Schmitt, O., O'Driscoll, K., Boyle, L. A. et al. 2019. Artificial rearing affects piglets pre-weaning behaviour, welfare and growth performance. Applied Animal Behaviour Science 210, 16-25.

One strategy adopted on farms to deal with managing large litters involves removing piglets from their mothers at seven days old to be reared in specialised accommodation with milk replacer. Effects on piglet behaviour, growth and some aspects of welfare were evaluated in this study by comparing 10 pairs of two litters (one sow-reared: SR, one artificially-reared: AR) selected at seven days-old at a similar weight. Piglet behaviour was recorded for 20 min following transfer of AR piglets to the artificial-rearing enclosure (D0) and for 20 min hourly between 09:00 h and 17:00 h (8 h) on D5 and D12. Hourly 5 min live observations were also undertaken. Qualitative Behavioural Assessment (QBA) was conducted on D14 to evaluate piglets’ emotional state. Survival and illness events were recorded until weaning. On D0, D1, D8 and D15 piglets were weighed and scored for tear staining, dirtiness of the face and severity of lesions on the snout, limbs, ear and tail. Survival and illness rates, as well as the rates of behaviours/min were analysed using GLMMs. Weights and QBA scores were analysed using GLM. Lesions, tear staining and dirtiness scores were averaged per litter and analysed using GLM. When AR piglets were transferred to the artificial-rearing enclosure, their behaviour was not different to SR piglets. Over the two observation days, AR piglets performed more belly-nosing (F1,76.53 = 42.25; P < 0.001), nursing-related displacements (F1,79 = 19.32, P < 0.001), visits to the milk cup (compared to nursing bouts; F1,73.8 = 38.42, P < 0.001), and oral manipulation of littermates’ ears (F1,91.95 = 12.79, P < 0.001) and tails (F1,58.54 = 15.63, P < 0.001) than SR piglets. However, SR piglets played alone (F1,88.99 = 8.29, P < 0.005) and explored their environment (F1,99.42 = 4.52, P < 0.05) more frequently than AR piglets. The QBA scores indicated a lower emotional state in AR piglets (t25.1=-3.25, P < 0.05). Survival rate and overall illness rate of piglets were similar between the treatments. AR piglets experienced a growth check following their transfer to the artificial-rearing enclosure and remained lighter than SR piglets through to weaning (6.53 ± 0.139 kg vs. 7.97 ± 0.168 kg, t256 = 9.79, P < 0.001). Overall, snout lesion scores were not different between the treatments, but AR piglets had lower limb (F1,10.1 = 5.89, P < 0.05) and ear (F1,14.5 = 24.89, P < 0.001) lesion scores and higher tail lesion scores (F1,34.5 = 15.54, P < 0.001). AR piglets were dirtier (F1,17.4 = 23.38, P < 0.001) but had lower tear staining scores (F1,19.1 = 68.40, P < 0.001) than SR piglets. In conclusion, artificial rearing impaired piglets’ behaviour, welfare and growth.