Allosuckling (suckling by a young of a female other than its mother) has been observed in many wild and domestic group living mammals (Riedman, 1982; Packer et al., 1992). The causation and function of allosuckling for females remains puzzling given that producing milk is costly and that allosuckling may augment the risk of pathogen transmission between mothers and alien offspring. Furthermore, based on the typical nursing and suckling behaviour in domestic pigs allosuckling should be quite difficult for alien piglets to achieve for following reasons. First, every piglet usually occupies and suckles from one teat or occasionally from two teats (Rosillon-Warnier and Paquay, 1984; de Passille´ et al., 1988), which it defends against littermates and alien piglets. A teat order develops within the first days of life and unused mammary glands atrophy during the first week after parturition. Allosuckling is often reported to result in several negative consequences, including fighting among piglets, disruption of the teat order and higher proportion of missed nursings (Andersson and Andreasson, 1992; Pedersen et al., 1998), resulting in reduced milk intake and weight gain (Puppe and Tuchscherer, 1995; Wattanakul et al., 1997, 1998). On the other hand these negative consequences seem to be rather short term and after some time the suckling strategies of faithful piglets and allosucklers are equally successful. Only little is known about the impact of allosuckling on the growth of the recipient mother’s own young. Víchová and Bartoš (2005) found that the growth of beef cattle calves was not negatively affected by allonursing of their mothers. Similar results were found also in red deer (Bartoš et al., 2001) and in bighorn sheep (Hass, 1990). On the contrary, it has been suggested that frequent allonursing of a dam may result in insufficient maternal nutrition provided to the own calf (Murphey et al., 1995; Owens et al., 1985; Stevens et al., 1982). In pigs, nothing is known about the impact of allosuckling on the weight gain of teat losers. The aims of the study were to identify the strategies used by allosucklers and teat losers during teat acquisition; to assess how teat fidelity was affected by allosuckling and how allosuckling affected weight gain of the allosuckler and teat loser. Ten pairs of sows and their litters were used in this study. For each pair, the two sows were housed individually until their litters were weaned; however, their litters had access to both sows from day 10 post-partum. The behaviour of the animals was videotaped for 6 h on days 10, 11, 16 and 24 postpartum. The strategy of teat acquisition and the teat fidelity were analysed for every pair and for every day of observation. All piglets were weighed on the day of birth, days 10 and 24 post-partum. The predominant takeover strategy (69%) was to occupy a teat from a piglet owning two teats. The other takeover strategy was to usurp a teat from a piglet owning one teat. In almost all cases (95%) teat losers were able to find a new teat in that nursing before milk ejection. The occurrence of allosuckling had no significant effect on the teat fidelity of the non-dam sow’s litter (GLMM, NS). Permanent allosucklers did not differ in weight gain (Student’s t-test, NS) from faithful piglets and the teat losers did not differ in weight gain from their littermates (Student’s t-test, NS) on day 24 post-partum before weaning. Our results indicate that allosuckling does not confer any major advantage for allosuckling piglets but it does not impair the growth of the non-dam sow’s litter.