Breeding values for fertility can now be calculated in a different way and with more accurate information. According to an on-going study at the Swedish University of Agricultural Sciences (SLU), data from progesterone samples of the cows can aid significant progress in the fertility of dairy cows.
Researchers from the Nordic countries are working on a joint project on reproduction in dairy cows. The Swedish part of the project is using information from milking robots in 14 farms having an advanced management equipment with in-line recordings of milk progesterone. The researchers believe there is a way to improve the breeding values for fertility by using this data of milk progesterone tests.
“We work with data from progesterone tests and the pregnancy hormone PAG to develop new properties that are more biologically relevant to our dairy cows”, says Britt Berglund, professor in applied animal genetics from SLU and with a long career dedicated to investigating and researching cattle breeding genetics with particular emphasis on fertility and health traits.
“Despite the fact that 90% of inseminations result in fertilization, our previous studies have shown that only every third insemination results in a viable calf”, she explains. “These results point to extensive embryo and foetal losses during pregnancy. By detecting fertility disorders and pregnancy losses at an early stage, empty cows can be identified, and losses reduced”, the professor adds.
Goal to improve breeding values
The overall goal is that we will be able to develop fertility characteristics that can be used to improve breeding values for fertility in dairy cows.
“We believe progesterone has a potential to improve fertility evaluations”, Berglund says. “We believe strongly that the progesterone-based measures of fertility have a potential to improve the genetic evaluation of fertility because in previous studies we have shown that some of those endocrine measures have four times as high heritability. The classical measure we use today as a proxy for luteal activity is the interval from calving to first insemination, which has a heritability of around 5%, but when luteal activity is monitored by progesterone, this increases to about 20% or even 25%”, she explains.
However, implementing the new measurement in breeding could take more time since it requires large amounts of data and a more complex method to obtain registrations. “We believe that if we could put this information from the progesterone analysis in the selection index it could help the evaluation. But there are some difficulties with this, in that of course progesterone is not sampled routinely today in the majority of herds but in-line recordings are becoming more common in future herds. Moreover, genomic selection opens up the possibility of collecting the recordings in a lower number of herds and using this information for the rest of the population¨.
14 herds involved in the project
The project is retrieving information from 14 herds in Sweden. Earlier studies have been performed in collaboration with countries mainly having the Holstein breed. In this Nordic project the Red Dairy Cattle is also included. With this information, scientists are able to see differences by breed, and from cow to cow when they start the fertile cycle, i.e. if it is a normal cycle or if there are atypical progesterone profiles. Based on these progesterone records, they can also detect the causes of embryo losses.
“In the future we can use this information to improve calculations and give farmers better tools to improve their herds”, she concludes.