Energy sources in multiple supplements for growing crossbred steers on pasture during the dry to rainy seasons: performance and nutritional characteristics

This study was conduced to evaluate the energy sources, rich in starch or fiber in multiples supplements on performance and nutritional characteristics of finishing crossbred steers in the dry/rainy transition season, grazing Brachiaria decumbens Stapf. The experimental area was divided into 5 paddocks with 2.0 ha each, with dry matter availability of 4.309,4 kg/ha. Twenty-four castrated crossbred steers were used, initially 24 month old and 314.46 kg. For each animal, one of the five treatments was randomly applied: mineral mixture ad libitum, pearl millet grain or corn grain, as starchy energy sources, citrus pulp or wheat bran, as fibrous energy sources. To the different energy sources, the following were added: mineral mixture, cotton seed meal and urea, so that they composed supplements with 30% of crude protein based on the natural matter, supplied at the level of 1.5 kg/animal/day. In relation to control group, significant effect of the supplementation on the diary gain was not verified. The average daily gain obtained with the fibrous sources was 17.43% higher than that obtained with the starchy sources. The dry matter (DM), organic matter, non-fibrous carbohydrates (NFC), crude protein (CP), ether extract, digestible DM, total digestible nutrients and neutral detergent fiber (NDF) indigestible intakes (kg/animal/day) was higher for supplemented animals in relation to the control group. CP and NFC total apparent digestibility were lower for animals that received only MM. Excretion of urea by urine, and the urea plasmatic level were lower for animals fed MM only. Multiple supplements with high digestible fiber sources in association with urea promoted better performance to the animals than that formulated with starchy sources and urea. The supplementation in the dry/rainy season, in 0.4% of the BW do not affect the NDF digestibility, regardless of the energy source.