Comparative Evaluation of Nutritional Strategies on Growth Performance, Meat Quality, and Gut Microbiota in Broiler Chickens under Heat-Stress Conditions

Project Abstract

This study investigates the effects of contrasting nutritional strategies on growth performance, meat quality, and gut microbiota of broiler chickens subjected to heat-stress conditions, with the aim of identifying practical feed formulations that mitigate thermal adversity while sustaining production efficiency. A 2x3 factorial design was employed across a 42-day growth period, comprising two ambient temperatures (thermoneutral at 22–24°C and heat-stress at 34–36°C) and three dietary regimes a control corn-soybean meal (CSM) diet, a reduced crude protein (RCP) diet supplemented with crystalline amino acids to meet essential amino acid requirements, and an antioxidant-rich diet augmented with vitamin E, selenium, and phytogenic compounds. A total of 480 day-old chicks were randomly allocated to six treatment groups with four replicates per treatment and 20 birds per replicate, housed in climate-controlled pens to ensure precise thermal exposure. Growth performance metrics, including body weight gain, feed intake, and feed conversion ratio, were recorded weekly. Carcass characteristics and meat quality attributes—pH, color (L*, a*, b*), drip loss, cooking loss, shear force, and proximate composition—were analyzed at 42 days. Blood biochemical profiles (uric acid, total protein, albumin, lipid fractions) and oxidative stress markers (malondialdehyde, total antioxidant capacity) were measured to elucidate systemic responses to heat and diet. Gut microbiota composition was assessed via 16S rRNA sequencing of ileal and cecal samples, with functional predictions made using PICRUSt to infer metagenomic potential related to short-chain fatty acid production, inflammatory signaling, and nutrient metabolism. Intestinal morphometry, including villus height, crypt depth, and villus height-to-crypt depth ratio, was evaluated to correlate morphological adaptations with nutrient absorption efficiency under thermal stress. Key findings reveal that heat-stress significantly reduced growth performance and altered meat quality, characterized by increased drip loss and higher pH values in the longissimus dorsi, compared with thermoneutral conditions. The RCP diet, when complemented with amino acids, mitigated adverse growth declines and improved feed efficiency under heat exposure, while maintaining comparable carcass yield to the control diet. The antioxidant-rich formulation further stabilized meat quality by reducing oxidative damage, preserving color, and lowering drip losses, particularly under heat stress. Gut microbiota analysis demonstrated a heat-induced decrease in diversity and a relative rise in pro-inflammatory taxa; however, antioxidant supplementation partially restored beneficial microbial populations, including Lactobacillus and Ruminococcaceae, and enhanced predicted butyrate biosynthesis pathways. Ileal villus height and the villus-to-crypt ratio were better preserved in birds fed the antioxidant and RCP diets under heat stress, indicating improved intestinal absorptive capacity. Correlation analyses indicated strong associations between microbial functional pathways related to butyrate production and improved feed efficiency and meat quality traits. Overall, the integration of an amino-acid-balanced protein substitute with strategic antioxidant and phytogenic supplementation emerged as a robust nutrition strategy to sustain growth performance, protect meat quality, and promote gut health in broilers facing heat-stress challenges. The findings offer practical implications for feed formulation under hot climates and contribute to the understanding of diet-microbiome-host interactions in avian thermotolerance.

Project Overview

What This Project Is About

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A plain-language overview of how different feeding strategies affect chickens raised in hot conditions, focusing on growth, meat quality, and gut health. The project compares how nutrition tweaks can help chickens grow better, stay healthier, and produce better meat when temperatures are high.

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The Problem It Addresses

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Extreme heat can slow growth, reduce feed efficiency, and alter meat quality in broilers. Gut microbiota (the community of microbes in the gut) plays a key role in digestion and health, but we don’t always know which nutrients help most under heat stress. This project looks for practical feeding options to improve outcomes.

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Objectives of the Project

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1. Identify nutritional strategies that improve growth performance under heat stress.
2. Assess impacts on meat quality traits such as tenderness and water-holding capacity.
3. Evaluate changes in gut microbiota composition associated with different diets.
4. Provide recommendations for cost-effective feeding plans for hot climates.

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What You Will Do Step by Step

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1. Review common heat-stress factors affecting broilers and relevant nutrition literature.
2. Design a simple feeding trial with several diet treatments.
3. Raise broilers under controlled heat conditions and monitor growth and feed intake.
4. Measure meat quality indicators at slaughter (e.g., tenderness, juiciness).
5. Collect gut samples and analyze microbial communities.
6. Analyze data to compare treatments and identify best options.
7. Discuss implications for farmers and animal welfare.

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Expected Outcome

Clear evidence on which nutritional strategies help broilers grow better, produce higher quality meat, and maintain a healthier gut under heat stress, with practical recommendations for farmers.