. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. THE SELECTION PROBLEM IN ANIMAL BREEDING 505 , fhose birds having the highest breeding vahie which have the highest selection index. By this method it is possible to substitute for a vague personal impression of breeding value, an exact numerical expression which is an accurate measure of the breeding value of any individual. It is possible to devise such selection index numbers for other purposes, and they should prove of utility in practical breeding operations. Another line in which still fu
. Genetics in relation to agriculture. Livestock; Heredity; Variation (Biology); Plant breeding. THE SELECTION PROBLEM IN ANIMAL BREEDING 505 , fhose birds having the highest breeding vahie which have the highest selection index. By this method it is possible to substitute for a vague personal impression of breeding value, an exact numerical expression which is an accurate measure of the breeding value of any individual. It is possible to devise such selection index numbers for other purposes, and they should prove of utility in practical breeding operations. Another line in which still further necessity for strictly scientific analysis is exemplified is that of detailed study of curves of production. Thus Pearl and Surface have made a detailed biometrical study of the seasonal distribution of egg production in domestic fowls. From tliis study thej' find that the polygon of monthly egg production is of the form shown in Fig. 195. They find that with pullets the normal season of egg. Nov. Dec. Jan. Feb. Mar. Apr. May June July Aug. Siipt. Oct. Fig. 195.—Diagram showing the weighted mean monthly egg production for each month of the pullet year. {After Pearl and Surface.) production begins in November. The mean rises rapidly during the following 2 months, but in February there is a characteristic slackening up in egg production. In March and April egg production is at a maxi- mum, and after that it decreases fairly regidarly until it reaches a mini- mum in October, with the exception of a slight, but significant, indenta- tion in May. These data taken together with certain other facts which have been determined during the course of the Maine Station investi- gations of egg production indicate that the laying year may be broken up into four periods which correspond broadly with natiu'al cycles of egg production in the domestic fowl. The first of these periods begins in November and ends at about March 1. The end of this winter-laying period is marked rather defini
Size: 2049px × 1220px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksu, booksubjectplantbreeding
