Dose Response of Milk Fat to Intravenous Administration of the trans-10, cis-12 Isomer of Conjugated Linoleic Acid

The Ruminal Microbiome Alterations Associated with Diet-Induced Milk Fat Depression and Milk Fat Globule Size Reduction in Dairy Goats

The aim of this study was to evaluate the effect of conjugated linoleic acid (CLA) on milk fat globule (MFG) size and the ruminal microbiome of goats. Twenty-four mid-lactation Saanen dairy goats weighing 49 ± 4.5 kg (168 ± 27 d in milk, 1.2 ± 0.1 kg milk/d, 2-3 years old) were randomly divided into four groups-a control (CON) group, which was fed a basal diet, and three CLA supplementation groups, in which 30 g CLA (low-dose group, L-CLA), 60 g CLA (medium-dose group, M-CLA), or 90 g CLA (high-dose group, H-CLA) was added to the basal diet daily. The experiment lasted for 21 days, during which time goat milk was collected for composition and MFG size analysis. On day 21 of feeding, ruminal fluid was collected from the CON and H-CLA groups for analysis of the changes in microorganismal abundance. The results showed that CLA supplementation did not affect milk production, milk protein, or lactose content in the dairy goats (p > 0.05), but significantly reduced the milk fat content (p < 0.01) compared with the CON group. The CLA supplementation significantly decreased the D[3,2] and D[4,3] of the MFGs in a dose-dependent manner (p < 0.01). Moreover, dietary CLA inclusion increased the proportion of small-sized MFGs and decreased that of large-sized ones. The results of 16S rRNA gene sequencing showed that CLA-induced milk fat depression in dairy goats was accompanied by significant changes in the relative abundance of ruminal bacterial populations, most of which belonged to the Firmicutes and Bacteroidetes phyla. The relative abundance of Rikenellaceae_RC9_gut_group and Prevolellaceae_UCG-003 in Bacteroidetes and UCG-002, Succiniclasticum, and norank_f__norank_o__Clostridia_vadinBB60_group in Firmicutes was significantly higher in the CON group than in the H-CLA group. In contrast, the relative abundance of norank_f__UCG-011, norank_f_Eubacterium_coprostanoligenes_group, unclassified_f__Lachnospiraceae, and UCG-001 in Firmicutes and norank_f__Muribaculaceae in Bacteroidetes was significantly higher in the H-CLA group than in the CON group. Correlation analysis showed that the milk fat content was negatively correlated with the relative abundance of some bacteria, including members of Firmicutes and Bacteroidetes. Similarly, MFG size (D[3,2] and D[4,3]) was negatively correlated with several members of Firmicutes and Bacteroidetes, including Lachnospiraceae, norank_f__UCG-011, UCG-001, norank_f__Eubacterium_coprostanoligenes_group (Firmicutes), and norank_f__Muribaculaceae (Bacteroidetes), while positively correlated with the relative abundance of some members of Firmicutes and Bacteroidetes, including Mycoplasma, Succiniclasticum, norank_f__norank_o__Clostridia_vadinBB60_group, UCG-002 (Firmicutes), and Rikenellaceae_RC9_gut_group (Bacteroidetes). Overall, our data indicated that CLA treatment affected milk fat content and MFG size in dairy goats, and these effects were correlated with the relative abundance of ruminal bacterial populations. These results provide the first evidence to explain the mechanism underlying diet-induced MFG from the perspective of the ruminal microbiome in dairy goats.

Short communication: A decrease in diameter of milk fat globules accompanies milk fat depression induced by conjugated linoleic acid supplementation in lactating dairy cows

Milk fat is secreted from the mammary gland in the form of milk fat globules (MFG). Although milk fat depression has been studied since the beginning of the last century, the extent to which this phenomenon alters MFG synthesis is not fully understood. The aim of this study was to evaluate the effect of conjugated linoleic acid (CLA) on the size and distribution of MFG during milk fat depression in dairy cows. Twelve Holstein cows in mid lactation (145 ± 31 d in milk, 583 ± 34.6 kg of body weight, and 27.2 ± 2.4 kg of milk/d) were randomly assigned to a control diet or control plus Ca-protected CLA at 15 g/kg of dry matter for a 6-d period. The average diameter and particle size distribution of MFG were measured using a Mastersizer 3000 laser particle size analyzer (Malvern Instruments Ltd., Malvern, UK). Feeding CLA did not affect dry matter intake (16.2 ± 0.4 kg/d), milk production (28.4 ± 0.4 kg/d), milk protein, or lactose, but it decreased milk fat content (3.46 vs. 2.52%). In addition, surface area-related mean diameter of fat globules in cows fed CLA was lower compared with controls (3.02 vs. 3.45 μm). The percentage of large fat globules decreased and that of small fat globules increased in response to CLA. Overall, the data suggest that the milk fat depression induced by CLA is accompanied by a decrease in average diameter of MFG.

