The Numbers of Daughters Necessary for Progeny Tests in the Fowl

INTRODUCTION FOR the past ten years the junior author has been breeding fowls resistant to disease, particularly to lymphomatosis. During the course of the work it became evident that limiting factors of great importance were (1) the relatively small numbers of breeding birds that could be tested in any year, (2) the difficulty of selecting unproven cockerels that would transmit viability, and hence (3) the very small number of good, proven sires available for use in a second year or longer. When the standards set up require that the sire’s progeny must excel the flock average, not merely in viability but also in egg production, and at the same time be satisfactory in egg size, in body size and in hatchability of eggs, it is unusual to find even a quarter of the cockerels tested in one year eligible for re-use in the next. Furthermore, when the flocks under test . . .