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© 2007 American Society for Nutrition J. Nutr. 137:1154-1160, May 2007

Nutrient Physiology, Metabolism, and Nutrient-Nutrient Interactions

Transfer of Absorbed cis-9, trans-11 Conjugated Linoleic Acid into Milk Is Biologically More Efficient than Endogenous Synthesis from Absorbed Vaccenic Acid in Lactating Cows1–3,

Kevin J. Shingfield*, Seppo Ahvenjärvi, Vesa Toivonen, Aila Vanhatalo4 and Pekka Huhtanen

Animal Production Research, MTT Agrifood Research Finland, Jokioinen, FIN 31600, Finland

* To whom correspondence should be addressed. E-mail: kevin.shingfield{at}mtt.fi.


   ABSTRACT
TOP
 ABSTRACT
Introduction
 Material and Methods
 Results
 Discussion
 LITERATURE CITED
 
Cis-9, trans-11, the major isomer of conjugated linoleic acid (CLA) in bovine milk fat, is derived from ruminal biohydrogenation of 18:2 (n-6) and endogenous conversion of trans-11 18:1 (vaccenic acid; VA) in the mammary gland. Most evidence to date suggests that endogenous synthesis is the major source of cis-9, trans-11 CLA, but the extent of VA desaturation is less well defined. Four lactating cows were used in consecutive 4 x 4 Latin squares to examine changes in milk fatty acid composition and secretion in response to abomasal infusions of lipid supplements enriched with cis-9, trans-11 CLA (88.8%) or VA (29.4%). Treatments were infused over 4-d, followed by a 3-d washout, during 7 d experimental periods and administered to deliver 0, 3, 6, and 12 g cis-9, trans-11 CLA/d (Expt. 1) or 0, 7.5, 15 and 30 g VA/d (Expt. 2). Infusions of cis-9, trans-11 CLA increased linearly milk cis-9, trans-11 CLA concentrations from 0.68 to 1.46 g/100 g fatty acids. Abomasal infusions of VA increased linearly milk VA and cis-9, trans-11 CLA content from 1.22 to 2.72 and 0.61 to 1.24 g/100 g fatty acids, respectively. Changes in milk fatty acid secretion indicated that 28.9% of VA was converted to cis-9, trans-11 CLA. Results provide evidence that conversion by {Delta}9-desaturase to cis-9, trans-11 CLA in the lactating cow is independent of postruminal VA supply. In conclusion, endogenous synthesis via VA was equivalent to ~21% of the response to increases in cis-9, trans-11 CLA available for absorption.


   Introduction
TOP
 ABSTRACT
 Introduction
Material and Methods
 Results
 Discussion
 LITERATURE CITED
 
Isomers of conjugated linoleic acid (CLA)5 have been shown to exhibit a wide range of physiological properties in cell culture and biomedical studies with the potential to improve long-term human health (1–3). Ruminant derived foods are the major sources of CLA in the human diet with the cis-9, trans-11 isomer accounting for between 75–90% of the total CLA in milk and dairy products (4).

The relatively high abundance of CLA in ruminant milk and meat originates from biohydrogenation of dietary lipids in the rumen. Ruminant diets are relatively rich in 18:2(n-6) and 18:3(n-3), which are extensively, but not completely, metabolized to 18:0 by rumen bacteria. The major pathway of 18:2(n-6) metabolism in the rumen involves the formation of cis-9, trans-11 CLA as an initial intermediate that is subsequently reduced to trans-11 18:1 [vaccenic acid (VA)] (5). Ruminal metabolism of 18:3(n-3) does not lead to the formation of cis-9, trans-11 CLA, but does result in VA being produced as a major intermediate (5). Following observations that feeding cows oils rich in 18:3(n-3) increased milk fat CLA content, it was proposed that endogenous synthesis in the mammary gland using VA as a substrate could be an important source of cis-9, trans-11 CLA (6).

Several approaches have been used to estimate the contribution of endogenous cis-9, trans-11 CLA synthesis in the lactating cow. These have involved postruminal infusions of sterculic oil to inhibit the {Delta}9-desaturase enzyme and measuring the changes in milk fatty acid composition (7–9) or comparison of the flow of cis-9, trans-11 CLA at the duodenum (10) or omasum (11) and secretion of this isomer of CLA in milk. Whereas these studies have provided clear evidence that endogenous synthesis is quantitatively the most important source of milk fat cis-9, trans-11 CLA, such experiments do not provide an estimate of VA desaturation in the mammary gland. Measurements of milk fatty acid composition responses to postruminal infusions of VA provided the 1st evidence of VA being a substrate for endogenous cis-9, trans-11 CLA synthesis in the bovine (7). More recent work using trace amounts of 13C-labeled VA confirmed that the mammary gland is the major site of endogenous cis-9, trans-11 CLA synthesis in the lactating cow (12). However, earlier experiments assessed responses to exogenous VA at one level of administration over a short interval (7) and it remains unclear if desaturation to cis-9, trans-11 CLA in the mammary gland varies according to VA supply.

