The Effect of Rearing Environment on Two Ractopamine Use Programs

The beta-adrenergic agonist ractopamine (RAC) is a feed additive used to increase lean growth rate, improve feed efficiency, and increase carcass lean percentage and dressing percentage (Moody et al., 2000). Health status of the individual pig can influence and determine the amount of lean tissue growth of the pig (Holck et al., 1998), especially during a time of rapid growth such as in response to ractopamine. Williams et al. (1997) reported that high health pigs consumed more feed, gained body weight faster, and produced bodies with more muscle and less fatty tissue than low health pigs. Since the level of disease pressure in swine facilities plays a major role in determining the growth rate of pigs in a particular environment, the objective of this study was to determine whether environmental health conditions affect the growth response of pigs fed ractopamine.