Enzyme supplementation and particle size of wheat in diets for nursery andfinishing pigs

Three experiments were conducted to determine the effects of enzyme supplem entation and particle size of wheat-based diets on growth performance and n utrient digestibility in nursery and finishing pigs. In Exp. 1, 180 weaned pigs (5.7 kg and 21 d of age) were fed diets in a 35-d growth assay without or with a Trichoderma longibrachiatium enzyme product (4,000 units of xyla nase activity per gram of product) and with wheat ground to mean particle s izes of 1,300, 600, or 400 mum. Enzyme supplementation had no effect on ADG or gain/feed (P > 0.32), but there was a trend (P < 0.10)for greater diges tibility of DM (d 6) in enzyme-supplemented diets. A particle size of 600 < mu>m supported the greatest overall gain/feed (quadratic effect, P < 0.01). An interaction of enzyme supplementation with particle size occurred; gain /feed was improved (P < 0.01) with enzyme supplementation at the coarse (1, 300 mum) particle size but not when the wheat was ground to 600 or 400 mum. In Exp. 2, 160 finishing pigs (67 kg) were fed a diet without or with the same enzyme used in Exp. occurred between enzyme supplementation and partic le size of the wheat.(P > 0.15). However, there were trends for greater gai n/feed (P < 0.10) during the 67- to 93-kg phase of the experiment and for g reater digestibility of DM (P < 0.10) and N (P < 0.07) with enzyme suppleme ntation. When particle size was reduced from 1,300 to 600 <mu>m, gain/feed was improved (P < 0.03) for the 93- to 114-kg phase of the growth assay, an d digestibilities of Dill (P < 0.02) and N (P < 0.04) were greater. In Exp. 3, 160 finishing pigs (63 kg) were given diets without or with the enzyme product and wheat ground to 600 or 400 <mu>m. Enzyme supplementation improv ed ADG (P < 0.04) in the 90- to 115-kg phase but otherwise did not affect g rowth performance, carcass measurements, or stomach lesions. A particle siz e of 400 <mu>m increased overall gain/feed (P < 0.04), digestibilities of D M and N (P < 0.01), and development of stomach lesions (P < 0.01). In concl usion, pigs did not benefit consistently from enzyme supplementation. Howev er, wheat particle sizes of 600 and 400 <mu>m supported the best overall pe rformance in nursery and finishing pigs, respectively.