Effect of heat processing on nutrient digestibility in pea and supplementing amylase and xylanase to raw, extruded or micronized pea-based diets on performance of early-weaned pigs

Two experiments were conducted to investigate the effect of heat processing on nutrient digestibility and of both processing and exogenous feed enzymes on growth performance of 16-d-old weaned piglets fed pea-based diets. In exp. 1, 12 Cotswold pigs [4.5 ± 0.5 kg initial body weight (BW)] fitted with simple-T cannulae were used to determine apparent and standardized ileal amino acid (AA) digestibilities in raw, extruded, and micronized peas supplemented with amylase and xylanase. In exp. 2, 70 16-d-old weaned pigs were randomly assigned to a soybean-meal- (SBM)-based control and six pea-based diets during two consecutive periods (Phase 1, 4.5-10.0, Phase 2, 10.0-20.0 kg BW). The pea- (raw, extruded and micronized) based diets were fed with or without enzyme supplementation. Pigs were weighed weekly and feed intake was monitored daily. Blood samples were obtained from 10 pigs per treatment on days 0, 7 and 14 for plasma urea nitrogen (PUN) analysis. Heat processing improved (P < 0.05) apparent ileal digestibilities (AID) of most AAs, including lysine, methionine, threonine, and valine in extruded and micronized peas, but not raw peas. The AID was higher (P < 0.05) in enzyme-supplemented extruded and micronized peas than in raw peas. Micronization improved (P < 0.05) AID of lysine from 82 to 91%. The standardized ileal digestibilities (SID) of arginine, lysine, methionine and threonine were higher (P < 0.05) in extruded and micronized pea-based diets than in raw pea-based diets. Mean AID of indispensable AA was numerically improved (P < 0.08) from 79 to 88.0% following micronization. Feed efficiency was improved (P < 0.05) from 1.4 to 1.20 by supplementing raw pea-based diet with amylase and xylanase in phase 1. Supplementing raw pea-based diet with enzyme resulted in reduced (P < 0.05) PUN levels from 9.01 to 5.73 mg dL^-1. The results demonstrate that compared to raw peas, extrusion and micronization improved AA digestibilities of amylase and xylanase supplemented pea-based diets and efficiency of feed utilization from 4.5 to 10.0 kg BW. However, feed intake and growth performance were not affected.