The effects of the Saccharomyces cerevisiae extract on some organ, liver, and pancreatic digestive enzymes in breeder hens fed on aflatoxin (AF)-contaminated feed were investigated. Forty-eight 58-wk-old Ross 308 breeder hens were used. The hens were fed diets containing 0 or 100 µg of AF/kg and 0 or 1 g of S. cerevisiae/kg in a 2×2 factorial arrangement of treatments. Although serum alkaline phosphatase levels were significantly higher, serum alkaline aminotransferase (P=0.068) and gamma-glutamyltransferase (P=0.067) levels tended to increase (P<0.05) in hens fed the AF-contaminated diet than those of hens fed the uncontaminated diet. Both AF and S. cerevisiae extract increased (P<0.001) pancreatic amylase activity, but the effect was not additive, resulting in an AF×S. cerevisiae extract interaction (P<0.001). α-Amylase activity in duodenum was lower (P<0.001) in hens fed the AF-contaminated diet. Duodenum α-amylase activity was higher (P=0.024), but jejunum α-amylase activity was lower in S. cerevisiae extract-supplemented hens than that of nonsupplemented hens. There was a significant interaction between AF and S. cerevisiae extract on pancreatic and duodenal lipase activity. Pancreatic lipase activity decreased in hens fed the AF-contaminated diet. However, S. cerevisiae supplementation extract minimized this effect of AF on pancreatic lipase activity. Duodenal lipase activity was decreased in hens fed the AF-contaminated diet without S. cerevisiae extract supplementation. However, there were not any significant differences between hens fed the AF-contaminated diet and hens fed the uncontaminated diet after S. cerevisiae extract supplementation. Pancreatic trypsin activity was higher (P=0.044) in hens fed the AF-contaminated diet than that of hens fed the uncontaminated diet. There was a significant interaction between AF and S. cerevisiae extract on pancreatic chymotrypsin activity. It was increased in hens fed the AF-contaminated diet without S. cerevisiae extract supplementation. However, S. cerevisiae extract supplementation counteracted this negative effect of AF on pancreatic chymotrypsin activity. The treatments did not result in any change in duodenal chymotrypsin activity, but S. cerevisiae supplementation decreased (P<0.05) jejunal chymotrypsin activity. In conclusion, our results showed that addition of 1 g/kg of S. cerevisiae extract reduces the toxic effects of AF on pancreatic lipase and chymotrypsin activity. Therefore, it may be useful to supplement feedstuff with S. cerevisiae extract to reduce the effects of AF in laying breeder hens.

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The aim of the study was to examine the effects of cage furnishing and social stress on some lymphoid organ weight and innate, cell-mediated, and humoral immune responses in laying hens. Sixty-four chickens were used. The chickens were divided into 2 groups; one of the groups was reared in furnished cages (RFC) and the other was reared in conventional cages (RCC). In wk 17, social stress was applied. Heterophil and lymphocyte percentages; liver, spleen, thymus, and bursa of Fabricius weights; phagocytic activity; oxidative burst and chemotaxic activity of heterophil; CD4+ and CD8+ cell proportions; and antibody production were measured. The effect of rearing methods was significant on heterophil, lymphocyte percentage, heterophil/lymphocyte (H/L) ratio, and antibody production. Heterophil percentage and H/L ratio were lower (P=0.001, P=0.001, respectively), and antibody production was higher (P=0.003) in RFC hens compared to RCC hens. The main effect of social stress was also significant on heterophil, lymphocyte percentages, and H/L ratio. Heterophil percentage was higher (P=0.049); H/L ratio tended to be higher (P=0.068); and lymphocyte percentage tended to be lower (P=0.072) due to stress. In addition, thymus and bursa of Fabricius weights tended to be lower (P=0.073 and P=0.074, respectively) in stressed hens. There were significant interactions between rearing methods and social stress on oxidative burst, chemotaxic activity, and CD4+ and CD8+ proportion (P=0.001, P=0.004, P=0.054, and P=0.001, respectively). These parameters were significantly higher in RFC hens, when they were exposed to stress. On the other hand, they did not differ in RCC or unstressed RFC hens. These results indicated that cage furnishing positively affected heterophil functions, CD4+ and CD8+ cell proportions, and antibody production. Therefore, we suggest that cage furnishing, which is recommended for improving the welfare of animals, is also beneficial for improving the immune response of hens under the stress condition.

The effects of environmental enrichment and transport stress on the immune system were investigated in laying hens. A total of 48 1-day-old chickens were used, half of the chickens were reared in conventional cages (RCC) and the rest in enriched cages (REC). Transport stress was applied in the 17th week. Liver weight decreased, spleen and bursa of Fabricius weights, white blood cell count, CD4+ and CD8+ cell proportions increased due to the transport. Environmental enrichment significantly increased antibody production and tended to increase monocyte percentage and CD8+ cell proportion. The effect of transport on, heterophil (H) and lymphocyte (L) percentages was not significant in RCC chickens. While heterophil percentage and H:L ratio increased, lymphocyte percentage decreased in REC chickens subjected to transport. Transport stress increased heterophil functions both in REC and RCC chickens, but the increase was higher in REC hens than in RCC hens. In conclusion, although environmental enrichment did not neutralize the effect of transport on lymphoid organs, it activated the non-specific immune system, cellular and the humoral branches of the specific immune system by increasing heterophil functions, CD8+ cells and antibody production, respectively. Therefore, environmental enrichment suggested for improving animal welfare may also be beneficial to improve the immune system of birds exposed to stress.

Long term ASA pretreatment could prevent and/or ameliorate certain hematological, serological and histological alterations caused by cerulein-induced AP.