# Effects of Reduced Amino Acids and Apparent Metabolizable Energy on Meat Processing, Internal Organ Development, and Economic Returns of Cobb 700 and Ross 708 Broilers

## TL;DR

This study shows how adjusting amino acids and energy in broiler feed can improve meat quality, reduce health issues, and boost profits.

## Contribution

The study introduces specific protein-to-energy ratios for different growth stages to optimize broiler health and economic returns.

## Key findings

- Reducing amino acids by 30% decreased severe woody breast and footpad dermatitis but increased body fat.
- Lowering energy by 16% reduced fat and improved muscle yield and economic returns, though normal breast meat decreased.
- Recommended protein–energy ratios for optimal returns were 19.78 (0–10 d), 17.51 (11–24 d), 16.03 (25–39 d), and 15.25 (40–63 d).

## Abstract

Broiler chickens have been bred for fast growth and high feed efficiency, but this has led to health and welfare challenges, including excessive body fat, muscle disorders like woody breast, and footpad dermatitis. These issues not only reduce meat quality but also lower economic returns for poultry producers. One possible solution is adjusting the balance of protein and energy in their feed. This study examined how reducing dietary amino acids and energy affects growth, organ development, meat quality, and economic value in two common broiler strains, Cobb 700 and Ross 708. The study found that reducing amino acids by 30% increased body fat while decreasing the incidence of severe woody breast and shortening the length of footpad dermatitis. Lowering dietary energy by 16% reduced fat accumulation and improved muscle yield and economic returns but slightly reduced the proportion of normal breast meat. Based on these findings, the study recommends specific protein-to-energy ratios for different growth stages to help farmers balance broiler health, meat quality, and profitability. These results provide practical feeding strategies to improve both broiler welfare and economic efficiency in poultry production.

The rapid growth and high nutrient density in modern broiler production have led to issues like woody breast myopathy (WBM), footpad dermatitis, and fat accumulation, affecting welfare and profitability. This study evaluated the effects of amino acid (AA) and apparent metabolizable energy (AME) reductions on organ development, carcass yield, WBM incidence, and economic returns in Cobb 700 and Ross 708 broilers. Two trials were conducted, one per strain, using a factorial design with 12 treatments (four AA × three AME). Each trial included 864 broilers, randomly assigned to six replicate blocks, with 12 pens per block (six males and six females per pen). Diets contained 70%, 80%, 90%, or 100% of digestible AA and 84%, 92%, or 100% AME based on breeder recommendations. A 30% AA reduction increased fat pad weight, promoted proventriculus and jejunum development (day 58), reduced carcass and tenderloin weights, lowered moderate/severe WBM incidence (day 47), and shortened footpad dermatitis. A 16% AME reduction decreased fat pad weight, improved muscle production and returns, but reduced normal breast percentage (days 40 and 47). The recommended protein–energy ratio (g/MJ) for optimal economic returns was as follows: 19.78 (0–10 d), 17.51 (11–24 d), 16.03 (25–39 d), and 15.25 (40–63 d).