Milk Trans Fatty Acid Research Articles

Overview of SNPs Associated with Trans Fat Content in Cow’s Milk

Lipids consumed with milk derivatives are one of the main parts of the human diet. Trans fatty acids in milk are causing a debate about their impact on the incidence of cardiovascular disease, pathological abnormalities, and cancer. The fatty acid profile of milk is influenced by a large number of different factors, one of which is genetic. The development of genetic studies, including Genome-Wide Association Studies (GWAS), may help define genomic regions associated with fatty acid content in milk, including trans fatty acids. This article provides an overview of international studies on the identification of genomic regions and SNPs associated with the trans fatty acids in cow’s milk. The results are based on research of cattle such as Norwegian Red cattle, Holstein, Jersey, and Brown Swiss. The presented review shows that 68 SNPs were localized on chromosomes 1, 2, 4–6, 8–10, 12, 14–20, 22–25, and 27–29. Further research in this direction will provide new information that will serve as an impetus for the creation of modern breeding technologies and increase the performance of the manufacture of high-quality dairy products. The search for genetic markers associated with the content of TFA in milk is a promising direction in agricultural science and will allow more complete breeding work with cattle.

Inclusion of brown midrib dwarf pearl millet silage in the diet of lactating dairy cows

Brown midrib brachytic dwarf pearl millet (Pennisetum glaucum) forage harvested at the flag leaf visible stage and subsequently ensiled was investigated as a partial replacement of corn silage in the diet of high-producing dairy cows. Seventeen lactating Holstein cows were fed 2 diets in a crossover design experiment with 2 periods of 28 d each. Both diets had forage:concentrate ratios of 60:40. The control diet (CSD) was based on corn silage and alfalfa haylage, and in the treatment diet, 20% of the corn silage dry matter (corresponding to 10% of the dietary dry matter) was replaced with pearl millet silage (PMD). The effects of partial substitution of corn silage with pearl millet silage on dry matter intake, milk yield, milk components, fatty acid profile, apparent total-tract digestibility of nutrients, N utilization, and enteric methane emissions were analyzed. The pearl millet silage was higher in crude protein and neutral detergent fiber and lower in lignin and starch than the corn silage. Diet did not affect dry matter intake or energy-corrected milk yield, which averaged 46.7 ± 1.92 kg/d. The PMD treatment tended to increase milk fat concentration, had no effect on milk fat yield, and increased milk urea N. Concentrations and yields of milk protein and lactose were not affected by diet. Apparent total-tract digestibility of dry matter decreased from 66.5% in CSD to 64.5% in PMD. Similarly, organic matter and crude protein digestibility was decreased by PMD, whereas neutral- and acid-detergent fiber digestibility was increased. Total milk trans fatty acid concentration was decreased by PMD, with a particular decrease in trans-10 18:1. Urinary urea and fecal N excretion increased with PMD compared with CSD. Milk N efficiency decreased with PMD. Carbon dioxide emission was not different between the diets, but PMD increased enteric methane emission from 396 to 454 g/d and increased methane yield and intensity. Substituting corn silage with brown midrib dwarf pearl millet silage at 10% of the diet dry matter supported high milk production in dairy cows. When planning on farm forage production strategies, brown midrib dwarf pearl millet should be considered as a viable fiber source.

Milk fat response to calcium salts of palm or soybean in a normal or milk fat depression scenario in dairy ewes

