Replacement of soya bean meal with peas and faba beans in growing/finishing pig diets: effect on performance, carcass composition and nutrient excretion

There is now an increasing debate about the viability of using temperate-grown legumesin pig diets as a potential replacement for imported soya bean meal (SBM) and this is dueto food security, sustainability and environmental concerns. Two trials were designed toexamine nitrogen (N) retention, growth performance and carcass quality of grower andfinisher pigs when fed nutritionally balanced SBM-free diets formulated to contain peas orfaba beans at 300 g/kg, compared to an SBM-containing, pulse-free control diet. Trial 1 eval-uated N digestibility/retention in four iso-energetic diets, comparing the SBM control withone diet formulated with peas and two with faba bean cultivars; a tannin-containing and atannin-free variety. This trial employed a four by four Latin Square design with four malepigs housed in metabolism crates, fed twice daily at 0.9 of assumed ad libitum intake overfour time periods during grower (30–55 kg) and finisher (55–95 kg) phases. Quantitativefaecal and urine collection allowed determination of N coefficient of total tract apparentdigestibility, coefficient of apparent metabolisability, and N balance. Results revealed thatdietary treatment did not affect these N parameters (P > 0.05) during either the grower orfinisher phase. Trial 2 evaluated growth performance (feed intake, daily live weight gainand feed conversion ratio) and carcass quality parameters. Five diets (based on SBM, peasand one of three faba bean cultivars) balanced for standard ileal digestible amino acidsand net energy were each fed to eight replicates of individually housed entire male pigsover the same growth phases as Trial 1. The inclusion of three faba bean varieties allowedcomparison of animal responses between tannin/tannin-free and spring vs. winter beancultivars. At ∼95 kg, pigs were slaughtered and a comprehensive range of carcass measure-ments undertaken. Samples of shoulder backfat were also taken at slaughter to determineskatole and indole concentrations. As with N balance, feeding treatment did not affect per-formance data. Carcass parameters revealed pigs fed with the pea-based diet had a greaterdressing percentage than those animals on faba bean-based diets. Pigs fed with the SBM or pea-based diets also had greater lean meat percentages than those on faba-bean diets.Mean skatole concentrations for all pigs were below the accepted maximum threshold levelof 0.2 g/g. In conclusion, it is suggested that peas and faba beans can be successfully fedin balanced pig diets throughout the grower/finisher periods as alternatives to SBM.