Animal science test 3

lectures 21-29

NZ beef industry – global relevance

Export-driven (>80%), major markets USA/China/Japan, dairy-beef integration important.

Beef production systems

Breeding herd (cows+heifers), finishing systems (weaned calves to slaughter), dairy-beef calves finished.

Measuring beef performance

Calf weaning %, growth (live weight gain), carcass yield.

Why is growth important?

Efficiency, timing of slaughter, meat yield and quality.

Measurements of growth

Absolute growth rate (ΔW/Δt), Relative growth rate (ΔW/W)/Δt, S-shaped growth curve.

Factors affecting growth

Genetics, nutrition, environment, hormones (GH, IGF-1, insulin).

Growth order of tissues

Bone → Muscle → Fat.

Carcass yield

Determined by lean:fat:bone ratio.

Meat quality factors

pH, glycogen stores, pre-slaughter stress, colour, tenderness, marbling, water-holding capacity.

Poultry industry relevance (NZ)

Fastest-growing meat industry, PIANZ = industry body.

Functions of poultry industry board

Welfare, biosecurity, market standards, exports.

Poultry production systems

Broilers (slaughter ~6 weeks), Layers (photoperiod controlled egg production).

Poultry feeding regime

High-protein, energy-balanced diets, light manipulation for growth/laying.

Pig industry in NZ

Small globally, self-sufficient, industry board = NZ Pork.

Functions of NZ Pork

Sets welfare standards, biosecurity, research, promotion.

Pig production systems

Farrow-to-finish (all phases), Feeder pig ops (nursery → finisher), cycle = breeding → gestation → farrowing → nursery → grow-finishing.

Pig feeding regime

High-energy cereals + protein meals, phase feeding for growth stage.

Gilt

Young female pig until 1st litter, then becomes sow.

Sow

Adult female pig.

Boar

Intact male pig.

Barrow

Castrated male pig.

Farrowing

Pig birth process.

Farrow-to-Finish Operation

System from breeding through market.

Feeder Pig Operation

Sells pigs after nursery phase to finisher farms.

Breeding herd

Sows, gilts, boars (vasectomised & intact).

Growing herd

Nursing, weaned, grower-finisher pigs.

Horse industry in NZ

~120,000 horses, uses = racing, sport, leisure, export.

Economic/cultural role of horses

High-value exports (racing, genetics), cultural role in rural + sport.

Horse production systems

Thoroughbred: stud → yearling sale → training → racing. Sport horses: bred/trained for performance.

Key horse industry goals

Fertility, foal survival, racing/sport performance.

Metabolism definition

All chemical reactions: Catabolic (breakdown, energy release) + Anabolic (build-up, energy use).

1st Law of Thermodynamics (biology)

Energy conserved, cannot be created/destroyed.

2nd Law of Thermodynamics (biology)

Energy transfers increase entropy, some lost as heat.

Homeostasis definition

Stable internal environment via hormones (insulin, thyroid, cortisol, leptin), hypothalamus regulates.

Measuring metabolic rate

BMR (strict basal), RMR (resting), measured by O₂ consumption, CO₂ output, heat.

Factors affecting MR

Food, activity, age, temperature, body size.

Metabolism in small vs large animals

Small animals = higher MR per gram (size scaling).

Endotherms vs Ectotherms

Endotherms = stable temp, high MR; Ectotherms = environment-dependent, lower MR.

MR

Metabolic rate.

BMR

Basal metabolic rate.

RMR

Resting metabolic rate.

GH

Growth hormone.

IGF-1

Insulin-like growth factor.

PIANZ

Poultry Industry Association of NZ.

Allometry

Different tissue growth rates.

Carcass yield

Lean:Fat:Bone ratio.