Effect of supplementation of fish and canola oil in the diet on milk Fatty Acid composition in early lactating holstein cows

Potential strategies to enhance conjugated linoleic acid content of milk and dairy products: A review

Conjugated linoleic acid (CLA) is a general term for all the geometric and positional isomers of linoleic acid. The cis-9, trans-11 CLA and trans-10 cis-12 CLA are considered to be the most abundant and essential isomers associated with health benefits. Though milk and dairy products are considered to be the major sources of CLA, the CLA content found in regular milk and dairy products is relatively low for effective health benefits in human beings. Thus, for effective health benefits, increasing the concentration of CLA in milk and dairy products is beneficial. Dietary supplementation with PUFA-rich lipid sources such as oilseeds and/or vegetable oils, fish meal, fish oil and microalgae and grass-based feeding can enhance the content of CLA in milk and dairy products. Application of CLA-producing bacterial strains during the fermentation process and ripening/storage are considered as potential strategies for enhancing the CLA content of fermented dairy products. Alternatively, the CLA content of milk and dairy products can be improved using genetic factor. In this paper, the latest scientific studies regarding CLA enrichment in milk and dairy products are reviewed, giving an overview of the effectiveness of the different CLA enrichment strategies and their combinations.

Dietary strategies to enrich milk with healthy fatty acids – a review

Feed is the main factor impacting the composition and quality of milk of dairy animals. Therefore, the present review explores the effects of feed and nutrition on milk fat content and levels of healthy fatty acids (FA) in milk consumed by humans. Milk and dairy products are two main sources of healthy and unhealthy FA in human nutrition. The concentrations of FA in milk depend mainly on diets; therefore, milk FA concentrations and ratios can be greatly altered by some feeding strategies. Dietary supplementation of the diets of dairy livestock with vegetable seeds or oils, microalgae and phytogenic feed additives, and feeding of some grasses can enhance the contents of healthy FA, including n-3 FA, α-linolenic acid, conjugated linoleic acid (CLA) and, generally, unsaturated FA in milk and dairy products. Enrichment of milk with healthy FA may make milk a source of anticarcenogens (CLA and polyphenols) for human health. This review, therefore, focusses on the current research findings on enrichment of milk with healthy FA and summarizes some effective supplementation strategies to alter milk FA profile.

Effects of Starch Level and a Mixture of Sunflower and Fish Oils on Nutrient Intake and Digestibility, Rumen Fermentation, and Ruminal Methane Emissions in Dairy Cows

Four multiparous dairy cows were used in a 4 × 4 Latin square to examine how starch level and oil mixture impact dry matter (DM) intake and digestibility, milk yield and composition, rumen fermentation, ruminal methane (CH4) emissions, and microbial diversity. Experimental treatments comprised high (HS) or low (LS) levels of starch containing 0 or 30 g of a mixture of sunflower and fish oils (2:1 w/w) per kg diet DM (LSO and HSO, respectively). Intake of DM did not differ between cows fed LS and HS diets while oil supplementation reduced DM intake. Dietary treatments did not affect milk and energy corrected milk yields. There was a tendency to have a lower milk fat concentration due to HSO compared with other treatments. Both high starch level and oil supplementation increased digestibility of gross energy. Cows receiving HS diets had higher levels of total rumen VFA while acetate was lower than LS without any differences in rumen pH, or ruminal CH4 emissions. Although dietary oil supplementation had no impact on rumen fermentation, decreased CH4 emissions (g/day and g/kg milk) were observed with a concomitant increase in Anoplodinium-Diplodinium sp. and Epidinium sp. but a decrease in Christensenellaceae, Ruminococcus sp., Methanobrevibacter ruminantium and Mbb. gottschalkii clades.

DHA content in milk and biohydrogenation pathway in rumen: a review

Docosahexaenoic acid (DHA) is an essential human nutrient that may promote neural health and development. DHA occurs naturally in milk in concentrations that are influenced by many factors, including the dietary intake of the cow and the rumen microbiome. We reviewed the literature of milk DHA content and the biohydrogenation pathway in rumen of dairy cows aim to enhance the DHA content. DHA in milk is mainly derived from two sources: α-linolenic acid (ALA) occurring in the liver and consumed as part of the diet, and overall dietary intake. Rumen biohydrogenation, the lymphatic system, and blood circulation influence the movement of dietary intake of DHA into the milk supply. Rumen biohydrogenation reduces DHA in ruminal environmental and limits DHA incorporation into milk. The fat-1 gene may increase DHA uptake into the body but this lacks experimental confirmation. Additional studies are needed to define the mechanisms by which different dietary sources of DHA are associated with variations of DHA in milk, the pathway of DHA biohydrogenation in the rumen, and the function of the fat-1 gene on DHA supply in dairy cows.

