Effect of olive leaves or marigold petal extract on oxidative stress, gut fermentative activity, and mucosa morphology in broiler chickens fed a diet rich in n-3 polyunsaturated fats

Abstract

An experiment in broilers was conducted to investigate the effect of olive (Olea europea) leaves and marigold (Calendula officinalis) petal extract supplementation on oxidative stress, characteristics ofintestinal contents, and on the morphology ofthe small intestine. Oxidative stress was induced by a n-3 polyunsaturated fatty acids rich diet. 1-day-old male broiler chickens, Ross 308, were housed in a deep litter system. After the first 21 days, animals were randomly divided into three groups of16 animals in two replicates and fed, until slaughter on day 39, a diet that contained 7% linseed oil. Control diet (Cont) remained unsupplemented, while both experimental diets were supplemented with olive leaves (OliveEx) or marigold petal (MarigEx) extracts. Oxidative stress was evaluated in blood and liver by measuring markers oflipid peroxidation (malondialdehyde (MDA), isoprostanes), rate ofDNA damage in lymphocytes and in blood (comet assay, 8-hydroxy-2’deoxyguanosine (8-OHdG)), and activity ofantioxidant and liver enzymes in blood. In different parts of the intestine, levels of short chain fatty acids (SCFA), and viscosity of intestinal contents were measured, and the health ofthe gastrointestinal tract was assessed using histological measure-ments. OliveEx significantly (p＜0.05) decreased the MDA and 8-OHdG concentration in plasma, and the level of ethanoic acid in small intestinal contents and total SCFA in caecum, indicating improved oxidative status and increased microbial activity in the intestine. MarigEx significantly (p＜0.05) decreased the rate oflymphocyte DNA damage and the crypt depth in duodenum, indicating potentially beneficial effects on the immune system and the health ofthe small intestine. In conclusion, dietary OliveEx and MarigEx supplementation improved some markers of oxidative stress and intestinal health. However, positive effects could be more pronounced in more unfavorable environmental conditions or in cases ofdiseases, but further studies are needed.