Suckling strategies in the pig: The Göttingen minipig as a model

Abstract

Göttingen minipig (GMP) has gained importance as model animal in human medicine. However, little is known about the suckling behaviour of GMP. Suckling is considered as a fundamental behavioural trait in mammals, most important for development and survival of the individual. Understanding its development and changes due to artificial selection is important when planning selection on reproductive traits in sows. GMP is a highly valuable model for studying the suckling behaviour in the pig, because its key features are intermediate between commercial breeds (CB) and wild boar (WB), namely, similar teat number as CB, similar litter size as WB and balanced muscularity of extremities. We compared the suckling behaviour of GMP and CB based on measures of suckling stability (the probability of consecutive sucklings on the same suckling position), suckling ranges (number of teat pairs in the range of the outermost teat pairs that piglets occupied) and piglets’ distribution along the udder by use of the MDE-model (effect of geometric constraints, normally expressed as a hump-shaped distribution of organisms). We also incorporated published date on suckling preferences of WB piglets. Our study revealed alterations of suckling behaviour in piglets, wherein GMP showed intermediate suckling strategies (i.e. suckling ranges). However, there appeared to be a certain degree of behavioural conservatism. Domestic piglets maintained the tendency to prefer abdominal (middle) teats, which are anatomically posterior in WB and preferred by wild piglets. It can be suggested, that this general tendency seen in domestic piglets (GMP and CB), is not generated by geometric constraints (mid-domain effect), but appears to originate from the wild ancestor. Results of the present study suggest that the selection of CB for increasing litter size and higher number of teats might have led to imbalances between suckling behaviour, teat number and udder space availability.