Sow reproduction and piglet performance in multi-suckling pens

Production systems with group housing of sows at different stages of production are increasing in Europe, as an effect of public demand for more animal welfare-friendly pig production. Some niche certified piglet production systems keep lactating sows with piglets in groups in multi-suckling pens. However, three factors have been identified as affecting certified piglet production in systems with multi-suckling pens: The occurrence of lactational oestrus, piglet mortality and within-litter weight variation at weaning. This thesis investigated the possibility to affect these three factors by altering management routines. Three different management routines that differed in terms of time spent in an individual farrowing pen post-farrowing, before the lactating sows with piglets were group-housed in a multi-suckling pen, were created. Time spent in the individual farrowing pen was one (W1), two (W2) or three weeks (W3). Piglets in all management routines were weaned at six weeks post-farrowing. Only one of 43 sows ovulated during lactation. This was determined by post-mortem macroscopic examination of the ovaries and progesterone metabolite concentration in faeces. Interestingly, the weaning to standing oestrus interval was significantly shorter (p<0.001) for W2 (2.6 ±0.3 days) and W3 (2.7 ±0.2 days) than W1 (4.0 ±0.3 days). Piglet mortality in the multi-suckling pen was significantly lower (p<0.05) in W3 and W2 than W1. Within-litter weight variation did not differ between the management routines. Stress induced by reallocation and mixing of sows can affect ovarian activity and was therefore assessed during the group-housing period by measuring cortisol concentrations in saliva sampled during the first four days post-mixing. Analysis showed that W3 sows were less stressed in the multi-suckling pen than W1 sows. Overall, the results in this thesis on sow reproduction and piglet performance can be used for development of housing and management routines.