Castration is stressful for newborn piglets, but three teams of researchers have concluded that the stress associated with handling appears to increase with the age of the pig.

That’s the finding of researchers at USDA’s Agricultural Research Service in Lubbock, TX; and the departments of animal science at the University of Missouri and the University of Tennessee.

The study was comprised of 90 pigs, 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 6-, 9- or 12-day-old pigs.

Researchers observed a trend for castrated pigs to be less active than non-castrated pigs, but castration didn’t affect the time that pigs spent nursing, lying, standing or sitting. Also, no overall treatment effect was seen on pig growth performance at 24 or 48 hours post-treatment.

Researchers said cortisol levels were greater in castrated pigs than non-castrated pigs, but there was no overall effect of age at castration on cortisol concentrations. The hormone cortisol is secreted in higher levels in the body in response to stress.

Serum cortisol concentrations returned to baseline in all treatment groups 24 hours after castration. But at 48 hours post-castration, cortisol concentrations were higher in the 6-, 9- and 12-day-old pigs in both the castrated and non-castrated groups.

In conclusion, regardless of age, castration is stressful, but the stress associated with handling increases with the age of the pig.