Effect of ruminal administration of soy sauce oil on rumen fermentation, milk production and blood parameters in dairy cows

Objective

To evaluate soy sauce oil (a by-product of making whole soybean soy sauce) as a new dietary lipid source, a large amount of soy sauce oil was administered into the rumen of dairy cows.

Methods

Four Holstein dairy cows fitted with rumen cannulae were used in a 56-day experiment. Ruminal administration of soy sauce oil (1 kg/d) was carried out for 42 days from day 8 to day 49 to monitor nutritional, physiological and production responses.

Results

Dry matter intake and milk yield were not affected by soy sauce oil administration, whereas 4% fat-corrected milk yield and the percentage of milk fat decreased. Although ruminal concentration of total volatile fatty acids (VFA) and the proportion of individual VFA were partially affected by administration of soy sauce oil, values were within normal ranges, showing no apparent inhibition in rumen fermentation. Administration of soy sauce oil decreased the proportions of milk fatty acids with a carbon chain length of less than 18, and increased the proportions of stearic, oleic, vaccenic and conjugated linoleic acids. Conjugated linoleic acid content in milk became 5.9 to 8.8 times higher with soy sauce oil administration. Blood serum concentrations of non-esterified fatty acid, 3-hydroxybutyric acid, total cholesterol, free cholesterol, esterified cholesterol, triglyceride and phospholipid increased with administration of soy sauce oil, suggesting a higher energy status of the experimental cows.

Conclusion

The results suggest that soy sauce oil could be a useful supplement to potentially improve milk functionality without adverse effects on ruminal fermentation and animal health. More detailed analysis is necessary to optimize the supplementation level of this new lipid source in feeding trials.

Does trans-10, cis-12 conjugated linoleic acid affect the intermediary glucose and energy expenditure of dairy cows due to repartitioning of milk component synthesis?

The overall goal of this study was to evaluate if intermediary energy metabolism of cows fed with trans-10, cis-12 conjugated linoleic acid (CLA) was modified such that milk-energy compounds were produced with less intermediary energy expenditure as compared to control cows. Published data on supplemented CLA were assembled. The extent was calculated to which the trans-10, cis-12 CLA isomer has an impact on glucose and energy conversion in the mammary gland by modifying glucose equivalent supply and energy required for fatty acid (FA) and fat synthesis, and if this will eventually lead to an improved glucose and energy status of CLA-supplemented high-yielding dairy cows. A possible relationship between CLA supplementation level and milk energy yield response was also studied. Calculations were conducted separately for orally and abomasally administered CLA and based on energy required for supply of glucose equivalents, i.e. lactose, glycerol and NADPH2. Further, modifications of milk FA profile due to CLA supplementation were considered when energy expenditures for FA and fat synthesis were quantified. Differences in yields between control and CLA groups were transformed into glucose energy equivalents. Only abomasal infusion (r2 = 0·31) but not oral CLA administration (r2 = 0·11) supplementation to dairy cow diets resulted in less glucose equivalent energy. Modifications of milk FA profiles also saved energy but the relationship with CLA supplementation was weaker for abomasal infusion (r2 = 0·06) than oral administration (r2 = 0·38). On average, 10 g/d of abomasally infused trans-10, cis-12 CLA saved 1·1 to 2·3 MJ net energy expressed as glucose equivalents, whereas both positive and negative values were observed when the trans-10, cis-12 CLA was fed to the cows.

