PSXVII-9 Effects of β-carotene and vitamins in grazing Nellore primiparous cows submitted to fixed timed artificial insemination (FTAI).

The aim was to evaluate the effects of feeding β-carotene and vitamins on reproduction performance of grazing primiparous beef cows. The experiment was conducted in a commercial farm located in Sidrolandia, MS, Brazil during the spring/summer reproduction season. A total of 204 suckled Nellore primiparous cows (Bos indicus) were used. The animals were maintained in 2 paddocks of Brachiaria brizantha with ad libitum access to water. The cows were homogeneously assigned into groups according the calving date (29.1 ± 5.0 days postpartum), BCS (3.77 ± 0.4) and β-carotene blood concentration (3.96 ± 0.7) to receive treatments for 90 days (30 before and 60 after IA): Control (mineral supplement, n=102) and treated (mineral supplement with 500 mg β-carotene, 70.000 IU vitamin A, 10.000 IU vitamin D3, 500 mg vitamin E and 20 mg biotin/cow/day; n=102). The supplements were daily offered in collective feeders. The β-carotene, vitamins and minerals were provided by DSM Produtos Nutricionais Brasil S.A. Cows were rotated through the paddocks every 15 days to avoid effects of pasture availability and quality. Cows were synchronized at 49 days postpartum using an estradiol/progesterone based FTAI protocol: D0 – insertion of progesterone device and treatment of 2.0 mg estradiol benzoate IM; D9 – treatment of 0.530 PFG2α analogue, 300 IU of eCG, 1.0 mg estradiol cypionate and progesterone device withdrawal; D11 - FTAI. Data were analyzed using the PROC MIXED procedure of SAS. The conception rate at FTAI tended to be greater (P=0.07) in primiparous cows supplemented with β-carotene and vitamins (68.6%; 70/102) compared to control group (58.8%; 60/102). In conclusion, feeding grazing primiparous Nellore cows with a combination of β-carotene and vitamin A, D, E and biotin can increase conception rate at FTAI by 16.6%.