Effect of milk fat to protein ratio on genetic variance for milk yield in Thai tropical Holstein cattle

Abstract

The objective of this research was to investigate the optimum fat to protein ratio (FPR) in Thai tropical Holstein dairy cattle. First parity data consisting of 20 492 milk yields (MY) records for 24 891 cows for the period 2001 and 2011, were used in the analysis. The analysis used a random regression test-day animal model of thirdorder Legendre polynomials through the creation of a covariance function based on different FPRs. Variance components were estimated using the Bayesian method via the Gibbs sampling. The estimated heritability of MY in relation to FPR ranged from 0.19 to 0.27 with the pattern being similar to the genetic variances. Genetic correlations of MY at different FPRs were high at consecutive FPRs and then declined to negative in response to greater differences in FPR. Based on the results, it is concluded that the optimum FPR is in the range of 0.9 to 1.9, corresponding to the genetically controlled energy balance for MY in tropical Holsteins.

First-lactation milk fat-to-protein ratio in tropically-raised dairy cows: environmental and genetic influences

“…In this study, the means were within the ranges reported in previous studies in Thailand. (Buaban et al, 2016;Puangdee et al, 2016;Wongpom et al, 2017) and similarly the result from Satola and Ptak (2019) in Polish HF.…”

“…In Thailand, there are several report and investigate the topic of FPR in Thai tropical Holstein dairy cattle. Puangdee et al (2016) Buaban et al (2016) Puangdee et al (2017. In the study of Buttchereit et al (2011) examining the genetic relationship between daily energy balance and FPR it was shown that the correlation was high at the beginning of lactation and decreased toward zero at 180 DIM.…”