Endocrine Gland and Brain Weights of Market Weight Bulls and Steers Representing the Shorthorn Breed and Several Breed Crosses

摘要

Thyroid, adrenal, pituitary and brain weights were first determined in 1971 in 492 market weight cattle representing purebred Shorthorns and crosses of “foreign” breeds, Charolais, Simmental and Limousin with Hereford, Angus and Shorthorn. Thyroid weights were also determined in a similar group of 433 cattle the following year. The data were reported on a per 100 kg body weight basis and analyzed within the subgroups of breed of sire, breed of dam and location.The average thyroid weight per 100 kg of body weight for males within subgroups over the two years ranged from 3.99 to 8.71 g, while that for steers ranged from 3.81 to 4.41 g. The average thyroid weight for a group of 18 Limousin sired heifers was 3.71 g. The average adrenal weight per 100 kg of slaughter weight ranged from 3.66 to 4.20 g in the males and from 3.66 to 3.86 g in the steers. Pituitary weight per 100 kg body weight at slaughter ranged from 486-511 mg in bulls and from 469-510 mg in steers. Average brain weight ranged from 85.5 to 97.3 g in males and from 92.2 to 94.1 g in steers.Breed differences existed only for the pituitary gland, with Simmental sired males and steers having heavier glands than Charolais sired males and steers.Sex differences were significant for the thyroid and the brain. Thyroids of males were generally heavier than those of steers, while brains of steers were heavier than those from males.Thyroid, adrenal and brain weights were significantly different between two genetically similar purebred herds of Shorthorns.