Annual phenotypic and genetic change of growth pattern for body measurements traits in Holstein females

Abstract

This study aimed to investigate phenotypic and genetic change over year for the growth pattern of body measurements traits using 3,215 to 3,485 Holstein females born between 2004 and 2015. We calculated growth parameters and predictions at 12, 24, 36, 48 and 60 month age for five traits of body weight (BW), height (HT), hip width (HP), rump length (RP) and heart girth (HG) by fitting a non-linear growth models. We used their breeding values by a single-trait animal model in genetic analysis. Significant annual phenotypic and genetic changes for the growth parameter of mature size were found with 7.40kg/yr and 1.99kg/yr in BW, 0.29cm/yr and 0.19cm/yr in HT, 0.13cm/yr and 0.06cm/yr in RP, 0.79cm/yr and 0.27cm/yr in HG, while HP showed a notable change with the value of 0.11cm/yr in only a genetic aspect． A similar tendency was also observed for growth values at each month age, and the results indicated an increase of body size in recent years. Moreover, the results of both phenotypic and genetic analysis suggested that the maturing of BW and HG may be getting later.