Advances in fatty acids nutrition in dairy cows: from gut to cells and effects on performance

Abstract

High producing dairy cows generally receive in the diet up to 5-6% of fat. This is a relatively low amount of fat in the diet compared to diets in monogastrics; however, dietary fat is important for dairy cows as demonstrated by the benefits of supplementing cows with various fatty acids (FA). Several FA are highly bioactive, especially by affecting the transcriptome; thus, they have nutrigenomic effects. In the present review, we provide an up-to-date understanding of the utilization of FA by dairy cows including the main processes affecting FA in the rumen, molecular aspects of the absorption of FA by the gut, synthesis, secretion, and utilization of chylomicrons; uptake and metabolism of FA by peripheral tissues, with a main emphasis on the liver, and main transcription factors regulated by FA. Most of the advances in FA utilization by rumen microorganisms and intestinal absorption of FA in dairy cows were made before the end of the last century with little information generated afterwards. However, large advances on the molecular aspects of intestinal absorption and cellular uptake of FA were made on monogastric species in the last 20 years. We provide a model of FA utilization in dairy cows by using information generated in monogastrics and enriching it with data produced in dairy cows. We also reviewed the latest studies on the effects of dietary FA on milk yield, milk fatty acid composition, reproduction, and health in dairy cows. The reviewed data revealed a complex picture with the FA being active in each step of the way, starting from influencing rumen microbiota, regulating intestinal absorption, and affecting cellular uptake and utilization by peripheral tissues, making prediction on in vivo nutrigenomic effects of FA challenging.

Keywords: Absorption; Dairy cow; Dietary fatty acids; Intestine; Liver; Metabolism; Performance; Transcription factors; Transport.

Fig. 1

Transcript abundance of various gene isoforms involved in fatty acid absorption in jejunum, liver, and mammary tissue from Chinese Holstein lactating cows [54]. Data were downloaded from Gene Expression Omnibus, dataset GSE78524. Data are mean ± SD of reads per kilo base per million mapped reads (RPKM) of all 18 cows

Fig. 2

Model summarizing in dairy cows the absorption of fatty acids by enterocytes and their utilization by peripheral tissues (especially liver) with indicated enzymes and other proteins/complexes involved. As discussed in detail in the review, the model is mostly based on data obtain from monogastric species together with available data in ruminants, including the transcription abundance of the various genes presented in Fig. 1. Abbreviations: Alb, albumin; CM, chylomicron; CM-R, chylomicron remnants; DAG, diacylglycerol; ER, endoplasmic reticulum; FA, fatty acids; FFA, free fatty acids; KB, ketone bodies; LCFA, long chain fatty acids; LD, lipid droplets; LP, lipoprotein(s); LPL, lipoprotein lipase; MCFA, medium chain fatty acids; NEFA, non-esterified fatty acids; TAG, triacylglycerol; TAG-rich LP, TAG-rich lipoproteins; VFA, volatile fatty acids; VLDL, very low density lipoproteins