Increasing hybrid rye level substituting wheat grain with or without enzyme on growth performance and carcass traits of growing-finishing barrows and gilts

New European, fall-planted hybrid rye grown in western Canada is more resistant to ergot and fusarium and has lower content of anti-nutritional factors than common rye. We evaluated the effect of feeding increasing hybrid rye level substituting wheat grain and non-starch polysaccharide (NSP) enzyme inclusion in diets fed to growing-finishing pigs raised under western Canadian commercial conditions. In total, 1,008 pigs (~44 kg body weight [BW]) housed in 48 pens by sex, 21 pigs per pen, were fed diets with one of three rye (var. KWS Bono; KWS LOCHOW GMBH) inclusion levels substituting wheat grain: low (L; one-third of wheat replaced), medium (M; two-thirds of wheat replaced), or high (H; most wheat replaced), either without (WO) or with (W) enzyme inclusion (280 units of β-glucanase and 900 units of xylanase per kilogram feed; Endofeed W DC; GNC Bioferm) over four growth phases (Grower 2: d 0 to 22, Grower 3: d 23 to 42, Finisher 1: d 43 to 63, Finisher 2: d 64 to slaughter). Pen BW, feed added, and orts were measured on d 0, 22, 42, 63, 76, 91, and at slaughter weight (130 kg). Warm carcasses were weighed and graded (Destron). BW was not affected by either increasing hybrid rye level substituting wheat grain or enzyme inclusion throughout the trial. For the entire trial (d 0 to 76), pigs fed increasing hybrid rye level substituting wheat grain had decreased (P < 0.050) average daily feed intake (ADFI; L 3.05, M 2.98, H 2.91 kg/d) and average daily weight gain (ADG; L 1.01, M 1.00, H 0.97 kg/d). Enzyme inclusion did not affect ADFI but tended (P = 0.080) to increase ADG (WO 0.98, W 1.00 kg/d). Enzyme inclusion improved (P < 0.050) gain-to-feed ratio only in pigs fed the H rye level. Most carcass traits were not affected by either increasing hybrid rye level substituting wheat grain or enzyme inclusion. Increasing dietary hybrid rye level substituting wheat grain increased (P < 0.001) cost per tonne of feed (L 240.28, M 241.28, H 242.20 Can$/kg), but did not affect feed cost per pig or per kilogram BW gain. Enzyme inclusion increased (P < 0.001) cost per tonne of feed (WO 240.36, W 242.15 Can$/kg), but feed cost per pig (WO 82.14, W 80.44 Can$ per pig) and per kilogram BW gain (WO 0.96, W 0.94 Can$/kg gain) were reduced (P < 0.050). In conclusion, fall-planted hybrid rye can completely replace wheat grain in grower-finisher pig diets without affecting feed efficiency, feed cost per pig or feed cost per kilogram BW gain. Inclusion of NSP enzyme would be recommended for diets including high rye levels to improve feed efficiency and ADG.