Abstract A limited number of studies in lactating sheep have compared milk fat responses to calcium salts (Ca-salts) differing in fatty acid (FA) composition and their interactions with different dietary conditions. The objective of this study was to evaluate the effects of Ca-salts of palm or soybean FA on milk fat under Normal and CLA-induced milk fat depression (MFD) scenarios in lactating dairy ewes. Thirty-eight Lacaune and thirty-seven East Friesian multiparous ewes were used in a 2 × 2 factorial design. The main factor consisted of two diets designed to create two distinct scenarios: Normal and CLA-induced MFD (CLA-MFD, 30 g/d of CLA 29.9% trans−10, cis−12 CLA as methyl ester). The subfactor was supplementation of Normal or CLA-MFD scenarios with 27 g/d of Ca-salts of palm FA, or 30 g/d of Ca-salts of soybean FA, resulting in four treatments: 1) Normal + Ca-Palm, 2) Normal + Ca-Soy, 3) CLA-MFD + Ca-Palm, and 4) CLA-MFD + Ca-Soy. Overall, the CLA-MFD scenario decreased milk fat concentration by 1.64% units and decreased milk fat yield by 17.3 g/d. Ewes that received Ca-Palm had overall 0.29% units higher milk fat concentration, and 13.4% greater milk fat concentration when fed the CLA-MFD diet. Ca-Soy increased trans−10 C18:1 (131.0%), trans-11 C18:1 (30.4%), and cis-9, trans-11 CLA (21.1%) in the CLA-MFD diet. In conclusion, supplementation with Ca-Palm resulted in overall greater milk fat concentration. In a MFD scenario, supplementation with Ca-Soy increased concentration of milk trans FA linked to altered rumen biohydrogenation and further aggravated MFD.

Short communication: Effects of lysolecithin on milk fat synthesis and milk fatty acid profile of cows fed diets differing in fiber and unsaturated fatty acid concentration

Thirteen multiparous Holstein cows were used in a crossover design that tested the effect of lysolecithin in diets differing in neutral detergent fiber (NDF) and unsaturated fatty acid (FA) concentrations. Experimental periods were 20 d in length and included two 10-d phases. A standard fiber and lower fat diet was fed the first 10 d (30.5% NDF, no added oil, lower-risk phase) and a lower NDF and higher oil diet was fed during the second 10 d (29.0% NDF and 2% oil from whole soybeans and soybean oil, high-risk phase). Treatments were control and 10 g/d of lysolecithin (LYSO) extended in a ground corn carrier. Milk was sampled on d 0, 5, and 10 of each phase for determination of fat and protein concentration and FA profile. We found no effect of treatment or treatment by time interaction for dry matter intake, milk yield, or milk protein concentration. A treatment by time interaction was observed for milk fat concentration and yield. Milk fat concentration was higher in LYSO on d 5 of the lower-risk phase, but decreased progressively in both treatments during the high-risk phase. Milk fat yield was not different among treatments during the lower-risk phase, but was lower in LYSO on d 15 and tended to be lower on d 20 during the high-risk phase. Concentrations of milk de novo FA decreased and preformed FA increased during the high-risk phase, but we found no effect of treatment or treatment by time interactions. We noted an effect of time, but no treatment or treatment by time interactions for milk trans FA isomers. Briefly, trans-11 C18:1 and cis-9,trans-11 conjugated linoleic acid progressively decreased as trans-10 C18:1 and trans-10,cis-12 conjugated linoleic acid progressively increased during the high-risk phase. The LYSO increased milk fat concentration when feeding a higher fiber and lower unsaturated FA diet, but decreased milk fat yield when feeding a lower fiber and higher unsaturated FA diet, although biohydrogenation pathways and capacity did not appear to be modified. The effect of lysolecithin on rumen fermentation warrants further investigation, but is not recommended when feeding lower fiber and higher unsaturated fat diets.

