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Comparison of the effects of reduced CP, amino acid supplemented diets on growth performance in swine
Seven hundred twenty, mixed sex pigs were placed in 12 rooms at the Purdue Swine Environmental Research Building to measure the effect of reduced CP, AA-supplemented diets on growth performance and carcass characteristics. Pigs were blocked by BW and gender and allotted to room and pen with 10 mixed-sex pigs/pen. Pigs were fed a 9-phase, wean-finish feeding program and weighed at the start and end of each dietary phase. Within each phase, control pigs consumed corn-soybean meal – 20% DDGS based diets containing no synthetic amino acids. The 2X diet was balanced using synthetic AAs to the seventh limiting AA and represented the lowest CP diet. The 1X diet was formulated using synthetic AA to meet a CP value halfway between the control and 2X diets. Diets were formulated to identical NE concentrations and balanced to meet SID AA requirements (NRC, 2012). Data were analyzed using the GLM procedure in SAS and treatment means were separated using the Tukey procedure in SAS. Pigs fed the Control and 1X diet consistently grew faster (P< 0.005), had greater feed efficiency (P < 0.001), and were 4 kg heavier at market weight (P < 0.001) than animals fed the 2X diet. There were no consistent effects of diet on ADFI throughout the project. Carcass data were analyzed for sex, diet and sex*diet effects. There were no (P > 0.10) interactions between sex and diet. Pigs fed the 1X (75.5 mm) and control (75.1mm) diets had greater (P < 0.02) loin depth compared to 2X (73.5mm) fed pigs. Backfat depth was not affected (P > 0.10) by diet. Pigs fed the 1X diet (55.78%) had greater percent lean than pigs fed the 2X diet (55.22%) with control fed pigs (55.62%) being similar to both (P<0.05). Gilts were leaner (P < 0.001), had reduced backfat (P < 0.02), and increased percent lean (P < 0.001) compared to barrows. Overall, the reduced performance and carcass characteristics observed in pigs fed the 2X diets indicates an inaccurate estimate of amino acid NRC (2012) requirements or ratios to lysine in this extremely low CP diet.
Keywords: swine, amino acids, growth