Trans-11 Cis-12 Conjugated Linoleic Acid Research Articles

Impact of a total mixed ration or pasture/pasture silage-based feeding strategy in the initial stages of lactation of spring-calving dairy cows on milk production, composition and selected milk processability parameters

The objective of this experiment was to investigate the effect of feeding strategy on milk production, composition and selected processability parameters in the initial stages of lactation. Twenty Holstein Friesian cows were allocated to one of two dietary treatments (n = 10; 7 multiparous and 3 primiparous) in a randomised complete block design for 21 d from day 10 to day 31 post-calving. Treatment 1 (pasture-based system [PBS]) was a pasture/pasture silage-based diet where cows were offered ad libitum grazed pasture or pasture silage (when weather did not permit grazing) plus 3 kg DM/d or 5 kg DM/d concentrate supplementation, respectively. On average, cows grazed pasture for 7.5 d and were fed pasture silage indoors for 13.5 d. Treatment 2 (TMR) was a total mixed ration (TMR) diet made up of concentrate, plus maize silage, pasture silage, beet pulp, soya bean meal and straw. Multiparous cows were blocked on calving date and balanced for parity and milk yield. Primiparous cows were balanced for live weight. Milk attributes pertinent to composition and functionality (e.g., fatty acids and rennet coagulation time [RCT]) were examined over a 21-d experimental period from day 10 to day 31 post-calving. Cows offered PBS tended to have a lower test day milk yield (PBS = 24.2 kg/cow vs. TMR = 26.8 kg/cow, P = 0.09) and a greater milk urea nitrogen (MUN) content compared to TMR (PBS = 0.030 g/100 g milk vs. TMR = 0.013 g/100 g milk, P < 0.001). Most notably, PBS-derived milks had a greater (P < 0.001) concentration of cis-9 trans-11 conjugated linoleic acid (CLA) compared to TMR. In conclusion, milk produced during early lactation from both feeding strategies was suitable for processing. Feeding a TMR compared with ad libitum pasture/pasture silage had no impact on average milk pH, casein concentration or RCT. Cows fed a pasture/pasture silage-based diet produced milk with a desirable RCT for milk processing, while the higher MUN content from cows offered PBS did not impact the processability of milk. Furthermore, milk from cows offered PBS had greater concentrations of cis-9 trans-11 CLA, which may offer human health benefits.

Fatty acid profile and nutrient composition of muscle and adipose tissue from Malpura and fat-tailed Dumba sheep

Fatty acid (FA) profile and nutrient composition of Longissimus dorsi (LD) muscle and various adipose tissues of adult Malpura sheep (4–6 years) and lambs (6 month), and fat tailed Dumba sheep (1 year) were evaluated. Compared to lamb, LD muscle of adult Malpura sheep had lower polyunsaturated FA (PUFA), ω-6, ω-6/ω-3, desirable FA (DFA) and higher atherogenic index (AI), monounsaturated FA (MUFA), ω-3, MUFA:PUFA ratio, short-chain FA (SCFA) and conjugated linoleic acid (CLA). Similarly, adipose tissue fat had higher MUFA, MUFA:PUFA ratio and AI in adult than the lamb. Dumba sheep showed a different FA profile with higher SFA in caul fat and lower in LD muscle, while proportionally lower PUFA in caul fat and higher in LD muscle. Likewise, ω-3 and ω-6 FA was comparatively more in LD muscle while c911 CLA was highest in the tail adipose tissue. Between Malpura and Dumba, the FA profile of LD muscle revealed higher SFA and cis-9 trans-11 CLA but lower PUFA and ω-6 FA in Malpura. It can thus be concluded that Malpura lamb meat is healthier having improved PUFA,ω-6:ω-3 ratio and AI than the adult. Furthermore, Dumba may also be considered a promising mutton breed with significant PUFA, ω-3 and ω-6 FA. Further studies are needed to ascertain the effects of different dietary regime on the FA profile of Dumba and Malpura sheep.

Kinetics of trans-10, cis-12-conjugated linoleic acid transfer to plasma and milk following an abomasal bolus in lactating dairy cows.

