We investigated the effect of a 12-d exposure to 34°C plus dietary inclusion of the probiotic Bacillus licheniformis on the egg production, gut morphology, and intestinal mucosal immunity of laying hens. Ninety-six commercial hens (Hy-Line Brown) at the age of 60 wk were randomly allocated to 4 groups. After a period of laying rate adjustment (14 d), all the hens were subjected to 2 temperature treatments (12 d). Birds in 1 group were raised at 21°C and fed a basal diet, and birds in the other 3 groups were raised at 34°C and fed a basal diet supplemented with 0, 10(6), or 10(7) cfu of B. licheniformis per gram of feed, respectively. Rearing at 34°C depressed egg production and feed intake (P < 0.05). Compared with birds kept at 21°C, birds kept at 34°C had elevated serum levels of tumor necrosis factor-α (d 6), IL-1 (d 6 and 12), and corticosterone (d 6); decreased villus height (ileum: d 6; cecum: d 6 and 12) and ratio of villus height to crypt depth (ileum: d 6; cecum: d 6 and 12); fewer intraepithelial lymphocytes (ileum: d 6; cecum: d 6) and IgA-secreting cells (ileum: d 6; cecum: d 6 and 12); and more mast cells (ileum: d 6; cecum: d 6 and 12; P < 0.05). The number of goblet cells in the cecum increased at d 6 in heat-treated birds, and then deceased at d 12 (P < 0.05). Moreover, morphological examination showed injury to the villi of birds kept at 34°C. In general, inclusion of 10(7) cfu/g of B. licheniformis in the diet of heat-stressed hens was effective in overcoming the observed decline in egg production and feed intake, restoring the impaired villus structure, and sustaining a balanced mucosal immune response. Therefore, the probiotic B. licheniformis may be useful for ameliorating the adverse influence of heat on the egg production and gut health of laying hens.

No abstract

Two hundred 1-day-old male commercial Arbor Acres broiler birds were randomly distributed to a control group and a polysavone group (5 replicates of 20 birds each) to investigate the influence of polysavone, a natural extract from alfalfa, on abdominal fat deposition and immunity in broiler chickens. Birds in the control group were supplied with a basal diet, and 0.06% polysavone was added to the basal diet of birds in the polysavone group. Body weight and feed consumption for each replicate were recorded weekly. At 3, 4, 5, and 6 wk of age, 4 birds from each replicate were randomly selected for blood and organ sampling. Polysavone had no significant effect on feed intake, BW, or feed:gain ratio in the experimental period, and it decreased the abdominal fat weights at 5 and 6 wk of age. Polysavone improved (P <0.05) the relative thymus and spleen weights at 6 wk of age and the bursa weights at 4 and 5 wk of age compared with the control group. At 4 and 6 wk of age, the proliferation of T and B lymphocytes in the polysavone group was significantly greater (P <0.05) than that in the control group. When birds were 4 and 5 wk of age, polysavone resulted in a significant increase (P <0.05) in serum anti-Newcastle disease virus hemagglutination inhibition antibody titer. These results showed that polysavone may decrease abdominal fat deposition and enhance immunity without an adverse effect on the performance of broiler chickens.

No abstract