Protease e amilase em silagem de milho reidratado na nutrição de ruminantes

Abstract

The aim of this study was to evaluate the addition of protease and amylase in moist rehydrated corn grain silage. Four experiments were carried out, divided into two chapters. Chapter II covers experiments 1 and 2. In Experiment 1, 30 experimental silos were prepared and sealed for 45 days. The silos were randomly distributed into 5 treatments: 0 g of protease (control); 250 g of protease; 500 g of protease; 750g of protease and 1000g of protease per ton of moist rehydrated corn (CINBENZA DP100®, enzymatic extract of Bacillus licheniformis, protease activity 600 IU/g). In addition to the enzymes, the bacterial inoculant, Kerasil Grão Úmido® (Kera Nutrição Animal, Bento Gonçalves, Brazil) – Lactobacillus plantarum 4*1010 g/CFU + Propionibacterium acidipropionici 2.6*1010 g/CFU – at a dose of 4 g/t fresh matter was added in all silos. Nutritional value, fermentative losses, aerobic stability, microbiological and fermentative profile and ruminal kinetics were evaluated in all silos. In Experiment 2, 5 crossbred sheep were housed in metabolic cages in a 5x5 latin square design. For 70 days, the animals consumed silage produced according to the treatments of Experiment 1. In addition to the experimental silages, the animals received hay and a mineral protein mixture. Intake and digestibility of dry matter and nutrients, rumen fermentation and nitrogen balance and microbial protein synthesis were evaluated. Comparing the enzymatic treatments to the control, it was possible to observe that the inclusion of enzyme increased the DM, CP and starch composition and reduced the NDF. The inclusion of protease decreased losses and increased recovery. The ambient temperature of the silos reduced in the control treatments, 250 and 500 (g/ton). Treatments 750 and 1000 (g/ton) showed pH stability throughout the evaluation period. For the microbiological and fermentative profile of the silos, the inclusion of protease brought effects especially in the treatments 500 and 750 (g/ton). Digestibility showed a quadratic behavior for starch. For ruminal fermentation, quadratic behavior was observed for propionate and butyrate. Effect was found only for microbial synthesis (g/day), with nitrogen and crude protein showing quadratic behavior. Thus, according to the regression equations the optimum protease inclusion is 427 g/ton. Chapter III covers Experiments 3 and 4. In Experiment 3, 28 experimental silos were prepared and randomly distributed into 4 treatments: CONTROL (without addition of enzymes); AMI (amylolytic enzyme); PROT (proteolytic enzyme); AMI + PROT (amylase + protease). The protease level used in Experiment 3 was 500 g/ton and the amylase dose used was 300 ml/ton of fresh matter. A bacterial inoculant, Kerasil Grão Úmido®, was also added at a dose of 4 g/t of fresh matter. The analyzed variables were the same as in Experiment 1. In experiment 4, 8 crossbred sheep were housed in metabolic cages in a contemporary 4x4 Latin square design, with 2 squares in a 2x2 factorial arrangement. For 56 days, the animals consumed silage produced according to the treatments in Experiment 3. As in Experiment 2, in addition to the experimental silages, the animals received hay and a mineral protein mixture. An effect was observed on NVfor DM, NDF and starch. In the fermentative losses, there was an effect for gases (NM) and (DM), effluent (NM) and (DM), total losses (DM) and recovery (DM). All variables related to aerobic stability had an effect, with practically stable pH. The population of lactic acid bacteria was higher in the interaction treatment, as well as the total bacteria. The population of molds, fungi and yeasts influenced AMI and PROT. Regarding the fermentative profile, there was a pH response as a function of PROT and the interaction, being greater in the interaction. There was also a difference for N-NH3(mg/dl) as a function of PROT and interaction, being greater in the PROT treatment. For the fatty acid (FA) profile, it was possible to observe a difference for lactate in the PROT treatment and in the interaction, with a higher average of lactate production in the PROT treatment. For valerate and total AG the response was significant for the PROT treatment. For degradability, an effect was observed for fractions A, A+B and DE 4%, 8% and 12%. Only the digestibility of dry matter and nutrients showed an effect. MS and the MO effect for PROT. EE AMI effect. And the NDF and the starch effect for the interaction. The pH had an AMI effect. The N-NH3 effect of PROT. And for organic acids, it was possible to verify an effect only for the PROT treatment for isobutyrate, valerate, isovalerate, AGCR and total AG. An effect of the interaction on microbial synthesis (g/day) was observed. It was estimated that the optimal inclusion of protease is 427 g/ton and that the combined use of protease with amylase improved the stability of the rehydrated corn grain silage while maintaining good nutritional characteristics.