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To investigate the metabolic changes in the adipose tissue (AT) of dairy cows under milk fat depression (MFD), 30 cows were randomly allocated to a control diet, a conjugated linoleic acid (CLA)-supplemented diet, or a high-starch diet supplemented with a mixture of sunflower and fish oil (2:1; as HSO diet) from 1 to 112 d in milk. Performance of animals, milk yield, milk composition, energy balance, and blood metabolites were measured during lactation. Quantitative PCR analyses were conducted on the AT samples collected at wk 3 and 15 of lactation. The CLA and HSO diets considerably depressed milk fat yield and milk fat content at both wk 3 and 15 in the absence of significant changes in milk protein and lactose contents. In addition, the HSO diet lowered milk yield at wk 15 and decreased dry matter intake of cows from wk 3 to 15. Compared with the control, both CLA and HSO groups showed reduced body weight loss, improved energy balance, and decreased plasma concentrations of nonesterified fatty acids and β-hydroxybutyrate at early lactation. The gene expression analyses reflected suppressed lipolysis in AT of the CLA and HSO groups compared with the control at wk 3, as suggested by the downregulation of hormone-sensitive lipase and fatty acid binding protein 4 and the upregulation of perilipin 2. In addition, the HSO diet promoted lipogenesis in AT at wk 15 through the upregulation of 1-acylglycerol-3-phosphate O-acyltransferase 2, mitochondrial glycerol-3-phosphate acyltransferase, perilipin 2, and peroxisome proliferator-activated receptor γ. The CLA diet likely regulated insulin sensitivity in AT as it upregulated the transcription of various genes involved in insulin signaling, inflammatory responses, and ceramide metabolism, including protein kinase B2, nuclear factor κ B1, toll-like receptor 4, caveolin 1, serine palmitoyltransferase long chain base subunit 1, and N-acylsphingosine amidohydrolase 1. In contrast, the HSO diet resulted in little or no change in the pathways relevant to insulin sensitivity. In conclusion, the CLA and HSO diets induced a shift in energy partitioning toward AT instead of mammary gland during lactation through the regulation of different pathways.

The liver of dairy cow naturally undergoes metabolic adaptation during the periparturient period in response to the increasing demand for nutrients. The hepatic adaptation is affected by prepartal energy intake level and is potentially associated with inflammatory responses. To study the changes in the liver function during the periparturient period, 16 cows (body condition score = 3.7 ± 0.3, mean ± standard deviation; parity = second through fourth) were allocated to a grass silage-based controlled-energy diet (104 MJ/d) or a high-energy diet (135 MJ/d) during the last 6 wk before the predicted parturition. Liver samples were collected by biopsy at 8 d before the predicted parturition (-8 d) and at 1 and 9 d after the actual parturition (1 and 9 d). The lipidomic profile of liver samples collected at -8 and 9 d was analyzed using ultra performance liquid chromatography-mass spectrometry-based lipidomics. Liver samples from all the time points were subjected to microarray analysis and the subsequent pathway analysis with Ingenuity Pathway Analysis software (Ingenuity Systems, Mountain View, CA). Prepartal energy intake level affected hepatic gene expression and lipidomic profiles prepartum, whereas little or no effect was observed postpartum. At -8 d, hepatic lipogenesis was promoted by prepartal high-energy feeding through the activation of X receptor/retinoid X receptor pathway and through increased transcription of thyroid hormone-responsive (THRSP). Hepatic inflammatory and acute phase responses at -8 d were suppressed (z-score = -2.236) by prepartal high-energy feeding through the increase in the mRNA abundance of suppressor of cytokine signaling 3 (SOCS3) and the decrease in the mRNA abundance of interleukin 1 (IL1), nuclear factor kappa B 1 (NFKB1), apolipoprotein A1 (APOA1), serum amyloid A3 (SAA3), haptoglobin (HP), lipopolysaccharide-binding protein (LBP), and inter-α-trypsin inhibitor heavy chain 3 (ITIH3). Moreover, prepartal high-energy feeding elevated hepatic concentrations of C18- (7%), C20- (17%), C21- (26%), C23-sphingomyelins (26%), and total saturated sphingomyelin (21%). In addition, cows in both groups displayed increased lipogenesis at the gene expression level after parturition and alterations in the concentration of various sphingolipids between the first and last samplings. In conclusion, prepartal high-energy feeding promoted lipogenesis and suppressed inflammatory and acute phase responses in the liver before parturition, whereas only minor effects were observed after parturition.

Thirty conventional and twenty-four organic dairy farms were divided into equal numbers within system groups: high-pasture, standard-pasture, and low-pasture groups. Milk samples were collected monthly for 12 consecutive months. Milk from high-pasture organic farms contained less fat and protein than standard- and low-pasture organic farms, but more lactose than low-pasture organic farms. Grazing, concentrate feed intake and the contribution of non-Holstein breeds were the key drivers for these changes. Milk Ca and P concentrations were lower in standard-pasture conventional farms than the other conventional groups. Milk from low-pasture organic farms contained less Ca than high- and standard-pasture organic farms, while high-pasture organic farms produced milk with the highest Sn concentration. Differences in mineral concentrations were driven by the contribution of non-Holstein breeds, feeding practices, and grazing activity; but due to their relatively low numerical differences between groups, the subsequent impact on consumers’ dietary mineral intakes would be minor.