Protein and Lipid Digestibility of Pasture-Raised and Grain-Finished Beef: An In Vitro Comparison

This study compared the digestibility of protein and fat components of pasture-raised and grain-finished beef using an in vitro oral-gastro-small intestinal digestion model. Two commonly consumed beef cuts, tenderloin (Psoas major) and striploin (Longissimus dorsi) were selected for this study. There were no substantial differences between the pasture-raised and grain-finished cuts of meat in terms of protein digestibility, as shown by the protein and peptide breakdown (observed through SDS-PAGE) and the degree of hydrolysis as measured by free amino nitrogen. Tenderloin, however, showed significantly (p < 0.05) higher overall protein digestibility than striploin. Both striploin and tenderloin digests from pasture-raised beef released significantly (p < 0.05) higher total amounts of free long-chain n−3 PUFAs and lower amounts of many free saturated fatty acids, notably palmitic and myristic acids, than those from grain-finished animals. The results suggest greater health benefits from consuming pasture-raised beef, particularly tenderloin.