Effect of flaxseed (Linum usitatissimum) and soybean (Glycine max) oils in Egyptian lactating buffalo and cow diets on the milk and soft cheese quality

Produce and compare soft cheese with potential benefits of human health from Egyptian buffalo's and cow's milk was studied. Eight Egyptian lactating buffalos and cows were fed a total mixed ration supplemented with either 0% oil (CD), 2% flaxseed oil (DFO), 2% soybean oil (DSO), or 2% of their mixture (1:1, DFSO) according to a double 4 x 4 Latin Square design. Milk yield was similar between buffalo's diets but was higher in cows fed a DFO, DSO or DFSO resulting in 11.15, 8.21% or 8.97% increases compared with the control diet, respectively. Milk composition was not significantly affected in both buffalos and cows fed diets. The DFO, DSO or DFSO displayed decreased short-chain fatty acids, especially DSO and DFSO (3.73 and 3.33%, respectively) when compared to CD for buffalo milk (6.32%). The DSO and DFSO were  more effective for increasing unsaturated fatty acids followed by the DFSO in buffalo's milk fat (42.31 and 41.90 %), whereas DFO and DFSO were more effective in cow's milk fat (39.67 and 39.84%), respectively. DFO, DSO or DFSO had no significant effect on the yield, composition and sensory properties of resultant soft cheese compared to the CD for both lactating cows and buffalos. During storage, a diet rich in unsaturated fatty acids enhances protein proteolysis and antioxidant activity of soft cheese during storage compared to the CD especially for soft cheese produced from buffalo's milk.

Conditions Associated with Marine Lipid-Induced Milk Fat Depression in Sheep Cause Shifts in the In Vitro Ruminal Metabolism of 1-13C Oleic Acid

Shifts in ruminal oleic acid (OA) metabolism have received little research attention but recent studies have suggested their association with marine lipid-induced milk fat depression (MFD) in ewes and cows. Measurement of specific products of OA within the complex mixture of digesta lipids is however challenging. Therefore, this in vitro trial combined the isotopic labelling technique with the use of rumen inoculum from cannulated sheep fed a diet supplemented or not with 2% of fish oil (which has been demonstrated to cause MFD in dairy ruminants) to characterize the metabolism of OA in response to ruminal alterations associated with MFD. The products of 13C-OA after 24 h of incubation were analysed by gas chromatography-combustion isotope ratio mass spectrometry (GC-C-IRMS). Numerous 13C-labeled 18:1 intermediates and oxygenated FA were detected and no elongation or desaturation of 13OA occurred. Diet supplementation with fish oil (i.e., MFD conditions) resulted in no unique metabolites of 13OA but in relevant changes in the relative contribution of specific metabolic pathways. The inhibition of 18:0 saturation caused by this treatment appeared largely attributable to increased oxygenated FA proportion, in particular the candidate milk fat inhibitor 10-oxo-18:0, and warrants further research on the association between MFD and oxygenated FA. Changes in the concentration of 13C-labeled trans 18:1 intermediates but not in cis 18:1, were also observed.

Co-Expression Network Analysis Identifies miRNA⁻mRNA Networks Potentially Regulating Milk Traits and Blood Metabolites

MicroRNAs (miRNA) regulate mRNA networks to coordinate cellular functions. In this study, we constructed gene co-expression networks to detect miRNA modules (clusters of miRNAs with similar expression patterns) and miRNA–mRNA pairs associated with blood (triacylglyceride and nonesterified fatty acids) and milk (milk yield, fat, protein, and lactose) components and milk fatty acid traits following dietary supplementation of cows’ diets with 5% linseed oil (LSO) (n = 6 cows) or 5% safflower oil (SFO) (n = 6 cows) for 28 days. Using miRNA transcriptome data from mammary tissues of cows for co-expression network analysis, we identified three consensus modules: blue, brown, and turquoise, composed of 70, 34, and 86 miRNA members, respectively. The hub miRNAs (miRNAs with the most connections with other miRNAs) were miR-30d, miR-484 and miR-16b for blue, brown, and turquoise modules, respectively. Cell cycle arrest, and p53 signaling and transforming growth factor–beta (TGF-β) signaling pathways were the common gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways enriched for target genes of the three modules. Protein percent (p = 0.03) correlated with the turquoise module in LSO treatment while protein yield (p = 0.003) and milk yield (p = 7 × 10⁻⁰⁴) correlated with the turquoise model, protein and milk yields and lactose percent (p < 0.05) correlated with the blue module and fat percent (p = 0.04) correlated with the brown module in SFO treatment. Several fatty acids correlated (p < 0.05) with the blue (CLA:9,11) and brown (C4:0, C12:0, C22:0, C18:1n9c and CLA:10,12) modules in LSO treatment and with the turquoise (C14:0, C18:3n3 and CLA:9,11), blue (C14:0 and C23:0) and brown (C6:0, C16:0, C22:0, C22:6n3 and CLA:10,12) modules in SFO treatment. Correlation of miRNA and mRNA data from the same animals identified the following miRNA–mRNA pairs: miR-183/RHBDD2 (p = 0.003), miR-484/EIF1AD (p = 0.011) and miR-130a/SBSPON (p = 0.004) with lowest p-values for the blue, brown, and turquoise modules, respectively. Milk yield, protein yield, and protein percentage correlated (p < 0.05) with 28, 31 and 5 miRNA–mRNA pairs, respectively. Our results suggest that, the blue, brown, and turquoise modules miRNAs, hub miRNAs, miRNA–mRNA networks, cell cycle arrest GO term, p53 signaling and TGF-β signaling pathways have considerable influence on milk and blood phenotypes following dietary supplementation of dairy cows’ diets with 5% LSO or 5% SFO.

