Associations between feed efficiency and reproduction function

In the midst of bull sale season, most producers have a few key traits in mind, depending on their operation. For producers looking for a bull to sire “easy keeping” cattle, researchers in Canada, have reason to believe that selecting for bulls with desirable feed efficiency might put negative selection on passing a breeding soundness examination as a yearling. In light of the exponentially increasing human population, producers and researchers have been diligently addressing tools to efficiently feed the growing world. One solution, utilizes Residual Feed Intake (RFI) as a way to quantify feed efficiency of cattle. A low RFI indicates an animal who is extremely efficient in comparison to their contemporaries, or one who gains weight on less feed.

In the research conducted, an inverse relationship between feed efficiency and reproductive function was found. This study divided bulls into low and high RFI categories to analyze performance. The two groups had a 1.40 kg difference in daily dry matter intake, with low-RFI bulls having a 25-35% reduction in rib fat than high-RFI bulls. Body fat composition influences age at puberty, and shows great importance in this study when considering growing, yearling bulls. Low-RFI bulls were found to have lower sperm motility, and increased sperm abnormalities, both indicators of delayed sexual maturity. This research confirms that genetic improvement requires a balanced selection of traits, not single trait selection. Improvements in traits such as feed efficiency are only valuable if they do not offset improvements made in reproduction performance.

A. B. P. Fontoura, Y. R. Montanholi1a, M. Diel de Amorim, R. A. Foster, T. Chenier and S. P. Miller. Associations between feed efficiency, sexual maturity and fertility-related measures in young beef bulls. Link

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