Prediction of Sire Merit for Calving Difficulty

Sire Evaluation for Economic Merit

Procedures for selecting sires are compared in terms of making maximum genetic progress in economic lnerit. A quadratic index, a simplified form of the quadratic index and a linear index to evaluate economic merit, and a restricted index to improve milk as much as possible while holding milk fat percentage constant, all result in nearly equal expected genetic progress in economic merit. Selecti...

Pelvic Measurements For Reducing Calving Difficulty

producers. This loss is estimated at $750 million annually nationwide. Calving difficulty increases calf death loss, cow mortality, labor and veterinary costs; it delays the return of cows to estrus and reduces conception rates. It also lowers calf weaning weight and market value, which results from breeding of young heifers and cows to easy calving bulls to reduce calving difficulty. Studies s...

Reducing Calving Difficulty in Simmental

Many factors contributed by calf, dam and sire are associated with CD and many of these are interrelated. Deutscher (1988) came to the conclusion that "the primary cause of CD in young cows is due to a disproportion between size of calf (birth weight) and size of birth canal (pelvic size) of the cow." The relationship of these two factors are presented in the figure below quoted by Deutscher (1...

Calving Difficulty in Beef Cattle

Factors influencing calving difficulty in beef heifers.

Records of 547, 2-yr-old heifers of three breed groups were used to evaluate the relative influence of dam's body and pelvic measurements, calf birth weight, sire birth weight and some relative measures (ratios) of calf birth weight and dam weight at calving on calving difficulty. The data were analyzed by regression and least squares procedures. The full model explained 32.5% of the variation ...