Speed of Hatching and the Resistance of Chickens to Ascaridia Galli

EVIDENCE has been presented which indicated that the resistance of chickens to infection by the large roundworm may be affected by several factors. Among these factors are genetic constitution (Ackert and Wilmoth, 1934; and Ackert et al., 1935a) and diet (Ackert and Beach, 1933; Ackert et al., 1927; Ackert and Spindler, 1929; and Riedel and Ackert, 1950a). Age as a factor of resistance was reported by Herrick (1926); Ackert et al. (1935b); and Riedel and Ackert (1950b). Histological studies made by Ackert and Edgar (1938) disclosed a progressive increase of goblet cells in the chicken duodenum. This increase of the number of goblet cells correlated with the increase of age resistance established formerly by Herrick (1926). The mucus secreted by the goblet cells was tested (Ackert, Todd and Tanner, 1938; and Frick and Ackert, 1948) and the results showed that the growth of young Ascaridia was retarded when placed in . . .