Effects of common dietary fatty acids on milk yield and concentrations of fat and fatty acids in dairy cattle

The objective of the present article was to summarise the effects of five common dietary fatty acids (C16:0, C18:0, C18:1, C18:2 and C18:3) on the major milk fat groups (<C16, C16 and C18). Forty published papers were reviewed to evaluate the effect of adding free fat or oil supplements rich in C16 and C18 fatty acids on the response of milk fat secretion and composition. From those 40 studies, 21 were used to investigate the effect of total dietary concentration of C16:0, C18:0, C18:1, C18:2 and C18:3 on milk secretion or concentrations of milk <C16, C16 and C18 fatty acid groups. The results indicated that C16 supplementation increased total milk fatty acids, mainly by increasing milk C16 yield, without affecting milk <C16 and C18 yield. Supplements rich in unsaturated fatty acid decreased total milk fatty acid by inhibiting secretion of milk fatty acids shorter than C18, with linoleic acid being the most inhibitory. Mixtures of feed fatty acid (C16:0 + C18:0 and C16:0 + C18:1) did not significantly affect total milk fatty acid yield. According to regression of milk C16 yield on dietary fatty acid, endogenous C16 contributes ~80% of total milk C16, but this proportion varies with the level and type of dietary fatty acid fed. Milk mid-infrared analysis can be used to routinely measure the presence of milk <C16 fatty acid, the concentration of which provides a good indicator of inhibition of milk fatty acid secretion. In contrast, measurement of total milk fat content is less effective as a diagnostic tool due to the masking effect of the exogenous supply of C16 and C18 dietary fatty acids.

Milk Yield, Composition, and Fatty Acid Profile in Dairy Cows Fed a High-concentrate Diet Blended with Oil Mixtures Rich in Polyunsaturated Fatty Acids

To evaluate the effects of feeding linseed oil or/and sunflower oil mixed with fish oil on milk yield, milk composition and fatty acid (FA) profiles of dairy cows fed a high-concentrate diet, 24 crossbred primiparous lactating dairy cows in early lactation were assigned to a completely randomized design experiment. All cows were fed a high-concentrate basal diet and 0.38 kg dry matter (DM) molasses per day. Treatments were composed of a basal diet without oil supplement (Control), or diets of (DM basis) 3% linseed and fish oils (1:1, w/w, LSO-FO), or 3% sunflower and fish oils (1:1, w/w, SFO-FO), or 3% mixture (1:1:1, w/w) of linseed, sunflower, and fish oils (MIX-O). The animals fed SFO-FO had a 13.12% decrease in total dry matter intake compared with the control diet (p<0.05). No significant change was detected for milk yield; however, the animals fed the diet supplemented with SFO-FO showed a depressed milk fat yield and concentration by 35.42% and 27.20%, respectively, compared to those fed the control diet (p<0.05). Milk c9, t11-conjugated linoleic acid (CLA) proportion increased by 198.11% in the LSO-FO group relative to the control group (p<0.01). Milk C18:3n-3 (ALA) proportion was enhanced by 227.27% supplementing with LSO-FO relative to the control group (p<0.01). The proportions of milk docosahexaenoic acid (DHA) were significantly increased (p<0.01) in the cows fed LSO-FO (0.38%) and MIX-O (0.23%) compared to the control group (0.01%). Dietary inclusion of LSO-FO mainly increased milk c9, t11-CLA, ALA, DHA, and n-3 polyunsaturated fatty acids (PUFA), whereas feeding MIX-O improved preformed FA and unsaturated fatty acids (UFA). While the lowest n-6/n-3 ratio was found in the LSO-FO, the decreased atherogenecity index (AI) and thrombogenicity index (TI) seemed to be more extent in the MIX-O. Therefore, to maximize milk c9, t11-CLA, ALA, DHA, and n-3 PUFA and to minimize milk n-6/n-3 ratio, AI and TI, an ideal supplement would appear to be either LSO-FO or MIX-O.