Trans-10, cis-12-conjugated linoleic acid (CLA) is a potent bioactive fatty acids (FA) that causes milk fat depression in lactating animals. FA are transferred to milk directly through chylomicrons and indirectly by recycling through other tissues. The objective of this study was to characterise the kinetics of trans-10, cis-12 CLA transfer to plasma and milk after a single bolus infusion. Five multiparous mid-lactation cows received a single abomasal bolus infusion of an enriched CLA mixture providing 15 g of trans-10, cis-12 CLA and 15 g of cis-9, trans-11 CLA over a 30-min period. Plasma concentration of trans-10, cis-12 and cis-9, trans-11 CLA peaked 2 h post-bolus, reaching 0·29 and 0·38 % of total plasma FA, respectively, and returned to pre-bolus values at 72 h post-infusion. Milk trans-10, cis-12 CLA yield and concentration peaked 14 h post-bolus (0·25 g/h) and was not detectable in milk after 86 h. Total apparent transfer of trans-10, cis-12 CLA to milk was 41 %, with 73 % transferred to milk through the direct pool (chylomicrons) and the remaining 27 % transferred through the indirect pool (tissue recycling). Compartmental modelling revealed the existence of a transient unavailable pool of trans-10, cis-12 CLA in extravascular tissues represented primarily by the mammary gland, which slowly exchanges with an available pool for secretion in milk fat and transfer to milk. In conclusion, trans-10, cis-12 CLA is predominantly transferred to milk through the direct pathway; however, how this CLA isomer is processed within the mammary gland requires further investigation.

Inflammatory and metabolic responses to an intramammary lipopolysaccharide challenge in early lactating cows supplemented with conjugated linoleic acid.

Supplementation of dairy cows with trans-10, cis-12 conjugated linoleic acid (CLA) allows nutrient repartitioning despite an energy deficiency in early lactation, which might be a benefit for the immune system, too. In this study, we investigated potential nutrient sparing effects of CLA in early lactating cows with low plasma glucose concentrations exposed to an intramammary lipopolysaccharide (LPS) challenge. Fifteen multiparous Holstein cows were exposed to an intramammary LPS challenge in week 4 p.p. Eight cows (CLA) were supplemented daily with 70g of lipid-encapsulated CLA (6.8g trans-10, cis-12 and 6.6g of the cis-9, trans-11 CLA isomer; CLA) and seven cows with 56g of control fat (CON). Blood samples were obtained every 30min along with rectal temperature, heart and respiratory rate, and milk samples were taken hourly until 10hr after the LPS application. Plasma was analysed for concentrations of glucose, free fatty acids, beta-hydroxybutyrate (BHB), cortisol, insulin and glucagon. In milk, somatic cell count and activity of lactate dehydrogenase were determined. Initial plasma glucose concentration was lower in CLA than in CON. During the immunostimulation, CLA had higher glucose concentrations than CON, and BHB decreased distinctly in CLA, whereas CON cows maintained BHB concentration at a lower level. Body temperature in CLA increased earlier, the difference between peak and basal temperature was higher, and the decline thereafter occurred earlier. In conclusion, CLA supplementation of early lactating cows exposed to an intramammary LPS challenge affected local and systemic immune responses. We assume that CLA supplementation triggered glycogen storage. Cows supplemented with CLA provided more glucose and preferentially used BHB as an energy source during the immune response. The more intense metabolic and more concentrated endocrine responses support an immunomodulatory effect of CLA supplementation.

The trans-10,cis-12 conjugated linoleic acid increases triacylglycerol hydrolysis in yeast Saccharomyces cerevisiae.

The trans-10,cis-12 conjugated linoleic acid (CLA) is known for its antilipogenic effect but the mechanism is not fully clear. In this study, the potential of yeast (Saccharomyces cerevisiae) metabolism to offer evidence for the mechanism was investigated. The inhibitory effect of CLA on lipid accumulation was studied by analysing the transcript abundance of selected genes involved in triacylglycerol synthesis (LRO1, DGA1, ARE1 and ARE2) in the presence of the two bioactive CLA isomers: trans-10,cis-12 and the cis-9,trans-11 CLA. None of the enzymes was reduced in transcription but the expression of ARE2 was induced by trans-10,cis-12 CLA. However, the ARE2 overexpression did not contribute to lipid accumulation. The expression of the Δ9 desaturase gene, OLE1, was reduced by the cis-9,trans-11 but not by the trans-10,cis-12 isomer. In the TGL3/TGL4-knockout strain the triacylglycerol content also remained high in the CLA fed cells. Triacylglycerol hydrolysis rather than synthesis was the most probable reason for the reduced lipid content in yeast induced by CLA. This study revealed new aspects of the functionality of CLA in eukaryotic lipid metabolism. Yeast was proven to be an applicable model to study further the mechanism of trans-10,cis-12 CLA functionality on lipid metabolism.

