Variabilité de la capacité d’adaptation des porcelets au sevrage en agriculture biologique | Variability of piglets adaptability at weaning in organic farming system

In organic farming, weaning piglets remains a critical period, although later than in the conventional system. The use of hormones being forbidden in organic system, heat synchronization is absent, which leads to spread of birth associated with heterogeneous ages, weight and health status of the piglets. The differences can be accentuated by a poorly adapted solid diet before and after weaning. The aim of the study was to understand the difference involved in the physiological mechanisms in piglet adaptation strategies to propose adapted feeding strategies. The studied population of fifty piglets, from four genetic lines, comes from 5 sows (Landrace x Duroc) of the INRA-Genesi unit and a boar (Pietrain x Large White). Five batches, of ten pigs per sow, were constituted by weight range: four “large” piglets, two "medium" and four "small". They had access to a second-age feed from ten days and to roughage, high protein, after weaning (Wrapped alfalfa). Animals weights were recorded on days (d) 1-10-21-28 42-48-55-62. Blood samples were collected at d 42-48-55-62 for inflammatory indicators and oxidative stress measurements around weaning. Behavioural observations in farrowing room at d 15-20-30-40 and at post-weaning at d 43, were carried out to establish weaning adaptation profiles. The results showed that the small piglets at d 42 were on the posterior teats and that there was no clear indication if the piglets ate more solid feed in the farrowing room compared to the larger piglets. At post-weaning, it was shown that the small piglets were on average more present in the area of feeding interest than the larger ones. The smaller piglets also had a higher haptoglobin rate than the large and medium piglets. Finally, there was no weight compensation from the smaller piglets compared to the mediums and larger piglets. The average weight significantly differs between all three categories at d 42 and d70.