After birth, piglets undergo procedures likely to cause stress, according to Jeremy Marchant-Forde of the USDA-ARS Livestock Behavior Research Unit at Purdue University.

In a paper published in Journal of Animal Science with co-authors, the researchers explain that the aim of this study was to evaluate stress responses evoked by two combinations - 'More Stressful' (all a) or 'Less Stressful' (all b) - of alternative methods for performing:

1. teeth resection: (a) clip versus (b) grind
2. identification: (a) ear tag versus (b) ear notch
3. iron administration: (a) inject versus (b) oral
4. castration: (a) cords cut versus (b) cords torn and
5. tail docking (TD): (a) cold clip versus (b) hot clip.

Ten litters of eight two- and three-day-old piglets were assigned to each procedure.

Within each litter, one male and one female piglet was assigned to one of four possible procedures: the two combinations, sham procedures and sham procedures plus blood sampling.

Blood was collected before processing and at 45 minutes, four and 48 hours, one and two weeks afterwards and assayed for cortisol and β-endorphin concentrations.

Procedures were videotaped and analysed to evaluate the time taken to perform the procedure and the number of squeals, grunts and escape attempts.

Vocalisations were analysed to determine mean and peak frequencies and duration.

Piglets were weighed before the procedure and at 24 and 48 hours, one and two weeks afterwards.

Identification, tail docking and castration lesions were scored on a 0 to 5 scale at 24 hours one and two weeks post-procedure.

Both combinations of methods took longer to carry out than sham procedures and resulted in more squeals, grunts and escape attempts during the procedures and higher peak frequencies of vocalisations compared with the control treatments (P<0.05).

Cortisol concentrations 45 minutes after processing were also higher in the two combination treatments than in the sham treatments (P<0.05).

Comparing between procedure treatments, the More Stressful combination of methods took longer to carry out, resulted in higher β-endorphin concentrations at one week, had higher peak frequency of vocalisations and increased ear (P<0.05) and tail wound (P<0.1) lesion scores at one week than the Less Stressful combination.

Growth during days 2 to 7 post-procedure was lower in More Stressful piglets than control piglets (P<0.05) but by two weeks, growth was unaffected.

Using measures of behaviour, physiology and productivity, the More Stressful combination of procedures decreased welfare relative to the Less Stressful combination, Marchant-Forde and co-authors concluded. However, both combinations decreased welfare relative to controls.

They added that the time taken to carry out the procedure would appear to be an important factor in the strength of the stress response.

Reference

Marchant-Forde J.N., D.C. Lay Jr., K.A. McMunn, H.W. Cheng, E.A. Pajor and R.M. Marchant-Forde. 2014. Postnatal piglet husbandry practices and well-being: The effects of alternative techniques delivered in combination. J. Anim. Sci. 92:1150-1160. doi: 10.2527/jas.2013-6929

March 2014