Genetic variation in PLAG1 is associated with early fertility in Australian Brahman cattle.

PLAG1 is a gene with allelic variation that has well-documented associations with stature and age at puberty in cattle. Here we extend knowledge of the effect of the PLAG1 alleles to later in life female fertility, as well as size and growth, in Australian Brahmans. Records were collected from 2,839 genotyped Brahman cows and used to generate fertility, growth, and weight phenotypes. A variant on chromosome 14 in PLAG1 (rs109815800) was previously determined to be highly associated with variation in cattle stature. The allele combination (the genotype) at this position was isolated for each animal and the effect of PLAG1 genotype on each trait was estimated using linear modeling. Regardless of how heifer fertility was measured, there was a significant and desirable relationship between PLAG1 genotype and successful heifer fertility. However, the effects of allele combination on fertility began to diminish as cows aged and did not significantly influence stayability at later ages. While there was no effect of genotype on growth, PLAG1 had a negative effect on mature cow weight. Selection emphasis on improved Brahman heifer fertility will likely increase the frequency of the desirable PLAG1 allele, which may have additional benefits on herd profitability and long-term sustainability.