On April 28th 2017 two events marked the end of the European research project PROLIFIC that focussed on the improvement of dairy fertility by using progesterone measures in milk. Amabel Tenghe successfully defended her PhD thesis and there was a meeting for participating dairy farmers in Wageningen.
Functional reproductive performance of dairy cows is important for the economics of the dairy farmer, but also for the longevity of dairy cows and a reduction in veterinary treatments. In the 90ths and in beginning of this century we have seen a strong decline in fertility of dairy cows, mainly due to the change in genetics. For this reason there has been a strong interest in genetic selection to improve fertility. Traditional fertility traits based on insemination and calving records are available on large scale, however they do not necessarily reflex the actual reproductive state of the cow. The European project PROLIFIC focussed therefore on progesterone measures in milk from the Herd Navigator.
Improving the reliability of fertility breeding values
The past four years Amabel Tenghe has studied fertility traits based on progesterone profiles from the Herd Navigator as part of the PROLIFIC project. Her PhD project was also part of the European Graduate School in Animal Breeding and Genetics and a collaboration with the Swedish Agricultural University (SLU) in Uppsala leading to a joint degree from both Wageningen University an SLU. The findings of this research are published in the PhD thesis entitled ‘Milk progesterone measures to improve genomic selection for fertility in dairy cows’ The main conclusions are: i) fertility traits based on progesterone are heritable and many genes with small effects are involved, a small number of candidate genes have been identified; ii) progesterone measures in milk in combination with genomics can improve the reliability of breeding values for fertility. However, at the moment there is not enough progesterone data available to improve the reliability of traditional fertility traits because they are recorded on such a large scale.
Relationship between fertility and milk production
On the same day as the defence there was a meeting to share the research results with participating dairy farmers. Based on 13 dairy farms the fertility of cows does not have to decline with high milk production. Most cows were inseminated for the first time at their 2nd or 3rd cycle, with a 40% success rate. Insemination success showed to be independent of the cycle of the cow, hence a relationship between milk production and progesterone cycle was not found. However, the high producing cows needed more inseminations to establish pregnancy.