Effect of conjugated linoleic acid and acetate on milk fat synthesis and adipose lipogenesis in lactating dairy cows

During biohydrogenation-induced milk fat depression (MFD), nutrients are spared from milk fat synthesis and are available for other metabolic uses. Acetate is the major carbon source spared and it may increase lipid synthesis in adipose tissue during MFD. The objective of this study was to compare the effect of trans-10,cis-12 conjugated linoleic acid (CLA) and the amount of acetate spared during CLA-induced MFD on adipose tissue lipogenesis. Nine multiparous, lactating, ruminally cannulated Holstein cows (244 ± 107 d in milk; 25 ± 8.4 kg of milk/d; mean ± standard deviation) were randomly assigned to treatments in a 3 × 3 Latin square design. Experimental periods were 4 d followed by a 10-d washout. Treatments were control (CON), ruminal infusion of acetate (AC; continuous infusion of 7 mol/d adjusted to pH 6.1 with sodium hydroxide), or abomasal infusion of CLA (10 g/d of both trans-10,cis-12 CLA and cis-9,trans-11 CLA). Dry matter intake, milk yield, and milk protein yield and percentage were not affected by treatments. Compared with CON, milk fat yield decreased 23% and fat percent decreased 28% in CLA, and milk fat yield increased 20% in AC. Concentration and yield of milk de novo synthesized fatty acids (<C16) were reduced and concentration of preformed fatty acids (>C16) was increased by CLA, compared with CON. Yield of de novo synthesized fatty acids and palmitic acid was increased by AC, compared with CON. Lipogenesis capacity of adipose tissue explants was decreased 72% by CLA, but was not affected by AC. Acetate oxidation by adipose explants was not affected by treatments. Treatments had no effect on expression of key lipogenic factors, lipogenic enzymes, and leptin; however, expression of fatty acid binding protein 4 was reduced in CLA compared with CON. Additionally, hormone-sensitive lipase and perilipin 1 were decreased by CLA and acetate. Plasma glucose and glucagon concentrations were not affected by treatments; however, CLA increased nonesterified fatty acids 17.7%, β-hydroxybutyrate 16.1%, and insulin 27.8% compared with CON, and AC increased plasma β-hydroxybutyrate 18%. In conclusion, during CLA-induced MFD in low-producing cow adipose tissue was sensitive to the anti-lipogenic effects of CLA, while spared acetate did not stimulate adipose lipogenesis. However, acetate may play an important role in stimulating lipogenesis and improving energy status in the mammary gland under normal conditions.

The effect of conjugated linoleic acid, acetate, and their interaction on adipose tissue lipid metabolism in nonlactating cows

During biohydrogenation-induced milk fat depression, adipose tissue lipogenesis may be increased through nutrients spared from milk fat synthesis. However, the direct effect of trans-10,cis-12 conjugated linoleic acid (CLA) and the indirect effect of spared nutrients on adipose tissue lipogenesis during milk fat depression is not clear. The objective of this study was to determine the direct effect of CLA, spared acetate, and their interaction on adipose tissue lipogenesis using nonlactating dairy cows as an experimental model, which allows separation of the effect of CLA and nutrient sparing. Eight ruminally cannulated, multiparous nonlactating and pregnant Holstein cows were randomly assigned to treatments in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Factors were CLA and acetate, and treatments were control (CON), rumen acetate infusions (Ac; continuous infusion of 7 mol/d adjusted to pH 6.1 with sodium hydroxide), abomasal infusion of trans-10,cis-12 CLA (CLA; 10 g/d of both trans-10,cis-12 CLA and cis-9,trans-11 CLA), and Ac + CLA (Ac + CLA). Dry matter intake was not affected by Ac, but tended to decrease by CLA. Plasma trans-10,cis-12 CLA concentration as a percentage of fatty acids was increased by 0.3 percentage points by CLA. No treatment effect was observed on plasma glucose and β-hydroxybutyrate, but an interaction was observed of CLA and Ac on plasma insulin and nonesterified fatty acids. Insulin was increased 24% by CLA, but not by Ac + CLA, and nonesterified fatty acids were increased 55% by Ac + CLA, but not by CLA alone. Lipogenesis and oxidation capacity of adipose tissue explants were not affected by treatments. Adipose expression of key lipogenic factors (peroxisome proliferator-activated receptor γ2 and sterol response element binding protein 1c) were reduced by CLA, by the interaction of Ac and CLA (sterol response element binding protein 1c), and tended to be reduced with Ac (S14 and peroxisome proliferator-activated receptor γ1). Expression of several adipose lipogenic enzymes (fatty acid synthase, acetyl-CoA carboxylase, and stearoyl-CoA desaturase 1) was reduced by CLA and Ac. An interaction was observed of Ac and CLA for fatty acid binding protein 4, which was decreased by Ac, but not Ac + CLA. In conclusion, in the nonlactating cow, adipose tissue is sensitive to the anti-lipogenic effects of trans-10,cis-12 CLA at the transcription level and acetate does not stimulate lipogenesis.

Effects of linseed oil or whole linseed supplementation on performance and milk Fatty Acid composition of lactating dairy cows.

