Metabolic aspects related to the use of crude glycerin and ractopamine in pig feeds

Abstract

The use of crude glycerin as an energy source in animal feed has been considered for several years; however, there are few scientific studies about glycerol metabolism in pigs. Similarly, although ractopamine is recognized as an animal metabolism modifier additive, it is still controversial whether its main mechanism of action in pigs is through inhibition of lipogenesis and/ or lipolysis stimulation. The understanding of the metabolism contributes for that nutritionists formulate diets more balanced and adequate nutritionally. For any living organism, including pigs, an important parameter that allows us to understand metabolic changes is by evaluation of changes in the expression and activity of key enzymes in certain metabolic pathways. Therefore the objective of this literature review is to discuss about the main metabolic aspects related to the use of crude glycerin and ractopamine in the pigs feeding. From this review it can be seen that both the inclusion of glycerin and the addition of ractopamine in the diet of pigs promote metabolic adjustments by changing the gene expression and activity of enzymes related to the metabolism of carbohydrates, lipids and proteins. However, further research is needed to better understand the integrated metabolism of pigs fed diets containing glycerin and/or ractopamine.