Short communication: Effect of a citrus extract in lactating dairy cows

Dry matter intake is a main driver of energy balance in lactating dairy cows, and some plant extracts have been commercially fed to dairy cows to stimulate feed intake. Citrus extracts contain several bioactive components and have been shown to modify metabolism in other animal models. Our hypothesis was that a citrus extract would increase dry matter intake. Two experiments were conducted to determine the effect of a citrus extract on intake and milk production in lactating dairy cows. In experiment one, 11 early-lactation dairy cows (experiment 1; 77 ± 15 d in milk, mean ± standard deviation) were used in a switchback design, and in experiment two, 15 mid-lactation Holstein cows (experiment 2; 157 ± 44 d in milk, mean ± standard deviation) were used in a crossover design. In both experiments, treatments were control (no supplement) or a citrus extract (4 g/d in experiment 1 and 4.5 g/d in experiment 2). Treatment periods were 21 and 14 d in experiment 1 and experiment 2, respectively, with the final 7 d used for sample and data collection. No effect was observed for treatment on dry matter intake, feeding behavior, milk yield, milk fat yield, milk protein yield, or milk composition in either experiment. Treatment also had no effect on milk trans fatty acid profile, but the extract increased total 16 carbon fatty acids 0.9 and 0.6 percentage points in experiment 1 and experiment 2, respectively. Plasma nonesterified fatty acids were decreased 6 h after feeding in both experiments (11.1 and 16.0 μEq/L in experiment 1 and experiment 2, respectively). Plasma insulin was increased 1 h before feeding compared with the control in experiment 1 (3.36 vs. 2.13 µIU/mL) and tended to increase 1.79 units 1 h before feeding in experiment 2. The citrus extract had no effect on feed intake or milk production at the dose investigated, but changed plasma insulin and nonesterified fatty acids, indicating some metabolic effects requiring further investigation.

Manipulation of milk fatty acid composition in lactating cows: Opportunities and challenges

Public health policies recommend a population wide decrease in the consumption of saturated fatty acids (SFA) to lower the incidence of cardiovascular and metabolic diseases. In most developed countries, milk and dairy products are the major source of SFA in the human diet. Altering milk fat composition offers the opportunity to lower the consumption of SFA without requiring a change in eating habits. Supplementing the diet of lactating cows with oilseeds, plant oils and marine lipids can be used to replace the SFA in milk fat with monounsaturated fatty acids (MUFA), and to a lesser extent, polyunsaturated fatty acids (PUFA). Due to ruminal metabolism, the decreases in milk SFA are also accompanied by increases in trans fatty acids (TFA), including conjugated isomers. The potential to lower SFA, enrich cis MUFA and PUFA, and alter the abundance and distribution of individual TFA in milk differs according to oil source, form of lipid supplement and degree of oilseed processing, and the influence of other components in the diet. The present review summarises recent evidence on changes in milk fat composition that can be achieved using dietary lipid supplements and highlights the challenges to commercial production of modified milk and dairy products. A meta‐analysis on the effects of oilseeds on milk fatty acid composition is also presented.Practical applications: Milk and dairy products are the major source of SFA in the diet in most developed countries. Including oilseeds, plant oils, and to a lesser extent, marine lipids in the diet of lactating cows can replace SFA with MUFA and PUFA in milk offering a mechanism to lower SFA consumption in human populations. Understanding the sources of variation in milk fat composition responses, and adjusting other ingredients in the diet to accommodate lipid supplements offers the opportunity to consistently produce milk with an altered fatty acid composition. However, commercialisation of dedicated supply chains will depend on whether the added costs of production and segregation of modified milk for processing can be recovered at retail.Dairy products are the major source of saturated fatty acids in diets of developed countries. There are various dietary strategies that can be employed at the dairy cow level to alter milk fat fatty acid composition, but it is important to understand variations in cow response to these interventions to consistently produce milk with altered fatty acid composition.

Effects of incremental amounts of extruded linseed on the milk fatty acid composition of dairy cows receiving hay or corn silage