The objective of this study was to determine the effects of linseed oil or whole linseed supplementation on performance and milk fatty acid composition of lactating dairy cows. Thirty six Holstein Friesian crossbred lactating dairy cows were blocked by milking days first and then stratified random balanced for milk yields and body weight into three groups of 12 cows each. The treatments consisted of basal ration (53:47; forage:concentrate ratio, on a dry matter [DM] basis, respectively) supplemented with 300 g/d of palm oil as a positive control diet (PO), or supplemented with 300 g/d of linseed oil (LSO), or supplemented with 688 g/d of top-dressed whole linseed (WLS). All cows were received ad libitum grass silage and individually fed according to the treatments. The experiment lasted for 10 weeks including the first 2 weeks as the adjustment period, followed by 8 weeks of measurement period. The results showed that LSO and WLS supplementation had no effects on total dry matter intake, milk yield, milk composition, and live weight change; however, the animals fed WLS had higher crude protein (CP) intake than those fed PO and LSO (p<0.05). To compare with the control diet, dairy cow’s diets supplemented with LSO and WLS significantly increased milk concentrations of cis-9, trans-11-conjugated linoleic acid (CLA) (p<0.05) and n-3 fatty acids (FA) (p<0.01), particularly, cis-9,12,15-C18:3, C20:5n-3 and C22:6n-3. Supplementing LSO and WLS induced a reduction of medium chain FA, especially, C12:0-C16:0 FA (p<0.05) while increasing the concentration of milk unsaturated fatty acids (UFA) (p<0.05). Milk FA proportions of n-3 FA remarkably increased whereas the ratio of n-6 to n-3 decreased in the cows supplemented with WLS as compared with those fed the control diet and LSO (p<0.01). In conclusion, supplementing dairy cows’ diet based on grass silage with WLS had no effect on milk yield and milk composition; however, trans-9- C18:1, cis-9, trans-11-CLA, n-3 FA and UFA were increased while saturated FA were decreased by WLS supplementation. Therefore, it is recommended that the addition 300 g/d of oil from whole linseed should be used to lactating dairy cows’ diets.

Fat source and dietary forage-to-concentrate ratio influences milk fatty-acid composition in lactating cows

On the basis of the potential benefits to human health there is an increased interest in producing milk containing lower-saturated fatty acid (SFA) and higher unsaturated fatty acid (FA) concentrations, including cis-9 18:1 and cis-9, trans-11-conjugated linoleic acid (CLA). Twenty-four multiparous Holstein cows were used in two experiments according to a completely randomized block design, with 21-day periods to examine the effects of incremental replacement of prilled palm fat (PALM) with sunflower oil (SFO) in high-concentrate diets containing 30 g/kg dry matter (DM) of supplemental fat (Experiment 1) or increases in the forage-to-concentrate (F : C) ratio from 39 : 61 to 48 : 52 of diets containing 30 g/kg DM of SFO (Experiment 2) on milk production, digestibility and milk FA composition. Replacing PALM with SFO had no effect on DM intake, but tended to increase organic matter digestibility, yields of milk, protein and lactose, and decreased linearly milk fat content. Substituting SFO for PALM decreased linearly milk fat 8:0 to 16:0 and cis-9 16:1, and increased linearly 18:0, cis-9 18:1, trans-18:1 (Δ4 to 16), 18:2 and CLA concentrations. Increases in the F : C ratio of diets containing SFO had no effect on intake, yields of milk, milk protein or milk lactose, lowered milk protein content in a quadratic manner, and increased linearly NDF digestion and milk fat secretion. Replacing concentrates with forages in diets containing SFO increased milk fat 4:0 to 10:0 concentrations in a linear or quadratic manner, decreased linearly cis-9 16:1, trans-6 to -10 18:1, 18:2n-6, trans-7, cis-9 CLA, trans-9, cis-11 CLA and trans-10, cis-12 CLA, without altering milk fat 14:0 to 16:0, trans-11 18:1, cis-9, trans-11 CLA or 18:3n-3 concentrations. In conclusion, replacing prilled palm fat on with SFO in high-concentrate diets had no adverse effects on intake or milk production, other than decreasing milk fat content, but lowered milk fat medium-chain SFA and increased trans FA and polyunsaturated FA concentrations. Increases in the proportion of forage in diets containing SFO increased milk fat synthesis, elevated short-chain SFA and lowered trans FA concentrations, without altering milk polyunsaturated FA content. Changes in fat yield on high-concentrate diets containing SFO varied between experiments and individual animals, with decreases in milk fat secretion being associated with increases in milk fat trans-10 18:1, trans-10, cis-12 CLA and trans-9, cis-11 CLA concentrations.

