PSXIV-13 Effects of supplementation of Natural Zeolite on digestibility and rumen fermentation characteristics of finishing Bos indicus.

Abstract The use of Natural Zeolites (NZ) to fed feedlot cattle modify the use of nitrogen in the rumen, which can improve nutrient digestibility, increase ruminal pH and reduce nitrogen losses. We hypothesized that NZ supplementation would reduce the ruminal ammoniacal nitrogen (NH3-N) and increase the pH ruminal in finishing Bos indicus cattle. On day -1, 24 rumen-cannulated Nellore bulls were blocked according to their initial BW (453.95 ± 24.31 kg) and assigned to individual pens in a randomized complete block design. Within block, steers were randomly assigned to treatments: CON= high moisture corn silage- based diet without Natural Zeolite (NZ; n=8); 1NZ = CON diet plus 1% NZ/ DM diet (n=8); and 2NZ = CON diet plus 2% NZ/ DM diet (n=8). The inclusion of NZ was carried out in the diet by removing high moisture corn silage. The experimental period lasted 25 days, while between days 19 to 23, total fecal collection was performed to evaluate the nutrient digestibility and on days 24 and 25, rumen fluid were collected at 0, 3, 6, 9, 12, 15, 18, and 21 h post-feeding for ammonia, VFA, and pH determination. Data were analyzed using the MIXED procedure of SAS. There was a quadratic effect for DM (P = 0.03), OM (P= 0.03), EE (P= 0.01), NDF (P = 0.03), ADF (P= 0.02), NFC (P = 0.02), TDN (P= 0.02) and starch intake (P < 0.01), with the highest values observed for the treatment with 1% inclusion of NZ. The inclusion of NZ linearly decreased the CP intake (P = 0.03). There was no effect of the experimental diets on nutrient digestibility (P ≥ 0.05). There was no effect of NZ levels on SCFA concentration (P ≥ 0.05), except for isobutyrate (P= 0.04). There was no treatment and collection time interaction for rumen fermentation parameters. The inclusion of NZ in the diet linearly increased the rumen pH (P = 0.02). There was no effect of the experimental diets on the other fermentation parameters evaluated (P ≥ 0.05). In conclusion, NZ supplementation, improve the rumen pH and not effect nutrient digestibility, and the inclusion of 1% NZ/ DM basis increase nutrients intake in Bos indicus bulls fed a finishing diet.