Interpretive Summary: Influence of feeding thermally peroxidized lipids on growth performance, lipid digestibility, and oxidative status in nursery pigs
By Caitlin Vonderohe
Lipids are added to swine diets as a concentrated source of energy. However, fats that are sourced from rendering plants, and the food and restaurant industries have undergone a variety of heating processes and may be of varying quality. Previous work has shown that feeding peroxidized lipids can reduce growth performance. Recently, Kerr et al. published “Influence of feeding thermally peroxidized lipids on growth performance, lipid digestibility and oxidative status in nursery pigs” in the Journal of Animal science to critically evaluate the impact of inclusions of differentially sourced lipids and thermally processed soybean oil in nursery pig diets.
The first experiment evaluated the effect of feeding unheated and thermally peroxidized palm oil, poultry fat, canola oil and soybean oil to nursery pigs. Generally, thermal processing of poultry fat and palm oil minimally affected composition or quality but thermal processing of canola and soybean oils significantly changed the fatty acid composition and measures of fat quality. Feeding pigs thermally peroxidized fat sources resulted in lower G:F, but there was no combined effect of thermal peroxidation and fat source on G:F, fecal score or oxidative status. Pigs fed peroxidized soybean oil and palm oil had reduced fat digestibility. Additional experiments indicated that increasing levels of peroxidized soybean oil resulted in reduced lipid digestibility, average daily gain and G:F when soybean oil was included at 3% and 7.5% added fat.
Overall, these studies demonstrated that feeding pigs increased levels of peroxidized lipids generally reduced total tract lipid digestibility and growth performance. Total tract lipid digestiblity drops by 1% for every unit increase in measures of lipid peroxidation in soybean oil. This study successfully confirmed and quantified some of the potential detrimental effects of feeding peroxidized lipid sources.