Effects of different fat mixtures on milk fatty acid composition and oxidative stability of milk fat

The experiment was carried out to determine effects of different fatty acids (FA) mixtures on milk FA composition and milk fat oxidation change. Thirty-six dairy cows were used in a completed design experiment for 8 weeks. Cows were fed one of three lipid supplements (1) short- and medium-chain fatty acids (SMCFA), (2) butterfat, and (3) long-chain fatty acids (LCFA). Data were analyzed using MIXED procedure of SAS. Daily dry matter intake (DMI), milk yield, and milk protein, total solids (TS), lactose, free fatty acids (FFA) content were unaffected among 3 treatments, whereas milk fat concentration was decreased (P<0.05) as carbon chain length increased in supplement lipid. Relative to SMCFA, 12:0, 14:0 and 16:0 concentrations in milk fat from cows on butterfat and LCFA treatment were decreased (P<0.05). Proportions of cis9-18:1, trans9-C18:1, and cis9, trans11-conjugated linoleic acid (CLA) were increased by 15.5, 74.3, and 20.3% (P<0.05) in milk fat from cows on LCFA compared with cows on SMCFA. Similar increases in trans9-18:1, trans11-18:1, cis9, trans11-CLA, 18:2n-6 and 18:3n-3 were 34.2, 31.5, 21.4, 11.0, and 15.4% (P<0.05) in butterfat treatments, respectively. Furthermore, activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) were decreased (P<0.05) when increased long-chain FA in diets, while concentration of malondialdehyde (MDA) was increased (P<0.01) in bovine milk. Our results indicated that long-chain FA exhibit positive effects on milk FA composition, but may decrease oxidative stability of milk fat.

Effect of Dietary Vegetable Oil Supplementation on C18 Fatty Acids and Conjugated Linoleic Acid Production; An In vitro Fermentation Study

An in vitro rumen fermentation trial was conducted to investigate effect of dietary vegetable oil supplement on fatty acids metabolism in cattle. The incubation was carried out using rumen fluid obtained from Brahman x Native crossbred beef cattle. The diets were formulated by using basal diet with no vegetable oil (CON), basal diet with 4% of palm oil (PO), 4% of canola oil (CA), 4% of coconut oil (CO) and 4% of sunflower oil (SF). Fatty acid profiles were determined at 12, 24 and 48 h after incubation time. The results found that linoleic acid (LA) was decreased with diet CON, diet PO, diet CA and diet SF (p<0.05). Stearic acid (SA) resulted increased with diet CON, diet CA, diet CO and diet SF at 24 and 48 h. The SF diet contain high level of LA showed the highest concentration of cis9 trans11 conjugated linoleic acid (CLA) when compared with other diets. Vaccenic acid (VA) was increased with all the five diet, especially with diet SF and diet CA after 24 h. Base on this study, it suggests that supplementation of SF could improve the concentration of VA and cis9 trans11 CLA in the rumen.

The management of the transition from hay- to pasture-based diets affects milk fatty acid kinetics

As fatty acids (FA) may become included among the quality parameters setting milk prices, their variation during diet changes needs to be investigated. The aim of this work was to study the kinetics of milk FA during rapid or progressive transition from hay- to pasture-based diets. Two farms in the southwestern Alps were selected. The milk of five Valdostana Red Pie cows from each farm was analysed on days 0, 1, 2, 3, 5 and 7 (at day 1, pasture was introduced into the diet), and thereafter twice a week. Changes in the milk FA became significant after days 3 or 5. The FA from C4:0 to C18:0, C18:2n-6, C18:3n-3 and C20:0 became stable after day 5 for both transition types. The cis9-C18:1, trans10 + trans11-C18:1 and cis9trans11-conjugated linoleic acid (CLA) became stable 3, 16 and 16 days after the maximum pasture intake, respectively. The C4:0 peaked at 3 days after pasture introduction or increase in the diet, probably reflecting high butyrate production in the rumen due to the high carbohydrate concentration in fresh herbage. The kinetics of all FAs fitted a log-normal cumulate distribution (except for C4:0), but model coefficients did not differ between the rapid and the progressive transition. After diet transition, only cis9-C18, cis9trans11-CLA, C18:3n-3, the mono-unsaturated and poly-unsaturated FA, and the sum of CLA isomers increased faster in the rapid transition than in the progressive transition diet (higher a coefficients), because of the higher initial pasture intake. Knowledge of the kinetics of milk FA when pasture is introduced into the diet could help farmers to improve milk nutritional quality.

Effect of conjugated linoleic acid on inhibition of prolyl hydroxylase 1 in hearts of mice.

