Animal Science and Livestock Production
Animal Science tests nutrition, digestion, reproduction and breeding of farm species, and whether you can turn feed and animal records into a management decision.
Core rules
- Ruminants (cattle, buffalo, goats) ferment feed in the rumen; microbes produce volatile fatty acids and microbial protein and synthesise B vitamins and vitamin K. Non-protein nitrogen such as urea can feed microbes, but only with adequate fermentable energy.
- Monogastrics (pigs, poultry) need preformed essential amino acids; in maize–soybean diets lysine and methionine are usually first limiting.
- Feed values are quoted on a dry matter (DM) basis: DCP, TDN, metabolisable energy. Always check whether a figure is as-fed or DM.
- Reproduction: oestrous cycle about 21 days in cattle and pigs, 17 days in sheep; gestation about 283 days (cattle), 114 days (pig), 150 days (goat).
Worked example
A broiler pen of 100 birds consumes 240 kg feed and gains 120 kg live weight: FCR = 240 ÷ 120 = 2.0. Feed efficiency = 1 ÷ FCR = 0.50 kg gain per kg feed. If feed costs Rs 120/kg, feed cost per kg gain = 2.0 × 120 = Rs 240. A rival ration with FCR 2.2 at Rs 112/kg costs Rs 246.4 per kg gain - the cheaper feed is not the cheaper ration.
Traps that cost marks
Comparing rations with different DM contents; confusing FCR with feed efficiency (they are reciprocals); applying poultry amino acid logic to ruminants; misremembering gestation length; forgetting that urea toxicity occurs when it is fed fast or without adaptation.