Protein sources in suplements to slaughter steers with 20 months old on pasture: rainy period

Abstract

Supplements with different protein sources were evaluated during the rainy period. Twenty animals with average live weight of 284 kg and approximate age of 14 months, grazing in five Brachiaria decumbens’s paddocks (2 ha),were used to evaluate the productive performance in a completely randomized design, with five treatments and four replicates. The daily supplements (500 g day^-1) had approximately 35% of CP in the DM. The following treatments were used: FSFT, FTU, FA38, FAFTU, and the control treatment mineral (CONTROL). The supply of multiple supplements during the rainy period allowed extra weight gains of 135 – 275 g day^-1. The treatment FAFTU and FTU showed superior gains over CONTROL. The nutritional parameters were evaluated in five animals with initial average weight of 219 kg and age of 14 months, fistulated in the esophagus and in the rumen, distributed in five paddocks of 0.3 hectares, in design of randomized blocks where each experiment period was treated as a block. There was no effect in the supplementation or protein sources on the fluxes of microbial protein and microbial efficiency. There was no effect in the treatments on the N-urea concentration in plasma that showed average value of 13.7 mg day^-1, nor on the excretion of nitrogen compounds (N) in the urine. However, the supplementation allowed bigger nitrogen balance.