Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/1/2008
Publication Date: 11/1/2008
Citation: Marchant Forde, J.N., Lay Jr, D.C., Marchant-Forde, R.M., Mcmunn, K.A., Richert, B.T. 2008. EFFECTS OF R-SALBUTAMOL ON BEHAVIOR AND PHYSIOLOGY OF FINISHING PIGS. Applied Animal Behaviour Science. 86:3110-3124. Interpretive Summary: Adrenergic receptors are part of the sympathetic nervous system and are present on cell surfaces within the body. They mediate the actions of epinephrine and related compounds and are divided into alpha and beta types, each with a number of sub-types. Activation of certain beta-receptors can result in breakdown of fat and increase in muscle mass. Thus, in the animal industries, they have become popular for increasing weight gain and lean tissue deposition and decreasing carcass fat content in animals destined for human consumption, such as swine and beef cattle. At present, the only FDA approved compound that activates beta-receptors (i.e. a beta-agonist) is ractopamine hydrochloride. However, previous research by our Unit on this compound in swine has shown that together with production benefits, it also adversely modifies behavior and stress physiology of the animal. The aim of the current study was to investigate an alternative compound, salbutamol on swine behavior and physiology. We carried out an experiment on 32 pens of 6 pigs, using a control diet and three diets containing different concentrations of salbutamol and we looked at home pen behavior, behavior during handling, behavioral and heart rate responses to human interaction, heart rate responses to transportation and blood physiology. We found that the doses we investigated resulted in no adverse changes in the animals' behavior or their stress physiology. Therefore, salbutamol has the potential to be a useful growth-promoting compound for use in swine with no obvious adverse implications for target animal well-being. Further studies will be needed to meet FDA requirements before the results can be transferred to the US swine industry, but salbutamol has the potential to have a positive financial impact for the pork producer.
Technical Abstract: The use of beta-agonists as repartitioning agents has been increasingly examined in US swine production. It has been proposed that a pure form of salbutamol will deliver production benefits and safeguard animal well-being. This experiment examined the effects of salbutamol on finishing pig behavior and physiology. The study used 192 pigs (88.8 +/- .9 kg BW) housed in groups of six in 32 pens (1.4 m x 4.1 m) and assigned to one of four treatments: 1) Control diet 1 - 0ppm salbutamol, 2) ALB-2R - diet 1 with 2ppm of the pure R-enantiomer of salbutamol, 3) ALB-4R - diet 1 with 4ppm of pure R-salbutamol, or 4) ALB-8RS - diet 1 with 8ppm of a racemic mixture of R- and S-isomers. All diets were energetically equal and were offered ad libitum for 4-wk. Behavioral responses to handling during weighing were recorded immediately before assignment to the treatments (Wk 0) and weekly over the subsequent 4-wk period. Behavioral and HR responses to a 10-min human presence test in the home pen were measured during Wks 0, 1 and 3. Finally, HR responses to 5-min loading, 26-min transport and 5-min unloading periods were recorded. One pig from each pen was chosen randomly and had blood sampled four times during Wks 0, 2 and 4 and at slaughter. Blood was analyzed for NEFA, CK, glucose, lactate, BUN, NH3, insulin, cortisol, and catecholamines. Data were analyzed using Proc GLM of SAS, with pen as the experimental unit. Treatment had no effect on time budgets (P>0.05) or on handling measures (P>0.05). Treatment also had no effect on behavioral responses to human presence (P>0.05), with all treatments willing to spend similar amounts of time interacting with the human. However, during the human presence test in Wk1 and Wk3, control pigs had lower heart rates (P<0.05) than salbutamol-fed pigs. During transport, overall heart rates were similar across treatments (P>0.05). However, at certain 1-min time points, control pigs had higher heart rates than salbutamol-fed pigs (P<0.05). There were no treatment differences in cortisol, insulin, lactate or catecholamine concentrations at any point. During Wk 4, Control pigs had lower CK (P<0.02) and greater BUN (P<0.005) compared to pigs fed salbutamol. Taken together these data indicate that salbutamol altered protein metabolism but that salbutamol-fed pigs did not show differences in home pen time budgets and behavioral and heart rate responses to handling and transportation. Salbutamol also did not alter stress hormone concentrations thereby appearing to safeguard well-being.