Sometimes an "achilles heel" in a production driven dairy industry is that sector's fertility rate in its milking cows.
The cost can be large with some farmers at times having dry cows at expensive and unacceptable levels.
Much work has been invested into trying to improve fertility in the national herd and for a few years inducing cows to abort foetuses early was a technique used to help late calving issues.
Animal welfare concerns have made this practice unacceptable and not a good look for our premier industry, and if this new work is successful such a barbaric practice should be banned.
Animal gene research is making great progress in unlocking the secrets of the mammals we farm, and this work will be a significant discovery to help solve poor fertlity statistics of dairy cows.
With a large percentage of this sector's animals being bred from a small amount of sires through extensive AI use, identifying above average fertility genes will flow on quickly through the national herd.
After examining more than 20,000 genes, a DairyNZ scientist has discovered why some cows are better at getting pregnant than others.
DairyNZ scientist Caroline Walker has discovered there are about 1,500 genes affecting the uterus that are altered in pregnant cows.
The results of her research Endometrial gene expression during early pregnancy differs between fertile and sub-fertile dairy cow strains have been published in the international journal Physiological Genomics.
"This gives us a greater understanding of the reasons for sub-fertility, and puts us in a better position to discover gene markers that will produce bulls that give greater fertility. It’s essentially enabled us to narrow down what we’re looking for." says DairyNZ Principal Scientist – Animals, Dr John Roche.
She studied two different strains of cows – US Holsteins and NZ Holsteins. Work done by DairyNZ scientists over the last decade confirmed that US-type dairy cows were less likely to get pregnant in the New Zealand pasture-based system.
“We already knew that the New Zealand cow is better at establishing pregnancy. Conception rates are 50-60 percent for New Zealand cows, compared with approximately 40 percent for US cows.“
"Caroline’s work has shown us some of the reasons why – basically the New Zealand cow is better at establishing pregnancy, and now she’s identified some of the genes which determine this. The next step is to look at epigenetic changes, which are things that happen to alter the expression of genes," says Dr Roche.
"It’s extremely exciting work because understanding the underlying physiology has great implications for improving the fertility of the national herd."
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