Effect of Bovine Milk Peptides on Cell Inflammation, Proliferation and Differentiation: Milk Potential Benefits Are Preserved in an Unconventional Cow Feeding Strategy

SIMPLE SUMMARY: Transitioning to sustainable food systems includes the reuse of agricultural by-products as alternative feed ingredients in farms with the aim to increase animal efficiency while reducing the environmental footprint. Olive oil pomace is a waste product obtained during olive oil milling, and its chemical composition makes it a suitable source of fiber, fat, protein and polyphenol in the diet of lactating cows. The inclusion of olive oil pomace in the dairy cow diet did not impair nutrient degradability at the rumen level and animal performances and increased the amount of milk polyunsaturated fatty acids. In this study, the milk protein content from cows fed with a diet supplemented with olive oil pomace was considered; a simulation of gastrointestinal digestion was used to obtain peptides from milk proteins. The peptides were characterized for their antioxidant and anti-inflammatory activity and for their ability to induce differentiation and reduce proliferation in human colon cancer cells. No significant differences were detected between peptides derived from cows fed with a commercial diet; therefore, milk from cows fed with olive oil pomace can be safely used in humans, having nutritional features like (if not superior) traditional milk, but it can be obtained with less use of hay. ABSTRACT: Animal feeding through the reuse of agro-industrial by-products in one of the ultimate goals of sustainable agriculture. Olive oil pomace (OOP) produced as a waste product during olive oil milling has been used as an ingredient in the diet for Holstein lactating cows. Recent findings have shown no decrease in animal performance, feed intake or detrimental effect on rumen microbiota. In contrast, an improvement in C18 polyunsaturated fatty acids has been observed. In this work, the milk protein content from cows fed a commercial diet (CON) or an experimental one supplemented with OOP was determined and compared, and the peptides derived from the simulated gastrointestinal digestion of raw milk were analyzed. After fractionation via RP-HPLC, peptides were characterized for their biological activity on different cell lines. The ability to reduce both the intracellular ROS content and the expression of inflammatory markers, such as Cyclooxygenase, isoenzyme 2 (COX-2) and inducible Nitric Oxide Synthase (iNOS), as well as the remarkable properties to induce cell differentiation and to slow down the proliferation of human intestinal cancer cells, enable us to define them as bioactive peptides. In spite of there being no observed significant difference between the healthy activity of CON and OOP peptides, the results allow us to broaden the knowledge about the biological activity of these bioactive peptides and to confirm that agro-industrial by-products may be successfully incorporated into the feeding strategy of dairy cows.