#07-011

Complete

Date Full Report Received

09/30/2008

Date Abstract Report Received

09/30/2008

Investigation

Institution:
Primary Investigator:

Energy is the most expensive dietary essential in pig diets, but it receives much less attention in North America than is deserved by its importance. The digestible energy (DE) and metabolizable energy (ME) systems widely used in North America share important shortcomings: they systematically overvalue fibrous or high-protein feedstuffs and they systematically undervalue fats. More sophisticated energy systems have been developed in Europe to overcome these shortcomings, but they have not been widely adopted in North America. We conducted this study to evaluate the European systems under North American conditions, as a first step in moving our industry to more accurate diet formulations and more profitable feeding programs. Our approach was to measure the net energy (NE) value of several ingredients and compare those values to the ones predicted by the European systems. To do that we measured the amount of energy retained in the pig’s body during the experiment by use of the comparative slaughter method in which we measured the body energy content of a sample of pigs at the beginning of the trial. All measurements were made in both early growing pigs in 4-week experiments and late finishing pigs in 5-week experiments. The project required grinding and analyzing the whole bodies of 703 pigs. We measured the NE values of corn in both low-fat and high-fat diets, of soybean meal and a low-oligosaccharide soybean meal, of soy oil and choice white grease, and of the fibrous ingredients wheat midds and soy hulls. We also measured the NE values of normal corn-soy diets and of low-protein corn-soy diets with aggressive use of crystalline amino acids. Results of all studies provided specific insights, and collectively they support important conclusions. Comparison of results for growing versus finishing pigs suggests there is value for an energy system to consider the animal’s use of nutrients (for protein versus fat gain) as well as the supply of those nutrients. Our NE values for diets and ingredients are all substantially lower than values predicted by the European systems, perhaps because of different measurement methods. Stated differently, these data strongly suggest that the European systems overestimate the energy value of diets and ingredients for growth in pigs. Our data will eventually provide further guidance concerning the practical usefulness of those systems in North American pig production, and that will guide us to the most effective energy system to control diet costs while achieving high productive performance.