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Materials and methods: A total of 144 barrows (22.96 ± 2.72 kg, Experiment One) or 360 barrows (27.80 ± 3.48 kg, Experiment Two) were assigned to six treatments. Diets in both experiments were based on corn and soybean meal, including an unsupplemented high-crude-protein (CP) diet (19.0% CP, 2.50 Mcal NE per kg) and five low-CP diets (4% lower CP) supplemented with lysine, methionine, threonine, and tryptophan. For Experiment One, five levels of NE (2.64, 2.58, 2.50, 2.42, and 2.36 Mcal per kg) were formulated in the low-protein diets. In Experiment Two, the low-protein diets contained 2.45, 2.40, 2.35, 2.30, and 2.25 Mcal NE per kg.
Results: In Experiment One, for pigs on low-CP diets with different NE levels, ADG (P < .05) and gain:NE intake (kg per Mcal NE) increased linearly with decreasing NE levels (P < .01). In Experiment Two, for pigs on low-CP diets with different NE levels, there was a significant quadratic increase in ADG, gain:feed, and gain:NE intake as net energy levels increased from 2.25 to 2.35 Mcal NE per kg (P < .05).
Implications: Feeding a low-CP, aminoacid-supplemented, corn-soybean-meal-based diet with a proper NE level maximizes the performance of growing pigs. Optimum performance will be obtained if the diet provides approximately 2.40 Mcal NE per kg.
Yi XW, Zhang SR, Yang Q, et al. Influence of dietary net energy content on performance of growing pigs fed low crude protein diets supplemented with crystalline amino acids. J Swine Health Prod. 2010;18(6):294–300.
