Abstract

RUIZ, Ana Z et al. Effect of nutritional level on ovarian activity, glucose transporters expression and insulin tolerance in dual purpose cows during the postpartum period. Zootecnia Trop. [online]. 2008, vol.26, n.2, pp.95-104. ISSN 0798-7269.

To evaluate the feeding effect on ovarian structure (OS), ovocyte quality, Glut-1 receptor expression, and insulin tolerance test, eight crossbred (Bos taurus x Bos indicus), dual purpose cows were used. The animals were randomly allocated to two treatments: Treatment 1: Four cows with low and high corporal conditions and a low feed level (LF) and Treatment 2: Four cows with low and high corporal conditions and a high feed level (HF). The evaluation of reproductive activity was done weekly using trans-rectal palpation and ultrasound from 15 to 45 days post-partum. The OS was assessed by the presence of corpus luteum and the classes of ovarian follicles. The ovocytes were classified as follows: A (ovocyte with the presence of a clear and compact cumulus oophurus and translucent ooplasm), type B (ovocyte with dark and compact cumulus oophurus and dark ooplasm), and type C (oocyte with dark and expanded cumulus oophurus and dark ooplasm). The expression of Glut-1and Glut-4 was evaluated by Western Blot analysis; additionally, an insulin tolerant test was performed. The correlation analysis showed an association between feed level and ovocytes type A (0.756; P<0.05). The Glut-1 expressed more in animals under Treatment 1 and Glut-4 in animal under Treatment 2. Also, the feed level affected plasmatic glucose concentration before and after insulin injection. The results of this study suggest that the feed level affects the follicular development at its final stage of maturation because the nutritional supply is capable of modulating the reproductive response both at the hypothalamic and ovarian levels.

Keywords : nutrition; ovarian activity; glucose transporter; insulin tolerance; dual purpose cattle.