Acceptability and nitrogen utilisation of tower and erglu rapeseed meals by the growing pig

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Abstract
Acceptability and nitrogen utilisation studies were made with diets containing barley and either extracted soy bean meal (SBM) or one of the two low glucosinolate extracted rapeseed meals Tower (TRSM) and Erglu (ERSM). In acceptability studies SBM, TRSM and ERSM were substituted isometrically at 20% in diets which were offered ad libitum for 8 weeks to pigs of 23 kg initial liveweight. There were four groups of four castrate male pigs, and four groups of four gilt pigs, per group, per diet. For the first 2 weeks intake per unit metabolic weight (W0.75) was greatest, but thereafter was least, for the SBM diet. In metabolism studies three diets were computed and fed so that 54.5 % of the daily intake of 170 g of crude protein was derived from SBM, TRSM or ERSM. Twelve caged castrate male pigs of 25 kg liveweight were fed on each diet. Apparent digestibility of crude protein was higher for the SBM diet compared with the TRSM (P0.05) diets. Nitrogen retention decreased significantly from the SBM to the ERSM to the TRSM diets. In an individual feeding growth experiment, using 12 castrate male and 12 gilt pigs per diet, isonitrogenous diets based on SBM, TRSM and ERSM were fed, on a liveweight related basis, between 23 and 67 kg liveweight. The SBM fed pigs grew significantly faster and required significantly less crude protein per unit of gain than those fed TRSM and ERSM, between which there were no significant differences.