Microbiota ruminal de novilhos mantidos a pasto, suplementados com quitosana e digestibilidade in vitro de diferentes dietas para ruminantes

Abstract

The objective of this study was to evaluate the microbiota of the rumen of cattle fed with chitosan inclusion in the diet and to evaluate the effect of the addition of additives (monensin (MON), cashew nut Shell (LCC), powdered chitosan (Q) and ricinoleic acid (AR)) on the in vitro digestibility of nutrients for ruminants. Five (5) rumen cannulated crossbred steers with an average weight of 350 kg were kept in individual paddocks of Urochloa brizantha cv Marandu and distributed in a 5x5 Latin square. The animals were supplemented daily at a ratio of 0.15% body weight (CP). Chitosan (85% distillation) was supplied in combination with a 30% protein mineral supplement. The doses of chitosan used were 0; 400; 800; 1200 and 1600 mg / kg DM. For the in vitro digestibility, two adults, castrated Jersey cattle with an average weight of 350 kg were used. They were kept in a Urochloa brizantha cv Marandu pasture, receiving mineral supplementation. In order to perform the test, three voluminous and concentrated ratios (100: 00, 50:50 and 20:80) and four additives on the in vitro digestibility of organic matter (IVDMD), dry matter (IVDMD), neutral detergent fiber DIVFDN) and protein (VPB). DNA extraction was performed following the methodology described by Stevenson and Weimer (2007). The yield and purification of the DNA were obtained by spectrophotometry. The yield and purity of the DNA extracted from samples of the total bovine rumen were considered adequate, with satisfactory quality. Because protocols for extracting DNA based on chloroform with phenol, and a mechanical lysis step extract DNA with higher quantity and quality, requiring no further purification. The bacterial DNA concentration showed a quadratic effect. The inclusion of chitosan acts by altering the concentration of ruminal microorganisms. It was verified effect on the variables IVDMD and DIVFDN for the different additives under study. In the IVDMD there was an increase in the inclusion of the additives, but treatments with the inclusion of MON and Q did not differ from the control treatment. In the DIVFDN there was a reduction with the inclusion of Q. The other additives did not influence the variable. After analysis of variance, significant effect (P <0.001) was observed only for the voluminous: concentrate relationships on IVDMD, VPB, and IVDMD for DIVFDN (P= 0.09). There was no significant interaction of treatments within the different voluminous: concentrate relationships on IVDMD, DIVFDN, VPB, and DEMO. The additives alone, added to the ruminant diet, act as modulators of ruminal fermentation, resulting in positive effects on nutrient digestibility, allowing the replacement of ionophore antibiotics.