The maternal stress effects of an omega 3 enriched diet in chickens
Résumé
The n-3 and n-6 fatty acid (FA) content of the maternal diet during the prenatal period influences brain and behavioural development in mammalian offspring. Although, maternal effects on offspring behaviour are well characterised in birds, maternal dietary effects of n-3 and n-6 FA still deserve consideration. This study examined effects of maternal diet with high levels of n-3 or standard n-3/n-6 FA levels (i.e. control (C)) on the FA composition and hormone concentrations in yolk, maternal basal faecal corticosterone metabolites (FCM), and offspring’s development and behavioural responses to novelty (novel food, novel object and novel environment), in white leghorn laying hens (n=18/group, offspring, n=48/n-3 vs n=50/C). The n-3 enriched diet increased yolk progesterone (1,145±151 vs 669±95 ng/g, P=0.02) and estradiol concentrations (10.5±0.5 vs 7.4±0.3 ng/g, P=0.002), and n-3 FA content in yolk while reducing essential arachidonic acid compared to control diet (0.6±0.05 vs 1.8±0.2% of total FA, P<0.01). The hens fed the n-3 FA enriched diet had higher FCM levels than hens fed control diet (397.5±56.8 vs 98.7±19.1 ng/g, P=0.003). Chicks obtained from hens fed the n-3 enriched diet (n-3 chicks) weighted less at hatch than chicks obtained from hens fed the C diet (C chicks): 39.4±3.4 vs 40.8±3.3 g (P=0.02). N-3 chicks spent less time eating novel foods, especially females (12±4 vs 23±5 s, P=0.01,), and took longer to approach a novel object (173.9±6 vs 144.6±11.56 s, P=0.01). In a novel environment, n-3 chicks walked less than C chicks (6.0±1.7 vs 11.4±2.3 line crosses, P=0.02). These data suggest a stress effect of the maternal n-3 enriched diet, by increasing steroid yolk-hormones levels and FCM. They highlight a potential trans-generational detrimental impact of n-3 enriched maternal diet on offspring emotional reactivity – a potential new pathway for maternal effects in birds via the n3/n6 ratio in the maternal diet.