The effect of supplementation of increasing amounts of extruded linseed in diets based on hay (H; experiment 1) or corn silage (CS; experiment 2) was investigated in regard to dairy performance and the milk fatty acid (FA) composition. In each experiment, 4 lactating multiparous Holstein cows were used in a 4×4 Latin square design (28-d periods). The cows were fed a diet (50:50 and 40:60 concentrate:forage ratio for experiments 1 and 2, respectively; dry matter basis) without supplementation (H0 or CS0) or supplemented with 5% (H5 or CS5), 10% (H10 or CS10), or 15% (H15 or CS15) of extruded linseed. Regardless of the forage type, diet supplementation with increasing amounts of extruded linseed had no effect on the dry matter intake, milk yield, or protein content or yield. In contrast, the milk fat content decreased progressively from H0 to H10 diets, and then decreased strongly with the H15 diet in response to increasing amounts of extruded linseed. For CS diets, the milk fat content initially decreased from CS0 to CS10, but then increased with the CS15 diet. For the H diets, the milk saturated FA decreased (−24.1g/100g of FA) linearly with increasing amounts of extruded linseed, whereas the milk monounsaturated FA (+19.0g/100g), polyunsaturated FA (+4.9g/100g), and total trans FA (+14.7g/100g) increased linearly. For the CS diets, the extent of the changes in the milk FA composition was generally lower than for the H diets. Milk 12:0 to 16:0 decreased in a similar manner in the 2 experiments with increasing amounts of extruded linseed intake, whereas 18:0 and cis-9 18:1 increased. The response of total trans 18:1 was slightly higher for the CS than H diets. The milk trans-10 18:1 content increased more with the CS than the H diets. The milk cis-9,trans-11 conjugated linoleic acid response to increasing amounts of extruded linseed intake was linear and curvilinear for the H diets, whereas it was only linear for the CS diets. The milk 18:3n-3 percentage increased in a similar logarithmic manner in the 2 experiments. It was concluded that the milk FA composition can be altered by extruded linseed supplementation with increasing concentrations of potentially health-beneficial FA (i.e., oleic acid, 18:3n-3, cis-9,trans-11 conjugated linoleic acid, and odd- and branched-chain FA) and decreasing concentrations of saturated FA. Extruded linseed supplementation increased the milk trans FA percentage.

Incremental effect of a calcium salt of cis-monounsaturated fatty acids supplement on milk fatty acid composition in cows fed maize silage-based diets

In most Western countries, saturated fatty acid (SFA) intake exceeds recommended levels, which is considered a risk factor for cardiovascular disease (CVD). As milk and dairy products are major contributors to SFA intake in many countries, recent research has focused on sustainable methods of producing milk with a lower saturated fat concentration by altering dairy cow diets. Human intervention studies have shown that CVD risk can be reduced by consuming dairy products with reduced SFA and increased cis-monounsaturated fatty acid (MUFA) concentrations. This milk fatty acid profile can be achieved by supplementing dairy cow diets with cis-MUFA-rich unsaturated oils. However, rumen exposure of unsaturated oils also leads to enhanced milk trans fatty acid (TFA) concentrations. Because of concerns about the effects of TFA consumption on CVD, feeding strategies that increase MUFA concentrations in milk without concomitant increases in TFA concentration are preferred by milk processors. In an attempt to limit TFA production and increase the replacement of SFA by cis-MUFA, a preparation of rumen-protected unsaturated oils was developed using saponification with calcium salts. Four multiparous Holstein-Friesian cows in mid-late lactation were used in a 4×4 Latin square design with 21-d periods to investigate the effect of incremental dietary inclusion of a calcium salt of cis-MUFA product (Ca-MUFA; 20, 40, and 60g/kg of dry matter of a maize silage-based diet), on milk production, composition, and fatty acid concentration. Increasing Ca-MUFA inclusion reduced dry matter intake linearly, but no change was observed in estimated ME intake. No change in milk yield was noted, but milk fat and protein concentrations were linearly reduced. Supplementation with Ca-MUFA resulted in a linear reduction in total SFA (from 71 to 52g/100g of fatty acids for control and 60g/kg of dry matter diets, respectively). In addition, concentrations of both cis- and trans-MUFA were increased with Ca-MUFA inclusion, and increases in other biohydrogenation intermediates in milk fat were also observed. The Ca-MUFA supplement was very effective at reducing milk SFA concentration and increasing cis-MUFA concentrations without incurring any negative effects on milk and milk component yields. However, reduced milk fat and protein concentrations, together with increases in milk TFA concentrations, suggest partial dissociation of the calcium salts in the rumen.

