# The Performance, Energy and Nutrient Utilization, and Bone Mineralization of Broiler Chickens Fed Corn-Soybean Meal-Based Diets with Reduced Metabolizable Energy, Calcium, and Available Phosphorus Supplemented with Exogenous Enzymes

## TL;DR

This study shows that adding enzymes to chicken feed improves growth, nutrient absorption, and bone health in broiler chickens.

## Contribution

The novel contribution is demonstrating the quadratic and linear effects of enzyme supplementation on nutrient utilization and performance in broiler chickens.

## Key findings

- Enzyme supplementation improved average daily gain, feed intake, and feed efficiency in broiler chickens.
- Nutrient utilization of DM, N, Ca, P, and energy increased with enzyme supplementation.
- Bone mineralization and breaking strength were positively correlated with enzyme levels.

## Abstract

Feed is an important component of poultry production. In addition to constituting a significant portion of production cost, undigested and unabsorbed nutrients could undermine the health of the gastrointestinal tract as well as contribute to environmental pollution. Exogenous enzymes have been shown to improve energy and nutrient digestion in poultry. This study examined the role of an enzyme combo (phytase and xylanase) in improving energy and nutrient digestibility and utilization in 21-day-old broiler chickens fed corn–soybean meal-based diets. Enzyme supplementation improved average daily gain, average daily feed intake (ADFI), and feed efficiency, while a linear relationship was observed for ADFI. Enzyme supplementation showed a quadratic relationship with the utilization of DM, N, Ca, P, and AMEn, as well as with the apparent ileal digestibility of essential and non-essential amino acids.

This study evaluated the performance and energy and nutrient utilization of broiler chickens fed corn-soybean meal-based diets supplemented with a naturally fermented enzyme complex containing xylanase and phytase. This was evaluated using 300 one-day-old male Cobb broiler chicks in a randomized complete block design with five dietary treatments replicated 10 times with 6 chicks per replicate. The treatments consisted of a positive control (PC) group containing commercially recommended energy and nutrient levels, a negative control (NC) group with reduced metabolizable energy, calcium, and available phosphorus, and three levels of exogenous enzyme supplementation to the NC diet at 150, 200, 250 mg/kg, respectively. At the end of the trial, ileal digesta and excreta were collected for nutrient and energy digestibility and utilization determination, while tibia bones were collected for bone ash determination. The data was analyzed using Proc GLM of SAS 9.4 v 4. Enzyme supplementation quadratically increased (p < 0.05) average daily gain, average daily feed intake (ADFI), and feed efficiency during days 9–21. There was also a linear increase (p < 0.01) between enzyme level and ADFI during days 0–21. Compared with birds fed the PC diet, chickens fed the NC diet had lower (p < 0.01) utilization of DM, N, Ca, P, and energy, as well as lower (p < 0.01) apparent ileal digestibility of essential and non-essential amino acids (AA). Enzyme supplementation level showed a quadratic relation (p < 0.01) with the utilization of DM, N, Ca, P, and AMEn, as well as with the apparent ileal digestibility of essential and non-essential AA. A quadratic relationship was also observed for apparent ileal digestibility of DM, N, P, and digestible energy, except for Ca, where the relationship was linear (p < 0.001). Bone breaking strength and bone ash quadratically correlated (p < 0.05) with the level of enzyme supplementation. The results from this study indicated that the supplementation of exogenous enzyme to a corn–soybean meal-based diet resulted in benefits to performance, nutrient digestibility and utilization, and bone mineralization of broiler chicks compared to birds on the NC diet.