- Based on the results of published literature, the dietary net energy (NE) concentrations to optimize growth performance of pigs with average body weight of 7 to 12 kg, 10 to 23 kg, 25 to 50 kg and 60 to 100 kg fed low protein diets are 10.4, 10.2, 10.0 and 9.9 MJ/kg (2.48, 2.43, 2.39, 2.36 Mcal/kg), respectively.
- The estimates of corresponding optimal standardized ileal digestible (SID) Lys:NE ratio for 7 to 12 kg, 10 to 23 kg, 25 to 50 kg and 60 to 100 kg pigs are 1.37, 1.31, 1.05 and 0.83 g/MJ, respectively.
- Growth responses of pigs fed diets with adequate Lys level are greater than pigs fed Lys-deficient diets even though diets were balanced for the same SID Lys:NE ratio. This suggests that balancing for an adequate Lys level is more crucial and it may not be appropriate to maintain the same SID Lys:NE ratio in pig diets when SID Lys levels are different in these diets.
- The NE requirement estimates presented in this review article are slightly lower than current recommendations for NE (AMINOPig®). One possible reason is that today’s pigs with a greater lean protein gain and less body fat would need somewhat lower NE compared with their counterparts with greater body fat, because energy requirements for retained protein are about 1.7 times lower than the same unit of body lipids. Furthermore, pigs fed with reduced protein diets require less energy for the breakdown of excess protein.
- More research is needed into energy nutrition of pigs to better understand under which dietary conditions the dietary NE level affects feed intake, body weight gain or gain:feed, and if the different sources of energy (starch, fiber, protein or lipids) influence these parameters.