Efeitos da presença de ácidos orgânicos na silagem de grãos de milho reidratados sobre o metabolismo e parâmetros ruminais de novilhas nelore

Abstract

The objective was to evaluate the use of rehydrated corn grain silage, with or without the addition of organic acids in the silage, on the metabolism and ruminal parameters of Nellore heifers. Six Nellore heifers, with an average initial weight of 310 kg, fistulated in the rumen were used. The experiment was conducted and analyzed according to a 2 * 2 Latin square design, with two diets and two experimental periods, 3 simultaneous QLs were performed with a duration of 48 days, which were repeated twice more with the purpose of at the end of the experimental period. generate 9 QL 2 * 2. The treatments evaluated were: silage of rehydrated corn grains without addition of organic acids in the silage (Control) and silage of corn grains rehydrated with the addition of organic acids in the silage (SMRA). In both treatments, grain silage was offered with an inclusion in the diet of 47% on a DM basis, the fiber source used in the diet was sugarcane bagasse with an inclusion of 14.5% on a DM basis, the of the diet was CP (14.48%) and starch (50.32%) on a DM basis. Feces collections were used to determine the total digestibility coefficients, omasal fluid collections using a double marker (NDFi and CoEDTA) to determine the partial digestibility coefficients of digesta, spot urine collections to determine the excretion of purine derivatives and the ruminal emptying to determine the rate of passage and digestion of the diet, all of this repeated for 6 periods. Effects (P<0.05) of treatment were observed on the consumption of DM and, consequently, of the other constituents: MO, CP, EE, NFC, NDF, starch and the dietary concentration of total digestible nutrients (TDN), being higher in the control treatment compared to the SMRA treatment. The total digestibility coefficients of DM, OM, EE, NDF and TDN had an effect (P<0.05) of treatment being greater in the control treatment. Although the animals in the control treatment showed higher consumption of CP, NFC and starch, their total digestibility was not affected (P>0.05). The passage and digestion rates of DM, MO, CP, NDF and starch showed no treatment effect (P>0.05). The concentration of ruminal N-NH3 and urea nitrogen in the serum did not show a treatment effect (P>0.05). Mean N-NH3 values were 11.57 and 12.40 mg/dL for control and SMRA, respectively. Similarly, ruminal pH was not affected (P>0.05) by the treatment, with a mean value of 6.34. There were higher (P<0.05) nitrogen consumption and nitrogen balance for the control treatment compared to the SMRA treatment. However, there was no effect (P>0.05) of the treatment on the synthesis of nitrogen compounds, the synthesis of microbial protein and the efficiency of microbial production. The addition of organic acids in the silage of rehydrated corn grains led to a decrease in the consumption of DM and consequently of the other nutrients in the diet without affecting their total digestion, however the addition of organic acids did not show changes in the ruminal parameters or metabolism of the animals evaluated.