Estimating myostatin gene effect on milk performance traits using estimated gene content for a large number of non-genotyped cows

Abstract

The objective of this study was to estimate the myostatin (mh) gene's effect on milk, protein and fat yield in a large heterogeneous cow population, of which only a small portion was genotyped. For this purpose, a total of 13 992 889 test-day records derived from 799 778 cows were available. The mh gene effect was estimated via BLUP using a multi-lactation, multi-trait random regression test-day model with an additional fixed regression on mh gene content. As only 1416 animals, (of which 1183 cows had test-day records) were genotyped, more animals of additional breeds with assumed known genotype were added to estimate the genotype (gene content) of the remaining cows more reliably. This was carried out using the conventional pedigree information between genotyped animals and their non-genotyped relatives. Applying this rule, mean estimated gene content over all cows with test-day records was 0.104, showing that most cows were homozygous 1/1. In contrast, when gene content estimation was only based on genotyped animals, mean estimated gene content over all cows with test-day records was with 1.349 overestimated. Therefore, the applied method for gene content estimation in large populations needs additional genotype assumptions about additional animals representing genetic diversity when the breed composition in the complete population is heterogeneous and only a few animals from predominantly one breed are genotyped. Concerning allele substitution effects for one copy of the 'mh' gene variant, significant decreases of 276.1 kg milk, 23.6 kg fat and 22.8 kg protein/lactation were obtained on average when gene content estimation was additionally based on animals with assumed known genotype. Based on this result, knowledge of the mh genotypes and their effects has the potential to improve milk performance traits in cattle.

Reproductive performance of Belgian Blue and Wagyu cross cows

“…Crossbreeding between Bos taurus and Bos indicus is effective in increasing milk yield and its nutrient contents, such as protein, fat, and total solid. A study by Buske et al (2011) showed that the myostatin mutant gene was responsible for higher milk, protein, and fat yield in Belgian blue cows. Belgian blue have muscle hypertrophy (mh) that implicates higher milk production and reduced saturated fatty acid content in milk.…”

The pattern of linkage disequilibrium in Dual‐Purpose Belgian Blue cattle

“…On the one hand, breeders of BBB used homozygous sires to increase the frequency of "mh" allele; thus, it is expected that nearly all BBB animals are mh/mh (Coopman, 2008; McPherron & Lee, 1997). On the other hand, it has been showed that the wild‐type allele of this gene (+) is responsible for a higher milk, protein and fat yields in DPBB cows; thereupon, currently the DPBB animals can be divided into three genotypes (+/+, +/mh and mh/mh) (Buske et al., 2010, 2011, 2011). Although it has been documented that milk produced by DPBB cows has a higher quality (e.g.…”