Large Bursae Fabricii in Leghorn-Type Baby Chickens

Glick (1955) observed that the weight of the bursa Fabricius at two weeks of age in White Leghorns (0.44 gm.) was larger (p<0.01) than that of Rhode Island Reds (0.39 gm.). Bursa weight in progeny of reciprocal crosses differed. When the Rhode Island Red was the sire, bursa weight (0.45 gm.) at two weeks of age was as large as that of the Leghorn dam, while in the crossbred progeny from Leghorn sires bursa weight was 0.41 gm., average for the two parental breeds. In baby chicks of a randombred broiler-type strain, 72 to 92 percent of the variance in weight of the bursa of Fabricius at a constant body weight was attributable to genetic effects (Jaap, 1958). Since Chang, Rheins and Winter (1957) had demonstrated the importance of the bursa in antibody production, it appeared desirable to explore whether breed differences in bursa size existed at hatching. MATERIALS AND . . .