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A total of 96 gilts and 96 barrows (88.8 ± 0.9 kg of BW) housed in groups of 6 in 32 pens, were blocked by BW and sex and assigned to 1 of 4 treatments: 1) control- 0 mg/kg of salbutamol, 2) 2R-control diet with 2 mg/kg of the pure R-enantiomer of salbutamol, 3) 4R-control diet with 4 mg/kg of pure R-salbutamol, or 4) 8RS-control diet with 8 mg/kg of a 50:50 mixture of the R- and S-enantiomers. All diets were offered ad libitum for 4 wk. Salbutamol diets were replaced with control diets 24 to 48 h before slaughter. Behavioural responses to handling during weighing were recorded immediately before assignment to the treatments (wk 0) and at weekly intervals over the next 4-wk period. Behavioural and heart rate (HR) responses to a 10-min human presence test in the home pen were measured during wk 0, wk 1, and wk 3. Heart rate responses to 36-min transportation were recorded. One pig from each pen had blood collected 4 times: during wk 0, 2, 4, and at slaughter. Blood was analyzed for non-esterified fatty acids, creatine kinase, glucose, lactate, blood urea nitrogen, ammonia, insulin, cortisol, norepinephrine, and epinephrine.
Treatment had no effect on time spent lying laterally, overall activity, or time spent alert. Neither effects were observed on handling measures (P>0.05) or on behavioral responses to human presence (P>0.05), with all pigs willing to spend similar amounts of time close to and touching humans. However, during the human presence test in wk 1 and wk 3, control pigs had HR around 10 peats per minute less (P<0.05) than pigs in the other 3 treatments. During transport, overall HR were similar across treatments (P>0.05). However, at certain 1-min time points, control pigs had greater HR than salbutamol- treated pigs (P<0.05). There were no treatment differences in lactate, epinephrine, or norepinephrine concentrations at any point. During wk 4, control pigs had less creatine kinase (P<0.02) and greater blood urea nitrogen (P<0.005) compared with pigs fed all the salbutamol treatments.
It is concluded that R-salbutamol fed at 2 and 4 mg/kg and R-S salbutamol fed at 8 mg/kg fed over a 4-wk period did not have a negative impact on behaviour and physiology of finishing pigs.
JN Marchant-Forde, DC Lay Jr., RM Marchant-Forde, KA McMunn, and BT Richert. 2008. Journal of Animal Science. 86:3110-3124.
