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Assessment Of Alternative Models For Genetic Analysis Of Worm And Tick Infestation In Nellore Cattle, T. L. Passafaro, F. B. Lopes, Thomas W. Murphy, B. D. Valente, R. C. Leite, G. J.M. Rosa, F. L.B. Toral
Assessment Of Alternative Models For Genetic Analysis Of Worm And Tick Infestation In Nellore Cattle, T. L. Passafaro, F. B. Lopes, Thomas W. Murphy, B. D. Valente, R. C. Leite, G. J.M. Rosa, F. L.B. Toral
Roman L. Hruska U.S. Meat Animal Research Center: Reports
Worms and ticks are important parasites in beef cattle, especially in tropical areas, causing significant economic and production losses. Understanding animal-to-animal variation on infestation for these parasites might guide genetic selection and improvement of management practices to attenuate its detrimental effects. Statistical models used to analyze such traits usually assume a Gaussian distribution for the observed data. However, this assumption is quite often inappropriate for counting data. Therefore, the objectives of this study were: 1) Estimate genetic parameters for worms and tick infestations in Nellore cattle, and 2) To compare the overall performance of six data analysis approaches for worm …
Genetic Changes In Beef Cow Traits Following Selection For Calving Ease, Gary L. Bennett, Richard M. Thallman, Warren M. Snelling, John W. Keele, Harvey C. Freetly, Larry A. Kuehn
Genetic Changes In Beef Cow Traits Following Selection For Calving Ease, Gary L. Bennett, Richard M. Thallman, Warren M. Snelling, John W. Keele, Harvey C. Freetly, Larry A. Kuehn
Roman L. Hruska U.S. Meat Animal Research Center: Reports
One approach to reducing calving difficulty is to select heifers with higher breeding value for calving ease. Calving ease is often associated with lower birth weight and that may result in other possible effects on lifetime productivity. Females from experimental select and control calving ease lines within each of the seven populations were compared. Random samples of 720 heifers from lines selected for better calving ease breeding values and 190 heifers from control lines selected for average birth weights were followed through four parities. Select and control lines within the same population were selected to achieve similar yearling weight breeding …