Doses de levedura in vitro em dietas a base de forragem para ruminantes

Abstract

National beef cattle ranks prominently on the international scene, as it has the largest cattle herd in the world and is the largest exporter of meat of that species. In addition, most of the cattle slaughtered in Brazil come from systems based on the use of pasture, especially in tropical grasses, which gives national livestock a high competitiveness. Although cattle, as ruminant animals, have a high capacity for digesting components of plant cell appearance (PCV), there is still a significant loss of these compounds in the fecal mass, which has led to the discovery of methods that can increase this efficiency. Among the various technologies under study, the use of Saccharamomyces serevisiae (SC) has been investigated. In this sense, the present work was developed with the objective of evaluating the effects of using a SC strain (Actisaf - SC47) on the in vitro digestion of samples of Marandu grass obtained in the rainy and dry season. The doses of SC tested are equivalent to zero, 1.33, 2.66 and 4.0 g of the product per animal per day, by means of a 2x4 factorial arrangement (two forages x doses of SC). There were 3 subsequent incubations, lasting 96 hours, in which the cumulative gas production curve was obtained, as well as the DM and NDF residues were evaluated, as well as the VGA and ammonia concentration in the liquid. For the final gas volume (FV), no interaction effect between forage and yeast dose (P> 0.05) was observed, however there was a difference (P <0.05) between the forage used, in which it was estimated for the forage obtained in waters greater FV. For the DM digestion rate (k), there was no interaction effect (P> 0.05), nor was there an interaction effect between forage and SC dose on DIV of DM (p> 0.05) and DIV of NDF (p> 0.05), nor effect of SC dose (p> 0.05). In contrast between the control treatment with the presence of yeast, there was a significant difference (p <0.05), the addition of yeast promoted a greater total gas production (FV) than the control. There was no interaction effect (p> 0.05) between forage and SC dose on NH3 concentration and total VGA. However, an SC dose effect (p <0.05) was detected for the proportion of acetate and propionate (p <0.05), in which it is verified that the SC doses reduced the proportion of acetate and increased the proportion propionate. Supplementing with yeast for animals fed with a tropical forage diet alters rumen fermentation and improves its efficiency.