Corpus Luteum Morphology and Function After Timed Artificial Insemination (TAI) in Nelore Heifers Supplemented with Sunflower Seed in their Diets 

The dietary Polyunsaturated Fatty Acids (PUFA) supplementation, before the Timed Artificial Insemination (TAI) protocol, may contribute to a reduction in embryonic mortality. In this context, we hypothesized that dietary supplementation with sunflower seed, before the TAI protocol, will promote an increase in the ovulatory Follicle Diameter (FD), with a consequent increase in the Corpus Luteum Diameter (CLD) and the plasma concentration of Progesterone (P4) in the subsequent diestrum. We evaluated the effect of sunflower seed supplementation, prior to TAI, on the ovulatory FD, CLD, lipid profile and plasma P4 concentration of both pregnant and non-pregnant Nelore heifers. Thirty heifers of 24-36 months old, kept on pasture with water and mineral salt ad libitum, were divided into two groups. The heifers received a 1.7 kg/day supplement containing 53% soybean meal and 47% corn (control group, n = 15) or 40% soybean meal and 60% sunflower seed (sunflower seed group, n = 15) for 56 days. All heifers received the TAI protocol 24 h after the final supplementation. At the time of TAI (D0), the ovaries of all animals were evaluated by ultrasound examinations to determine the FD. Every 48 h for 26 days, the CLD was measured using ultrasound. Blood samples were collected for P4 determinations (except on D8, D20 and D24) and total cholesterol, triglycerides, High-Density Lipoprotein cholesterol (HDL) and Low-density Lipoprotein Cholesterol (LDL), analyses were conducted on D0 and D21. There was no effect of sunflower seed supplementation on mean FD on TAI day, CLD and P4 concentration or lipid profile after TAI in pregnant or non-pregnant heifers. In conclusion, sunflower seed supplementation for 56 days preceding TAI did not change the FD, CLD, P4 concentration, or lipid profile in Nelore heifers.