Caroline Clouard

Le porc est une espèce sociale, qui évolue au sein de groupes dont la structure hiérarchique est régulée par un ensemble d’interactions agonistiques, comme les agressions, et non agonistiques, comme les contacts du groin. Cette revue vise à i) faire un bilan des connaissances sur le comportement social du porc domestique, ii) décrire l’impact de certaines pratiques d’élevage sur l’expression de ces comportements, et iii) proposer des perspectives de recherche sur le comportement social pour améliorer le bien-être animal en élevage. De nombreuses conditions et pratiques d’élevage, comme les allotements successifs, la constitution de groupes de taille ou de composition inadéquates, et des infrastructures inadaptées, impactent les comportements et les relations sociales entre les porcs. Jusqu’à récemment, la recherche sur le comportement social du porc s’était principalement focalisée sur les interactions agonistiques. Ainsi, leur rôle dans les relations de dominance et la défense des ressources, ainsi que l’impact des pratiques d’élevage sur ces comportements, ont été particulièrement bien caractérisés. Au contraire, les comportements non agonistiques ont reçu un intérêt beaucoup plus récent. Pourtant, leur prévalence est bien plus élevée que celle des comportements agonistiques, et ils seraient impliqués dans de nombreux processus biologiques, comme la reconnaissance et la communication sociale, l’affinité ou la réduction du stress. En favorisant des états mentaux positifs, ces comportements pourraient être d’une importance capitale pour le maintien du bien-être des porcs en élevage, et il est nécessaire de mieux comprendre leurs fonctions et déterminants. Ces connaissances devraient être prises en compte pour faire évoluer les pratiques dans les systèmes d’élevage.

Social behavior is a key component of pig welfare on farms, but little is known on the development of social behaviors in piglets. This study aimed to explore social behaviors and identify early social styles in suckling piglets. Social behaviors of 68 piglets from 12 litters were scored continuously for 8 h per day at 21 and 42 days of age, and were included in a Hierarchical Clustering on Principal Components analysis to identify clusters of pigs with similar social styles. Social nosing represented 78% of all social interactions given. Three social styles were identified: low-solicited inactive animals (inactive), active animals (active), and highly-solicited avoiders (avoiders). Belonging to a cluster was independent of age, but was influenced by sex, with females being more represented in the ‘inactive’ cluster, and males in the ‘active’ cluster, whereas both sexes were equally represented in the ‘avoider’ cluster. Stability of piglets’ allocation to specific clusters over age was high in the ‘inactive’ (59%) and ‘active’ (65%) clusters, but low in the ‘avoider’ cluster (7%). Haptoglobin and growth rate were higher in ‘active’ than ‘inactive’ pigs, and intermediate in ‘avoiders’. Our findings suggest the existence of transient social styles in piglets, likely reflective of sexual dimorphism or health status.

Introduction: Oligosaccharides found in mammalian milk have shown the potential to alter brain development across multiple species. The diversity and concentration of these oligosaccharides is species-specific and varies greatly between individuals, thus understanding their role in cognitive development is warranted. We investigated the impact of early life dietary fucosylated/neutral or sialylated human milk oligosaccharides (HMO) on behaviours in tasks assessing anxiety, motivation, appetite, learning, and memory. Methods: Sixty-four female Göttingen minipigs were artificially reared from 2 weeks postnatal and provided milk replacers. The study used four groups: no additional oligosaccharides (Con), fucosylated and neutral oligosaccharides (FN, 4 g/L), sialylated oligosaccharides (SL, 0.68 g/L), or both FN and SL (FN + SL, 4 g/L) from 2 to 11 weeks postnatal. One reference group was sow-reared. Weaning occurred between 10 and 11 weeks postnatal, and thereafter an obesogenic diet was provided. Behavioral tasks were conducted over three periods: 1) 0–11 weeks; 2) 16–29 weeks; 3) 39–45 weeks. Tasks included a spatial holeboard task, open field task, exposure to a novel object, runway task, single-feed task, and home pen behaviour observation. Results: In the holeboard, the SL group demonstrated improved reference memory during reversal trials between 16-29 weeks. All groups demonstrated equivalent behavior in open field, novel object, runway, and single-feed tasks, as well as in their home pens (Ps > 0.05). Discussion: These results suggest that early life dietary intake of sialylated oligosaccharides may provide an improvement to cognition during the equivalent developmental stage of adolescence.