BackgroundResults from different trails have provided evidence of protective effects of cis-9,trans-11-conjugated linoleic acid (CLA) on cardiovascular diseases. But the inhibition of prolyl hydroxylase 1 (PHD1) associated with induction of hypoxia inducible factors (HIFs) by CLA in these protective effects has never been reported before. The objective of this study was to evaluate if the two predominant cis-9,trans-11 (c9, t11), trans-10,cis-12 (t10, c12) CLA isomers and mixture of these two isomers can inhibit PHD1 with induction of HIFs in myocardium in mice and subsequent effects on myocardium metabolism.ResultsCLA mixture and c9, t11 CLA inhibited PHD1 protein expression and increased the levels of protein and mRNA in HIF-2α in myocardium in mice. Meanwhile, CLA mixture and c9, t11 CLA also elevated the expression of HIF related transcriptional factors like PDK4 and PPARα. The reprogramming of basal metabolism in myocardium in mice was shown on increasing of GLUT4 gene expression by c9, t11 CLA supplemented group. UCP2 was increased by CLA mixture and c9, t11 CLA for attenuating production of ROS.ConclusionCLA mixture and c9, t11 CLA could inhibit PHD1 and induce HIF-2α in myocardium in mice, which is associated with upregulation of PDK4 by activation of PPARα. This process also implies a reprogramming of basal metabolism and oxidative damage protection in myocardium in mice. All the effects shown in hearts of mice are due to c9, t11 CLA but not t10, c12 CLA.

Effects of breed on milk fatty acid profile in dairy ewes, with particular reference to &lt;i&gt;cis-9, trans-11&lt;/i&gt; conjugated linoleic acid

The objective of this study was to determine and compare the fatty acid profile of milk fat, with particular reference to cis-9, trans-11 conjugated linoleic acid (CLA), in two indigenous Romanian sheep breeds (Spanca and Turcana), irrespective of the effects of diet and season. The ewes (n = 25 for each breed) received the same feed (total mixed rations) and were maintained under identical conditions. Four samples were collected from each individual ewe to determine fatty acids (FA), as methyl esters, using gas chromatography. The fatty acid groups, namely saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) acids were examined together with individual acids. Differences have been obtained between the two local breeds for the majority of FA. Fat in the milk of Turcana ewes has a healthier fatty acid profile than that of Spanca breed which has a lower concentration of SFA (60.9 vs. 73.3%) and higher concentrations of MUFA (31.0 vs. 21.0%) and PUFA (8.06 vs. 5.61%, respectively). Compared with the Spanca breed, fat in the milk of Turcana ewes had higher concentrations of trans -11 C18:1, C18:1 n9c, and cis-9 trans-11 CLA (2.67 vs. 1.01%, respectively). Δ 9 -desaturase activity is breed specific; vaccenic acid (trans-11 C18:1) desaturation and its conversion into cis-9, trans-11 CLA were more intense in the Turcana breed ewes. In conclusion, breed has a strong effect on the FA composition of ewe milk fat, and on cis-9, trans-11 CLA, in particular. The results obtained, support the sustainable use of animal genetic resources to improve the milk fat quality of ewes. Keywords : CLA, ewe’s milk, fatty acid profiles, Spanca, Turcana

A high intake of industrial or ruminant trans fatty acids does not affect the plasma proteome in healthy men

Consumption of industrial trans fat raises the risk of cardiovascular disease, but it is unclear whether cis9,trans11-conjugated linoleic acid (CLA)--a trans fatty acid in dairy products--modulates disease development. We investigated the effects of complete diets providing 7% of energy as industrial trans fat or cis9, trans11 CLA, compared with oleic acid, on regulation of plasma proteins in 12 healthy men. Diets were provided for 3 wk each, in random order. Plasma was collected at the end of each 3 wk intervention period, depleted of its 12 most abundant proteins and analyzed by 2-DE. Principal component analysis of protein spot intensity values revealed that the nature of the dietary intervention did not significantly affect the plasma proteome. The intervention provided in the 1st period produced a significant treatment effect compared with the interventions provided in the other two periods, and there was a significant subject effect. In conclusion, the nature of an extreme dietary intervention, i.e. 7% of energy provided by industrial trans fat or cis9,trans11 CLA, did not markedly affect the plasma proteome. Thus plasma proteomics using 2-DE appears, by and large, an unsuitable approach to detect regulation of plasma proteins due to changes in the diet.

