Compensatory growth response, environmental nitrogen mitigation, and economic efficiency in broilers fed low-protein diets

Reducing dietary crude protein (CP) minimizes nitrogen pollution, but the limits of restriction and compensatory growth require clarification. This study evaluated graded CP reductions, enriched with essential amino acids, on growth, nitrogen excretion, meat quality, and economic efficiency in 1050 male Ross-308 broilers over 37 days. Birds received one of three diets: a standard high-protein control (LP-1), a moderate low-protein diet 1% reduction (LP-2), or a severe low-protein diet 2% reduction (LP-3). Severe restriction initially decreased body weight (p < 0.05). However, subsequent compensatory growth resulted in similar final weights across all treatments (p > 0.05) with unchanged feed conversion. Fecal nitrogen dropped linearly (p < 0.001), falling by 11.5% in LP-2 and 13.7% in LP-3. The LP-2 diet significantly increased intramuscular fat (p < 0.01) and reduced feed costs by 6.5%, maximizing economic efficiency. Balancing amino acids allows up to a 2% CP reduction without compromising slaughter weight, while moderate reduction optimizes environmental, biological, and profitable outcomes.