Effects of pasture versus confinement and marine oil supplementation on the expression of genes involved in lipid metabolism in mammary, liver, and adipose tissues of lactating dairy cows

Abstract

Research was conducted to evaluate the effects of management system (MS), marine lipid supplementation (LS), and their interaction on the relative mRNA abundance of 11 genes involved in lipid synthesis in mammary, liver, and subcutaneous adipose tissues in lactating dairy cows. These genes included those involved in FA uptake (LPL), de novo FA synthesis (ACACA, FASN), FA desaturation (SCD1, FADS1, FADS2), and transcriptional regulation of lipogenesis (SREBF1, SCAP, INSIG1, THRSP, and PPARG). Forty-eight peripartal Holstein cows were blocked by parity and predicted calving date and assigned to either a pasture (n=23) or confinement (n=25) system. Within each system, cows were allocated randomly (7-9 cows per treatment) to a control (no oil supplement) or 1 of 2 isolipidic (200 g/d) supplements, fish oil (FO) or microalgae (MA), for 125 ± 5 d starting 30 d precalving. The experiment was conducted as a split-plot design, with MS being the whole plot treatment and LS as the subplot treatment. At 100 ± 2 DIM, 4 cows from each treatment combination (24 cows in total) were euthanized and tissue samples were collected for gene expression analysis. No interactions between MS and LS were observed regarding any of the variables measured in this study. Milk production (34.0 vs. 40.1 kg/d), milk fat (1.10 vs. 1.41 kg/d), protein (0.95 vs. 1.22 kg/d), and lactose (1.56 vs. 1.86 kg/d) were lower for pasture compared with confinement. The effect of LS on milk production and milk composition (yields and contents) was significant only for milk fat content that was reduced with MA compared with FO (3.00 vs. 3.40%) and the control (3.56%). The mammary mRNA abundance of PPARG (-32%) and FASN (-29%) was lower in grazing compared with confined cows, which was accompanied by reduced (-43%) secretion of de novo synthesized fatty acids in milk. Grazing was associated with reduced expression of ACACA (-48%), FASN (-48%), and THRSP (-53%) in subcutaneous adipose tissues, which was consistent with the lower body condition score (i.e., lower net adipose tissue deposition) in grazing compared with confined cows. Feeding either FO or MA downregulated hepatic expression of FASN, SCD1, FADS2, and THRSP. The reduced secretion of de novo synthesized fatty acids in milk of grazing cows compared with confined cows might be related in part to the downregulation of genes involved in lipid synthesis, and that LS have tissue-specific effects on expression of genes involved in lipid metabolism, with liver being the most responsive tissue.

Milk Fat Globule in Ruminant: Major and Minor Compounds, Nutritional Regulation and Differences Among Species

“…Similarly, in cows, the use of marine products alone or in combination with plant lipids induces a dramatic decrease in milk fat yield (up to −50%) associated with a lower expression of the genes involved in de novo synthesis, and/or long chain FA uptake, TAG synthesis and transcription factor SREBP1. Conversely, in a study using rumen‐protected FO or microalgae in cows, effects were neither observed on milk fat yield or in lipogenic gene expression, except for a decrease of SREBF1 expression (−15%). This absence of effect on milk fat yield is probably due to the protection treatment of oil that avoids any disturbances of ruminal metabolism and suggests that long‐chain PUFA had no effect on mammary gene expression.…”

“…Milk and fat yields in grazing cows are lower compared to those of indoors cows, suggesting a lower DMI at pasture . In contrast, grazing cows have higher milk yield than that of zero‐grazing cows due to the grass selection of the leafy and digestible parts of grass …”

Milk saturated fatty acids, odd- and branched-chain fatty acids, and isomers of C18:1, C18:2, and C18:3n-3 according to their duodenal flows in dairy cows: A meta-analysis approach

“…These interactions have not been addressed directly here, with 2 exceptions. First, we provided a specific set of equations to predict milk FA profile for cows fed marine products, assuming that long-chain PUFA may affect the mammary lipogenesis (Angulo et al, 2012), mammary Δ 9 -desaturase activity (Kairenius et al, 2015) and possibly the transfer of preformed FA into the mammary gland (Vahmani et al, 2014). Second, the reduction of de novo mammary lipogenesis by duodenal total C18 FA flows or concentrations (Shingfield et al, 2010) has been partly taken into account by indexing the prediction of milk C4:0 to C14:0 on the availability of their ruminal precursors but also on the duodenal flow of total C18 FA (see below).…”

Effects of Dietary Vegetable Oils on Mammary Lipid-Related Genes in Holstein Dairy Cows

“…Angulo et al [4] studied effects of polyunsaturated FA from plant oils (sunflower and linseed oils) and algae on mammary gene abundance and reported that milk fat profile was associated with down-regulation of both mammary lipogenic enzyme gene abundance (SCD1 and FASN) and abundance of the regulatory element binding transcription factor (SREBF1; involved in the transcriptional regulation of lipogenesis). Vahmani et al [5] studied the effects of pasture versus housing and marine oil supplementation on abundance of genes involved in lipid metabolism in mammary tissue of lactating cows and found that mammary mRNA abundance of PPARG and FASN were lower in grazing compared with cows in confinement. That was accompanied by reduced secretion of de novo synthesized FA in milk.…”