A close linear relation is known to exist between VA and cis-9, trans-11 CLA content in bovine (6,13) and caprine milk (14). A relatively constant product to substrate ratio of ~0.4 can be interpreted in 1 of 2 ways: {Delta}9-desaturase activity and endogenous synthesis of cis-9, trans-11 CLA is constant, irrespective of VA supply, or that incremental increases in milk fat cis-9, trans-11 CLA content are associated with a progressive reduction in VA desaturation and concomitant increase in the contribution of ruminal synthesis to milk fat cis-9, trans-11 CLA. However, direct experimental evidence reporting the relative value of VA and cis-9, trans-11 CLA leaving the rumen as substrates for cis-9, trans-11 CLA secretion in bovine milk is lacking.

The objectives of this study were to directly compare the transfer efficiency of VA and cis-9, trans-11 CLA from the abomasum into milk and estimate the conversion of VA to cis-9, trans-11 CLA in lactating cows.


   Material and Methods
TOP
 ABSTRACT
 Introduction
 Material and Methods
Results
 Discussion
 LITERATURE CITED
 
    Cows and experimental design. All experimental procedures were approved by the Animal Experiment Committee of MTT Agrifood Research Finland in accordance with the 1985 Use of Vertebrates for Scientific Purposes Act. Four rumen fistulated multiparous cows (192 ± 11.4 d postpartum; mean ± SD) were used in 2 consecutive experiments to evaluate the effects of postruminal infusions of cis-9, trans-11 CLA (Expt. 1) and VA (Expt. 2). Cows were randomly assigned to 4 x 4 Latin Squares in both experiments. Treatments consisted of abomasal infusions of (5 kg/d) of skim milk (control) or lipid supplements emulsified in skim milk providing 0, 3, 6, and 12 g/d of cis-9, trans-11 CLA (Expt. 1) or 0, 7.5, 15.0 and 30.0 g/d of VA (Expt. 2). Commercially prepared mixtures of nonesterified fatty acids (Natural ASA) were used due to availability and cost. The cis-9, trans-11 CLA preparation was relatively pure, whereas the lipid supplement used in Expt. 2 was comprised of VA and trans-12 18:1 as major constituents, but also contained ~25% of total fatty acids as cis-11 and cis-12 18:1 in equal amounts and as by-products of chemical synthesis (Table 1). Stock emulsions were prepared immediately before each infusion period by mixing 93.5 or 700 g of the CLA or VA enriched lipid supplement, respectively, with 28 kg of preheated skim milk (55°C) and passage through a 2-step homogenizer (Flow-Sheet HTST, Frautech) at 5 and 17 MPa, respectively. The resultant emulsions were pasteurized at 72°C for 15 s, cooled, and stored at 4°C before being diluted daily with skim milk to prepare experimental treatments. Treatments were administered into the abomasum by means of polyamide tubing (i.d. 4 mm) that passed through the rumen fistula and reticulo-omasal orifice and a peristaltic pump (Watson-Marlow) calibrated to deliver 5 kg of infusate/d. Infusions started at 0800 h and lasted for 4 d with a 3-d interval between infusion periods to minimize treatment carry-over effects.


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  		TABLE 1 Fatty acid composition of lipid supplements used as a source of trans-11 18:1 and cis-9, trans-11 CLA1

 
    Sampling and analysis. During both experiments, cows were housed in individual stalls in a dedicated metabolism unit with continuous access to water and fed, ad libitum, a diet (Table 2) formulated to meet or exceed nutrient requirements (15). Individual cow intakes and milk yields were measured daily. Representative samples of fresh diets and feed refusals were collected daily and composited for each infusion period. Chemical composition and nutritive value of experimental feeds was determined using reference methods (16). Cows were milked twice daily at 0700 and 1700 h. Samples of milk for the determination of fat, crude protein, and lactose were collected from each cow at each milking 24 h before and throughout the 96-h infusion period. Milk samples treated with Bronopol preservative were analyzed for milk fat, crude protein, and lactose by near infrared analysis (16). Untreated samples of milk were also obtained, composited according to yield for each 24 h of infusion, and stored at –20°C until submitted for fatty acid determinations. Samples of lipid supplements and experimental infusions were also collected and submitted for fatty acid analysis.


