Effects of dietary guar meal with or without beta-mannanase on performance and egg quality traits in laying hens

In this study, the effects of beta-mannanase supplementation to laying hens' diets with different guar meal (GM) ratios on performance and egg quality traits were investigated. The experimental period lasted 126 days. Ninety-six Lohman Brown hens at the age of 56 weeks were kept in individual cages. They were divided into 8 treatment groups as follows: 0% guar meal (GM0) (control); 0% GM + 0.05% beta-mannanase (GM0E); 8% GM (GM8); 8% GM + 0.05% beta-mannanase (GM8E); 16% GM (GM16); 16% GM + 0.05% beta-mannanase (GM16E); 24% GM (GM24); and 24% GM + 0.05% beta-mannanase (GM24E). A photoperiod of 16.5 h light and 7.5 h dark was applied throughout the experiment. The present treatments had significant effects on changes in final live body weight, feed consumption, feed efficiency, egg production, egg weight, shell thickness, eggshell weight, shape index, yolk index, Haugh unit, and yolk pigmentation values (P < 0.05). However, albumen index, shell strength, and mortality were not affected significantly by any of the treatments (P > 0.05). According to our results, guar meal might be used maximally at 16% in laying hen diets, because of its negative effects on laying performance and egg quality traits.