The aim of this study was to evaluate the use of self-control supplements on nutritional parameters of steers grazing Brachiaria decumbens Stapf. during the rainy-dry season transitional period. Four crossbred steers fistulated in rumen, abomasum and esophagus were used. Mineral salt (SAL) and supplements based on: mineral mix, salt, and ground corn grain (GCG); mineral mix, urea and ground corn grain (UGCG); and mineral mix, urea, grounded corn grain and soybean meal (UGCSM), with different protein contents were given. The supplements did not promote significant differences for intake of nutrients except for crude protein intake whose greater values were obtained with the use of supplements of ground corn grain and soybean meal. There was no effects of the supplements on transit kinetic parameters of the particles; the mean values found for rate of passage and mean retention time in the rumen and gastrointestinal tract were 0.018 h-1 and 106.93 hours, respectively. Supplementation changed ruminal ammonia concentration whose greatest values were obtained with the supplement containing soybean meal (31.25 mg/dL) and ground corn grain (24.22 mg/dL). There was no effect of supplementation on apparent total, ruminal and intestinal digestibility of dry matter, organic matter, total carbohydrates, neutral detergent fiber and neutral detergent fiber but it affected crude protein apparent digestibility which was the highest in the animals fed supplement with soybean meal. Supplements with mineral mixture, urea, ground corn grain and soybean meal promote the highest N-urea excretions and it shows more microbial efficiency.
Brachiaria decumbens; cattle; microbial efficiency; supplements
