title: An approach of estimating individual growth curves for young thoroughbred horses based on their birthdays.
abstract: We propose an approach of estimating individual growth curves based on the birthday information of Japanese Thoroughbred horses, with considerations of the seasonal compensatory growth that is a typical characteristic of seasonal breeding animals. The compensatory growth patterns appear during only the winter and spring seasons in the life of growing horses, and the meeting point between winter and spring depends on the birthday of each horse. We previously developed new growth curve equations for Japanese Thoroughbreds adjusting for compensatory growth. Based on the equations, a parameter denoting the birthday information was added for the modeling of the individual growth curves for each horse by shifting the meeting points in the compensatory growth periods. A total of 5,594 and 5,680 body weight and age measurements of Thoroughbred colts and fillies, respectively, and 3,770 withers height and age measurements of both sexes were used in the analyses. The results of predicted error difference and Akaike Information Criterion showed that the individual growth curves using birthday information better fit to the body weight and withers height data than not using them. The individual growth curve for each horse would be a useful tool for the feeding managements of young Japanese Thoroughbreds in compensatory growth periods.
authors.affiliation: Comparative Agricultural Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Onoda
authors.affiliation: The Japan Bloodhorse Breeders' Association, Tokyo 105-0004, Japan.
authors.forename: Ryuta
authors.initials: R
authors.lastname: Yamamoto
authors.affiliation: JRA Facilities Co., Ltd., Tokyo 105-0004, Japan.
authors.forename: Kyohei
authors.initials: K
authors.lastname: Sawamura
authors.affiliation: Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan.
authors.forename: Harutaka
authors.initials: H
authors.lastname: Murase
authors.affiliation: Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Nambo
authors.affiliation: Hidaka Training and Research Center, Japan Racing Association, Hokkaido 057-0171, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Inoue
authors.affiliation: Equine Research Institute, Japan Racing Association, Tochigi 320-0856, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Matsui
authors.affiliation: Comparative Agricultural Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Miyake
authors.affiliation: Comparative Agricultural Sciences, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Hirai
keywords: Thoroughbred; birthday; body weight; individual growth curve; withers height