Feed form and probiotic supplementation improve egg production and reduce environmental impact in laying hens

Context. Laying hens are influenced by various factors, including diet, which can have a significant impact on egg production and quality, as well as overall animal health. Aims. This study aimed to evaluate egg production and quality, environmental impact, reproductive organs and plasma mineral profiles of laying hens fed diverse forms of feed supplemented or not with a probiotic mixture. Methods. Ninety-six-week old laying hens were randomly distributed among four groups. The hens were housed in 32 cages (three hens/cage, eight replicates per treatment) during 112–127 weeks of age. The first group was fed a mash diet; and the second group was fed a pelleted diet with a diameter of 3 mm. The third and fourth groups were fed the same diets as for Groups 1 and 2 respectively, but supplemented with a mixture of probiotics (PM) Saccharomyces cerevisiae and Bacillus subtilis. Key results. The pelleted diet significantly increased egg weight and mass, and feed intake compared with the mash diet. PM supplementation significantly decreased the number of broken eggs and yolk index compared with the unsupplemented control. Fresh eggs showed a significantly higher egg grade, Haugh unit score, yolk color, and percentage albumen weight than did the stored eggs, but the yolk index and percentage were lower. Pelleting the feed significantly decreased excreta dry matter, organic matter, crude protein, and nitrogen (N) outputs. Excreta crude fiber was significantly decreased by PM supplementation compared with the unsupplemented control. The PM supplementation increased the true protein in the mash feed while decreasing it in the pelleted feed. Percentage heart and gizzard were significantly decreased because of feeding pelleted feeds compared with mash one to which PM was integrated. Pelleting significantly increased serum calcium (Ca), iron (Fe), and alkaline phosphatase concentrations compared with the mash feed, but decreased serum phosphorus (P) and zinc (Zn). Conclusions. Pelleting laying hen diets improved economic traits and yielded stronger effects than did PM supplementation, decreased excreta dry matter, organic matter, and N pollution, and increased serum Ca and Fe concentrations. Implications. These results suggest that pelleted diets could be a more effective strategy to improve production efficiency and reduce the environmental impact of poultry.