ANSC 160 Lecture Notes - Lecture 5: Weaning, Birth Weight, Total Variation
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. Qualitative traits- traits that determine phenotypic characteristics such as coat color or presence of horns. Quantitative traits-traits usually controlled by many genes, each having a small effect; these traits must be numerically measured. Weaning weights: an unshrunk, off cow weight adjusted to 205-d of age and to mature dam age equivalence. Yearling weights: an unshrunk weight adjusted to 365-d of age. Average daily gain (adg: measurement of daily body weight change in animal on a feed test. Most bull tests are 140 or 160 days in length. Scrotal circumference: the dia(cid:373)eter of a (cid:271)ull"s testi(cid:272)les. This refle(cid:272)ts (cid:374)ot o(cid:374)ly fertility, (cid:271)ut also the age at which daughters may reach sexual maturity.