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  		TABLE 2 Ingredient and chemical composition of the experimental diet

 
    Lipid analysis. Lipid in 1 mL of milk was extracted using diethylether/hexane and transesterified to fatty acid methyl esters (FAME) using freshly prepared methanolic sodium methoxide (17) as outlined previously (11). The same extraction procedures were applied to samples of infused emulsions. Fatty acids in CLA- and VA-enriched preparations and samples of infused emulsions were converted to FAME using 1% (v:v) sulphuric acid in methanol at 50°C for 30 min (18). Fatty acid content of emulsions was determined using tridecanoic acid (N-13A; Nu-Chek-Prep) as an internal standard. Methyl esters were quantified by GLC using a gas chromatograph fitted with a 100-m fused silica capillary column (CP-SIL 88; Chrompack 7489) and hydrogen as the carrier gas. Total FAME profile in a 2 µL sample volume at a split ratio of 1:50 was determined using a temperature gradient program (11). Individual isomers of 18:1 and 18:2 were further resolved in a separate analysis under isothermal conditions at 170°C (11). Peaks were identified using authentic standards and GC-MS analysis of FAME (11). Methyl esters not contained in commercially available standards were formally identified by GC-MS analysis of 4,4-dimethyloxazoline fatty acid derivatives prepared from FAME in lipid supplements and selected samples of milk (19,20). The distribution of CLA isomers in lipid supplements and milk was determined by HPLC using 4 silver impregnated silica columns (ChromSpher 5 Lipids, 250 x 4.6 mm; 5 µm particle size, Varian) coupled in series using 0.1% (v:v) of acetonitrile in heptane (11,21) as the mobile phase.

    Statistical analysis. Dry matter intake, milk yield, and composition data were analyzed by ANOVA for a 4 x 4 Latin Square design with a statistical model that included the random effect of cow and fixed effect of period and treatment using the mixed procedure of SAS (version 8.2, SAS Institute). Measurements of milk fatty acid composition were analyzed by repeated measures ANOVA using a model that included the fixed effect of period, treatment, time, and their interaction and random effects of cow assuming an auto regressive order one covariance structure fitted on the basis of Akaike Information and Schwarz Bayesian model-fit criteria. Sums of squares for treatment effects were further separated into orthogonal contrasts to evaluate the significance of linear and quadratic components of the response to treatments. Values are means ± SEM, and effects were declared significant at P < 0.05.


   Results
TOP
 ABSTRACT
 Introduction
 Material and Methods
 Results
Discussion
 LITERATURE CITED
 
    Expt. 1. Treatments supplied 2.96 ± 0.002, 5.92 ± 0.003, and 11.83 ± 0.011 g cis-9, trans-11 CLA/d, respectively. Postruminal infusions of CLA had no effect (P > 0.10) on dry matter intake, milk yield, or composition (Supplemental Table 1). Infusions decreased (P < 0.01) milk 16:0 and 22:0 concentrations linearly and increased milk cis-9, trans-11 CLA, total CLA, and 18:3(n-3) content (Table 3), but had only minor effects on milk 18:1 composition (Supplemental Table 2). Furthermore, abomasal infusions also enhanced linearly (P < 0.01) milk fat trans-9, cis-11 CLA, trans-10, cis-12 CLA and trans-9, trans-11 CLA concentrations, minor isomers contained in the infused lipid supplement (Supplemental Table 3). Increases in milk fat cis-9, trans-11 CLA concentrations in response to postruminal infusions varied over time, reaching a maximum by d 3 (Fig. 1). Measurements of milk fatty acid composition on d 4 indicated that infused cis-9, trans-11 CLA was transferred into milk with a mean efficiency of 39.8 ± 3.26% (Fig. 2).


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  		TABLE 3 Effect of abomasal infusion of conjugated linoleic acid on milk fatty acid composition in lactating cows1

 

Figure 1
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  		FIGURE 1  Temporal pattern of the incorporation of cis-9, trans-11 CLA into milk fat of lactating cows receiving abomasal infusions of 0, 3, 6, or 12 g cis-9, trans-11 CLA/d. Values are means ± SEM = 0.091 g/110 g fatty acids, n = 4.

 

Figure 2
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  		FIGURE 2  Secretion of cis-9, trans-11 CLA in milk of lactating cows receiving abomasal infusions of cis-9, trans-11 CLA. Values are means, n = 4, on d 4 of infusion.

