BREED, NUTRITIONAL AND HETEROTIC EFFECTS ON AGE OF TEETH EMERGENCE IN CATTLE

Under experimentally controlled nutritional levels using Hereford, Hereford .times. Dairy Shorthorn, Dairy Shorthorn and Friesian breed-types, 288 animals were studied for age of eruption of the 4 pairs of front permanent teeth. Standard deviations are similar to those of other reports on Bos taurus. Breed differences were negligible and there is no evidence of heterosis. Lower nutritional levels delayed and higher levels advanced eruption. This effect had a maximum difference of 72 days if the differential nutrition was applied in calfhood. Differential nutrition later produced a smaller effect. In practice the age of teeth eruption cannot be used to determine accurately the previous nutritional status of individual animals. [The presence of a specified number of pairs of permanent fron teeth is used in animal production practice to judge the approximate age of an animal].