Rapeseed or linseed supplements in grass-based diets: Effects on milk fatty acid composition of Holstein cows over two consecutive lactations

Persistency of changes in milk fatty acid (FA) composition to 4 different oilseed supplements rich in cis-9 18:1 or 18:3n-3 was determined over 2 consecutive lactations in 58 and 35 Holstein cows during the first and second years, respectively. During the initial 5wk of the study, all experimental cows were fed the same diet. Thereafter, cows received 1 of 5 treatments for 2 consecutive lactations, including the prepartum period. Treatments comprised the basal diet with no additional lipid, or supplements of extruded linseeds (EL), extruded rapeseeds (ER), cold-pressed fat-rich rapeseed meal (FRM), or whole unprocessed rapeseeds (WR). Oilseeds were offered to provide between 2.5 to 3.0% of additional oil in diet dry matter. During indoor periods, cows received a mixture (3:1, wt/wt) of grass silage and grass hay, whereas cows were at pasture during outdoor periods. Over the entire study, oilseed supplements decreased the concentration of milk FA synthesized de novo and increased 18:0 and cis-9 18:1 content, with a ranking of treatment responses (highest to lowest) of FRM, EL, ER, and WR. Irrespective of period, both EL and FRM increased total milk trans FA content, whereas WR resulted in lower concentrations in milk from grazing cows. Relative to rapeseed, EL resulted in higher increases in milk cis-12,cis-15,trans-12 to -16 18:1, nonconjugated trans 18:2 (especially ∆11,15), and 18:3n-3. In contrast, rapeseed supplements resulted in a greater enrichment of cis-11 18:1, trans-4 to -9 18:1, and cis 20:1 than EL. Changes in milk FA composition to oilseeds were of greater magnitude during indoor than outdoor periods, where oilseed supplements often decreased cis-9,trans-11 conjugated linoleic acid content. During the second indoor period, both EL and ER resulted in higher total trans FA content, trans-10 18:1 in particular, than during the first indoor period, consistent with an interaction between dietary starch content and oilseed supplement. Overall, the extent of changes in milk FA composition were related to the nature (rapeseed or linseed) and form of oilseed (extruded, cold-pressed fat-rich meal or whole unprocessed), and their interactions with the composition of the basal diet (grass silage and hay or pasture; or dietary starch content). Milk FA responses were stable within each period and repeatable over both outdoor feeding periods, with extent of changes being comparable to reports from relatively short-term (1- to 3-mo) studies.

Effects of dietary protein concentration and coconut oil supplementation on nitrogen utilization and production in dairy cows

The objective of this study was to investigate the effect of metabolizable protein (MP) deficiency and coconut oil supplementation on N utilization and production in lactating dairy cows. The hypothesis of the study was that a decrease in ruminal protozoal counts with coconut oil would increase microbial protein synthesis in the rumen, thus compensating for potential MP deficiency. The experiment was conducted for 10 wk with 36 cows (13 primiparous and 23 multiparous), including 6 ruminally cannulated cows. The experimental period, 6 wk, was preceded by 2-wk adaptation and 2-wk covariate periods. Cows were blocked by parity, days in milk, milk yield, and rumen cannulation and randomly assigned to one of the following diets: a diet with a positive MP balance (+44g/d) and 16.7% dietary crude protein (CP) concentration (AMP); a diet deficient in MP (−156g/d) and 14.8% CP concentration (DMP); or DMP supplemented with approximately 500g of coconut oil/head per day (DMPCO). Ruminal ammonia tended to be greater and plasma urea N (20.1, 12.8, and 13.1mg/dL, for AMP, DMP, and DMPCO diets, respectively) and milk urea N (12.5, 8.3, and 9.5mg/dL, respectively) were greater for AMP compared with DMP and DMPCO. The DMPCO diet decreased total protozoa counts (by 60%) compared with DMP, but had no effect on the methanogens profile in the rumen. Total tract apparent digestibility of dry matter and CP was decreased by DMP compared with AMP. Fiber digestibility was lower for both DMP and DMPCO compared with AMP. Urinary N excretion was decreased (by 37%) by both DMP and DMPCO compared with AMP. The DMP and DMPCO diets resulted in greater milk N efficiency compared with AMP (32.0 and 35.1 vs. 27.6%, respectively). Milk yield was decreased by both DMP and DMPCO compared with AMP (36.2, 34.4, and 39.3kg/d, respectively) and coconut oil supplementation suppressed feed intake and caused milk fat depression. Coconut oil supplementation decreased short-chain fatty acid (C4:0, C6:0, and C8:0) concentration and increased medium-chain (C12:0 and C14:0) and total trans fatty acids in milk. Overall, the MP-deficient diets decreased N losses, but could not sustain milk production in this study. Coconut oil decreased feed intake and similar to DMP, suppressed fiber digestibility. Despite decreased protozoal counts, coconut oil had no effect on the methanogen population in the rumen.

