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Herd life, stayability and lifetime production in beef cattle
Abstract
Herd life, stayability, cumulative number of calves born and weaned, and cumulative 200-d weight of calves weaned were analyzed to estimate differences between 16 breeds of sires, heterosis and breed direct and maternal effects, and to estimate genetic parameters between stayability traits and traits measured early in a cow's life and to evaluate the importance of the method of analysis on prediction of genetic values of selected sires. Record from the Germplasm Evaluation project at the U.S. Meat Animal Research Center were used. Performance with (1) actual culling of cows nonpregnant in two consecutive years or with (2) imposed annual culling of any non-pregnant cows was analyzed. Herd life was analyzed using a Weibull regression model, stayability to various ages with a mixed threshold model, and cumulative traits with linear mixed models. Similar rankings of the sire breeds were found with the actual and imposed culling policies. Breed groups differed in survival with a range of .72 to .96 in the probability of survival from the beginning of the first breeding season of the cows to 7 yr of age. The range in probability of a cow weaning five calves given that she had already calved as a 2-yr-old was from .54 to .89. Cumulative 200-d weaning weight of calves ranged from 814.8 kg to 1016.8 kg by 6 yr of age. Breeds that have been selected for milk production tended to rank better for cumulative number of calves born, weaned and cumulative 200-d weaning weight. Evaluation of herd life, stayabilities and life-time production traits up to 8 yr of age of cows from a four-breed diallel involving Brown Swiss, Red Poll, Hereford and Angus breeds revealed that crossbred cows had less risk of being culled, and a correspondingly greater (30%) probability of having and weaning six calves given that the cows had weaned one calf Crossbred cows accumulated more calves born (7.6%), more calves weaned (9.7%) and more kg of calf weaned (13.5%) than purebred cows, mainly due to less mortality and less culling for physical impairments. The moderate association of weaning weight with stayability, stayability to calving and stayability to weaning suggests that selection for heavier weaning weight of females may be positively associated with survival of the cows and their potential to produce and wean more calves. The efficacy of using weaning weight or age at puberty as early selection criteria for stayability traits is dubious, because genetic correlations were not in agreement. The small estimates of heritability, however, suggest that genetic influence on stayability is small, which further suggest that genetic gain would be very slow if direct selection were applied for stayability.
Subject Area
Genetics|Livestock
Recommended Citation
Vega-Murillo, Vicente Eliezer, "Herd life, stayability and lifetime production in beef cattle" (1999). ETD collection for University of Nebraska-Lincoln. AAI9951309.
https://digitalcommons.unl.edu/dissertations/AAI9951309