The rate of improvement of milk production increases, if the characters related milk production can measure in calves and young bulls. Many reports assumed that the relationship between physiological characters related with energy metabolism and genetic ability for milk production is linear. In this study, two traits and quadratic covariance analysis was employed to investigate the relationship between the genetic ability for milk production and metabolites change during 1 day of fasting in young calves. Four different types of covariates were used; first dimension of one metabolite (Method 1), first and second dimensions of one metabolite (Method 2), first dimensions of two metabolites (Method 3), first and second dimensions of two metabolites (Method 4). Contribution ratio of regression (R2) in Method 4 among all the four methods (p<0.01) and highest during 36 hours of fasting among the other length of fasting (p<0.01). Especially, Method 4 at 36 hours of fasting gave high (0.70, 0.64 and 0.61) R2 values in TG and NEFA, TG and Ket and Glu and NEFA, respectively. Therefore, the first and second dimensions of two metabolite change during 36 hours of fasting at early growing stage of calves can give estimation of future breeding value for milk yield. Environmental factors should be considered since the environmental group effects in the changes of concentrations of Glu, TG and Ket during fasting were significant (p<0.0

O. Sasaki, N. Yamamoto, K. Togashi, M. Minezawa

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 23: Opening: plenary; technology; transfer; beef cattle; dairy cattle; pigs., , 451–454, 1998
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