Growth performance, nutrient digestibility and carcass characteristics of finisher pigs offered either a by-product or cereal based diet at two different concentrations of net energy

Abstract

A 2 (cereal plus soybean meal (SBM) and by-product based diets) × 2 (9.3 MJ NE (net energy)/kg and 9.9 MJ NE/kg) factorial experiment was used to investigate the inclusion effects of a combination of rapeseed meal (RSM) and maize distillers dried grain with solubles (MDDGS) at two NE concentrations in diets offered to finisher pigs on growth performance, nutrient digestibility and carcass characteristics. One hundred and sixty pigs (80 males, 80 females) with an initial live weight of 47.5 kg (SD 3.93 kg) were assigned to one of four dietary treatments: (T1) a cereal based diet formulated to give 9.3 MJ NE/kg; (T2) a cereal based diet formulated to give 9.9 MJ NE/kg; (T3) a by-product based diet formulated to give 9.3 MJ NE/kg; (T4) a by-product based diet formulated to give 9.9 MJ NE/kg. The by-product diet included 350 g/kg MDDGS and 210 g/kg of RSM. The diets were formulated to contain similar levels of standardized ileal digestible lysine (8.5 g/kg). Soya oil was included in the diet to increase the NE content. Pigs offered the cereal based diet had a higher (P < 0.001) average daily gain (ADG), average daily feed intake (ADFI) and a poorer feed conversion ratio (FCR) compared to the by-product based diet. The diets containing the high energy concentration decreased ADFI (P < 0.010) and improved FCR (P < 0.002). Pigs offered the cereal based diet had increased coefficient of apparent ileal digestibility (CAID) (P < 0.001) and coefficient of apparent total tract digestibility (CATTD) (P < 0.001) of nitrogen (N) and gross energy (GE) compared with pigs offered the by-product based diet. The diets containing the high energy concentration had increased CATTD of dry matter (DM) (P < 0.045) and GE (P < 0.014) as well as the digestible energy (DE) (P < 0.001) and predicted NE (P < 0.008) values compared to the low energy concentration diets. Pigs offered the cereal based diet had a higher carcass weight (P < 0.050), carcass ADG (P < 0.024) and kill out percentage (P < 0.050) compared to pigs offered the by-product based diet. In conclusion, including high levels of by-product feeds negatively affected animal performance, nutrient digestibility and carcass characteristics. The high energy concentration of the diets reduced ADFI but improved FCR.