Plasma Levels of trans‐Fatty Acids are Low in Exclusively Breastfed Infants of Adolescent Mothers

The purpose of this study was to determine the levels of trans-octadecenoic acid (C18:1-trans) and trans-isomers of linoleic acid (18:2-trans), as well as long-chain polyunsaturated fatty acids (LC-PUFA), in the plasma from infants of adolescent mothers at 3 months of age, exclusively breastfed, and the relationship with the levels of the same isomers in plasma and milk of the mothers. Samples of blood and mature milk were obtained from 49 healthy adolescent mothers and their exclusively breastfed infants treated at the Instituto Fernandes Figueira-Fundação Oswaldo Cruz (IFF-FIOCRUZ) in Rio de Janeiro, Brazil. trans-Fatty acids (TFA) were analyzed by gas chromatography. The results of this study showed low levels of TFA in milk (1.53%), maternal plasma (0.50%), and plasma of infants (0.74%). The results show that, although TFA have been found in the plasma of the studied infants, the LC-PUFA levels are kept within normal limits. No association between TFA presence and parameters of nutritional status of the infants was observed, probably due to the low levels of these fatty acids found in this study.

Effect of replacing calcium salts of palm oil distillate with incremental amounts of conventional or high oleic acid milled rapeseed on milk fatty acid composition in cows fed maize silage-based diets

Based on potential benefits to human health, there is increasing interest in altering the composition of ruminant-derived foods. Including rapeseeds in the dairy cow diet is an effective strategy for replacing medium-chain saturated fatty acids (SFA) with cis-monounsaturated fatty acids (MUFA) in bovine milk, but there is limited information on the optimum level of supplementation. Decreases in SFA due to plant oils are also accompanied by increases in milk trans fatty acid (FA) content and it is possible that high oleic acid rapeseeds may result in a higher enrichment of cis-9 18:1 and lower increases in trans FAs in milk compared with conventional varieties. Seven multiparous lactating Holstein–Friesian cows were allocated to one of seven treatments in an incomplete Latin square design with five 28-day experimental periods, to evaluate the effect of replacing calcium salts of palm oil distillate (CPO; 41 g/kg diet dry matter, DM) with 128, 168 or 207 g/kg diet DM of conventional (COR) or a high oleic acid (HOR) rapeseed fed as a supplement milled with wheat. Rapeseed variety and inclusion level had no effect (P > 0.05) on DM intake, milk yield and composition. Both rapeseed varieties decreased linearly (P < 0.001) milk fat SFA content, which was partially compensated for by a linear increase (P < 0.001) in cis-9 18:1 concentration. Reductions in milk SFA were also associated with increases (P < 0.05) in trans 18:1 and total trans FA content, with no difference (P > 0.05) between rapeseed varieties. Replacing CPO in the diet with milled rapeseeds had no effect (P > 0.05) on total milk conjugated linoleic acid (CLA) concentration. Relative to a COR, inclusion of a high oleic acid variant in the diet increased (P = 0.01) the ratio of trans-MUFA : trans-polyunsaturated fatty acids in milk that may have implications with respect to cardiovascular disease risk in humans. In conclusion, data indicated that replacing CPO with milled rapeseeds at levels up to 1150 g oil/day could be used as a nutritional strategy to lower milk SFA content without inducing adverse effects on DM intake and milk production. HOR reduced milk fat SFA content to a greater extent than a conventional variety, but did not minimise associated increases in trans FA concentrations. However, the high oleic acid variant did alter the relative abundance of specific trans 18:1, CLA and trans 18:2 isomers compared with conventional rapeseeds.