Isomer-specific effects of conjugated linoleic acid on proliferative activity of cultured neural progenitor cells

Conjugated linoleic acid (CLA) has been shown to have a variety of biological activities. However, the effects of CLA on the proliferation of neural progenitor cells (NPCs) are not clear. The objective of this study was to determine the effects of cis-9 trans-11 CLA and trans-10 cis-12 CLA, the predominant individual isomers, on the proliferative activity of NPCs in vitro. Cell counts showed that treatment of NPCs with cis-9 trans-11 CLA increased the cell number in a dose- and time- dependent manner while significant inhibition effect of trans-10 cis-12 CLA was observed. Western blot analysis revealed the elevated expression of cyclin D1 induced by cis-9 trans-11 CLA treatment and the decreased expression of cyclin D1 by trans-10 cis-12 CLA treatment in NPCs. Cyclin D1-siRNA transfection significantly inhibited the promotion of cell proliferation by cis-9 trans-11 CLA. In addition, trans-10 cis-12 CLA inhibited the phosphorylation of protein kinase B (PKB/Akt), while cis-9 trans-11 CLA had no effect on phospho Akt levels. Furthermore, immunofluorescence assay showed that after CLA treatment, the cells retained their functional characteristics of neural progenitors. These results indicated that cis-9 trans-11 CLA can effectively enhance the proliferation of hADSCs. The effect of cis-9 trans-11 CLA may be associated with the up-regulation of cyclin D1 expression.

Effect of pH and level of concentrate in the diet on the production of biohydrogenation intermediates in a dual-flow continuous culture

Milk fat depression in cows fed high-grain diets has been related to an increase in the concentration of trans-10C18:1 and trans-10,cis-12 conjugated linoleic acid (CLA) in milk. These fatty acids (FA) are produced as a result of the alteration in rumen biohydrogenation of dietary unsaturated FA. Because a reduction in ruminal pH is usually observed when high-concentrate diets are fed, the main cause that determines the alteration in the biohydrogenation pathways is not clear. The effect of pH (6.4 vs. 5.6) and dietary forage to concentrate ratios (F:C; 70:30F:C vs. 30:70F:C) on rumen microbial fermentation, effluent FA profile, and DNA concentration of bacteria involved in lipolysis and biohydrogenation processes were investigated in a continuous culture trial. The dual-flow continuous culture consisted of 2 periods of 8 d (5 d for adaptation and 3 d for sampling), with a 2×2 factorial arrangement of treatments. Samples from solid and liquid mixed effluents were taken for determination of total N, ammonia-N, and volatile fatty acid concentrations, and the remainder of the sample was lyophilized. Dry samples were analyzed for dry matter, ash, neutral and acid detergent fiber, FA, and purine contents. The pH 5.6 reduced organic matter and fiber digestibility, ammonia-N concentration and flow, and crude protein degradation, and increased nonammonia and dietary N flows. The pH 5.6 decreased the flow of C18:0, trans-11C18:1 and cis-9, trans-11 CLA, and increased the flow of trans-10C18:1, C18:2n-6, C18:3n-3, trans-11,cis-15C18:2 and trans-10,cis-12 CLA in the 1h after feeding effluent. The pH 5.6 reduced Anaerovibrio lipolytica (32.7 vs. 72.1 pg/10ng of total DNA) and Butyrivibrio fibrisolvens vaccenic acid subgroup (588 vs. 1,394 pg/10ng of total DNA) DNA concentrations. The high-concentrate diet increased organic matter and fiber digestibility, nonammonia and bacterial N flows, and reduced ammonia-N concentration and flow. The high-concentrate diet reduced trans-11C18:1 and trans-10C18:1, and increased C18:2n-6, C18:3n-3 and trans-10,cis-12 CLA proportions in the 1h after feeding effluent. The increase observed in trans-10,cis-12 CLA proportion in the 1h after feeding effluent due to the high-concentrate diet was smaller that that observed at pH 5.6. Results indicate that the pH is the main cause of the accumulation of trans-10C18:1 and trans-10, cis-12 CLA in the effluent, but the trans-10,cis-12 CLA proportion can be also affected by high levels of concentrate in the diet.

Effects of dietary sources of vegetable fats on performance of dairy ewes and conjugated linoleic acid (CLA) in milk