 
    Expt. 2. Due to availability and cost a commercially available lipid supplement was used as a source of VA. This material also contained approximately the same amount of trans-12 18:1 that also serves as a substrate for {Delta}9-desaturase. Postruminal infusions supplied 7.35 ± 0.005, 14.7 ± 0.010, and 29.4 ± 0.023 g trans-11 18:1 and 7.14 ± 0.004, 14.3 ± 0.009, and 28.5 ± 0.022 g trans-12 18:1/d. Treatments tended (P = 0.06) to decrease dry matter intake, but had no effect (P > 0.10) on milk yield or milk fat, protein, or lactose content (Supplemental Table 4).

Infusions of a mixture of fatty acids containing VA altered milk fatty acid composition, changes that were characterized as linear decreases (P < 0.05) in the concentrations of 8:0, 10:0, 12:0, 14:0 and 16:0 synthesized de novo, reductions in 15:0 and 17:0 and concomitant increases (P < 0.05) in milk fat VA, trans-12 18:1, cis-9, trans-12 18:2, cis-9, trans-13 18:2, cis-9, trans-11 CLA, and total CLA content (Table 4). Treatments also resulted in linear or quadratic increases in the concentrations of cis-11 and cis-12 18:1 (Supplemental Table 5), trans-9, cis-11 CLA, trans-7, trans-9 CLA, and trans-8, trans-10 CLA (Supplemental Table 6). Infusions increased the appearance of VA and trans-12 18:1 and their respective {Delta}9-desaturase products cis-9, trans-11 CLA, and cis-9, trans-12 18:2 in milk within 1 d, with concentrations reaching a maximum by d 3 of infusion (Fig. 3).


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  		TABLE 4 Effect of abomasal infusion of a mixture of 18:1 fatty acids on milk fatty acid composition in lactating cows1

 

Figure 3
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  		FIGURE 3  Temporal pattern of the incorporation of trans-11 18:1 (A), trans-12 18:1 (B), cis-9, trans-11 CLA (C) and cis-9, trans-12 18:2 (D) into milk fat (g/100 g fatty acids) of lactating cows receiving abomasal infusions of a mixture of fatty acids providing 0, 7.5, 15.0, and 30.0 g/d of trans-11 18:1 and trans-12 18:1. Values are means ± pooled SEM = 0.082, 0.057, 0.059 and 0.007 g/100 g fatty acids for trans-11 18:1, trans-12 18:1, cis-9, trans-11 CLA and cis-9, trans-12 18:2, respectively, n = 4.

 
The lipid supplement used as a source of VA also contained minor amounts of cis-9, trans-11 CLA (Table 1). Using the efficiency of transfer determined in Expt. 1 to account for the contribution of cis-9, trans-11 CLA from infusions and measurements of milk fatty acid secretion on d 4 of infusion, indicated that 20.4 ± 0.88% and 8.2 ± 1.07% of infused VA was recovered as VA and cis-9, trans-11 CLA in milk, respectively (Fig. 4). Infused VA was transferred from the abomasum into milk with a mean efficiency of 28.6 ± 1.85%. Apparent transfer of trans-12 18:1 was marginally higher (33.7 ± 2.64%) than that of VA, with 31.7 ± 2.51% and 2.0 ± 0.14% of infused trans-12 18:1 being recovered in milk as trans-12 18:1 and cis-9, trans-12 18:2, respectively (Fig. 4). Comparison of the relation between product vs. substrate + product for {Delta}9-desaturase indicated that 28.9 ± 2.01% of VA and 5.9 ± 0.10% of trans-12 18:1 was desaturated to cis-9, trans-11 CLA and cis-9, trans-12 18:2, respectively, with evidence that the extent of the conversion was independent of the amount of fatty acid substrate infused (Fig. 5).


Figure 4
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  		FIGURE 4  Secretion of trans-11 18:1 and cis-9, trans-11 CLA (A), or trans-12 18:1 and cis-9, trans-12 18:2 (B) in milk of lactating cows receiving abomasal infusions of a mixture of fatty acids containing trans-11 18:1 and trans-12 18:1. Values are means, n = 4, determined on d 4 of infusion.

 

Figure 5
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  		FIGURE 5  Relation between the secretion of cis-9, trans-11 CLA vs. trans-11 18:1 + cis-9, trans-11 CLA (A) and cis-9, trans-12 18:2 vs. trans-12 18:1 + cis-9, trans-12 18:2 (B) in milk of cows receiving abomasal infusions of a mixture of fatty acids containing trans-11 18:1 and trans-12 18:1. Values are means, n = 4, determined on d 4 of infusion.

