Genotype by Region Interaction on Milk Production Traits of Holstein Crossbred Dairy Cows in Thailand

Abstract

This study was designed to examine the existence of a genotype × region interaction on milk production traits in Holstein crossbred dairy cows in Thailand. The data set for this study was provided by Department of Livestock Development of Thailand. The data were divided into five regions (Central, East, North, Northeast and West). The factors having genotype × region interaction on milk production traits were region, year-season of calving, breed group and breed group × region interaction. The investigated traits were actual total milk yield (ATMY), 305 d milk yield (MY305) and adjusted 305 d milk yield (AJ305), respectively. The breed group of cow had a significant (P < 0.05) effect on MY305 and a highly significant (P < 0.01) effect on ATMY and AJ305 while the effect of year-season of calving and region had very highly significant (P < 0.001) effects for all the studied traits. Breed group × region had a highly significant interaction (P < 0.01) for the milk production traits. The estimated heritability for the milk production traits ranged between 0.17 to 0.24 for the Central region and 0.29 to 0.57 for the Eastern region. It was suggested that the performance of breed group of cows from different regions should differ significantly or there was a genotype × region interaction in this particular study.