Indicadores fecais de bovinos nelore alimentados com dietas de alta proporção de concentrado

Abstract

The present work had as objective to evaluate the effects of high grain diets on fecal parameters in 20 Nellore bovines at 28 months of age. The experimental design was completely randomized. Treatments were constituted of the following diets: total mixed ration + sugarcane bagasse DT + BIN (10% in natura sugarcane bagasse, 54.52% ground sorghum, 10.94% cottonseed, 18% soybean hull, 2.54% soybean meal, and 4% premix); whole corn grain MGI (75% whole corn grain, 10% soybean hull, and 15% premix) and total mixed ration DT (44.41% ground sorghum, 16.7% cottonseed, 28.89% soybean meal, and 10% premix). For the assessment of feces pH and fecal starch, samples of feces were taken from the rectum of each animal on the 54th, 55th, 56th and 57th days of the experiment in the morning. Fecal pH was determined after the addition of 100 mL of distilled water in 15 g of fresh feces by the introduction of the tip of the electrode of a microprocessed pH meter. The remaining sample was stored in ice for later freezing. Fresh feces of the animals were evaluated daily during the whole experimental length in three periods aiming at evaluating occurrences of gut disturbances. Percentage means of fecal starch, fecal dry matter, pH in the site of starch fermentation and starch intake were not influenced by treatments (P>0.05). NDF of feces and score of fecal consistency were influenced by treatments (P<0.05). The MGI diet (with lowest content of peNDF) presented the lowest score of feces and percentage of fecal NDF. However, the percentage of starch and fecal pH, fecal dry matter and starch intake were not affected by peNDF contents in the diets. Animals fed MGI had lower fecal NDF. The concentration of fecal NDF was similar for the treatments DT + BIN and DT. The lower content of fecal NDF in the treatment MGI is due to lower intake of NDF and possibly because of better digestibility of this diet. Animals in MGI treatment presented feces with softer consistence (score 2.92). Feces of the animals in DT + BIN treatment were more consistent (score 3.12), and the ones from the animals DT + BIN treatment DT were even harder (score 3.2). There was positive correlation between fecal starch and intake efficiency and a tendency of positive correlation between fecal starch and GMD. Diets with high concentrate proportion with the addition of 10% BIN in dry matter produces a higher frequency of consistent feces.