Effects of dietary peroxidized lipids on the growth performance and metabolic oxidative status of nursery pigs

Supplemental lipids and lipid rich ingredients with high concentrations of polyunsaturated fatty acids may peroxidize during processing and storage. Exposure to heat, air, moisture, and other pro-oxidants accelerate peroxidation, and peroxidation is impeded by antioxidants. Metabolic oxidative stress occurs when pro-oxidants overload the antioxidant capacity of an animal. This dissertation explores the impact of lipid peroxidation in DDGS and corn oil on the growth performance, health, and metabolic oxidative status of young pigs. An extensive summary of published research revealed that feeding peroxidized lipids to pigs and broilers reduced growth, feed intake, and gain efficiency by 11.2, 7.5, and 4.3%, respectively, and resulted in metabolic oxidative stress. Similar, negative effects were confirmed in 2 additional experiments which evaluated increasing dietary levels of peroxidized corn oil. Our findings suggest the magnitude of reduction in growth depends on the conditions used to peroxidize corn oil. However, in a separate experiment, the dietary inclusion of a highly peroxidized source of DDGS did not affect the growth performance of nursery pigs. Numerous compounds are produced and degraded during peroxidation, and some of these products have been associated negatively animal health and performance. The dynamic nature of peroxidation creates a challenge for nutritionists and formulators assessing the feeding value of dietary lipids. An in vitro experiment was conducted to compare several indicators of peroxidation when heating refined corn oil at either 185°C or 95°C. Results suggest that thermal processing and storage conditions should be considered when selecting indicators of peroxidation, but this information is seldom available. An additional experiment was conducted to assess peroxidation in distillers corn oil and DDGS during storage in the presence or absence of antioxidants. Peroxidation increased during 28 d of storage at 38°C and 90% relative humidity. However, peroxidation was attenuated partially by antioxidants. Our results clearly demonstrate negative effects of dietary peroxidized lipids on the growth performance and metabolic oxidative status of nursery pigs. Future research is necessary to develop an accurate model for predicting reductions in growth performance and metabolic oxidative status when feeding diets containing peroxidized lipids.