Author
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Macneil, Michael |
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Submitted to: Beef Improvement Federation Proceedings
Publication Type: Proceedings Publication Acceptance Date: 6/1/2001 Publication Date: 7/1/2001 Citation: MACNEIL, M.D. COMPARISON OF MASS SELECTION BY INDEPENDENT CULLING LEVELS FOR BELOW AVERAGE BIRTH WEIGHT AND GREATER YEARLING WEIGHT WITH SINGLE-TRAIT MASS SELECTION FOR GREATER YEARLING WEIGHT IN LINE 1 HEREFORD CATTLE. BEEF IMPROVEMENT FEDERATION PROCEEDINGS. 2001. p. 125-128. Interpretive Summary: Selection for below average birth weight and high yearling weight simultaneously is a selection strategy that may appeal to beef producers. While this strategy can result in improved post-natal performance relative to random selection, growth performance is compromised somewhat with the resulting cattle becoming earlier maturing, smaller, and fatter at all ages than under selection for high yearling weight alone. However, hastening maturation and reducing cow size and milk production may improve efficiency of beef production by reducing energy required by the cow herd in some production systems. The popular appeal of selecting for low birth weight and high yearling weight may stem from the perception that this strategy should change the relationship between cow size and calf birth weight and thus continually improve calving ability while maintaining an increasing genetic trend in juvenile growth. Based on the results of this research, this perception may be flawed. Direct selection may be more effective in reducing dystocia than pressure applied to indicator traits. Technical Abstract: Selection for below average birth weight and high yearling weight simultaneously is a selection strategy that may appeal to beef producers. While this strategy can result in improved post-natal performance relative to random selection, growth performance is compromised somewhat with the resulting cattle becoming earlier maturing, smaller, and fatter at all ages than under selection for high yearling weight alone. However, hastening maturation and reducing cow size and milk production may improve efficiency of beef production by reducing energy required by the cow herd in some production systems. The popular appeal of selecting for low birth weight and high yearling weight may stem from the perception that this strategy should change the relationship between cow size and calf birth weight and thus continually improve calving ability while maintaining an increasing genetic trend in juvenile growth. Based on the results of this research, this perception may be flawed. Direct selection may be more effective in reducing dystocia than pressure applied to indicator traits. |
