The new NRC(2012) nutritional requirements have been released and address some of the current concerns and advancements that have taken place. The NRC (2012) includes Excel nutritional requirement models for gestating sows, lactating sows, and grow-finish pigs. The main two limitations of  the models are the lack of cost-benefit analysis, and that the model does not accurately predict feed intake. The new NRC (2012) nutritional requirements also includes analysis of gender, Ractopamine inclusion, and immunocastration – including the weight at which it is done. These new inclusions will help producers who decide to use entire, or immunocastrated, boars, and to aid those who decide to split-feed based on sex. Good performance is indicated by feed efficiency and lean growth. The NRC also takes into account feed that contains lower energy and/or co-products, as these are used increasingly often with the current high feed costs. The use of these should be based on cost-benefit analysis, and the cost of energy in a diet.