Animal Breeding

What does heritability measure in a population?

The proportion of phenotypic variation due to genetic variation.

What is the heritability range for lowly heritable traits?

0 - 0.2, typically reproductive traits like fertility and litter size.

What heritability range indicates moderately heritable traits?

0.2 - 0.4, including growth traits like birth and weaning weights.

What is the heritability range for highly heritable traits?

0.4 - 0.6, such as carcass traits like hot carcass weight and marbling.

What is the formula for phenotype?

Phenotype = Genotype + Environment.

What does a heritability value of 0.7 indicate about an animal's genetic merit?

It suggests good genetic merit if the animal overperforms.

What are estimated breeding values (EBVs)?

Predictions of an individual's genetic worth based on performance data.

What are expected progeny differences (EPDs)?

Predictions of the average performance of an animal's offspring compared to the population.

What is the purpose of performance records in animal breeding?

To keep track of traits like birth weight and average daily gain for genetic predictions.

What is a random mating plan?

Selecting breeding animals without choosing specific pairs, often used in large herds.

What is positive assortative mating?

Breeding animals of similar quality to produce exceptional offspring.

What is negative assortative mating?

Breeding animals of dissimilar quality to correct poor performance traits.

What is inbreeding?

Mating closely related animals, increasing homozygosity and uniformity in traits.

What is inbreeding depression?

A decrease in performance associated with inbreeding due to increased homozygosity.

What is outbreeding or outcrossing?

Mating less-related individuals to increase genetic diversity and reduce recessive gene expression.

What is crossbreeding?

Mating individuals from separate breeds to enhance performance through hybrid vigor.

What is breed complementarity?

Mating different breeds with complementary strengths to improve overall performance.

What is heterosis (hybrid vigor)?

The superior performance of outbred individuals compared to their parent populations.

How can heritability and performance be used in culling decisions?

To assess which animals should be removed from breeding based on their genetic merit.

What is the importance of record-keeping in seedstock operations?

To track performance and avoid inbreeding depression while enhancing genetic quality.

What are estimated transmitting abilities (ETAs)?

Predictions of the genetic potential an animal will pass on to its offspring.

What factors can influence mating plans in animal breeding?

Randomness, performance/visual appearance, and genetic relationships.

What is the significance of the heritability value in animal breeding?

It helps predict the potential success of breeding decisions based on genetic traits.

What is the role of commercial producers in using genetic predictions?

To make informed decisions about purchases and mating to improve herd performance.

What is the expected progeny difference for Bull A compared to Bull D?

Calves sired by Bull A will be 12.5 lbs heavier at birth and 53.9 lbs heavier at one year.

What is the goal of corrective mating in negative assortative mating?

To improve poor performance traits by pairing superior males with inferior females.

What is the outcome of inbreeding on genetic traits?

It can fix desired traits but also increase the risk of detrimental recessive traits.