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Effect of feeding increasing inclusion of extruded-pressed Brassica juncea canola meal on growth performance and diet nutrient digestibility in weaned pigs
The feed value of extruded-pressed (EP) Brassica (B.) juncea canola meal (CM) was evaluated with 240 weaned pigs (initial BW 7.6 kg), starting 1 wk after weaning at 19 d of age, in a randomized-complete block design. The EP B. juncea CM contained 34.4% CP (as fed), 1.72% Lys, 16.9% ether extract, 12.7% ADF, 19.5% NDF, and 10.9 µmol/g total glucosinolates. Pigs were fed 5 pelleted wheat-based diets including 0, 6, 12, 18, and 24% EP B. juncea CM in substitution of SBM, and acid-insoluble ash as marker. Pigs were fed Phase 1 test diets for 2 wk (d 0-14; 2.39 Mcal NE/kg, 4.9 g standardized ileal digestible (SID) Lys/Mcal NE) and Phase 2 for 3 wk (d 15-35; 2.31 Mcal NE/kg, 4.4 g SID Lys/Mcal NE). Diets were balanced for SID AA by increasing crystalline AA and for NE by decreasing canola oil. Feces were collected by grab sampling and digestibility analyzed using the indicator method. Data were analysed as repeated measures using MIXED procedure and orthogonal contracts. Increasing inclusion of EP B. juncea CM linearly reduced (P<0.001) apparent total tract digestibility of diet DM, GE, and CP and diet DE values for Phase 1 and 2. For d 0-35, increasing inclusion of EP B. juncea CM did not affect G:F but quadratically increased (P<0.01) ADFI and ADG that corresponded with a quadratic increase (P<0.01) in intake of NE and g SID Lys. On d 35, pigs fed 6, 12, 18 and 24% EP B. juncea CM were 1.1, 1.5, 1.5, and 1.1 kg heavier (P<0.05), respectively, than pigs fed 0% EP B. juncea CM. Feed energy values may explain the achieved performance. For diet formulation, we used 5.37 Mcal NE/kg for canola oil (NRC, 1998), but this value was increased afterwards to 7.55 Mcal/kg (NRC, 2012). Using the revised oil NE values, predicted diet NE values (as fed) decreased from 2.52 to 2.46 in Phase 1 and from 2.37 to 2.32 Mcal NE/kg in Phase 2 diets for pigs fed 0 to 24% EP B. juncea CM. In conclusion, increased ADFI did increase NE and g SID Lys intake that consequently increased ADG. A linear increase of growth performance up to 24% EP B. juncea CM may have been halted at the highest inclusion level of EP B. juncea CM by increased dietary glucosinolates that reduced ADFI.
Keywords: Extruded-pressed Brassica juncea canola meal, performance, weaned pig