Fatty acids play a key role in the maintenance of intestinal health which strongly depends on the intestinal barrier function and symbiotic microbiota. Especially PUFA are able to affect both. In this context, beneficial effects of essential fatty acids (EFA) and CLA as special representatives of PUFA are also discussed. In turn, the present study aimed to investigate the effects of an abomasal supplementation of CLA, EFA, or a combination of both from wk 9 before to 9 wk after calving on indicators of intestinal permeability and the adherent intestinal microbiota in 38 dairy cows. Fat supplementations with coconut oil (CON, 76 g/d), EFA (78 and 4 g/d; linseed/ safflower oil), CLA (38 g/d Lutalin), or EFA+CLA were studied according to their effects on jejunal fatty acid composition as well as gene and protein expression of tight junction proteins and fatty acid binding proteins, free fatty acid receptors and further factors characterizing the intestinal barrier and immune function and the intestinal microbiota on d 63 after calving. Proportions of PUFA in jejunal tissue increased in the CLA and EFA+CLA groups compared with control cows. Proportions of n-3 fatty acids were increased by EFA. The EFA+CLA cows showed higher jejunal n-3 proportions compared with the other groups. Proportions of n-6 fatty acids were reduced in the EFA and EFA+CLA group compared with the CON and CLA group. The relative jejunal gene expression of fatty acid binding protein 2 (FABP2) was increased in CLA cows compared with cows without CLA supplementation. Mucin 2 (MUC2) gene expression tended to be higher in the CLA group compared with the CON group. Essential fatty acids increased the jejunal interleukin 1 (IL1) and tended to increase tight junction protein 1 (ZO1) gene expression compared with cows without EFA supply. The EFA+CLA group increased the jejunal IL1 gene expression compared with CON cows. Protein expression of occludin tended to decrease in cows with CLA. Alpha diversity chaos richness estimator (Chao1) index was higher and abundance-based coverage estimator index tended to be higher in EFA cows compared with non-EFA cows. Chao1 and Fisher diversity index tended to be higher in the EFA group compared with the CON group. The relative abundance of Bacteroidota were reduced in EFA+CLA cows compared with CON animals. Proteobacteria, Bacteriaᵤnclassified and Planctomycetota abundance tended to be reduced in EFA compared with CON cows. Proteobacteria were more abundant in the EFA+CLA compared with the EFA group. On class level, EFA cows showed a higher abundance of WCHB1-41 compared with EFA+CLA cows. On family level, the relative abundance of WCHB1-41fa was higher in EFA cows compared with EFA+CLA cows. In summary, the abomasal fatty acid supplementation modulates the total intestinal fatty acid composition. There is evidence that CLA had slight effects on intestinal barrier function. A combination of EFA and CLA seemed to enable an increased colonization of microbes to the intestinal epithelium inducing a pro-inflammatory response.
Liermann et al. (Sun,) studied this question.