Two experiments were carried out to study the effects of supplementing the ration of lactating ewes with vegetable fats (sunflower oil, SO or hydrogenated palm oil, HPO; HIDROPALM ®) on diet digestibility, milk yield and milk composition, and on the concentration of the conjugated linoleic acid (CLA) C18:2 cis-9 trans-11 and C18:1 trans-11 (vaccenic acid, VA) and other main fatty acids in milk fat. Treatments involved a control diet, without added oil, and 2 diets supplemented with either 12 g/kg SO or 12 g/kg HPO on a dry matter (DM) basis. In the first experiment, 6 non-pregnant, non-lactating Lacaune ewes were used following a 3 × 3 replicated Latin Square design. Addition of vegetable fat supplement to the diet increased digestibility of DM, organic matter (OM) and crude protein (CP), but did not affect that of the ether extract (EE), neutral detergent fibre (NDF) or acid detergent fibre (ADF). In the second experiment, 60 Lacaune dairy ewes mid-way through lactation (120 ± 12 days in milk, 0.98 ± 0.03 kg/day average milk yield) were divided into three equal-sized groups each of which was assigned to one of the three experimental diets for 4 weeks. Compared with the control treatment, supplementation with HPO increased milk yield and energy-corrected milk. But neither vegetable fat supplement modified percentages of fat and protein in milk. Supplementation with HPO increased C14:1, C16:1 and C16:0 content and reduced C18:0 and C18:1 cis-9 content in milk fat. Supplementation with SO increased the VA content in milk fat by 36% and that of cis-9 trans-11 CLA by 29% in comparison with the control diet. Supplementation with HPO led to milk fat with 15% more cis-9 trans-11 CLA than control milk. In conclusion, adding a moderate dose of HPO or SO to the diets increased CLA concentration in milk fat. Nevertheless, supplementation with SO was more effective than HPO in increasing CLA concentration in milk fat and reducing the atherogenicity index, improving milk quality from the human health standpoint.

Effects of a potato pulp silage supplement on the composition of milk fatty acids when fed to grazing dairy cows

This study was completed to determine the effects of potato pulp silage (PPS) as a diet supplement on the composition of milk fatty acids in grazing dairy cows in comparison to a barley grain supplement. Eight late lactation Holstein dairy cows were fed grazing based diets supplemented with 150 g/kg of PPS (‘PPS’) as a substitute for barley (‘barley’), and grazed on 4.3 ha swards, mainly containing orchard grass, for 56 days. Total dry matter (DM) and pasture DM intake and milk yields, as well as milk composition, did not differ between treatments. The linolenic acid intake did not differ (329 g/day vs. 323 g/day DM). The trans11C18:1vaccenic acid (VA) concentration in blood was higher in cows fed PPS (2.4 g/100 g FA) compared to those fed barley (1.9 g/100 g FA). There were no differences between treatments in the cis9 trans11conjugated linoleic acid (CLA) concentration in blood. The short-chain and medium-chain fatty acids in milk also did not differ between treatments. The VA concentration in milk was increased in cows fed PPS (2.32 g/100 g FA) compared to those fed barley (1.84 g/100 g FA), and CLA was higher in cows fed PPS (1.25 g/100 g FA) than those fed barley (0.95 g/100 g FA). Milk CLA concentration was positively correlated to blood VA concentration. Results suggest that an increase in milk CLA concentration is related to an increase of the VA concentration in blood by Δ 9-desaturase in mammary glands in the PPS fed compared to barley fed groups.

Isomerisation of cis-9 trans-11 conjugated linoleic acid (CLA) to trans-9 trans-11 CLA during acidic methylation can be avoided by a rapid base catalysed methylation of milk fat

This study investigated the evolution of trans-9 trans-11 conjugated linoleic acid (CLA) from cis-9 trans-11 CLA during methylation and its avoidance through a rapid base methylation of milk fat. The study examined three conditions shown to result in loss of cis-9 trans-11 CLA during methylation namely: temperature, methylation time, water contamination in old reagents and acidic conditions. Three techniques currently used for the conversion of milk fat into fatty acid methyl esters for analysis of CLA content by gas liquid chromatography and a fourth procedure designed to eliminate acidic conditions and to limit methylation temperature and time were used. The four methods were: (i) acidic methylation (AM); (ii) acidic and basic bimethylation with fresh reagents (FBM); (iii) acidic and basic bimethylation with pre-prepared reagents (PBM) and (iv) basic methylation (BM). Each regime was carried out on six milk samples over two periods and methylated 1 ml freeze-dried milk (n=12 per regime). Total CLA was not different across methylation regimes (0.30 mg/ml). Isomer cis-9 trans-11 was higher (P<0.01) with BM than the other regimes and lowest with AM: 21.2, 17.8, 18.8 and 14.7 mg/100 ml for BM, FBM, PBM and AM, respectively. The inverse relationship was shown for trans-9 trans-11 with higher (P<0.001) amounts with AM than the other regimes and lowest with BM: 0.57, 2.55, 2.36 and 3.69 mg/100 ml for BM, FBM, PBM and AM, respectively. The trans-10 cis-12 isomer was also shown to alter with methylation procedure being higher (P<0.001) with AM than the other regimes: 0.43, 0.47, 0.29 and 1.20 mg/100 ml for BM, FBM, PBM and AM, respectively. Validation with known CLA free fatty acid and triacylglycerol standards confirmed that AM resulted in conversion of cis-9 trans-11 to trans-9 trans-11, and also elevated trans-10 cis-12 whilst BM of triacylglycerol CLA did not isomerise cis-9 trans-11 and was comparable to FBM.