Effects of Ractopamine and Level of Dietary Crude Protein on Nitrogen and Phosphorus Excretion from Finishing Pigs

Purdue University 2002 Swine Research Report. Ractopamine (RAC; Paylean) is used as a feed ingredient for finisher swine diets that increases the amount of lean pork production with reduced feed inputs. Ractopamine functions as a leanness enhancer that acts as a nutrient-repartitioning agent, which directs nutrients away from fat deposition and to increase lean tissue accretion. Pigs fed the beta agonist, ractopamine have increased average daily gain (ADG), improved feed efficiency (G:F), increased nitrogen retention, and require a decreased number of days to market (Anderson et al., 1987; Watkins et al., 1990). Because of this increased efficiency in producing pork resulting from the addition of ractopamine to the diet, there may be positive environmental benefits to using ractopamine. Potential benefits of ractopamine to improve stewardship of farmland resources may include, increasing nutrient retention, especially nitrogen and phosphorus, while decreasing these nutrients in total manure output. Currently, applications of nitrogen and phosphorus from manure to farmland is a major environmental concern. Excess nitrogen can leach into groundwater or runoff into surface water sources and soluble phosphorus can be a runoff threat to surface water. Moody et al. (2000) reports potential environmental impacts of ractopamine being decreased nitrogen excretion, decreased P excretion, and decreased total waste. However, this has not been verified through research. Therefore, the objective of this experiment was to determine the effects of dietary ractopamine and crude protein level on nitrogen and phosphorus retention and excretion in both urine and feces of finishing pigs.