Abstract: The 3 years of data from 464 purebred Holstein and Holstein cross (unimproved Holstein-Chinese Yellow cattle crosses, improved Holstein-Chinese Yellow cattle crosses) cattle were used to evaluate effects of polymorphisms in both GH and GHR on milk yield and quality. Traits evaluated included 305 days milk, milk fat, milk protein and lactose yield and 305 days milk fat, milk protein and milk lactose percentage. Three genotypes and two genotypes were found within the GH and GHR genes, respectively. Based on mixed model least squares analyses (SAS®, Raleigh, NC, USA) there was evidence of genotypic difference for GH in 305 days milk yield for improved Holstein-Chinese Yellow cattle and purebred Holstein (p<0.10) but only a weak trend for genotypic differences across breed groups (p<0.15). Genotypic differences for GH in milk fat, protein and lactose yield were not evident in unimproved Holstein-Chinese Yellow cattle or purebred Holstein cattle (p>0.10) but there were trends for genotypic differences in milk fat, protein and lactose yield in improved Holstein-Chinese Yellow cattle (p<0.10). There was little evidence of genotypic differences for GHR in any trait (p>0.20). Results from this research suggest polymorphisms in GH can affect milk yield and quality but such effects may be dependent on percentage Holstein in the cow.
Yao-Dong Li, Yan-Nan Ma, Peng-Jia He, Michael A. Brown, Zhao-Min Lei, Jing Zhu, Hai-Rong Zhang, Jun Li and Jian-Ping Wu, 2013. Effects of Growth Hormone (GH) and Growth Hormone Receptor (GHR) Gene Polymorphisms on Milk Production Traits in Holstein and Holstein x Chinese Yellow Cattle Crosses. Journal of Animal and Veterinary Advances, 12: 1210-1216.