| Popis: |
THE role of vitamin B12 as an essential factor in reproduction of poultry was established by Lillie, Olsen and Bird (1949) and Olcese and Couch (1950). Carver and McGinnis (1950) and Olcese, Couch and Lyman (1950) showed that hatchability was improved by a fermentation product now known to contain an antibiotic as well as vitamin B12. Olcese et al. (1950) reported that a definite peak of embryonic mortality occurred at the 17th day of incubation in eggs from hens fed a diet deficient in vitamin B12. Elam, Gee and Couch (1951a) reported that penicillin increased egg production and hatchability. Lillie and Bird (1952) reported that the presence of an antibiotic in the vitamin B12-aureomycin supplement appeared to have no influence on hatchability. Streptomycin and aureomycin did not improve hatchability when fed to hens receiving a sub-optimum amount of vitamin B12 (Petersen et al., 1952). Sunde et al. (1952) reported that … |
