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Interpretive Summary: Genetic parameter estimation for beef bull semen attributes

By: Anne Kamiya, MS

Improving the efficiency of cattle production ideally involves selecting for both male and female animals with desired traits and high fertility. A significant portion of the current genetic research however only focusses on improving the heritable traits of female animals. Expanding focus to study the heritable traits of male animals as well may help to maximize performance.

In this recent Journal of Animal Science study, researchers chose to better understand the genetic parameters of bull fertility using fixed effect modeling. Data for the model was taken from bull semen collection facilities and used to estimate variance components, heritabilities and correlations between semen attributes (phenotypes) and fertility.

Nine attributes were evaluated and included volume, concentration, motility and percent of normal spermatozoa. Heritability of traits was low. However, most of these traits except for motility and concentration were also highly genetically correlated. The authors could not find an attribute that could become an indicator for bull fertility. The following class effects also impacted fertility: age of the bull, collection location and day and days since the last collection. Overall, this study shows there is potential for using genetic selection tools in predicting and improving bull fertility, but this area of research is very lacking and requires expanded study.

The full paper can be found on the Journal of Animal website.