Davis K C, Kress D D, Doornbos D E, Anderson D C
Montana State University, Bozeman 59715, USA.
J Anim Sci. 1998 Mar;76(3):701-5. doi: 10.2527/1998.763701x.
Records from 595 straightbred Hereford (HH), straightbred Tarentaise (TT), and reciprocal-cross (HT) females, randomly mated to HH, TT, or HT bulls, were analyzed for estimates of heterosis and breed additive effects for calf traits that included birth weight (BWT), calving difficulty (DIFF), prebreeding (PRE) and postbreeding (PST) weight, weaning weight (WWT), weaning condition score (WCS), weaning hip height (WHH), and preweaning average daily gain (ADG). The statistical model included year, age of dam, sex, regression on age at time of measurement, and regressions for the genetic effects of breed individual, breed maternal, breed grandmaternal, individual heterosis, and maternal heterosis. Breed effects were coded to reflect TT- HH differences. Age at the time of measurement, year, age of dam, and sex were significant for most traits. Individual breed effects were important (P < .05) for BWT, PRE, PST, WCS, and WHH but not for WWT, resulting in lower weights, less condition, and taller animals for TT. Maternal breed effects did not influence BWT, but they were important ( P < .05) for PRE, PST, WWT, WCS, WHH, and ADG. Grandmaternal effects were only important for BWT and ADG. Individual and maternal heterosis were important (P < .05) for most traits measured, resulting in increased calf size, weight, and body condition.
对595头纯种海福特牛（HH）、纯种塔朗泰斯牛（TT）以及正反交（HT）母牛的记录进行了分析，这些母牛随机与HH、TT或HT公牛交配，以估计犊牛性状的杂种优势和品种加性效应，这些性状包括出生体重（BWT）、产犊难度（DIFF）、配种前（PRE）和配种后（PST）体重、断奶体重（WWT）、断奶体况评分（WCS）、断奶时臀高（WHH）以及断奶前平均日增重（ADG）。统计模型包括年份、母牛年龄、性别、测量时年龄的回归，以及品种个体、品种母体、品种祖母体、个体杂种优势和母体杂种优势的遗传效应回归。品种效应进行编码以反映TT - HH的差异。测量时的年龄、年份、母牛年龄和性别对大多数性状具有显著影响。个体品种效应对于BWT、PRE、PST、WCS和WHH很重要（P < 0.05），但对WWT不重要，导致TT的体重较低且体况较差，但动物较高。母体品种效应不影响BWT，但对PRE、PST、WWT、WCS、WHH和ADG很重要（P < 0.05）。祖母体效应仅对BWT和ADG重要。个体和母体杂种优势对所测量的大多数性状很重要（P < 0.05），导致犊牛体型、体重和身体状况增加。
