Beneficial effects of Beta-carotene injections prior to treatment with PGF2α on the fertility of postpartum dairy cows

This study examined the effects of Beta-carotene (beta C) injections before estrus synchronization with PGF(2)alpha on fertility parameters in cows. A total of 124 postpartum (pp) cows were used. In GI (n=25), beta C (Carofertin (R), 0.4 mg/kgBW, i.m.) was injected on d 15 and 45 pp. In GII (n=25), beta C was administered on d 15 pp. In GIII (n=25), beta C was administered on d 45 pp. In GIV (n=25), beta C was injected on d 35 and 45 pp. GV (n=24) was set aside as a control group. All animals received PGF(2)alpha (Iliren (R), 0.0015 mg/kgBW, i.m.) on d 50 and 61 pp. Blood samples were collected on d 15,48 and three days after each beta C injection. The overall pregnancy rate was determined to be higher in GI (100%) and GIV (88.0%) than GV (70.8%) (P<0.01). The number of services per conception was the lowest in GI (1.4) and GII (1.4), while days of first service were lower in GIII (90.3 d) and GIV (90.8 d) (P<0.05). The insemination index was found to be lowest in GI (1.4). These results suggest that two administrations of beta C in the early and late pp period before administering PGF(2)alpha can improve fertility. It was concluded that when serum beta C concentrations remain high for a long time (30d) as a results of beta C injections, fertility can be improved.