 

   Discussion
TOP
 ABSTRACT
 Introduction
 Material and Methods
 Results
 Discussion
LITERATURE CITED
 
Previous research has examined endogenous synthesis of cis-9, trans-11 CLA via action of the {Delta}9-desaturase enzyme system on VA in a number of species including rats, mice, pigs, humans, and ruminants (4). Several studies provided data allowing endogenous cis-9, trans-11 CLA synthesis in lactating (7–12) and growing ruminants (22) to be estimated. The present work served to extend these findings by comparing the desaturation of infused VA to cis-9, trans-11 CLA relative to the transfer of cis-9, trans-11 CLA from the abomasum into milk in lactating cows.

Abomasal infusion of cis-9, trans-11 CLA had no effect on dry matter intake, milk yield, or milk composition consistent with earlier studies examining responses to postruminal infusions of mixture of CLA isomers (23,24) or relative pure preparations of cis-9, trans-11 CLA (25,26). As expected, postruminal infusions of a lipid supplement enriched with cis-9, trans-11 CLA enhanced milk fat cis-9, trans-11 CLA concentration over time in a linear dose-dependent manner, responses that were associated with a mean apparent transfer efficiency of 39.8%. Earlier studies have reported that cis-9, trans-11 CLA is transferred from the abomasum with a mean efficiency of 33.5% (23) and 34.1% (25) in lactating cows. A much lower recovery of 16% has been reported in cows infused with 15 g cis-9, trans-11 CLA/d over a 48-h interval (26), indicating that infusions of at least 72 h are required to accurately determine the efficiency of transfer, as would be inferred based on the findings of the present experiment (Fig. 1). Flows of cis-9, trans-11 CLA and VA at the omasum (1.2 ± 0.17 and 14.5 ± 0.53 g/d, respectively) measured in all cows 14 d before the start of abomasal infusions coupled with the mean efficiency of transfer determined for cis-9, trans-11 CLA in Expt. 1, implied that 84.4 ± 2.45% of cis-9, trans-11 CLA in milk on the control treatments was derived from {Delta}9 desaturation of VA. This estimate is in good agreement with a value of 83% determined from the area under the curve analysis of 13C enrichment of VA and cis-9, trans-11 CLA in the milk of cows administered 13C-labeled VA at the abomasum (12). Studies utilizing postruminal infusions of cyclopropenes in sterculic oil to partially inhibit {Delta}9-desaturase activity in the mammary gland have also provided evidence that endogenous synthesis accounts for 64–91% of cis-9, trans-11 CLA in milk (7–9). Similarly, comparisons of the flow of cis-9, trans-11 CLA at the duodenum (10) or omasum (11) with the secretion of this isomer of CLA in milk also suggest that between 66 and 97% of cis-9, trans-11 CLA in milk is derived from endogenous sources. Overall, the current data confirm that desaturation of VA is the major source of cis-9, trans-11 CLA in bovine milk. However, the intercept of regressions of cis-9, trans-11 CLA output in milk against postruminal VA or cis-9, trans-11 CLA administration was higher than would be predicted based on measurements of fatty acid flow at the omasum and apparent transfer efficiencies of VA and cis-9, trans-11 CLA into milk. A higher than expected secretion of cis-9, trans-11 CLA in milk may be explained by {Delta}9-desaturase activity in tissues other than the mammary gland, including adipose and intestinal mucosa (4).

Infusion of VA over a 4-d period had no effect on milk fat content, consistent with earlier observations in cows administered 12.5 g VA/d over a 3-d period (7) but tended to decrease dry matter intake, an effect that may, at least in part, be mediated by increased secretion of glucagon-like peptide-1 amide in the small intestine (27). Administration of VA at the abomasum enhanced VA and cis-9, trans-11 CLA concentrations in milk and provides rather compelling evidence that VA is desaturated to cis-9, trans-11 CLA in lactating cows in a dose-dependent manner. The slope of the relation between product vs. product + substrate for {Delta}9-desaturase, based on the incorporation of these fatty acids in milk, indicated that 28.9% of VA was converted to cis-9, trans-11 CLA. Direct measurements of 13C enrichment in milk and plasma lipids of cows following abomasal administration of 1.5 g 13C-labeled VA have established that 25.7% of VA is desaturated in the bovine mammary gland (12). The close agreement of estimates of VA conversion to cis-9, trans-11 CLA across studies, despite the differences between individual animals, breeds, and experimental approaches, is consistent with the view that the action of {Delta}9-desaturase on VA to cis-9, trans-11 CLA is essentially constant under most conditions (6,12). A constancy of VA desaturation and in the transfer of cis-9, trans-11 CLA from the abomasum into milk would also account for the close linear relation between product and substrate for {Delta}9-desaturase observed for bovine (6,13) and caprine (14) milk fat.

