I. Yu. Lebedeva, O. S. Mityashova
Federal Research Center for Animal Husbandry named after Academy Member L.K. Ernst, pos. Dubrovitsy, 60, Podol’skii r-n, Moskovskaya obl., 142132, Russian Federation
Abstract. We studied the content of thyroxine and triiodothyronine in the blood of first-calf heifers of the Black-and-White breed in the first trimester of lactation to determine the time points of the thyroid profile, which are critical for maintaining the reproductive ability of animals. Blood tests were made 2 weeks before calving and in 1, 3, 5, 7, and 13 weeks after calving. In 12 months of lactation, cows were divided into 3 groups: the first group included animals with a service period of fewer than 100 days (n = 10); the second group included animals with a service period of from 100 days to 250 days (n = 8), the third group included infertile animals with a service period of more than 365 days (n = 8). Compared with the concentration of total thyroxine 2 weeks before calving, this value decreased 1.5–1.9 times in 1 week of lactation in group I, in 3 weeks in group III and 13 weeks in group II. In three weeks after calving, the value of this indicator in the second group was 1.4 times higher than in the first group (89.0 ± 12.1 nmol/L versus 61.5 ± 4.1 nmol/L). In the first group, the content of total triiodothyronine was the highest in a week of lactation (2.42 ± 0.10 nmol/L) and decreased 1.4–1.7 times during the period from the third to the seventh week. In the third group, in the period from 2 weeks before calving to 7 weeks after calving, it decreased 1.6 times; in the second group, it increased 1.6 times. in 7 weeks of lactation, the concentration of total triiodothyronine in the second group (2.39 ± 0.22 nmol/L) was 1.7 times higher than in the other groups. The content of free triiodothyronine in a week after calving in the second group was 1.7 times lower than in the first group (1.75 ± 0.19 pmol/L versus 2.94 ± 0.30 pmol/L).
Keywords: first-calf heifers of Black-and-White breed; first trimester of lactation; service period; prolonged infertility; thyroid hormones.
Author Details: I. Yu. Lebedeva, D. Sc. (Biol.), head of laboratory (е-mail: Этот адрес электронной почты защищён от спам-ботов. У вас должен быть включен JavaScript для просмотра.); O. S. Mityashova, Cand. Sc. (Biol.), senior research fellow (е-mail: Этот адрес электронной почты защищён от спам-ботов. У вас должен быть включен JavaScript для просмотра.).
For citation: Lebedeva IYu, Mityashova OS. [Dependence of reproductive ability of first-calf heifers on the dynamics of the content of thyroid hormones in the blood in the first trimester of lactation]. Dostizheniya nauki i tekhniki APK. 2020;34(10):91-6. Russian. doi: 10.24411/0235-2451-2020-11014.