RESPONSES OF GROWING-FINISHING PIGS TO CANOLA-SUPPLEMENTED DIETS BASED ON BARLEY, SPRING OR WINTER WHEATS

Abstract

Six diets were prepared using Bonanza barley (B, 1.78% N), Neepawa spring wheat (SW, 2.50% N) or Norstar winter wheat (WW, 2.11% N) with canola meal (CM, 5.70% N) or soybean meal (SBM, 7.62% N) as the protein supplement. Four of the diets (B-15%SBM, B-22%CM, SW-5%CM and WW-15%CM) were formulated to contain 16% crude protein (CP, N × 6.25), while the other diets (SW-15%CM, 18% CP; WW-5%CM, 14% CP) were included to facilitate comparison of both CM inclusion rates in diets based on each wheat. One pen, containing two females and two male castrates, was assigned to receive each diet, ad libitum, from two initial weights (averaging 22.6 and 31.7 kg) to market weight (91 kg). Among pigs receiving the 16% CP diets, growth rates favored the barley-fed groups (802 g∙pig−1∙day−1) and were lowest for those fed the SW-5% CM diet (732 g∙pig−1∙day−1, P < 0.05). Feed:gain ratios ranged from 3.48:1 (B-22%CM) to 3.93:1 (SW-5%CM). Carcass measurements revealed a corresponding pattern with barley-fed pigs producing the leaner carcasses. Results from pigs fed the four wheat-based diets suggested that cultivar effects were minor when the same level of protein supplement was used. Apparent digestibilities of energy ranged from 76% for B diets to 89% for SW and WW diets while coefficients of N digestibility were 68% (B diets), 85% (WW diets) and 88% (SW diets). A palatability study, based on relative consumption of paired diets, revealed a preference for Neepawa over Norstar and for the lower CM levels. Key words: Barley, canola, growing pigs, wheat