Incidence of Ketosis, other Diseases, and Some Postpartum Reproductive Ailments in Normal and Triiodothyronine-Treated Cows

The incidence of ketosis in 1,032 cows calving between November and December was 19%. Triiodothyronine (T3) implants increased either the severity or incidence of ketosis symptoms. This might have been due to increasing the relative caloric deficiency. More than two-thirds of the cows displaying clinical symptoms of ketosis did not have other diseases or elevated temperatures. Uterine involution was more rapid in ketotic cows and in Ts-implanted cows than in controls. Regression of pregnancy corpora lutea was more rapid in the T3-implanted cows. The calving interval was seven days shorter for thyronineimplanted cows. Milk production was 11% greater for ketotic cows than for nonketotie cows, with thyronine causing a slight depression in the second month of lactation.