[Serum insulin and glucose concentrations in sheep during late pregnancy in relation to the number and sex of the fetuses]. / Insulin- und Glukosekonzentration im Blutserum hochträchtiger Schafe in Abhängigkeit von Anzahl und Geschlecht der Feten.

OBJECTIVE: The objective of this study was to investigate whether the serum concentration of glucose and insulin in the blood of pregnant sheep depends on the number and the sex of the fetuses. MATERIAL AND METHODS: The presented research was carried out on Pomeranian (n = 42) and Suffolk sheep (n = 42) towards the end of the pregnancy. The following groups were established amongst the Pomeranian sheep: single pregnancies with a female fetuses (n = 19) and male fetuses (n = 10), twin pregnancies with female fetuses (n = 8), male fetuses (n = 8) and fetuses of different sex (n = 7). Similarly, in the Suffolk sheep, the following groups were formed: single pregnancies with female fetuses (n = 9) and male fetuses (n = 12), twin pregnancies with male fetuses (n = 12) and fetuses of different sex (n = 9). RESULTS: In Suffolk sheep, serum insulin concentration was significantly higher than in Pomeranian sheep (p < 0.05). The average insulin concentration in Pomeranian sheep with a single pregnancy was higher than in sheep of the same breed with a twin pregnancy (p < 0.05). In the Pomeranian breed, the highest insulin concentration was recorded in sheep with male fetuses (p < 0.01). Similarly, in Suffolk sheep, the insulin concentration was higher in sheep with male fetuses than female ones (p < 0.05). On the other hand, the concentration of glucose in Pomeranian sheep, with both single and twin pregnancies and with female fetuses, was higher than in sheep with male fetuses or different sex fetuses (p < 0.05 and p < 0.01, respectively). In the Suffolk breed, the glucose concentration was also higher in sheep with female fetuses (p < 0.05). In Suffolk sheep a positive correlation was found between the birth weight of lambs and their mother's glucose concentration (r = 0.56; p < 0.01). CONCLUSION: The differences in the concentration of insulin and glucose in the blood of pregnant sheep demonstrated in this study suggest that sex and the number of fetuses may be further factors affecting the energy metabolism in the late stages of pregnancy. Based in the presented findings these differences may depend on the breed and may be related to the birth weight of lambs.

Conception rates in farm mink (Neovison vison) in relation to first mating date, age and color variety.

The aim of the study was to analyze the effects of the first mating date, age and color variety on the conception rates in farm mink. We analyzed female mink reproductive performance in 492 Sapphire and 463 Standard Black females over 3 or 4 years. The analysis included the number of inefficient matings, the interval between the first inefficient mating and the efficient mating (copulation) and the conception rates. The results show a significant effect of female's age and color variety on the conception rates. The youngest, yearling females of either color needed a higher number of matings per conception, as compared to older, 2- and 3-year-old females. Black females demonstrated a higher number of inefficient matings (1.066), as compared with Sapphires (0.730). Yearling females were most often mated from 1 to 10 March, and older females from 11 to 20 March. Older females achieved better conception rates than the yearlings. Dates between 11 and 25 March proved to be the optimum for the first mating, since the highest conception rates were observed if the females had mated during this period.

Pregnancy detection in putatively unmated mink (Mustela vison) by serum progesterone level.

The aim of this study was to determine whether blood plasma progesterone is a reliable indicator of pregnancy in mink at an early stage of gestation. We also attempted to establish the threshold value of progesterone as a pregnancy indicator. The analysis was carried out at a production farm on 42 standard female mink aged 1 year, which were grouped both according to the observed success of mating ("mated" and "unmated") and the level of blood serum progesterone measured afterwards ("pregnant" and "nonpregnant"). It was next verified whether a particular female had been assigned to the proper group in the first place. An analysis of accuracy of mating success assessment within the group of unmated females revealed that more than one-third of decisions were wrong, since some females that had been considered unmated ultimately whelped. This suggests that mating supervision by farm workers lacks reliability. A progesterone test for verification of such management decisions should limit the risk of err,or. We suggest that progesterone tests could be carried out using the threshold values 1.9 ng/ml and 20 ng/ml in blood sampled on 25 March and 8 April, respectively, although some level of uncertainty should be taken into account.