Effect of removal of antibiotics from the diet on welfare indicators of weaner pigs

The objective of this study was to evaluate the effects of removing antibiotics (AB) from the diet of 1st and 2nd stage weaners on welfare indicators.

The study involved a total of 12 pens of 35 pigs each where in-feed antibiotics were either removed (NO) or maintained in the diet (AB) during the 1st and 2nd weaner stages (9 weeks in total). Ten focal pigs were randomly selected from each group (AB, n = 60 and NO, n = 60). Limb lesions (i.e. calluses and swellings) were recorded as present or absent. Skin lesions in 11 regions of the pig’s body were scored according to severity on a weekly basis and summed to give a total skin lesion score. Tail (TL, 0 to 5), ear (EL, 0 to 3) and flank (FL, 0 to 3) lesions were scored according to severity. Body temperature (BT) was also measured at each inspection. Pigs were weighed at weaning (i.e. on transfer into the 1st stage weaner accommodation) and on transfer to the 2nd stage weaner accommodation. Skin lesions were analysed using generalised mixed model equation methods. Tail lesions were re-classified as a binomial variable where 1 = presence and 0 = absence and along with limb lesions were analysed using binomial logistic regression. For all the studied variables, models included treatment, sex, inspection time and their interactions as fixed effects. Lesion scores at the start of the trial, stocking density, body weight and BT were included as linear covariates. Pig within inspection time was included as a random variable.

Treatment and sex were not a significant source of variation for any of the variables studied (P > 0.05). Skin lesion scores increased as time progressed (P < 0.05) and pigs were also more likely to have calluses and swellings on the limbs during the subsequent weekly inspections compared to when the trial started (P < 0.05). Pigs were less likely to have tail lesions as time progressed compared to the first week on trial (P < 0.05). Higher stocking densities were related to higher body lesion scores (P < 0.05). Heavier pigs had higher skin lesion scores and were more likely to have swellings on the limbs (P < 0.05). Pigs with higher skin lesion scores also had higher BT (P < 0.05).

Removing antibiotics from the diet of weaner pigs had no effect on lesions related to pig welfare. However, variables such as time, stocking density and body weight seem to have an influence on welfare lesions.

Disclosure of Interest: None Declared.