Background: In recent years, lactose-free infant formulas have been increasingly used. Digestible maltodextrins are commonly used as a substitute for lactose in these formulas, but the effects on energy metabolism are unknown. Objective: We aimed to evaluate the differences in energy metabolism and substrate oxidation in piglets fed milk replacers containing lactose compared with maltodextrin as the only source of carbohydrates. Methods: Piglets (Tempo x Topigs 20) from 8 litters were fed milk replacers containing lactose or maltodextrin (28% w/w, milk powder basis) from 1 to 9 wk of age (n = 4 litters/milk replacer). At 5 wk of age, 4 females and 4 entire males (mean +/- SEM bodyweight, 10 +/- 0.3 kg) were selected per litter, and housed in 16 groups of 4 littermates, with 2 females and 2 males per pen (n = 8 groups/milk replacer). Between 7 and 9 wk of age, groups were housed for 72 h in climate respiration chambers, and fed their experimental milk replacer in 2 meals per day, at 08:30 and 16:30. Heat production data were calculated from the continuous measurement of gaseous exchanges and analyzed using general linear models in SAS. Results: Resting metabolic rate was 6% less in maltodextrin-than in lactose-fed piglets, notably before the morning meal. The postprandial respiratory quotient was 13% greater inmaltodextrin-than in lactose-fed piglets after bothmeals. Net rates of carbohydrate oxidation were on average 5% greater in maltodextrin-than in lactose-fed piglets, particularly after the afternoon meal, whereas net rates of fat oxidation were 9% less in maltodextrin-than in lactose-fed piglets, particularly after the morning meal. Conclusions: Compared with lactose, maltodextrin in milk replacers reduced resting metabolic rate in the fasting state, and induced a shift in postprandial substrate oxidation profiles in pigs. Further research is warranted to evaluate the consequences of these metabolic changes for body composition.

The objective of this study was to evaluate effects of different dosages of dietary nitrate supplementation to sows from d 108 of gestation until d 5 of lactation on reproductive performance of sows and piglet performance from birth until weaning. Dietary nitrate supplementation leads to nitric oxide (NO) formation that can potentially increase blood flow to the fetuses (by the vasodilative effect of NO), leading to a decrease in the loss of potential viable piglets in the form of stillbirth and preweaning mortality. Three hundred and five gilts and sows were allocated to one of six diets from d 108 of gestation until d 5 of lactation, containing 0.00% (Control), 0.03%, 0.06%, 0.09%, 0.12%, or 0.15% of dietary nitrate. The source of nitrate used was calcium nitrate double salt. Calcium levels were kept the same among diets by using limestone. Gilts and sows were weighed and backfat was measured at arrival to the farrowing room (d 108 of gestation) and at weaning (d 27 of age). Data included number of piglets born alive, born dead, and weaned, as well as individual piglet weights at d 0, 72 h of age and weaning. Preweaning mortality was determined throughout lactation. Body weight d 0 (P = 0.04) as well as BW at 72 h of age (P < 0.01) increased linearly with increasing dosages of nitrate in the maternal diet. Litter uniformity (SD) at birth was not affected by maternal nitrate supplementation level (P > 0.10), but tended to be higher at 72 h of age in the control treatment than in all nitrate-supplemented treatments (P = 0.07), and SD decreased linearly (increased uniformity) at weaning with increasing dosages of nitrate (P = 0.05). BW at weaning (P > 0.05) and average daily gain of piglets during lactation (P > 0.05) were not affected by maternal nitrate supplementation. A tendency for a quadratic effect (P = 0.10) of the dosage of maternal dietary nitrate was found on preweaning mortality of piglets with the lowest level of mortality found at 0.09% to 0.12% of maternal nitrate supplementation. We conclude that the use of nitrate in the maternal diet of sows during the perinatal period might stimulate preweaning piglet vitality. Exact mode of action and optimal dose of nitrate still need to be elucidated.