Interpretive Summary: Genetic parameter estimations and genomic insights for teat and udder structure in young and mature Canadian Angus cows
By Caitlin Vanderhoe
Beef cow teet and udder structure are highly significant facets of cow longevity, productivity, and health as well as calf morbidity and mortality. Previous work exploring the incidence of mammary structural and functional abnormalities has shown to increase with parity, but general assessments of teat structure and function are not regularly performed on beef cows, making it challenging to determine the generic repeatability of these traits over the cow’s lifetime. Devani et al. (2021) recently published a study, in the Journal of Animal Science, that used genome-wide association study (GWAS) to estimate the genetic correlation between young and mature teat and udder scores to determine if these traits are influenced by the same genes.
Four thousand, one hundred ninety two Angus cows were scored for teat and udder structure within 24 hours of calving. Smallest teats and tightest udders were scored 9, and large, bottle shaped teats and pendulous udders were assigned a score of 1. Young Teat and Young Udder Scores were scores from first or second parity cows, whereas Mature Udder and Mature Teat scores were from cows in the fourth parity or above. Of these cattle, 1,856 were genotyped to discern 30,419 SNPs for GWAS analysis.
As expected, higher udder scores (better conformation) correlated with younger cows, and teat and udder structure deteriorated with age. Young and mature teat score had greater genotypic correlation than udder score, indication that udder score may be more susceptible to environmental influences. Interestingly, despite the genotypic correlations, GWAS analysis provided very few common SNPs. Genes that were found to influence udder and teat score were also associated with a variety of cell processes but seldom overlapped, demonstrating the necessity to evaluate teat and udder scores at a variety of ages when making selections to improve the Angus breed.