Animal Domestication and Breeding

Domestication

• The dog is the only animal domesticated during the paleolithic era
• Most animals that we farm today were domesticated during the neolithic era
• Most recent attempts have been unsuccessful, the exception being the Eland

Selective Breeding

• Farmers can improve their animals by improving their feeding, housing, and by eliminating diseases
• Breeders often try to improve too many character traits, which slows progress
• Breeders and geneticists often disagree on the selection criteria for their programs

Trait Classification

• Traits are classified as either simple traits (like coat color) or complex traits (like growth and survival)
• Traits can be classified as either objective (can be measured) or subjective (can be assessed according to someone's opinion)
• Objective traits are measured in terms of weight, length, volume, etc.

Survival

• Survival is more important than mortality
• It is important to determine the cause of death, but this is often difficult
• It is important to understand why living offspring live
• The ability to determine parentage is important
• There are many ways to establish parentage: direct observation, records, birth fluids, and blood typing
• Animal behaviour can greatly affect the outcome of a breeding program

Maternal Ability

• Good maternal ability is essential in farm animals
• It is a complex trait that is difficult to describe objectively
• The ability to feed, shelter, and protect the offspring are all important
• Breeders use indirect measures of maternal ability such as the offspring's weight at weaning
• The shape of the udder is important, especially in dairy animals
• Poorly attached udders can cause stress and disease
• Udders and teats must be suited to machine milking

Growth & Development

• Growth is best looked at as an increase in size or weight
• Development is the change in proportion of the different parts of an animal
• Growth is usually shown as an S-shaped curve
• Different tissue types have different nutritional priorities
• The placenta and the fetus have the highest priority followed by the brain and central nervous system
• Breeders aim to alter the ratios of bone, muscle, and fat
• Different breeds can mature to different sizes
• Different stages of growth are not independent
• The live weight of an animal is a simple trait to measure, but the ratio of muscle, fat, and bone can vary
• The contents of the digestive tract can account for 10-25% of the weight of ruminants
• Animals should be weighed uniformly full or empty after standardised fasting periods
• Fleece weight can be influenced by the amount of water in the wool

Carcass Quality

• The carcass is a stage nearer the consumer than the live animal
• Special breeding plans are needed to select for carcass traits in breeding stock
• Carcass traits are measured by using ultrasonic aid or examining the carcasses of offspring or relatives
• The weight of the cold carcass is easily measured at slaughter
• Carcass composition can be an important trait for survival

Temperament

• Temperament is an important trait in farm animals
• Animals should be calm to avoid stress in herds
• Quiet temperament is important for draught animals that have to spend long periods of time waiting
• Social hierarchy often results in aggressive individuals getting more access to food, water, and resources
• Lower order animals eat less, produce less, and are more prone to disease
• The optimal group size can be determined to reduce stress factors
• Breeders need to breed animals able to cope with high-stress environments

Poultry

• Poultry breeders have taken advantage of advances in genetics
• The very concept of breed is outdated in commercially raised poultry
• The primary concern for poultry producers is feed conversion efficiency
• Broiler breeders prefer birds that grow quickly
• Broilers have to have large breasts, fleshy thighs, short legs, and a desirable skin color
• Breeders are trying to reduce internal fat depots in broilers