supplement
• Done by producers or consultants using computer formulas but…….
•Pearson square method can be used for simple rations (two
ingredients only) pg 268
• Rules for Pearson Squares: Remember to read across!
• 1)Subtract nutrient value diagonally across square – ignore
negatives!
• 2)Add total of parts needed
• 3)Divide each part needed by total parts (and multiply by 100) to get
amount or percentage of each ingredient needed