Supplement use of mineral sodium glycerophosphate injection, and sodium phosphate monosodium selenite during the protocol of ovulation timing in females Nelore design

Phosphorus deficiency is one of the most serious problems of Nutrition in Ruminants. High levels of iron and aluminium are common in Brazilian pastures, forming insoluble complexes with phosphorus and thus accentuating Phosphorus deficiency in cattle. The low dietary supply of phosphorus to cows may increase the incidence of irregular oestrus cycles, follicular cysts and the degree of anoestrus. The aim of this study was to evaluate the effect of supplementation with a injectable formulation of sodium glycerophosphate (1.40 g / 10mL), monosodium phosphate (1.2 g / 10mL) and sodium selenite (0.024 g / 10 mL) (Fosfosal®, Virbac Animal Health, Brazil) on reproductive performances of Nelore heifers and cows submitted to FTAI. The work has been carried out in three commercial farms of beef cattle in the state of Mato Grosso, Brazil. The experimental group consisted in 809 Nelore females, including 266 heifers (24 month old on the average, average BCS = 2.97 ± SD), 253 primiparous cows (BCS = 2.56 ± SD) and 290 multiparous cows (BCS = 3.16 ± 0.39). Animals were then randomly allocated into two groups, control (CON, n = 404) or treatment (FOS, n = 405). All animals underwent the following protocol of synchronization of ovulation and FTAI: Day D0 - insertion of intravaginal P4 device (DIB®, Zoetis, Brazil), injection 2.0 mg estradiol benzoate i.m. (Gonadiol®, Zoetis, Brazil) and; Day D8 – P4 device removal, injection of 300 IU eCG i.m. (Folligon®, MSD, Brazil), 1.0 mg i.m. estradiol cipionate (ECP®, Zoetis, Brazil), 0.500 mg i.m. cloprostenol (Ciosin®, MSD, Brazil); Day D10 - IA. Animals of the FOS group where also dosed with 10 mL Fosfosal® i.m. on day D0 and on D8. Conception rate after first AI (CR-1) was the main criteria on of this study. Data were analyzed using proc GLIMMIX SAS and considered significant when P < 0.05. There was no interaction of treatment with bull, batch of semen palette and inseminator. There was an interaction between treatment and category (P = 0.04983). The multiparous females showed greater conception / IA (Control = 62%a; Fosfosal® = 62% a), followed by heifers (Control = 56% b; Fosfosal® = 61% a) and primiparous (Control = 47% b; Fosfosal® = 53% ab). Injectable Phosphorus supplementation of heifers and primiparous cows at the beginning of the oestrus cycle synchronisation protocol and 8 days later, results in numerically higher conception rates in treated animals, around 10% and 15% more for heifers and primiparous, respectively the groups treated with Fosfosal®. Supplemented primiparous cows conception rates was similar to those observed in adult cows. Injectable Glycerophosphate, sodium Phosphate and Monosodium Selenite suplementation should be considered when FTAI is applied in heifer and primiparous Nelore cattle.