Gastric and small intestinal lipid digestion kinetics as affected by the gradual addition of lipases and bile salts

We studied the effect of evolving from static in vitro digestion conditions towards the gradual addition of essential digestive compounds for lipid digestion.Two oil-in-water emulsions were considered:a low(5%w/w)and high(20%w/w)triolein-based emulsion with identical surfactant-to-oil ratio(0.2).Emulsions were subjected to in vitro static digestion conditions or gradual gastric lipase addition,gradual pancreatic lipase addition,and/or gradual bile salt addition.For these three latter cases,similar amounts of gastric/pancreatic lipase and/or bile salts were provided as in the static case,however divided over 4 doses added during the first 30 min of each digestive phase.For the low-lipid emulsion,gradually adding lipases and bile salts did not significantly affect lipolysis kinetics.This can be related to the sufficient amounts of digestive compounds present even in the smallest initial dose.For the high-lipid emulsion,the gradual addition of bile salts significantly reduced the lipolysis rate.Bile salts are essential to remove lipid digestion products from the interface and thus allow the continuation of the lipid digestion process at the interface.Oppositely,the lipolysis extent after 2 h of small intestinal phase was not significantly influenced by the digestion approach.This is again explained by the simple nature of the emulsions studied and the excess of lipase even in the smallest initial dose.Overall,this work showed that evolving towards more(semi-)dynamic digestion conditions can impact(lipid)digestion kinetics,even for relatively simple food compositions,and is of interest to obtain more physiological relevant digestion kinetics.

Characteristics of lipids and their feeding value in swine diets

In livestock diets, energy is one of the most expensive nutritional components of feed formulation. Because lipids are a concentrated energy source, inclusion of lipids are known to affect growth rate and feed efficiency, but are also known to affect diet palatability, feed dustiness, and pellet quality. In reviewing the literature, the majority of research studies conducted on the subject of lipids have focused mainly on the effects of feeding presumably high quality lipids on growth performance, digestion, and metabolism in young animals. There is, however, the wide array of composition and quality differences among lipid sources available to the animal industry making it essential to understand differences in lipid composition and quality factors affecting their digestion and metabolism more fully. In addition there is often confusion in lipid nomenclature, measuring lipid content and composition, and evaluating quality factors necessary to understand the true feeding value to animals. Lastly, advances in understanding lipid digestion, post-absorption metabolism, and physiological processes（e.g., cell division and differentiation, immune function and inflammation）; and in metabolic oxidative stress in the animal and lipid peroxidation, necessitates a more compressive assessment of factors affecting the value of lipid supplementation to livestock diets. The following review provides insight into lipid classification, digestion and absorption, lipid peroxidation indices, lipid quality and nutritional value, and antioxidants in growing pigs.