Desempenho reprodutivo de vacas de leite de alta produção suplementadas com um complexo de minerais via parenteral

Abstract

The transition period is the most critical moment in the production cycle of dairy cows, especially for high-production animals, which are subject to great challenges and changes in their natural metabolism. Strategic mineral supplementation at this stageis an alternative oalleviate the nutritional and metabolic problems of this period, given that minerals play important roles in the animal organism, such as in metabolic, immunological and hormonal dynamics. Therefore, parenteral injectable mineral supplementation is expected to positive affect the metabolic status, with positive effects on there productiveaxis, body condition score and reproductive performance of high-producing dairy cows. In the present study, 108 black and white Holstein cows, between primiparous and multiparous, withan average weight of 600 kg will beused. Cows will be blocked by milk production, parity, expected calving date, and later allocated toone of two treatments (FOSF, n=54) orcontrol (CONT, n=54). In the FOSF will be administered 10 mL of Phosphosal®, intramuscularly, approximately 30 (±15) days before parturition, at parturition and 30 (±15) days after parturition, while the animals in the control group will not receive supplementation. All animals will be submitted to thefixed-time artificial insemination protocol (FTAI); D0: 2 mL of estradiol benzoateand 1 mL of GnRH, followed by the placement of 2 intravaginal progesterone implants, one for thefirst use and the other for the third use; D7: 5 mL of prostaglandinand the first progesterone implant will be removed; D9: 5 mL of prostaglandin, 0.5 mL of estradiol cypionate and removal of these cond progesterone implant; D11: insemination. Blood samples will be collected from a subgroup of 27 animals from each treatment to obtain plasma on D0 and D8 of the hormonal protocol and 10 days after FTAI, to measure the concentrations of progesterone (P4) and insulin-like growth factor 1 (IGF-1). The body condition score (BCS) will be evaluate dat 30 (±15) days before delivery, at delivery, 30 (±15) days post partumand on D0 of the FTAI. The ovarian tructures will also beevaluated, with the following measurement response variables: diameter of the preovulatory follicle (DFD) on the day of removal of thefirst CIDR (D8 of the FTAI protocol) and thediameter of the corpus luteum (DCL) 10 after the FTAI. The period (1, 2, 3 and 4) influenced (P<0.00001) theBCS, however, there was no effect of the treatment or the treatment VS period interaction. The pregnancy rate at 30 and 60 days (p=0,01) weres ignificantly higherfor the FOSF group, being respectively 32.58% for the CON and 48.94% for the FOSF groupa nd 59.57% for the CON and 83.33% FOSF, respectively. The number of services per conception was lower (p=0,04) for the FOSF group. There was a trend of and effect of treatments on the diameter of the dominant follicle (DF), wherethe DF in the FOSF group was greater (p=0.075) than the control group. Theuse of this mineral complex was able to improve there productive performance of high producing dairy cows, through actions independent of the production of progesteroneor IGF-I, butrelate donly to a larger dominant follicle.