Good management of high genetic merit dairy cows can result in high levels of reproductive performance
Take Home Message: Good reproductive performance can be achieved from high genetic merit dairy cows if high levels of fertility management and nutrition are achieved.
Dairy cow fertility is negatively associated with both genetic merit and level of production, and various other factors including season of calving, lactation number and difficult calvings.
“Level of production had a larger effect on fertility performance than genetic merit for milk production suggesting that infertility at an individual cow level is more likely to be associated with increased production and an inability to meet the nutritional requirements of the cow,” said the Hillsborough-based Agri-Food and Bioscience Institute’s David Mackey.
He and his team examined the relationships between genetic merit for milk production and animal parameters and various parameters of reproductive performance using multi-level binary response analysis in a study of 19 dairy herds for three successive years, representing approximately 2,500 cows per year.
The proportion of cows intended for rebreeding that were back in-calf again within 100 days of calving and the proportion of cows that reappeared again with 365 and 400 days of a previous calving were considered in addition to the traditional measures of reproductive performance.
“And we found that level of production has the greatest negative effect, particularly when considered over a 305-day lactation, indicating that infertility at an individual cow level in this study is predominantly due to an inability to meet the nutritional requirements of high genetic merit dairy cows, as evidenced by lower nadir milk protein concentrations.
“These results also suggest that it is possible to achieve good reproductive performance from high genetic merit dairy cows providing high levels of fertility management and appropriate nutrition are achieved,” added Dr Mackey.
Full details: Mackey DR, Gordon AW, McCoy MA, Verner M and Mayne CS: “Associations between genetic merit for milk production and animal parameters and the fertility performance of dairy cows.” ANIMAL 1, 29-43 www.bsas.org.uk
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