# Association of NCOA6 Gene Polymorphism with Milk Production Traits in Chinese Holstein Cows

## TL;DR

This study found that two genetic variations in the NCOA6 gene are linked to higher milk production in Chinese Holstein cows.

## Contribution

The study identifies two SNPs in the NCOA6 gene that significantly affect milk yield and fat content in Chinese Holstein cows.

## Key findings

- The SNP g.87310A > G is strongly associated with increased daily milk yield and 305-day milk production.
- Cows with the AA genotype for g.87310A > G produce 1.64 kg more milk daily and 500 kg more over 305 days.
- The two SNPs, g.71544C > T and g.87310A > G, are in linkage disequilibrium and influence milk production traits.

## Abstract

Milk is the most vital commodity that is used worldwide. In the dairy industry, traits that are linked with milk production are of economic importance, increasing the focus of dairy farmers on enhancing milk quality. Nuclear receptor coactivator 6 is a gene that is involved in controlling gene expression by encoding a protein that enhances the activity of transcription factors. It is involved in many cellular and homeostatic processes. An SNP is a variation in a single nucleotide at a specific position in a DNA location. These polymorphisms affect the milk production traits of dairy cows. In this study, we identified two SNPs, g.71544C > T and g.87310A > G, in the NCOA6 gene in Chinese Holstein cows, which ultimately affected the 305-day milk yield, fat content, and to some extent the somatic cell score. The reference sequences of these two SNPs were taken from the NCOA6 Bos taurus gene on chromosome 13, having a reference sequence number of NC_037340.1. In brief, polymorphisms of the NCOA6 gene for milk production traits were studied, serving as a valuable reference in the genetic selection of Chinese Holstein cows and supporting improved economic returns.

Nuclear receptor coactivator 6 is a gene that produces a protein that regulates transcriptional activity. It is also involved in many processes like cell survival, metabolism, homeostasis, and embryonic development. This study focused on studying the genetic influence of single-nucleotide polymorphisms (SNPs) within the NCOA6 gene on lactation performance characteristics. The objective of this study was to determine the genetic impact of SNPs of the NCOA6 gene on milk production traits. After the random selection of twenty cows, PCR amplification and sequencing were performed from their blood samples to find the SNPs present in the bovine NCOA6 gene. As a result, two SNPs, g.71544C > T and g.87310A > G, were found. Then, the genotyping of the cows (n = 985) was conducted using a Sequenom MassARRAY based on previously identified SNP information. The least-square method was applied to study the links between lactation traits, somatic cell score (SSC), and 305-day milk output. The results indicated that the SNP g.87310A > G was strongly associated with g.71544C > T in linkage disequilibrium. The single-nucleotide polymorphism g.87310A > G showed a very strong association with daily milk yield and 305-day milk production. Individuals with the AA genotype exhibited a notable increase in daily milk production by 1.64 kg, and their 305-day milk yield was approximately 500 kg higher. This variation demonstrated a significant genetic effect on milk output. In brief, the pleiotropic influence of the cattle NCOA6 gene on lactation traits was revealed in this study. However, additional research will provide a basis for further exploring the underlying correlation and theoretical framework of the molecular genetics of milk composition and the production attributes of Holstein cows.