This study revealed a weak to moderate dose-dependent relationship between the amount of trans-10, cis-12 CLA administered and the amount of energy in glucose equivalents and energy for the synthesis of milk fat conserved from milk ingredient synthesis. Because abomasal infusion of the trans-10, cis-12 CLA more consistently conserved energy in glucose equivalents compared with oral CLA intake, rumen protection of the fed CLA products appears incomplete. Milk fat synthesis showed an energy saving with a weak dose-dependent relationship when CLA was supplemented orally or by abomasal infusion.

Conjugated linoleic acid synthesis-related protein proteasome subunit α 5 (PSMA5) is increased by vaccenic acid treatment in goat mammary tissue

This study was conducted to identify proteins associated with the endogenous synthesis of conjugated linoleic acid (CLA) from trans-vaccenic acid (TVA; trans-11 C18:1, a precursor for CLA endogenous synthesis) in mammary tissues. Six lactating goats were divided into 2 groups. One group was given an intravenous bolus injection of TVA (150mg) twice daily over 4 d; the other group received saline injections. Treatment with TVA increased the concentration of cis-9,trans-11 CLA and TVA in goat milk. Additionally, TVA treatment increased the expression of stearoyl-CoA desaturase (SCD) in mammary tissue. Using 2-dimensional gel electrophoresis and electrospray ionization quadrupole time-of-flight mass spectrometry, 3 proteins affected by infusions of TVA were identified. Proteasome (prosome, macropain) subunit α type 5 (PSMA5) was upregulated, whereas peroxiredoxin-1 and translationally controlled tumor protein 1 were downregulated in TVA-treated animals compared with the vehicle-injected controls. Only the effect of TVA on PSMA5 could be confirmed by Western blot analysis. To further explore the regulation of PSMA5 in mammary epithelial cells when TVA is converted into CLA, we used a differentiated bovine mammary epithelial cell line treated with TVA for 6h. Changes in cis-9,trans-11 CLA concentrations and mRNA expression patterns of both SCD and PSMA5 were monitored. The concentration of cis-9,trans-11 CLA increased after TVA treatment. The mRNA expression level of PSMA5 was significantly elevated to 6h, but SCD mRNA expression only increased in 2h after TVA treatment. These results indicate that PSMA5 is highly expressed in goat mammary tissue and bovine mammary epithelial cells when TVA is converted into CLA. Our data suggest that PSMA5 protein is associated with CLA biosynthesis in mammary tissue.

Effects of fish oil and starch added to a diet containing sunflower-seed oil on dairy goat performance, milk fatty acid composition and in vivo delta9-desaturation of [13C]vaccenic acid

The potential benefits on human health have prompted an interest in developing nutritional strategies for specifically increasing rumenic acid (RA) in ruminant milk. The aims of the present study were to (i) compare two dietary treatments with lipid supplements on milk yield and composition, (ii) measure the in vivo delta9-desaturation of vaccenic acid (VA) to RA using 13C-labelled VA and (iii) determine the effect of the dietary treatments on this variable. Treatments were 90 g sunflower-seed oil (SO) per d or 60 g sunflower-seed oil and 30 g fish oil per d plus additional starch (SFO), in a grassland hay-based diet given to eight Alpine goats in a 2 x 2 cross-over design with 21 d experimental periods. Milk yield and composition were similar between treatments. Goats fed SFO had higher milk 6 : 0-16 : 0 concentration, lower milk sigmaC18 concentrations and showed no effect on milk VA and RA, compared with SO. At the end of the experiment, intravenous injection of 1.5 g [13C]VA followed by measurements of milk lipid 13C enrichment showed that in vivo 31.7 and 31.6 % of VA was delta9-desaturated into milk RA in the caprine with the SO and SFO treatments, respectively. The expression of genes encoding for delta9-desaturase (or stearoyl-CoA desaturase; SCD1, SCD5) in mammary tissues and four milk delta9-desaturation ratios were similar between treatments. In conclusion, the present study provides the first estimates of in vivo endogenous synthesis of RA (63-73 % of milk RA) from VA in goats, and shows no difference between the two lipid supplements compared.

Rumen-protected conjugated linoleic acid supplementation to dairy cows in late pregnancy and early lactation: effects on milk composition, milk yield, blood metabolites and gene expression in liver

Background

Conjugated linoleic acid (CLA) is a collective term for isomers of octadecadienoic acid with conjugated double-bond system. Thus, it was the objective to investigate whether milk composition and metabolic key parameters are affected by adding CLA to the diet of dairy cows in the first four weeks of lactation.

