The development of suckling frequency in pigs from birth to weaning of their piglets: a sociobiological approach

The suckling frequency in 34 first-lactation sows and their litters in conventional farrowing pens was observed during a 35-day lactation period from birth to weaning. In order to quantify the ontogenetic development of this behaviour a non-linear regression function was used as a model. The maximum (MAX) of the curve was determined at day 8.5 (31.4 sucklings per 24-h period) and was considered as the biological beginning of the weaning process. The occurrence of MAX was shifted towards an earlier time by about 6 days earlier from small (4 to 7 piglets per litter) to large litters (11 to 14 piglets per litter). However, no significant influence of the litter size on the development of the daily suckling frequency and the average individual piglet weight was found. Nevertheless, there was a tendency for an inverse relationship between the litter size and the piglet weight during lactation and, further for an increased daily suckling frequency during early lactation and a lower frequency during late lactation in larger litters. As a compensation for the decreasing suckling frequency piglets markedly increased their creep food consumption in the last week of the suckling period (day 28 to 35). The results indicate that the suckling behaviour in domestic pigs reflects sow-piglet relationships which are consistent with a theoretically predicted model of weaning conflict. Hence, it is suggested that modelling the suckling behaviour using well defined and comparable measures may be a suitable approach for the evaluation of the weaning process both in terms of sociobiology (e.g. weaning conflict, parent-offspring conflict) and of farm animal science (e.g. performance, housing conditions).