ANIMSCI 2200.01 Lecture Notes - Lecture 12: Heterosis, Outcrossing, Zygosity
7 Apr 2016
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Document Summary
Objective- produce animals that excel for desired traits while eliminating/minimizing occurrence of undesirable traits. Involves culling of less desirable animals and selection of superior replacements. Subjective measure- descriptive or categorical and classified into groups: red or black. Controlled by a few genes- progress of selection not difficult. Objectively (numerically) measured- milk production, loin eye area, weight, and speed. Polygenic- controlled by many genes, often on different chromosomes, each contributing a small effect. Selection- obtaining a desirable phenotype by choosing animals for mating. Qualitative traits- less environmental influence and greater heritability. Influence of genetics on expression of a trait (% of phenotypic variation inherited) Superiority of selected animals compared to the herd average for a particular trait. Heritability of the trait- proportion of phenotypic variation that can be passed from parent to offspring. Generation interval- average time required to replace one generation with the next. The shorter the generation interval the greater rate of change.
