Enhancing Nutrient Utilisation, Growth Performance, Gut Functionality and Meat Quality of Broiler Chickens through Multi-Enzyme Super-Dosing

Poultry meat is a particularly important protein source as broilers have a high feed efficiency and short production cycle compared to other animal products, making it an affordable, nutritious source of animal protein (Marangoni et al., 2015). Therefore, strategies to improve production performance of broilers will require significant research as this is key to future food security. One nutritional strategy to improve sustainability of poultry production systems is improving the efficiency of feed utilisation via the addition of exogenous enzymes into broiler diets for a cost-effective production system. Identifying the effective enzyme inclusion-rate is vital to ensure that farmers get the best performance and return on investment. This study aimed to identify the optimal dose-rate of a multienzyme (Natuzyme) at three energy levels, based on production performance, gut morphology and meat quality. A 3 x 4 factorial design of 12 dietary treatments (576 birds, 6 replicates/treatment, and 8 birds/pen) was implemented over a 42-day broiler growth trial, with weekly weights and performance data recorded. Diets were wheat-corn-soybean meal at three levels (no reduction, -0.63 and -0.84 MJ/kg) and four enzyme inclusion levels (0, 350, 700, and 1000 g/ton). One bird per pen was slaughtered at 42 days (n=72) for sample collection. Meat quality analysis was performed using breast meat, where pH, meat colour, water holding capacity, and cooking loss were measured 18 hours post-mortem. Gut morphology was studied for villi abundance, crypt depth, height, and presence of blood.

Performance data revealed that addition of Natuzyme mitigated the negative effect of energy reduction (p≤0.0001) on feed conversion ratio. Reducing dietary energy content increased average daily feed intake (ADFI) (p≤0.0001) to compensate for the energy deficiency, thus increasing the feed conversion ratio (FCR), while adding enzyme to the standard diet improved the feed conversion ratio (p≤0.05) and average daily gain (ADG) (p≤0.05). The meat quality analysis revealed that there was no difference in meat quality among treatment groups, indicating that there was no effect of multienzymes and dietary energy reduction on meat quality. The gut morphology results found that there was no significant difference among treatment groups regarding villi height, crypt depth, and goblet cell abundance. However, super-dosing (1000g/t) in the standard diet created bloody lesions in the small intestine, indicating potential damage to the intestinal wall caused by the high dose of protease which may have begun digesting the intestinal wall. In conclusion, super-dosing with multi-enzymes in reduced energy diets can improve performance parameters and thus profitability for producers and improve sustainability of production at a dose of 350g/t. However, the concentration of protease in the multienzyme may need to be altered to protect the gut lining from potential damage.