Predicting duodenal flows and absorption of fatty acids from dietary characteristics in ovine and bovine species: a meta-analysis approach

Dietary and ruminal factors modify the ruminal biohydrogenation (RBH) of polyunsaturated fatty acids (FA), with duodenal FA flowsbeing quantitatively and qualitatively different from FA intake. Using a meta-analysis approach from a database on duodenal flows ofFA in ruminants, this study aimed to determine predictive equations for duodenal and absorbed flows of saturated FA, C18:1, C18:2and C18:3 isomers, odd- and branched-chain FA (OBCFA), C20:5n-3, C22:5n-3 and C22:6n-3 and to quantify the effects of dietary anddigestive factors on those equations. The database was divided into four subsets: forage, seed, vegetable oils or animal fats (oil/fat),and fish products (fish) subsets. Models of duodenal and absorbed FA flows were obtained through variance–covariance analysis.Effects of potential interfering factors (conservation mode and botanical families of forages, lipid source, technological processing oflipid supplements, diet composition and animal characteristics) were analysed. We obtained 83 models for duodenal FA flows as afunction of FA intake for saturated FA (C14:0, C16:0 and C18:0), C18:1, C18:2 and C18:3 isomers and seven other models for OBCFA.For the seed/oil/fat subset, intakes of total C18:3, C18:2 and starch content increased the duodenal t11-C18:1 flow with 0.08, 0.16 and0.005 g/kg of dry matter intake (DMI), respectively, whereas intake level [(DMI ×100)/BW] decreased it. The c9c12c15-C18:3 RBH washigher for oil/fat than seed (96.7% v. 94.8%) and a protective effect of Leguminosae v. Gramineae against RBH for that FA appearedin the forage subset. The duodenal C17:0 flow increased with starch content and decreased with ruminal pH, respectively, whereasduodenal iso-C16:0 flow decreased with dietary NDF content for the seed/oil/fat subset. The duodenal C20:5n-3, C22:5n-3 andC22:6n-3 flows depended on their respective intake and the inhibitory effect of C22:6n-3 on duodenal C18:0 flow was quantified.Thirteen models of absorbed FA flows were performed depending on their respective duodenal flows. This study determined the effectsof different qualitative and quantitative dietary and digestive factors, allowing for improved predictions of duodenal and absorbedFA flows.