Optimizing tryptophan supplementation for stress reduction and enhanced productivity in aging laying hens

Area of Science:

• Animal Science
• Poultry Nutrition
• Avian Physiology

Background:

• Aging laying hens under high-density conditions often experience stress, impacting productivity and egg quality.
• Dietary supplementation is a key strategy to mitigate stress and improve performance in poultry.
• Tryptophan (Trp) is an essential amino acid precursor to serotonin, influencing mood and stress responses.

Purpose of the Study:

• To investigate the effects of dietary tryptophan supplementation on stress indicators and production parameters in aging laying hens.
• To determine the optimal level of Trp supplementation for enhancing hen-day egg production, egg mass, and feed conversion ratio.
• To evaluate the impact of Trp on physiological and biochemical stress markers and egg quality traits.

Main Methods:

• A total of 700 Hy-line laying hens (70 weeks old) were divided into four groups.
• Diets were supplemented with 0%, 0.25%, 1%, and 2% Trp over a four-week period.
• Evaluated Hen-Day Egg Production (HDEP), egg mass, feed conversion ratio (FCR), blood parameters (stress indicators), and egg quality.

Main Results:

• Hen-day egg production and egg mass showed a quadratic response, peaking at 1% Trp supplementation.
• Feed conversion ratio improved quadratically at 0.25% and 1% Trp.
• Blood stress indicators (corticosterone, heterophiles, lymphocytes) decreased linearly with Trp supplementation, while serotonin levels varied.
• Egg quality traits (yolk color, shell strength, shell thickness) improved linearly with Trp inclusion in week 4.

Conclusions:

• Dietary Trp supplementation effectively mitigates stress in aging laying hens.
• 1% Trp supplementation optimizes production parameters (HDEP, egg mass) and improves feed conversion ratio.
• Trp supplementation enhances egg quality and contributes to overall hen well-being under challenging conditions.