This is the findings of researchers at Livestock Issues Research Unit, Agricultural Research Service-USDA, Lubbock, Texas; Department of Animal Sciences, University of Missouri; and and Department of Animal Science, University of Tennessee. reports the National Institute for Animal Agriculture. The study involved 90 total pigs, with nine to 13 pigs per treatment group.

The researchers found that, during the first two hours after castration, 3-day-old pigs stood more than the 6-, 9- or 12-day-old pigs. Although the researchers noted a trend (P=0.08) for castrated pigs to be less active than non-castrated pigs, treatment did not influence the time that pigs spent nursing, lying, standing or sitting, and no overall treatment effect was detected on growth performance of pigs at 24 or 48 hours post treatment.

While the cortisol was greater in the castrated pigs than in the non-castrated pigs, no overall effect of age at castration was observed on cortisol concentrations. Serum cortisol concentrations returned to baseline in all treatment groups 24 hours after castration, but at 48 hours post castration, the overall cortisol concentrations were elevated (P<0.01) in the 6-, 9-, and 12-day-old pigs in both the castrated and non-castrated groups compared to baseline concentrations.

There was an overall age effect on the time that pigs spent standing (P=0.01) in the first two hours after castration, as 3-day-old pigs stood more than did the older age groups. Treatment did not influence the time that the pigs spent nursing, lying, standing or sitting, however, there was a trend (P = 0.08) for castrated pigs to be less active than the non-castrated pigs. The data from this study indicates that, regardless of age, castration is stressful, but the stress associated with handling increases with the age of the pig.

The full report, Hormonal profiles, behavioral responses, and short-term growth performance after castration of pigs at three, six, nine or 12 days of age' is available in the J. Anim. Sci. 2006. 84:1271-1278.