Can't have your cake and eat it too
To make matters worse, this particular mutation has become rather common in Nordic Red cattle, however, the deletion is totally absent in Nordic Holstein and Danish Jersey populations. Based on the frequency of the mutation in the population, it is estimated that 2.89, 1.32 and 0.42% of embryos are dying in Finnish Ayshire, Swedish Red and Danish Red cattle respectively due to this mutation.
The reason that the deleted gene sequence causing embryo mortality has become relatively widespread is that it has such as strong positive effect on milk yield. By selecting for high milk yields, breeders have inadvertently also selected for embryo mortality a situation of so-called hitchhiking.
Our study demonstrates that embryonic lethal mutations account for a non-negligible fraction of the decline in fertility of domestic cattle and that associated positive effects on milk yield may account for part of the negative genetic correlation. This is at least the seventh example in livestock of an allele that is deleterious in the homozygous state being maintained at high frequency in the populations because of the selective advantage it confers to heterozygotes.
Read the scientific article in PloS Genetics here.
|Contact: Goutam Sahana|