Genetic parameters for new fertility traits were presented during a meeting for dairy farmers participating in the European project PROLIFIC. The project focusses on the development of new fertility traits, identification of genes related to reproduction, and genomic selection for fertility traits. This will contribute to robust and sustainable improvement of fertility of cows.
At the herd level, good reproductive performance is crucial for economic sustainability. At the individual level, it is a key factor that affects the cow’s health, welfare, and also the animal’s robustness. Genetic selection has been highly successful and has resulted in modern dairy cows with very high milk yields, but there has been a parallel reduction in fertility, therefore PROLIFIC focusses on the genetic aspects of fertility.
New fertility traits
All participating dairy farms are equipt with a Herd Navigator (DeLaval, FOSS), that measures the progesterone level in milk routinely. This way the reproductive cycle of each cow can be monitored to determine the most optimal moment for insemination and eventually determine pregnancy. During this meeting Researchers of Wagenigen UR Livestock Research presented new fertility traits defined with the data from the Herd Navigator. The new traits were defined as: commencement of luteal activity, interval from commencement of luteal activity to first service, luteal activity during first 60 days in milk, proportion of samples with luteal activity, luteal phase length, inter-ovulatory intervals, and number of inter-ovulatory intervals before first service. Genetic parameters were estimated for these new fertility traits. The new traits commencement of luteal activity, interval from commencement of luteal activity to first service, and proportion of samples with luteal activity showed a higher heritability as compared to the traditional fertility traits calving interval and period between calving and first insemination. These higher heritabilities are due to the more accurate measurement and the frequency of measuring, and offer opportunities for breeding as the breeding values for these new fertility traits are more reliable.
The cows with fertility records were also genotyped. The cattle breeding organisation CRV gave a presentation about the differences in traditional breeding values bases on pedigree and genomic breeding values based on DNA information. The translation of the results from PROLIFIC to official national evaluation for these new fertility traits is currently not possible, because the number of farms equipped with a Herd Navigator is limited. Therefore PROLIFIC will focus on the identification of genes related to reproduction in further research.