ANSC 160 Lecture Notes - Lecture 2: Total Variation, Heredity, Heterosis
Document Summary
Heritability: the portion of the total variation or phenotypic differences among animals that is due to heredity. Heterosis: performance of offspring that is greater than the average of the performance of the parents, also referred to as hybrid vigor. Heritability estimates: closer to 1 is the higher heritability. Traits that determine phenotypic characteristics such as coat color or presence of horns, etc: quantitative traits. Traits controlled by many genes, each having a small effect; these traits must be numerically measured. Scrotal circumference: bigger testicles make more sperm, also determines the age at which daughters may reach sexual maturity. Independent culling: this is the practice of culling animals based upon cattle meeting speci c levels of performance. Quantitative value: expected progeny differences (epd) The difference in performance to be expected from future progeny of a sire or dam, compared with that expected from future progeny of an average bull or dam in the same test or breed.
