Diet nutrient digestibility and growth performance of weaned pigs fed solvent-extracted Brassica juncea canola meal

Abstract

The effects of substituting soybean meal (SBM) with increasing levels of solvent-extracted canola meal (CM) derived from modern Brassica juncea were evaluated on diet nutrient digestibility and growth performance of young pigs. In total, 240 weaned pigs with an initial body weight of 7.7kg, starting 1 week after weaning at 19 days of age were involved. Pigs were fed Phase 1 test diets for 2 weeks (days 0–14) and sequentially Phase 2 test diets for 3 weeks (days 15–35). Five pelleted wheat-based diets containing 0, 60, 120, 180 or 240g juncea CM/kg were formulated to contain 10.0 and 9.7MJ net energy (NE)/kg and 1.2 and 1.1g standardised ileal digestible (SID) lysine/MJ NE, for the Phase 1 and 2 diets, respectively. Juncea CM was added at the expense of SBM and the diets were balanced for NE by increasing canola oil from 56 to 80 and 26 to 50g/kg for Phase 1 and 2 diets, respectively, and for amino acids by increasing crystalline amino acids. Increasing inclusion of juncea CM linearly reduced (P<0.001) the apparent total tract digestibility of gross energy, dry matter, and crude protein for both feeding phases. Increasing inclusion of juncea CM also decreased diet digestible energy values in Phase 1 (P<0.001) and Phase 2 (P<0.05). For the entire trial (days 0–35), increasing inclusion of juncea CM linearly reduced (P<0.01) body weight gain, feed intake and feed efficiency (gain:feed). At the end of the experiment, pigs fed 60, 120, 180 and 240g juncea CM/kg were 0.9, 1.1, 1.3 and 1.9kg lighter than pigs not fed juncea CM. In conclusion, substitution of SBM with increasing inclusion of juncea CM in nursery diets formulated to equal NE and SID amino acid content linearly reduced diet nutrient digestibility and growth performance of weaned pigs in a dose–response manner. These reductions were likely due to a sensitivity of young pigs to the glucosinolate gluconapin that is the most abundant in juncea CM or high dietary crude fat content due to oil addition.