LYSINE SUPPLEMENTATION OF GROWER AND FINISHER PIG DIETS BASED ON HIGH PROTEIN BARLEY, WHEAT AND SOYBEAN MEAL OR CANOLA MEAL, WITH OBSERVATIONS ON THYROID AND ZINC STATUS

Abstract

A factorial experiment with four dietary levels of supplemental lysine (0.10, 0.15, 0.20, 0.25%), three protein supplements (soybean meal (SBM), canola meal (CM), CM + 50 mg iodinated casein per kg diet), and two sexes of pigs (barrows, gilts) was conducted. Crossbred Lacombe × (Yorkshire × Landrace), specific pathogen-free pigs were randomly allotted at 23 ± 1 kg weight in four replicates to pens of four pigs, individually fed. The pigs were slaughtered at 100 ± 2 kg. The diets were based on barley and wheat (2:1) and were pelleted (4.8 mm diam.). Average daily gain (ADG) responses during the growing period (23–57 kg) to increments of lysine were not significant (P > 0.05) but when ADG was adjusted by regression for variation in feed consumption there was a significant (P < 0.05) linear response (743, 748, 757, 772 g d−1). Feed:gain ratio also showed improvement (P < 0.05): 2.45, 2.44, 2.40, 2.35. Responses to lysine were similar for SBM and CM diets but pigs fed SBM had greater (P < 0.05) ADG than those fed CM (779 vs. 745 g). There was no response to added lysine in the 57–100 kg weight range but pigs fed SBM had greater adjusted ADG than those fed CM (908 vs. 873 g) and better feed:gain ratio (3.33 vs. 3.46). Thyroid status was not affected but iodinated casein improved grower period feed:gain ratio. Carcass quality index was not affected (P > 0.05) by lysine level, protein source, iodinated casein or sex of pig. Pigs fed CM had lower serum zinc than those fed SBM. It was estimated that the addition of 0.25% lysine to diets containing 0.8% lysine resulted in 7% improvement in ADG and efficiency of feed utilization. Key words: Lysine, canola meal, zinc, thyroid, pigs