Pratt S L, Spitzer J C, Webster H W, Hupp H D, Bridges W C
Dept. of Anim. Sci., Clemson University, Clemson, SC 29634-0361.
J Anim Sci. 1991 Jul;69(7):2711-20. doi: 10.2527/1991.6972711x.
From 1981 through 1986, BW, hip height, and scrotal circumference (SC) measurements were obtained on 329 bulls at the start of a 140-d gain test (SOT) and every 28 d to the end of test (EOT). Age, overall ADG, weight per day of age, ADG by period, and SC growth (cm/d) were calculated. Data were analyzed in two data sets because age of dam (AOD) and birth weights were unavailable between 1981 and 1983. Correlations of SC to other traits measured and probabilities for bulls attaining 30 or 32 cm SC by 365 d of age were calculated. Two adjusted 365-d SC (365-d SC) were calculated for each individual from regression analysis and from the following formula: 365-d SC = [(SCEOT-SCSOT)/140 d] x [365-ageSOT] + SCSOT. Except for ADG in Data Set 2, breed group differences (P less than .05) were observed for correlations of SC to all growth traits, age, and AOD. To attain 30 cm SC by 365 d of age with nearly 100% probability, Angus, Simmental and Zebu-derived bulls needed a 23-cm SCSOT, whereas continental (other than Simmental) and Polled Hereford bulls required a 26-cm SCSOT. Overall, 365-d SC means calculated by regression analysis or formula method did not differ (P greater than .10) for either data set.
1981年至1986年期间，在一项为期140天的增重试验开始时（试验起始点，SOT），对329头公牛进行了体重（BW）、体高和阴囊周长（SC）测量，并在之后每隔28天测量一次，直至试验结束（试验终点，EOT）。计算了年龄、总体平均日增重（ADG）、日龄体重、各阶段ADG以及SC生长速度（厘米/天）。由于1981年至1983年期间无法获取母牛年龄（AOD）和出生体重数据，因此对数据进行了两个数据集的分析。计算了SC与其他测量性状之间的相关性，以及公牛在365日龄时达到30或32厘米SC的概率。通过回归分析和以下公式为每个个体计算了两个调整后的365日龄SC（365-d SC）：365-d SC = [(EOT时的SC - SOT时的SC)/140天]×[365 - SOT时的年龄] + SOT时的SC。除了数据集2中的ADG外，观察到不同品种组在SC与所有生长性状、年龄和AOD的相关性方面存在差异（P小于0.05）。要使安格斯牛、西门塔尔牛和瘤牛杂交公牛在365日龄时达到30厘米SC的概率接近100%，则SOT时的SC需要达到23厘米，而欧洲大陆品种（西门塔尔牛除外）和无角海福特牛则需要26厘米的SOT时的SC。总体而言，通过回归分析或公式法计算的两个数据集的365日龄SC均值没有差异（P大于0.10）。