Methods

A study was carried out with five primiparous cows fed a CLA supplemented diet compared to five primiparous cows without CLA supplementation. CLA supplemented cows received 7.5 g CLA/day (i.e. 50% cis(c)9,trans(t)11- and 50% t10,c12-CLA) starting two weeks before expected calving and 20 g CLA/day (i.e. 50% c9,t11- and 50% t10,c12-CLA) throughout day 1 to 28 of lactation.

Results

The CLA supplement was insufficiently accepted by the animals: only 61.5% of the intended amount was ingested. Fed CLA were detectable in milk fat, whereas contents of c9,t11-CLA and t10,c12-CLA in milk fat were higher for CLA supplemented cows compared to the control group. On average over the entire treatment period, there was a decrease of saturated fatty acids (FA) in milk fat of CLA supplemented cows, combined with a higher content of monounsaturated and trans FA.

Our study revealed no significant effects of c9,t11- and t10,c12-CLA supplementation either on milk yield and composition or on metabolic key parameters in blood. Furthermore the experiment did not indicate significant effects of c9,t11- and t10,c12-CLA-supplementation on gene expression of peroxisome proliferator-activated receptor-alpha (PPARα), PPARγ, sterol regulatory element-binding protein-1 and tumor necrosis factor-alpha in liver tissue.

Conclusions

Feeding c9,t11- and t10,c12-CLA during the first weeks after calving did not affect metabolic key parameters of blood serum or milk composition of fresh cows. Milk fatty acid composition was changed by feeding c9,t11- and t10,c12-CLA resulting in higher contents of these isomers in milk fat. High contents of long chain FA in milk fat indicate that CLA supplementation during the first four weeks of lactation did not affect massive peripheral lipomobilization.

Physico-chemical modifications of conjugated linoleic acid for ruminal protection and oxidative stability

Conjugated linoleic acid (CLA) is a mixture of positional and geometric isomers of octadecadienoic acid [linoleic acid (LA), 18:2n-6]. Although ruminant milk and meat products represent the largest natural source of CLA and therefore, their concentration in ruminant lipids are of interest to human health, chemical or physical modifications of CLA should be needed as a means to enhance oxidative stability, to improve post-ruminal bioavailability, and to increase the clinical application. In fact, CLA are rapidly decomposed to form furan fatty acids when its are oxidized in air, and the effectiveness of dietary supplements of CLA may be related to the extent that their metabolisms by rumen bacteria are avoided. For these reasons, many scientists have examined the effect of manufacturing and protection on the stability of CLA in ruminants and food products. In this review, physico-chemical modifications of CLA for ruminal protection such as calcium salt (Ca), formaldehyde protection (FP), lipid encapsulation (LE), and amide linkage (AL), and for oxidative stability such as green tea catechin (GTC), cyclodextrin (CD), arginine (Arg), amylase, and PEGylation are proposed.

Expression and nutritional regulation of lipogenic genes in the ruminant lactating mammary gland

The effect of nutrition on milk fat yield and composition has largely been investigated in cows and goats, with some differences for fatty acid (FA) composition responses and marked species differences in milk fat yield response. Recently, the characterization of lipogenic genes in ruminant species allowed in vivo studies focused on the effect of nutrition on mammary expression of these genes, in cows (mainly fed milk fat-depressing diets) and goats (fed lipid-supplemented diets). These few studies demonstrated some similarities in the regulation of gene expression between the two species, although the responses were not always in agreement with milk FA secretion responses. A central role for trans-10 C18:1 and trans-10, cis-12 CLA as regulators of milk fat synthesis has been proposed. However, trans-10 C18:1 does not directly control milk fat synthesis in cows, despite the fact that it largely responds to dietary factors, with its concentration being negatively correlated with milk fat yield response in cows and, to a lesser extent, in goats. Milk trans-10, cis-12 CLA is often correlated with milk fat depression in cows but not in goats and, when postruminally infused, acts as an inhibitor of the expression of key lipogenic genes in cows. Recent evidence has also proven the inhibitory effect of the trans-9, cis-11 CLA isomer. The molecular mechanisms by which nutrients regulate lipogenic gene expression have yet to be well identified, but a central role for SREBP-1 has been outlined as mediator of FA effects, whereas the roles of PPARs and STAT5 need to be determined. It is expected that the development of in vitro functional systems for lipid synthesis and secretion will allow future progress toward (1) the identification of the inhibitors and activators of fat synthesis, (2) the knowledge of cellular mechanisms, and (3) the understanding of differences between ruminant species.

