This experiment was carried out to evaluate the effect of dietary guar meal levels with or without β-mannanase on layer performance. One hundred and sixty eight 22-week-old Golden Montazah pullets divided randomly into seven treatment groups each group had 24 pullets divided into three replicates with 8 pullets per each. The 1st group fed on corn - soybean meal diet and served as control group. The 2nd, 4th and 6th groups fed on diets contain 5%, 10% and 15% guar meal respectively without β-mannanase. The 3rd, 5th and 7th groups fed on diets contain 5%, 10% and 15% guar meal with 250 mg/kg β-mannanase respectively. The experiment was extended for three months to estimate production performance. At the end of the experiment egg quality was assayed and slaughter assay was conducted. The following results were obtained:-
Adding 10% guar meal had no harmful effects on egg production performance, however increasing guar meal up to 15% retarded clearly egg production performance compared with control. Remarkable improvements in production performance were observed when β-mannanase supplemented to guar diets.
Significant improvement in shell weight percent and shell thickness were observed by increasing guar level up to 15% with or without β-mannanase compared with control treatment, in contrast significant decrease was observed in albumen weight. Neither guar meal levels nor β-mannanase supplementation influenced liver, gizzard, heart and spleen weight percent. All guar meal treatments with or without β-mannanase recorded significantly (P≤ 0.05) lower abdominal fat percent than control treatment. Increasing guar meal than 5% increased significantly (P≤ 0.05) thymus weight percent but supplemented β-mannanase decreased significantly (P≤ 0.05) thymus weight percent.
The best relative economic efficiency value recorded for diet that contains 5% guar meal with β-mannanase.