Understanding Heat Stress in Broiler Chickens: A New Perspective on Fat Metabolism

The rising global temperatures pose unprecedented challenges for the poultry industry, particularly for broiler chickens, which are bred for rapid growth. Recent research from Japan has provided new insights into the impact of heat stress, revealing that this environmental stressor significantly alters fat metabolism in chickens, ultimately affecting meat quality and production efficiency.

The Economic Burden of Heat Stress

Chronic heat stress has been identified as a significant issue affecting poultry production, costing the industry an estimated US$128–165 million annually. Broiler chickens are particularly vulnerable, as they eat less during heat exposure while paradoxically accumulating more fat relative to their body weight. This phenomenon significantly deteriorates meat quality and production efficiency.

Uncovering the Mechanisms Behind Fat Storage

While existing research has highlighted how heat stress enhances fat production in the liver, the mechanisms by which this newly produced fat is stored in adipose tissue remain poorly understood. A research team led by Assistant Professor Yukako Tokutake at Shinshu University aimed to explore these complexities in detail, contributing to a more nuanced understanding of fat metabolism in chickens under heat stress.

The Study Design and Findings

In their study published in Scientific Reports, the research team exposed 21-day-old broilers to an elevated temperature of 32°C for two weeks while maintaining a control group at a comfortable 24°C. A ‘pair-fed’ group, subjected to the same comfortable conditions but limited to the food intake of the heat-exposed group, allowed the researchers to differentiate the impacts of heat stress from food intake reduction.

Surprisingly, even with reduced food consumption, the heat-stressed chickens maintained an abdominal fat-to-weight ratio comparable to the control group, suggesting that heat stress actively promotes fat deposition rather than resulting solely from limited food intake. Blood analyses also showed lower levels of free fatty acids, indicating a complex metabolic adjustment due to higher temperatures.

Insights into Gene Expression

Following a comprehensive transcriptome analysis of abdominal fat from both groups, the researchers identified 459 genes that exhibited changes in expression levels due to heat stress. Intriguingly, genes responsible for fat storage and synthesis, like lipoprotein lipase (LPL), were found to be more active in heat-stressed chickens. Conversely, genes associated with fat breakdown saw decreased activity.

Implications for Poultry Production

These discoveries signify a shift in understanding how heat stress affects fat accumulation in broilers. The study suggests that adipose tissue plays a more active role in fat storage than previously recognized. Dr. Tokutake indicated, “Our findings are the first to illustrate that increased LPL expression in adipose tissue likely contributes to enhanced fat accumulation in broilers experiencing heat stress.”

Future Directions

This research highlights critical avenues for improving poultry industry practices. By better understanding the fat metabolism processes influenced by heat stress, strategies such as regulating fat metabolism through feed additives or selectively breeding for heat resistance may enhance poultry health and meat quality. The ongoing quest for innovative solutions is vital for achieving sustainable poultry production amidst rising global temperatures.

Source: Phys.org