Protein sources in suplements to bovines on pastur in the dry and transition between the dry and the rainy periods Fontes de proteína em suplementos para bovinos em pastejo nos períodos da seca e de transição seca-águas

Abstract

Supplements with different protein sources were evaluated during the dry season and between the dry and the rainy seasons. We used 20 animals, with 220 kg average body weight and 10 months old age, in five paddocks (2 ha), in a completely randomized design, with five treatments and four replicates. The supplements with 38% of crude protein (CP) in the dry matter (DM) basis were supplied daily at 0.5% of their weight. The treatments employed were supplements based on: soybean meal /wheat meal (SMWM), wheat meal/urea (WMUR), cottonseed meal 38% of CP (CM38), cottonseed meal 28% of CP/urea (CMU28), wheat meal, cottonseed meal 38% of CP/urea (WCMU), and mineral salt was present in all the supplements. The treatment CM38 allowed superior animal performance compared with the treatments SMWM, WMUR and CM28; the treatment WCMU was superior to the treatments WMUR and CM28. We also used five Holstein-zebu steers, 10 months old and initial weight of 170 kg, fistulated in the esophagus and rumen. These animals were grazing in five paddocks (0.3 ha) each in a completely randomized design. The intake of neutral detergent fiber (NDF) was superior in treatments of WMU and CM28 in relation to CM38 and WCMU; and the digestibility of DM obtained in SMWM and WMUR treatments were superior to those of CM38, CM28, and WCMU, and the digestibility of CP’s WMU was superior to those of CM38 and CM28.Suplementos múltiplos com diferentes fontes de proteína foram fornecidos a bovinos, na seca e transição seca/águas, com o objetivo de avaliar o desempenho. Foram utilizados 20 animais com peso vivo (PV) médio de 220 kg e idade aproximada de 10 meses, em cinco piquetes de dois hectares cada, em delineamento inteiramente casualizado, cinco tratamentos e quatro repetições. O fornecimento dos suplementos, que tinham aproximadamente 38 % de proteína bruta (PB) na matéria seca (MS), foi diário, em nível de 0,5 % do PV. Os tratamentos foram constituídos de suplemento à base de farelo de soja e farelo de trigo (FSFT), farelo de trigo e uréia (FTUR), farelo de algodão 38 % de PB (FA38), farelo de algodão 28 % de PB e uréia (FA28), e farelo de trigo, farelo de algodão 38 % de PB e uréia (FATU). O tratamento FA38 apresentou ganhos superiores aos tratamentos FSFT, FTUR e FA28, e o tratamento FATU foi superior aos tratamentos FTUR e FA28. Os parâmetros nutricionais foram avaliados utilizando-se cinco animais com idade e peso médios iniciais de 10 meses e 170 kg de PV, fistulados no esôfago e rúmen distribuídos em cinco piquetes de 0,3 hectare, em delineamento de blocos casualizados. As digestibilidades da MS obtidas nos tratamentos FSFT e FTUR foram superiores às dos tratamentos FA38, FA28 e FATU. O FA38 apresentou melhor desempenho bovino na seca.