Effects of peroxidized soybean oil on growth and energy digestibility in broilers

This research evaluates how the oxidative status of soybean oil, a critical energy source in poultry nutrition, directly impacts bird performance and energy utilization. Conducted by Brian J. Kerr, Victoria C. Wilson, Patrick C. von Schamburg, and Carl M. Parsons, this study was published in Poultry Science (2025), DOI: 10.1016/j.psj.2024.104725. By subjecting soybean oil to various thermal treatments, the authors aimed to quantify the relationship between primary and secondary peroxidation products and their measurable effects on growth and digestibility.

For the professional seeking to optimize feed formulations, the study reveals that lipid peroxidation is not a uniform process but a complex chain reaction influenced by temperature, oxygen, and time. The researchers found that soybean oil processed at high temperatures, specifically 135 degrees Celsius for 42 hours, led to a significant reduction in average daily gain and average daily feed intake. These findings underscore the necessity of moving beyond simple peroxide value (PV) tests to include secondary measures like the p-anisidine value (AnV) to accurately assess the quality of fats entering the mill.

Producers can directly apply these findings by recognizing that "damaged" oils have a lower energy value than their appearance might suggest. The experiment demonstrated that the relative bioavailability of energy in peroxidized soybean oil can drop by 12 to 29 percent compared to fresh, unheated oil. This reduction in energy availability means that birds may not meet their growth potential even if the diet appears balanced on paper, directly impacting the final gain-to-feed ratio and overall flock profitability.

Academics and technical consultants will find the proposed prediction equations particularly compelling as a starting point for more precise nutritional modeling. The authors integrated their findings with existing literature to create regression models where the combination of peroxide and anisidine values accounted for 27 to 43 percent of the variance in performance variables. Notably, while peroxide value is a common industry standard, it was not a significant individual predictor in these equations, suggesting that secondary oxidation products (measured by AnV) may be more indicative of long-term performance impacts.

The study also highlights the role of fatty acid profiles, noting that oils high in polyunsaturated fatty acids are more susceptible to the oxidative damage that triggers these performance declines. In the experimental trials, birds fed oil processed at 90 degrees Celsius showed a specific reduction in feed efficiency (gain-to-feed), demonstrating that even moderate thermal stress can disrupt the metabolic utilization of dietary lipids. This result nuances our understanding of how different stages of oxidation affect bird physiology differently.

From a practical management perspective, the results suggest that blending oils of different oxidative qualities—a common industry practice—may not always yield predictable results. While some mixtures in the study did not show significant negative effects, the underlying trend remains clear: as secondary oxidation products like aldehydes and ketones increase, bird performance predictably suffers. The data indicate that bird performance relative to those consuming fresh lipids can indeed be estimated if the dietary levels of both primary and secondary oxidation markers are known.

In conclusion, this research provides a vital bridge between laboratory markers of oil quality and the economic reality of broiler production. It challenges the industry to adopt more comprehensive lipid quality testing and offers a mathematical framework to account for the energy "leakage" caused by peroxidized ingredients. Ensuring the stability and quality of the lipid fraction is not just a matter of shelf-life, but a fundamental requirement for maintaining the growth efficiency and health of modern broiler strains.