اثر متقابل آنزیم کربوهیدراز و ترکیب فیتوژنیک بر عملکرد، قابلیت هضم و خصوصیات کیفی تخم مرغ در مرغ‌های تخم گذار تغذیه شده با سطح انرژی کاهش یافته

Introduction: As the cost of high-energy feed ingredients like oils and cereals continues to rise, creating cost-effective poultry diets while maintaining production performance has become increasingly challenging. One approach to tackle this issue is to lower dietary metabolizable energy (ME) levels and offset the reduction by incorporating feed additives such as multi-enzymes and phytogenic compounds. Multi-enzymes enhance nutrient digestibility by breaking down anti-nutritional factors like non-starch polysaccharides, which improves gut function and nutrient absorption. Phytogenic compounds, sourced from herbs and spices, are recognized for their antimicrobial, antioxidant, and digestive stimulant properties. However, their effectiveness in low-energy diets is not yet fully understood. This study aimed to assess the individual and combined impacts of multi-enzymes and a phytogenic compound on the performance, nutrient digestibility, and egg quality of laying hens fed reduced-energy diets.
Materials and methods: A total of 320 Hy-Line W-36 laying hens, aged 70 weeks, were randomly assigned to eight dietary treatments using 2×2×2 factorial arrangements in a completely randomized design, with eight replicates of five birds each. The study continued until the hens reached 78 weeks of age. The experimental factors included two levels of dietary metabolizable energy (2800 and 2650 kcal/kg), the inclusion or exclusion of multi-enzyme supplementation (200 g/ton), and the presence or absence of a standardized phytogenic compound (0.02%). The eight dietary treatments were as follows: (1) control diet (2800 kcal/kg), (2) control diet with enzyme, (3) control diet with phytogenic compound, (4) control diet with both enzyme and phytogenic compound, (5) reduced-energy diet (2650 kcal/kg), (6) reduced-energy diet with enzyme, (7) reduced-energy diet with phytogenic compound, and (8) reduced-energy diet with both enzyme and phytogenic compound. Data were collected on feed intake, egg production, egg weight, feed conversion ratio, mortality, nutrient digestibility (using acid-insoluble ash marker), and egg quality traits, including yolk color, shell strength, and Haugh unit.
Results and discussion: Hens on the control diet (2800 kcal/kg) demonstrated significantly superior (P<0.05) performance in egg production, egg weight, egg mass, and feed conversion ratio compared to those on a reduced-energy diet (2650 kcal/kg). However, supplementing the reduced-energy diet with multi-enzymes and phytogenic compounds markedly enhanced these parameters. Notably, hens receiving both enzyme and phytogenic compound supplements with the reduced-energy diet achieved production performance comparable to the control group, indicating that these additives effectively offset the lower energy content. Digestibility studies revealed that supplementation with enzymes and phytogenic compounds, whether alone or combined, significantly improved (P<0.05) the digestibility of dry matter, crude protein, crude fiber, and metabolizable energy, especially in reduced-energy diets. This improvement likely resulted from enhanced enzyme-substrate interactions, better gut morphology, and improved microbial balance in the gastrointestinal tract. Egg quality also benefited from the supplements. Phytogenic compounds enhanced yolk color through their natural carotenoid content, while enzyme supplementation improved eggshell strength, likely by increasing calcium absorption. A significant three-way interaction among energy level, enzyme, and phytogenic compound was observed for various traits, including egg production, egg mass, feed conversion ratio, and yolk pigmentation, underscoring a synergistic effect of these dietary components.
Conclusions: Reducing dietary energy from 2800 to 2650 kcal/kg adversely affected the performance, nutrient digestibility, and egg quality of laying hens. However, adding multi-enzymes and phytogenic compounds helped counteract these negative effects. The combination of these additives was especially effective in improving performance, digestibility, and egg quality in hens on reduced-energy diets. This makes the additives a viable strategy for cost-effective and sustainable poultry production. These findings highlight the potential of integrating enzyme-phytogenic mixtures into layer diets with lower metabolizable energy to maintain optimal productivity without sacrificing economic efficiency.