Effect of lipid-enriched diet associated with bovine recombinant somatotropin on superovulation response and embryo recovery in heifers

The current study aimed to evaluate the effects of soybean oil supplementation associated with the administration of bovine recombinant somatotropin (rBST) on the population of ovarian follicles, standardization of both the superovulation response and embryo recovery in heifers. We used 40 Holstein heifers submitted to a 2 x 2 factorial, forming the experimental groups: DC-SL (control diet plus saline solution application); OL-SL (diet with soybean oil plus saline application); DC-rBST (control diet plus application of 320 mg rBST) and OL-rBST (diet with soybean oil plus the application of 320 mg rBST). The animals received two applications of 500 mg of PGF2 alpha for estrus synchronization and were superovulated with 400 IU of FSH in decreasing daily doses for four consecutive days. On the day before the start of superovulation, the two largest follicles were punctured to quantify the intrafollicular concentration of high-density lipoprotein (HDL). Embryo collection took place seven days after the first insemination. There were no differences between the treatments adopted regarding follicular activity, P4 concentration, and superovulation response. The OL-rBST's corpus luteum (CL) area and HDL intrafollicular (4.67 +/- 0.67 cm2, 53.67 +/- 10.35 mg/dL, respectively) were significantly higher than the OL-SL treatment. Soybean oil supplementation in the diet associated with the administration of rBST did not provide uniformity in the superovulation response and the embryonic recovery of heifers.