Statistical Studies of the Variations in the Growth of Single Comb White Leghorns and their Significance

Abstract

Economical poultry flock management requires early selection of those individuals that are to be used for flock replacement. The weight of the individual is considered of primary importance in this selection. A study of the variations in growth and their relationship at different ages should improve the available knowledge in regard to early selection. A measurement of variation in growth should also prove valuable in future investigations.REVIEW OF LITERATURE Very few studies of this nature have been made and these involve only Single Comb Rhode 15, 1928) report growth curves of Single Comb Rhode Island Reds. In summarizing they state that a period of high variability in live weight was observed. This period was between 0 and 7 or 8 weeks of age for those receiving skim milk and 0 and at least 12 weeks of age for those not receiving skim milk.Henderson, D. C, (POULTRY SCIENCE, Vol. VII, No. 4, May 1, 1928) reports on the relation of the weight of Rhode Island Red pullets at four weeks to their subsequent rate of growth. The coefficients of correlation were all very significantly positive. He concludes, "The variation in weight of chicks relative to the mean weight remains nearly constant from four to sixteen weeks. The correlation of the weights of female chicks at four weeks and the weights at eight, twelve and sixteen weeks are positive and show that the chicks that are relatively large at four weeks are relatively large at eight, twelve and sixteen weeks, respectively. "

Interrelationship of Body Weight, Egg Weight, and Age at Sexual Maturity

“…In the first place, chick weight at hatching appears to bear no relation to subsequent weights at either 3, 8, or 16 weeks of age or to weight at sexual maturity. These findings are in general agreement with those previously reported for smaller numbers of individuals of the same strain of White Leghorns by Funk, Knandel, and Callenbach (1930). They also agree with the conclusions of Upp (1928) working with Rhode Island Reds, Latimer (1924) working with White Leghorns, and in part with Heuser and Andrews (1932) working with White Leghorns and mixed heavy breeds.…”

Inheritance of Rate of Growth in Barred Plymouth Rocks

“…Statistical studies of the growth of White Leghorns by Funk, Knandel, and Callenbach (1930) show that the coefficient of variability may be as large as 19.4 at four weeks of age and that it varies from 14.6 to 19.4 in four different broods. At 16 weeks they found less variability of the individual weights, but between the heaviest and the lightest chicks, within each of the four broods, there were differences varying from a little less than one pound to one and threefourths pounds.…”

Título en español.

“…Body weight was taken in pounds at the end of the first, second, third, and fourth month of age. Funk, Knandel, and Callenbach (1930) found that initial chick weights and subsequent weights showed little correlation but that weights at 4, 8, 16, and 24 weeks show a high positive correlation with each other.…”