Role of trans fatty acids in the nutritional regulation of mammary lipogenesis in ruminants

Fat is an important constituent contributing to the organoleptic, processing and physical properties of ruminant milk. Understanding the regulation of milk fat synthesis is central to the development of nutritional strategies to enhance the nutritional value of milk, decrease milk energy secretion and improve the energy balance of lactating ruminants. Nutrition is the major environmental factor regulating the concentration and composition of fat in ruminant milk. Feeding low-fibre/high-starch diets and/or lipid supplements rich in polyunsaturated fatty acids induce milk fat depression (MFD) in the bovine, typically increase milk fat secretion in the caprine, whereas limited data in sheep suggest that the responses are more similar to the goat than the cow. Following the observation that reductions in milk fat synthesis during diet-induced MFD are associated with increases in the concentration of specific trans fatty acids in milk, the biohydrogenation theory of MFD was proposed, which attributes the causal mechanism to altered ruminal lipid metabolism leading to increased formation of specific biohydrogenation intermediates that exert anti-lipogenic effects. Trans-10, cis-12 conjugated linoleic acid (CLA) is the only biohydrogenation intermediate to have been infused at the abomasum over a range of experimental doses (1.25 to 14.0 g/day) and shown unequivocally to inhibit milk fat synthesis in ruminants. However, increases in ruminal trans-10, cis-12 CLA formation do not explain entirely diet-induced MFD, suggesting that other biohydrogenation intermediates and/or other mechanisms may also be involved. Experiments involving abomasal infusions (g/day) in lactating cows have provided evidence that cis-10, trans-12 CLA (1.2), trans-9, cis-11 CLA (5.0) and trans-10 18:1 (92.1) may also exert anti-lipogenic effects. Use of molecular-based approaches have demonstrated that mammary abundance of transcripts encoding for key lipogenic genes are reduced during MFD in the bovine, changes that are accompanied by decrease in sterol response element binding protein 1 (SREBP1) and alterations in the expression of genes related to the SREBP1 pathway. Recent studies indicate that transcription of one or more adipogenic genes is increased in subcutaneous adipose tissue in cows during acute or chronic MFD. Feeding diets of similar composition do not induce MFD or substantially alter mammary lipogenic gene expression in the goat. The available data suggests that variation in mammary fatty acid secretion and lipogenic responses to changes in diet composition between ruminants reflect inherent interspecies differences in ruminal lipid metabolism and mammary specific regulation of cellular processes and key lipogenic enzymes involved in the synthesis of milk fat triacylglycerides.

Diet, rumen biohydrogenation and nutritional quality of cow and goat milk fat

AbstractThe potential to modify the milk fatty acid (FA) composition by changing the cow or goat diets is reviewed. Ruminal biohydrogenation (RBH), combined with mammary lipogenic and Δ‐9 desaturation pathways, considerably modifies the profile of dietary FA and thus milk composition. The pasture has major effects by decreasing saturated FA and increasing FA considered as favorable for human health (c9‐18:1, 18:3n‐3 andc9t11‐CLA), compared to winter diets, especially those based on maize silage and concentrates. Plant lipid supplements have effects similar to pasture, especially linseed, but they increase to a larger extent, simultaneously severaltransisomers of 18:1 and, conjugated or non‐conjugated 18:2, especially when added to maize silage or concentrate‐rich diets. The goat responds better for milk 18:3n‐3 andc9t11‐CLA, and sometimes less forc9‐18:1, and is less prone to the RBHtrans‐11 totrans‐10 shift, which has been shown to be time dependent in the cow. The respective physiological roles of most milktransFA have not been studied to date, and more studies in rodents and humans fed dairy products modified by changing ruminant diet are required before recommending a larger use of lipid sources and how to combine them with the different feeding systems used by dairy farmers.

