Efeito de diferentes dosagens de vitamina A injetável na produção e qualidade de embriões bovinos da raça Nelore

Abstract

The objective was to evaluate the effect of four different dosages of retinol palmitate 0 - (n=14), 500,000 (n=15), 1,000,000 (n=17) and 1,500,000 (n=16) International Units (IU) of vitamin A in the form of retinol palmitate on production and quality of embryos recovered from Nelore donor cows (n=64). The experiment was carried out in the Embryo Transfer Company Cauembryo in the county of Funilândia - MG. Cows were superovulated on the 10th (n=18),11th (n=10),12th (n=26) or 13th (n=10) days after estrus onset with an injection of 20 ml of Folltropin® (Vetrepharm, Belleville, Canada) or 10 ml of Pluset® (I.F. Serono,Roma, Itália) administered in decreasing doses for four days twice daily (each 12 h). Vitamin A injection was delivered with the first FSH injection. Luteolysis was induced on the 4th day of FSH treatment by giving 0.75 mg of sodium cloprostenol (Ciosin®, Coopers do Brasil, São Paulo, Brasil) and donors observed in estrus were artificially inseminated 12 and 24 hours after the onset of estrus using semen of different bulls of proven fertility. Statistical analysis was carried out using the GENMOD procedure of SAS (SAS INSTITUTE, 1995). The number of viable embryos differed (P<0.0001), between control (3.6), and 500,000 (6.1), 1,000,000 (6.5) and 1,500,000 (6.7) vitamin A treatments. Percentage of viable embryos also increased (P<0.01), from 0.51 in the control, to 0.57, 0.63 and 0.60 in order of increasing Vitamin A treatment groups, respectively. Number of total structures recovered (ER) was not different between supplemented (9.5, 8.3 and 10.5 respectively for 500,000, 1,000,000 e 1,500,000 IU of vitamin A) and not supplemented (8.2). These results indicate that supplementation of vitamin A i.m. before flushing improves embryo quality without interfere in the quantity of embryos recovered.