Conversion of VA to cis-9, trans-11 CLA has also been demonstrated in several mammalian species. Determinations of carcass composition of mice fed pure VA indicated that, on average, 11.4% of VA in the diet was converted to cis-9, trans-11 CLA (28). Controlled intervention studies with human volunteers consuming VA have provided evidence that 19–24% of VA is desaturated to cis-9, trans-11 CLA (29,30).

The lipid preparation used as a source of VA also contained trans-12 18:1, which serves as a substrate for endogenous cis-9, trans-12 18:2 synthesis. Milk fat responses to infusions of trans-12 18:1 implied a mean 5.9% conversion to cis-9, trans-12 18:2 in the lactating cow. Comparison of the profile of fatty acids in omasal digesta (data not presented) and milk fat also indicated that the appearance of cis-9 15:1, cis-9 17:1, trans-7, cis-9 CLA, and cis-9, trans-13 18:2 in milk was derived exclusively via {Delta}-9 desaturase activity. Endogenous synthesis is known to be the major source of trans-7, cis-9 CLA in lactating cows (10,11,31,32).

The transfer of long-chain fatty acids into milk is dependent on the partitioning of absorbed fatty acids between chylomicrons and very-low–density lipoproteins vs. incorporation into cholesterol esters and phospholipids (33). Apparent transfer of cis-9, trans-11 CLA from the abomasum into milk was higher than VA, suggesting that these fatty acids are preferentially deposited into different plasma lipid fractions. In humans, cis-9, trans-11 CLA is readily incorporated into plasma phosphatidylcholine and cholesterol esters CE (34), whereas triacylglycerides and nonesterified fatty acids are the main repository in the lactating cow (12,26,35). In contrast, VA has, in some (12,36) but not all cases (37), been reported to be preferentially partitioned into phospholipids fractions of high-density lipoprotein phospholipids that have a low affinity with mammary lipoprotein lipase (38).

In conclusion, this study provided strong evidence that VA is desaturated to cis-9, trans-11 CLA in the lactating cow. Data also implied that conversion of VA to cis-9, trans-11 CLA was constant irrespective of postruminal VA supply. Overall, the relative value of VA as a substrate for cis-9, trans-11 CLA incorporation into milk fat was equivalent to ~21% of the response to abomasal cis-9, trans-11 CLA infusion.


   ACKNOWLEDGMENTS
 
The authors gratefully acknowledge and appreciate the assistance of Minna Aalto and Piia Kairenius during sample lipid analysis and the technical expertise of Tuomo Tupasela and Juha Lundström in preparing experimental treatments.


   FOOTNOTES
 
1 Supported by funding received from the European Union within the 5th framework program; Project QLK1-2002-02362, production of CLA-enriched products by natural means. Back

2 Author disclosure: K. J. Shingfield, no conflicts of interest; S. Ahvenjärvi, no conflicts of interest; V. Toivonen, no conflicts of interest; A. Vanhatalo, no conflicts of interest; and P. Huhtanen, no conflicts of interest. Back

3 Supplemental Tables 1–6 are available with the online posting of this paper at jn.nutrition.org. Back

4 Current address: Department of Animal Science, University of Helsinki, FIN 00014, Finland. Back

5 Abbreviations used: CLA, conjugated linoleic acid; FAME, fatty acid methyl ester; VA, vaccenic acid. Back

Manuscript received 7 November 2006. Initial review completed 4 December 2006. Revision accepted 19 February 2007.


   LITERATURE CITED
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 ABSTRACT
 Introduction
 Material and Methods
 Results
 Discussion
 LITERATURE CITED
 

1. Belury MA. Dietary conjugated linoleic acid in health: physiological effects and mechanisms of action. Annu Rev Nutr. 2002;22:505–31.[Medline]

2. Wahle KW, Heys SD, Rotondo D. Conjugated linoleic acids: are they beneficial or detrimental to health? Prog Lipid Res. 2004;43:553–87.[Medline]

3. Yaqoob P, Tricon S, Burdge GC, Calder PC. Conjugated linoleic acids (CLAs) and health. In: Improving the fat content of foods. Cambridge, UK: Woodhead Publishing Limited; 2006. p. 182–209.

4. Palmquist DL, Lock AL, Shingfield KJ, Bauman DE. Biosynthesis of conjugated linoleic acid in ruminants and humans. In: Advances in food and nutrition research, vol. 50. San Diego, CA: Elsevier Academic Press; 2005. p. 179–217.

5. Harfoot CG, Hazlewood GP. Lipid metabolism in the rumen. In: The rumen microbial ecosystem. London, UK: Elsevier Science; 1988. p. 285–322.

