Abstract
OBJECTIVE: Evaluate the partial replacement of soybean meal with different protein sources in piglet feed during the nursery phase in terms of digestibility of feed, nitrogen balance, growth performance and blood parameters. METHODS: Experiment I involved 24 crossbred entire male pigs with an initial body weight of 18.28 ± 0.7 kg, and used a randomized complete block design consisting of three treatments (Fish Meal - FM, Soybean Protein Concentrate - SPC, and Soybean Meal - SM) and eight replicates, with one pig per experimental unit. Experiment II involved 1843 crossbred male and female pigs with an initial body weight of 6.79 ± 0.90 kg, and was based on a completely randomized design with a 2 × 3 factorial arrangement (two sexes and three protein sources) and 13 replicates. RESULTS: The results of Experiment I indicate a significant effect (p <0.05) of the treatment on digestible protein (FM: 17.84%; SPC: 16.72% and SM: 18.13%) and on total nitrogen excretion (TNE, g/kg BW0.75/day) in which pigs fed with SM-based feed had TNE values that were 5.36% and 3.72% higher than SPC and FM, respectively. In the Experiment II, there was difference (p <0.01) between sexes in the starter phase and total period in daily feed intake (DFI) values, which were higher in females, and between the protein sources in DFI, final weight and daily weight gain, which were higher in piglets fed with SPC. For urea in both phases and glucose in the pre-starter II phase, there was a difference (p <0.05) between protein sources and between sexes, in starter phase in urea levels (females: 57.11 mg/dL and males: 50.60 mg/dL). CONCLUSION: The use of feed only at basis of SM influences larger TNE (g/kg BW0.75/day), promotes a reduction in the growth performance of piglets and increases plasma urea levels in pre-starter II.