Dose-dependent effects of dietary sunflower meal in diets supplemented with commercial enzymes on aged laying hens

The present study investigated the impact of elevating the proportion of sunflower meal (SFM) in a diet comprising NSPase (Non-Starch Polysaccharide degrading enzyme) and 6–phytase on performance, egg quality, gut integrity, tibia traits, and nutrient digestibility in aged laying hens. A total of 120 laying hens were allocated to five dietary treatments, eight replicates, and three birds per replicate from 61 to 81 weeks of age. The treatments comprised levels of SFM as 10% (control), 12%, 14%, 16%, and 18% and the same levels of commercial NSPase and phytase. Treatments had no significant effect on the performance, damaged and dirty egg ratios, shell thickness, or internal egg quality. Crypt depth (CD) decreased in birds fed on diets containing 16% and 18% SFM. The villus height:crypt depth ratio (VH:CD) and the goblet cells linearly increased in response to diets with 16% and 18% SFM. Total number of aerobic bacteria and Lactobacillus increased along with increasing dietary SFM. The administration of different levels of SFM did not significantly impact the coliform count. The concentration of caecal acetate, propionate, butyrate, isobutyrate and total SCFA, tibia phosphorus (P), ileal P and crude protein (CP) digestibility exhibited linear increase with the dietary inclusion of SFM. It can be concluded that the inclusion of dietary SFM in a diet supplemented by NSPase and phytase can enhance gut integrity by improving jejunal histomorphometry, caecal microbial population, SCFAs profile, ileal P and CP digestibility without any detrimental effects on performance and egg quality.