Formation of teat order and estimation of piglets’ distribution along the mammary complex using mid-domain effect (MDE) model
Publication Type: |
Journal Article |
Year of Publication: |
2013 |
Authors: |
Janko Skok, Dejan Škorjanc |
Publication/Journal: |
Applied Animal Behaviour Science |
Keywords: |
domestic pig, geometric constraints, mammary complex, mid-domain effect (mde), suckling behaviour, teat order |
ISBN: |
0168-1591 |
Abstract:
Domestic piglets (Sus scrofa domesticus) establish relatively stable teat order after the first week postpartum. Formation of teat order is normally accompanied by intense competition between littermates. In this period, piglets’ behaviour and their distribution along the mammary complex is subject to various external influences. In the present study, time-dependent changes of suckling pattern in domestic piglets and the potential factors affecting piglets’ suckling distribution along the mammary complex were investigated. Eleven sows with their litters (110 piglets) were included in the analysis. Throughout the lactation period there were 27 observations per litter. In addition to milk intake and piglet body weight we focused on the impact of geometric constraints (physical limitation of the mammary complex), which has previously been disregarded in studies of piglet suckling behaviour but could play a crucial role, especially at the beginning of the lactation period. Changes in piglets’ distribution were analysed for correlation with changes in milk intake and body weight during lactation. The impact of geometric constraints was estimated using mid-domain effect (MDE) models. Analysis of the first two-weeks of lactation revealed that teat order stability increased after the first week, reaching a transition maximum by the second week (58%), when the effect of geometric constraints was still significant (r2 = 0.679; p < 0.05). Longer periods of lactation led to consistent suckling order, which was no longer affected by geometric constraints (p ≥ 0.05). Alteration of piglet distribution was not associated with the quantity of milk they consumed (r2 = 0.612; p > 0.05). Variation in milk intake was explained by piglet body weight (r2 = 0.701; p < 0.05). Results indicate that the physical limitation of the mammary complex was the only factor that directly affected piglets’ distribution, which was thereby subject to the MDE. The MDE model enabled precise estimation of the piglets’ behaviour on the mammary complex and provides novel information towards understanding of the suckling process.