Rearing Techniques, Management and Evaluation

Rearing, management and evaluation

Rearing means looking after animals from birth to sale or use. Management is the plan: feed, housing, health and records. Evaluation is the check: are the animals meeting the targets?

Useful measures: body weight against age; feed conversion ratio (FCR) = feed eaten / weight gained (a broiler with FCR 1.7 needs 1.7 kg of feed for 1 kg of body weight); mortality (percent that die); production (eggs per hen, milk per cow). A lower FCR means less money spent on feed. Weigh a sample every week. If weight is below target, check feed, water, temperature and disease.

The environment matters too. Day-old chicks need warmth near 32 degrees C with a brooder lamp; adult pigs are comfortable at about 18 to 24 degrees. Cold animals huddle together; hot animals spread out and pant. Watch their behaviour: it tells you if the shed is right.

Feed and management

Feed has four main parts: protein (builds muscle and eggs), energy from grains and fat, fibre (important for cattle), and vitamins and minerals. Each animal and age needs a different mix. A chick needs about 22 percent protein in the starter feed. A growing pig needs about 16 percent, and a dairy cow about 14 percent in the ration. Too little protein slows growth. Too much wastes money.

Management of feed: give feed at fixed times, store it dry and clean (damp feed grows mould that harms animals), give clean water all day, and change feed gradually over a few days when the stage changes. Record how much feed each pen eats so FCR can be worked out.

Animal biotechnology and breeding techniques

Artificial insemination (AI): semen is collected from a chosen bull, tested, diluted and frozen in small straws. A trained person places it into the cow. One bull can father thousands of calves, there is no need to move the bull, and it lowers the spread of some diseases. Natural mating allows only about 15 cows per bull in a season in this model.

Embryo transfer (ET): a top donor cow is given hormones to release several eggs; after AI the embryos are flushed out about a week later, checked, and placed in recipient cows who carry and give birth. The donor can have many calves a year. Other tools: genomic selection (reading DNA markers to choose young animals), sexed semen (to get more female calves) and cloning (making a copy of an animal, still costly and rare). Each technique needs trained staff, hygiene and good records. There are also ethical and animal-welfare rules to follow.

Try it

Take a growing pet or a school plant-and-animal record (a chick, a rabbit or even a goldfish) and weigh or measure it every week. Draw the curve on graph paper. It should rise steeply first and then flatten. Compare the shape with the weight curve in the 3D. Also note what the animal does when the room is cold or hot.

Key formulas and definitions

• FCR = feed eaten / weight gained
• Feed needed = weight gain x FCR
• Mortality (%) = deaths / animals x 100
• Protein need: chick about 22%, pig about 16%, dairy cow about 14%
• Cows served by natural mating = min(number of cows, 15) in this model

Worked examples

Common mistakes

• Giving feed with the same protein to every animal and every age.
• Not weighing the animals, so slow growth is found too late.
• Keeping a hot shed closed. Animals spread out, pant and eat less.
• Thinking embryo transfer is just a bigger kind of AI. AI gives semen, ET moves a ready embryo to another mother.