Madalena F E, Teodoro R L, Madureira A P
Department of Animal Sciences, School of Veterinary Sciences, Federal University of Minas Gerais, Caixa Postal 567, 30123-970 Belo Horizonte, MG, Brazil.
Genet Mol Res. 2003 Sep 30;2(3):271-8.
Serial data on live weights, height at withers and the weight/height ratio of 263 cows (3 to 9 years old) and 196 heifers (2 to 5 years old) were studied. The animals were of six red and white Holstein-Friesian (HF)/Guzera crosses (1/4, 1/2, 5/8, 3/4, 7/8 and > or = 31/32 HF-expected gene fraction). Separate analyses were performed for cows and heifers using the Proc Mixed of the SAS package. Models included the fixed effects of farm, season, reproductive and lactation status, two-factor interactions, quadratic regressions on age and age x crossbred group interaction, as continuous co-variables and regressions on the HF gene fraction and on breed heterozygosity, plus the animal random effect. Only heifer growth in height and weight/height was linear with age. In all three traits in both categories the individual additive-dominance model explained the variation between crossbred groups. The breed additive difference was not significant (P > 0.05) for cow and heifer live weight and for heifer weight/age ratio. Heterosis was significant for all traits except height of cows. Linear and quadratic regression coefficients for cows, were, respectively, for live weight, 35.20 +/- 5.23 kg/year and -1.54 +/- 0.43 kg/year2, for withers height, 2.49 +/- 0.29 cm/year and -0.15 +/- 0.02 cm/year2 and for weight/height, 0.22 +/- 0.04 kg/cm/year and -0.01 +/- 0.003 kg/cm/year2. Corresponding values for heifers were, for live weight, 153.46 +/- 37.06 kg/year and -15.69 +/- 4.91 kg/year2, while only linear coefficients applied to withers height (1.63 +/- 0.43 cm/year) and weight/height (0.16 +/- 0.03 kg/cm/year).
对263头母牛（3至9岁）和196头小母牛（2至5岁）的体重、肩高以及体重/身高比的系列数据进行了研究。这些动物是六个红白花荷斯坦-弗里生（HF）/古泽拉杂交品种（HF预期基因比例为1/4、1/2、5/8、3/4、7/8和≥31/32）。使用SAS软件包的Proc Mixed程序分别对母牛和小母牛进行了分析。模型包括农场、季节、繁殖和泌乳状态的固定效应、双因素交互作用、年龄的二次回归以及年龄×杂交组交互作用，作为连续协变量以及HF基因比例和品种杂合度的回归，再加上动物随机效应。只有小母牛的身高和体重/身高增长与年龄呈线性关系。在这两个类别中的所有三个性状中，个体加性-显性模型解释了杂交组之间的变异。母牛和小母牛的体重以及小母牛的体重/年龄比的品种加性差异不显著（P>0.05）。除母牛身高外，所有性状的杂种优势均显著。母牛的线性和二次回归系数分别为：体重，35.20±5.23千克/年和-1.54±0.43千克/年²；肩高，2.49±0.29厘米/年和-0.15±0.02厘米/年²；体重/身高，0.22±0.04千克/厘米/年和-0.01±0.003千克/厘米/年²。小母牛的相应值为：体重，153.46±37.06千克/年和-15.69±4.91千克/年²，而只有线性系数适用于肩高（1.63±0.43厘米/年）和体重/身高（0.16±0.03千克/厘米/年）。
