Cross-suckling and associated behaviour in piglets and sows

In order to reveal factors that cause piglets to become cross-suckers and t o study the behaviour associated with cross-suckling, the nursing and suckl ing behaviour of sows and piglets was first observed in a farrowing pen 4 t o 7 days after farrowing and later in pens for group housed lactating sows (i.e., from day 5 to 14 after moving to the multi-suckling pen which occurr ed on day 11 after birth). Three groups of six sows and their litters (189 piglets in total) were studied. About 34% of all piglets were seen cross-su ckling at least once. However, it appear that in the multi-sucking system t here were at least two groups of individuals present; those that suckled al ien sows habitually (16% of the piglets cross-suckled more than five times) and those that cross-suckle only occasionally (84% of the piglets cross-su ckled between 0 and 4 x including). Cross-sucking was found to be associate d with low milk yield of the mother in the farrowing pen. The cross-sucklin g piglets compensated for the low milk yield by cross-suckling a sow with a higher milk yield and by moving to a teat with a higher milk yield. Intere stingly, this study showed that sows distinguished between their own and ot her piglets, as the sows showed more aggression towards both cross-suckling and cross-fostered piglets. (C) 1998 Elsevier Science B.V. All rights rese rved.