Grossman M, Bohren B B, Anderson V L
J Hered. 1985 Sep-Oct;76(5):397-9.
Parameters of a mathematical function of growth, fit to the body weight curve of two randombred control populations of each sex of chickens from hatching through 45 weeks of age, were estimated. The logistic function was chosen from among growth formulae that express rate of gain as a function of weight at a given time and gain to be made. Two logistic parameters, growth-rate constant and age at the point of inflection, were estimated by the methods of sample quantiles and nonlinear regression from weekly mean body weights of 225 males and 281 females of the Rhode Island Red (RIR) line, and 164 males and 239 females of the White Leghorn (WL) line. Males had a larger growth-rate constant than females of the same line. The RIR line had a larger rate constant than the WL line, for each sex. Age at the point of inflection was similar for males and females in the RIR line, but smaller for males than females in the WL line. Sample quantiles yielded larger, less precise estimates of the growth-rate constant than nonlinear regression. Estimates of age at the point of inflection were usually smaller using sample quantiles.
对从孵化到45周龄的每个性别的两个随机繁殖对照鸡群的体重曲线进行拟合的生长数学函数参数进行了估计。逻辑函数是从将给定时间的增重率表示为体重和预期增重的函数的生长公式中选择的。通过样本分位数法和非线性回归法，根据罗德岛红（RIR）品系的225只雄性和281只雌性以及白来航（WL）品系的164只雄性和239只雌性的每周平均体重数据，估计了两个逻辑参数，即生长速率常数和拐点年龄。同一品系中，雄性的生长速率常数大于雌性。对于每个性别，RIR品系的速率常数大于WL品系。RIR品系中雄性和雌性的拐点年龄相似，但WL品系中雄性的拐点年龄小于雌性。与非线性回归相比，样本分位数法对生长速率常数的估计值更大，但精度更低。使用样本分位数法估计的拐点年龄通常更小。
