Blend de taninos associados com suplemento contendo diferentes teores de proteína degradada no rúmen incubados com forragem tropical

Abstract

Two experiments were carried out to evaluate the effect of the in vitro incubation of Marandu grass with low and high crude protein content associated with tannins and supplements with different levels of rumen degraded protein (RDP) on kinetic parameters, digestibility of neutral detergent fiber (IVDNDF) and in vitro fermentation profile. Were added 0; 0.05; 0.10 and 0.15% DM of the incubated diet of a tannin blend (Silvafeed-Bypro®, Silvateam) associated with low RDP (LRDP) and high RDP (HRDP). In both experiments, were used as reference Nelore cattle rearing on pasture and multiple supplementation. In the experiment 1, forages with low crude protein (CP, 5,30% CP) content and proportion of 75.6% of bulky and 24.4% of concentrate were used. In the experiment 2, forages of high crude protein (11,74% CP) and proportion of 85.6% of bulky and 14.4% of concentrate in the animal’s diet were used. For both experiments, ruminal inoculum of two cattle, cannulated in the rumen, were used. In each experiment, the incubations were conducted in two consecutive weeks with gas production (GP) measured by Ankom’s automated system with 10 minute of intervals for 72 hours, totaling 432 readings. The (IVDNDF), production and profile of short chain fatty acids (SCFA), methane production (CH4), ammoniacal nitrogen (N-NH3) and pH values were evaluated. When incubating the forage with low CP, interaction between the RDP and tannin doses was observed for the final volume (FV) estimates, with quadratic effect of the tannin doses for the HRDP supplement. However, for high CP forage, no interaction between RDP levels and tannin doses was observed for all variables evaluated. The HRDP resulted in higher FV for high CP forage and gas production rate (Kd) for both forages. The HRDP supplement increased gas production in both experiments. This supplement resulted in higher IVDNDF, production of SCFA, propionate, butyrate, pH and N-NH3 only for low CP forage, without influencing the IVDNDF and production and profile of SCFA for high CP forage. For the production of CH4, it was verified the interaction of the RDP and tannin doses with the low CP forage, with quadratic effect of the tannin doses for LRDP and linear increase for the HRDP. However, with high CP forage, the HRDP supplement resulted in lower CH4 production. The tannin doses resulted in different behavior in the production of CH4 in relation to the contents of RDP incubated with low CP forage. There was a quadratic and linear effect for the supplement LRDP and HRDP, respectively. However, with the high RDP forage, no isolated effect of tannin doses was observed. The supplement with HRDP increased GP for both forages, with increase of IVDNDF only for low CP forage.