6. Griinari JM, Bauman DE. Biosynthesis of conjugated linoleic acid and its incorporation into meat and milk in ruminants. In: Advances in conjugated linoleic acid research, vol. 1. Champaign, IL: AOCS Press; 1999. p. 180–200.

7. Griinari JM, Corl BA, Lacy SH, Chouinard PY, Nurmela KVV, Bauman DE. Conjugated linoleic acid is synthesized endogenously in lactating dairy cows by delta-9-desaturase. J Nutr. 2000;130:2285–91.[Abstract/Free Full Text]

8. Corl BA, Baumgard LH, Dwyer DA, Griinari JM, Phillips BS, Bauman DE. The role of {Delta}9-desaturase in the production of cis-9, trans-11 CLA. J Nutr Biochem. 2001;12:622–30.[Medline]

9. Kay JK, Mackle TR, Auldist MJ, Thomson NA, Bauman DE. Endogenous synthesis of cis-9, trans-11 conjugated linoleic acid in dairy cows fed fresh pasture. J Dairy Sci. 2004;87:369–78.[Abstract/Free Full Text]

10. Piperova LS, Sampugna J, Teter BB, Kalscheur KF, Yurawecz MP, Ku Y, Morehouse KM, Erdman RA. Duodenal and milk trans octadecenoic acid and conjugated linoleic acid (CLA) isomers indicate that postabsorptive synthesis is the predominant source of cis-9-containing CLA in lactating dairy cows. J Nutr. 2002;132:1235–41.[Abstract/Free Full Text]

11. Shingfield KJ, Ahvenjärvi S, Toivonen V, Ärölä A, Nurmela KVV, Huhtanen P, Griinari JM. Effect of dietary fish oil on biohydrogenation of fatty acids and milk fatty acid content in cows. Anim Sci. 2003;77:165–79.

12. Mosley EE, Shafii B, Moate PJ, McGuire MA. Cis-9, trans-11 conjugated linoleic acid is synthesized directly from vaccenic acid in lactating dairy cattle. J Nutr. 2006;136:570–75.[Abstract/Free Full Text]

13. Chilliard Y, Ferlay A, Doreau M. Effect of different types of forages, animal fat or marine oils in cow's diet on milk fat secretion and composition, especially conjugated linoleic acid (CLA) and polyunsaturated fatty acids. Livest Prod Sci. 2001;70:31–48.

14. Chilliard Y, Ferlay A. Dietary lipids and forages interactions on cow and goat milk fatty acid composition and sensory properties. Reprod Nutr Dev. 2004;44:467–92.[Medline]

15. MTT Rehutaulukot ja ruokintasuositukset 2006. Märehitijät-siat-siipikarja-turkiseläimet-hevoset [Feed tables and feeding recommendations for ruminants, pigs, poultry, fur animals and horses]. [cited 2006 Jan]. Available from: http://agronet.fi/rehutaulukot

16. Shingfield KJ, Jaakkola S, Huhtanen P. Effects of level of nitrogen fertiliser application and various nitrogenous supplements on milk production and nitrogen utilization of dairy cows fed grass silage-based diets. Anim Sci. 2001;73:541–54.

17. Christie WW. A simple procedure for rapid transmethylation of glycerolipids and cholesteryl esters. J Lipid Res. 1982;23:1072–75.[Abstract]

18. Sæbø A, Sæbø P-C, Griinari JM, Shingfield KJ. Effect of abomasal infusions of geometric isomers of 10,12 conjugated linoleic acid on milk fat synthesis in dairy cows. Lipids. 2005;40:823–32.[Medline]

19. Shingfield KJ, Reynolds CK, Hervás G, Griinari JM, Grandison AS, Beever DE. Examination of the persistency of milk fatty acid composition responses to fish oil and sunflower oil in the diet of dairy cows. J Dairy Sci. 2006;89:714–32.[Abstract/Free Full Text]

20. Wasowska I, Maia M, Niedzwiedzka KM, Czauderna M, Ramalho Ribeiro JMC, Devillard E, Shingfield KJ, Wallace RJ. Influence of fish oil on ruminal biohydrogenation of C18 unsaturated fatty acids. Br J Nutr. 2006;95:1199–211.[Medline]

21. Shingfield KJ, Reynolds CK, Lupoli B, Toivonen V, Yurawecz MP, Delmonte P, Griinari JM, Grandison AS, Beever DE. Effect of forage type and proportion of concentrate in the diet on milk fatty acid composition in cows fed sunflower oil and fish oil. Anim Sci. 2005;80:225–38.