Trans Fatty acids in milk produced by women in the United States

trans Fatty acids (FAs) have been identified as negatively affecting human health. The trans FA composition of human milk fat must be examined to establish its influence on the nutritional quality of milk consumed by infants. We sought to ascertain the individual and total trans FA isomers (sum of FAs containing at least one trans double bond) in human milk and to identify relations between individual FAs and milk fat concentration (% by wt). The FA composition of milk samples (n = 81) from women living in the southwestern United States was ascertained. The individual 18:1t isomers were separated. Correlations between each FA, total trans FAs, groups of similar FAs, and milk fat concentrations were examined. The mean total trans FA concentration was 7.0 +/- 2.3% (range: 2.5-13.8%). The concentration of total 18:1t was 5.1 +/- 2.0% (range: 1.5-11.6%), and Delta10t (range: Delta9-12t) was the most abundant isomer. Milk fat from women living in the United States contains concentrations of trans FAs similar to those in milk from Canadian women but greater than those reported in milk from women in other countries. In decreasing order of concentration, the Delta10t, Delta11t, Delta9t, and Delta12t isomers represented 78.9% of the total 18:1t. These FAs generally originate from partially hydrogenated vegetable oils and ruminant fat in the diet. No relation was found between the concentration of total trans FAs and milk fat concentration.

Phytonutrients and children: The other side of the medallion

Phytochemicals, prominent for their antioxidant and anticancer activities, differ in their chemical properties. These differences may affect bioavailability and distribution of each within the body in which they may act as prooxidants. The use of dietary supplements is growing among children. In higher concentrations, a risk of toxicity may exist. Maternal nutrition is important for fetal development and during lactation, breast feeding periods. Children are more sensitive than adults. Compounds, doses of which may be tolerated by adults may not be readily overcome by infants. Vitamin A supplements increase the risk of mother-to-child transmission of HIV. Trans-fatty acids in milk, a basic nutrient during childhood, which is affected by even cow’s diet, are potential atherosclerosis progression factors and risk factors for obesity, a major health problem among children. Glycoalkaloids, aflatoxins, acrylamid are threatening compounds found in snacks. Regular mass administration of foods, or supplements should be done prudently during childhood.

Dietary trans Fatty Acids Affect the Essential Fatty-Acid Concentration of Rat Milk

Increasing efforts have been made to determine the distribution and concentration of trans fatty acids in milk, due to the importance of lipids in infant growth and development. In general, trans fatty acid concentration of milk reflects trans fatty acid intake, but insufficient data are available to assess the effects of dietary trans fatty acids on maternal milk. Thus, controlled studies are needed to establish whether there is a dose-response relationship and whether trans fatty acids could affect the concentration of essential fatty acids (EFA), long-chain polyunsaturated fatty acids (PUFA) and the (n-6)/(n-3) ratio in milk. Three groups of six rats each were fed for 10 wk one of three diets differing in trans fatty acid concentration (Control, 0 mol/100 mol; high trans concentration (H), 14.5 mol/100 mol; very high trans concentration (VH), 30 mol/100 mol), but containing the same proportions of linoleic and alpha-linolenic acids and a ratio of 18:2(n-6)/18:3(n-3) of about 7:1. Trans fatty acids were incorporated into maternal milk in a dose-dependent manner. In addition, rats fed trans isomers had greater linoleic acid levels than controls. The proportion of alpha-linolenic acid in milk was lower in the VH group, and the (n-6)/(n-3) cis PUFA ratio in milk of the VH group was greater than that in controls. Total long-chain PUFA levels did not differ among groups. These results suggest that high intakes of trans fatty acids affect the EFA concentration but not that of long-chain PUFA of rat milk, provided that EFA are supplied in sufficient amounts.

Trans fatty acids in human milk lipids: influence of maternal diet and weight loss

Geometric and positional isomers of octadecanoic acid in milk expressed during the first 9 weeks of lactation were determined for mothers delivering prematurely (PT) and at term (FT). Total C18:1 concentration was lower in PT than FT milk. C18:1 trans (elaidic acid) content was higher in PT and FT colostrum compared with subsequent milk samples. No relationship was observed between C18:1 trans level in milk and oleic acid, linoleic acid, total fatty acid levels, or volume of milk expressed. While gestational age and lactational stage appeared to affect the trans fatty acid pattern, the overriding influence was rate of maternal postpartum weight loss. Effect of weight loss on milk trans fatty acid levels was independent of maternal diet. Trans fatty acid content of milk as a function of recent maternal fat intake was also demonstrated. This study indicates that infants receiving human milk ingest levels of trans fatty acids reflecting short and long term maternal diet.