Effect of Feeding Wet Feed or Wet Feed Fermented by Bacillus licheniformis on Growth Performance, Histopathology and Growth and Lipid Metabolism Marker Genes in Broiler Chickens

SIMPLE SUMMARY: Heat stress is an abiotic environmental factor that affects poultry performance and results in several physiological, immunological and behavioral changes in birds. Previous works have illustrated that wet feeding has been considered as a useful agent to improve birds’ ability to resist high ambient temperatures and to enhance our understanding of feed consumption limitations when broilers are fed dry diets. In broilers, wet feeding enhances nutrient use. This research reveals the impacts of three feeding methods (dry feed, wet feed or wet feed fermented with Bacillus licheniformis) on the growth efficiency, intestinal histomorphometry and gene expression of the lipid metabolism- and growth-related genes of broiler chickens. Our findings confirm improved growth and digestibility for fermented wet feed compared with control and wet feed diets; however, wet feed has a negative effect on performance compared with the control group (dry feed). Additionally, fermented wet feed caused a reduced hepatic gene expression of peroxisome proliferator-activated receptor γ (PPARγ) and increased that of fatty acid synthase (FAS). ABSTRACT: The present study evaluated the effect of three feeding methods (dry feed, wet feed or wet feed fermented with Bacillus licheniformis) on the growth performance, intestinal histomorphometry and gene expression of the lipid metabolism- and growth-related genes of broiler chickens. A total of 360 one-day-old Cobb-500 broiler chicks were randomly allotted into three groups containing four replicates with 30 birds each. The first group (control) was fed a dry mash basal diet. The second and third groups were fed wet feed and fermented wet feed. The final body weight and weight gain were reduced (p < 0.01) in the wet feed group, while they did not differ between the fermented wet feed and dry feed groups. Feed intake was not altered, and feeding on wet feed significantly (p < 0.01) increased the feed-to-gain ratio compared to the remaining groups. No differences between the three feeding methods in carcass characteristics, blood biochemistry and nutrient digestibility were observed except for crude protein digestibility, which was increased (p < 0.01) in the fermented wet feed group. Duodenal and ileal villi heights were elevated in birds fed fermented wet feeds, while crypt depth was not altered. The expression fold of IGF-1, GH and m-TOR genes in the pectoral muscle of birds fed wet feed was decreased (p < 0.05), while myostatin gene expression was elevated. Feeding on wet feed reduced the hepatic gene expression of PPARγ and increased that of FAS. In conclusion, wet feed negatively affected the broiler chickens’ efficiency under heat stress; however, fermenting the wet feed with Bacillus licheniformis improved feed utilization and birds’ performance compared to the dry feed group.