22. Palmquist DL, St-Pierre N, McClure KE. Tissue fatty acid profiles can be used to quantify endogenous rumenic acid synthesis in lambs. J Nutr. 2004;134:2407–14.[Abstract/Free Full Text]

23. Chouinard PY, Corneau L, Sæbø A, Bauman DE. Milk yield and composition during abomasal infusion of conjugated linoleic acids in dairy cows. J Dairy Sci. 1999;82:2737–45.[Abstract]

24. Perfield, II JW, Saebø A, Bauman DE. Use of conjugated linoleic acid (CLA) enrichments to examine the effects of trans-8, cis-10 CLA, and cis-11, trans-13 CLA on milk fat synthesis. J Dairy Sci. 2004;87:1196–202.[Abstract/Free Full Text]

25. Baumgard LH, Corl BA, Dwyer DA, Saebø A, Bauman DE. Identification of the conjugated linoleic acid isomer that inhibits milk fat synthesis. Am J Physiol Regul Integr Comp Physiol. 2000;278:R179–84.[Abstract/Free Full Text]

26. Loor JJ, Herbein JH. Reduced fatty acid synthesis and desaturation due to exogenous trans10, cis12-CLA in cows fed oleic or linoleic oil. J Dairy Sci. 2003;86:1354–69.[Abstract/Free Full Text]

27. Litherland NB, Thire S, Beaulieu AD, Reynolds CK, Benson JA, Drackley JK. Dry matter is decreased more by abomasal infusion of unsaturated free fatty acids than by unsaturated triglycerides. J Dairy Sci. 2005;88:632–43.[Abstract/Free Full Text]

28. Santora JE, Palmquist DL, Roehrig KL. Trans-vaccenic acid is desaturated to conjugated linoleic acid in mice. J Nutr. 2000;130:208–15.[Abstract/Free Full Text]

29. Turpeinen AM, Mutanen M, Aro A, Salminen I, Basu S, Palmquist DL, Griinari JM. Bioconversion of vaccenic acid to conjugated linoleic acid in humans. Am J Clin Nutr. 2002;76:504–10.[Abstract/Free Full Text]

30. Kuhnt K, Kraft J, Moeckel P, Jahreis G. Trans 11–18:1 is effectively {Delta}9-desaturated compared with trans 12–18:1 in humans. Br J Nutr. 2006;95:752–61.[Medline]

31. Yurawecz MP, Roach JAG, Sehat N, Mossoba MM, Kramer JKG, Fritsche J, Steinhart H, Ku Y. A new conjugated linoleic acid isomer, 7 trans, 9 cis-octadecadienoic acid, in cow milk, cheese, beef and human milk and adipose tissue. Lipids. 1998;33:803–9.[Medline]

32. Corl BA, Baumgard LH, Griinari JM, Delmonte P, Morehouse KM, Yurawecz MP, Bauman DE. Trans-7, cis-9 CLA is synthesized endogenously by {Delta}9-desaturase in dairy cows. Lipids. 2002;37:681–8.[Medline]

33. Christie WW. The effect of diet and other factors on the lipid composition of ruminant tissues and milk. In: Lipid metabolism in ruminant animals. Oxford, UK: Pergamon Press; 1981. p. 193–226.

34. Burdge GC, Lupoli B, Russell JJ, Tricon S, Kew S, Banerjee T, Shingfield KJ, Beever DE, Grimble RF, et al. 2004. Incorporation of cis-9, trans-11 or trans-10, cis-12 conjugated linoleic acid into plasma and cellular lipids in healthy men. J Lipid Res. 2004;45:736–41.[Abstract/Free Full Text]

35. Loor JJ, Herbein JH. Exogenous conjugated linoleic acid isomers reduce bovine milk fat concentration and yield by inhibiting de novo fatty acid synthesis. J Nutr. 1998;128:2411–19.[Abstract/Free Full Text]

36. Offer NW, Speake BK, Dixon J, Marsden M. Effect of fish-oil supplementation on levels of (n-3) poly-unsaturated fatty acids in the lipoprotein fractions of bovine plasma. Anim Sci. 2001;73:523–31.

37. Loor JJ, Herbein JH, Polan CE. Trans 18:1 and 18:2 isomers in blood plasma and milk fat of grazing cows fed a grain supplement containing solvent-extracted or mechanically extracted soybean meal. J Dairy Sci. 2002;85:1197–207.[Abstract]

38. Olivecrona T, Bengtsson-Olivecrona G. Milk lipoprotein lipase. In: Lipoprotein lipase. Chicago: Evener; 1987. p. 15–58.




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