Submission Number: NOR-4-15-17

Abstract Number: 491

MIXED MODEL ANALYSIS OF MARKERS IN GROWTH HORMONE AND ITS RECEPTOR AND THEIR ASSOCIATION WITH LACTATIONAL PERFORMANCE IN HOLSTEINS.

Norio Kansaku, Samuel E Aggrey, Babu AS Gollapudi, Urs Kuhnlein and David Zadworny*

Dept. Animal Science, McGill University, Montreal, PQ, Canada ¹

Abstract:
In daily cattle, treatment with exogenous growth hormone (GH) affects growth and function of the mammary gland. The actions of GH are mediated via interaction with GH receptor (GHR). The first step in signal transduction is homodimerization of two GHR molecules by GH. This step is critical since mutation in either GH or GHR can block dimerization and thus target cell activation. Genetic variants of GH or GHR and their association with milk related traits have been reported. However, association between milk related traits and combination of GH and GHR variants are not known. Accordingly, DNA genotypes in the GH and GHR genes were investigated for association with milk, fat and protein lactation yield in Holsteins. The marker data were obtained on 873 progeny tested bulls by using PCR-RFLP and -SSCP. There were five markers in GH and three in GHR. Daughter yield deviations (DYDs) were obtained from the Canadian Daily Network for milk, fat and protein lactation yields for the 873 genotyped bulls. There was significant difference in GH6.1 (C-to-G transversion at position 2141) for milk yield (p<0.05). There were significant differences in GHR Alu I (A-to-T transversion at -1182) for milk (p<0.05) and fat (p<0.05), and in GHR Stu I (C-to-T transition at -232) for fat (p<0.0001) and protein (p<0.05). Allele frequencies for GH6.1C, GHR Alu I (+) and GHR Stu I (+) alleles in the 873 bulls genotype were 0.94, 0.62 and 0.95, respectively. Bulls with GH6.1 (C/C) genotype had higher milk expected breeding value (EBV) (p<0.05) compared to (C/G) bulls. Bulls with Alu I (+/+) gonotype had higher milk EBV (p<0.01) and fat EBV (p<0.005) compared to Alu I (-/-). Bulls with Stu I (+/+) genotype had higher fat EBV (p<0.0001) and protein EBV (p<0.05) compared to Stu I (+/-). This study indicates that the combination of GH and GHR markers could serve a tool to aid selection for improved milk, fat and protein production. .

Keywords: GH, GHR, Lactation

This abstract is being presented at: 8:00 AM in session:
Growth Factors II