Seasonal variation in the concentrations of conjugated linoleic and trans fatty acids in milk fat from commercial dairy farms is associated with pasture and grazing management and supplementary feeding practices

A study of irrigated pasture-based dairy farms that used split calving (autumn and spring) was undertaken in northern Victoria, Australia, to examine associations between nutrition, time of year and season of calving on the concentrations of isomers of trans 18  :  1 fatty acids and conjugated linoleic acids (CLA) in milk fat. Factors associated with time of year explained most of the variation, with the highest concentrations observed in spring and summer when pasture intake by herds was high. However, there was substantial variation observed between herds and time of year. The mean total CLA concentration was 9.1 mg/g milk fatty acids (range 1.1–35.4 mg/g) with the cis,trans-9,11 accounting for ~84% of the total CLA. The mean total trans 18 : 1 concentration was 60.5 mg/g milk fatty acids (range 13.6–267 mg/g) with vaccenic acid (trans-11 18 : 1) accounting for ~53% of total trans 18 : 1 fatty acids. Total CLA and vaccenic acid were highest in August–September (southern hemisphere spring) (15.1 and 76.3 mg/g milk fat) and lowest in November–March (5.6 mg/g milk fat) and May–July (9.53 mg/g milk fat), respectively. There was no association between season of calving and milk CLA or trans 18 : 1 fatty acid concentrations. Trans-10 and -11 18 : 1 fatty acids and trans/trans-CLA were negatively correlated with milk fat concentrations. Management strategies designed to increase the concentration of CLA and trans 18 : 1 fatty acids in milk fat would not need to consider the effects of season of calving or stage of lactation, but should focus on pasture availability and quality.

Dose response to vaginal administration of 1,25-dihydroxyvitamin D3 to cows

It was previously reported that intravaginal (IVAG) administration of 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) might be protective against bovine hypocalcaemia. In the present study, various doses of exogenous 1,25(OH)(2)D(3) were administered IVAG to ovariectomised cows, and the subsequent changes in the biochemical parameters of the blood were measured to assess the characteristics of vaginal absorption. Five cows received 1,25(OH)(2)D(3) IVAG at a dose of 0.125, 0.25, 0.5, or 1.0microg/kg of body weight (BW) or intravenously at a dose of 1.0microg/kg BW. Dosing was at intervals of at least two weeks in a 5x5 Latin square design. Vaginally administered 1,25(OH)(2)D(3) was absorbed in a dose-dependent manner. There was no correlation between the IVAG dose of 1,25(OH)(2)D(3) and subsequent changes in plasma calcium concentrations. The bioavailability of 1,25(OH)(2)D(3) administered IVAG at 1.0microg/kg BW was approximately 93%.

Effects of Amide-Protected and Lipid-Encapsulated Conjugated Linoleic Acid (CLA) Supplements on Milk Fat Synthesis

The trans-10, cis-12 isomer of conjugated linoleic acid (CLA) is a potent inhibitor of milk fat synthesis; its ability to reduce milk fat output in a controlled manner as a feed supplement, has potential management applications in the dairy industry. The effectiveness of dietary supplements of trans-10, cis-12 CLA is related to the extent to which their metabolism by rumen bacteria is minimized. A number of processes have been used to manufacture "rumen-protected" feed supplements, and their efficacy can be described by the extent of protection from rumen bacteria as well as postruminal bioavailability. The objective of this study was to investigate the effects of 2 rumen-protected CLA supplements on milk fat synthesis. Using the same initial batch of CLA, supplements were manufactured by the formation of fatty acyl amide bonds or by lipid encapsulation. Three rumen fistulated Holstein cows were randomly assigned in a 3 x 3 Latin square experiment. Treatments were 1) no supplement (control), 2) amide-protected CLA supplement, and 3) lipid-encapsulated CLA supplement. Supplements were fed to provide 10 g/d of the trans-10, cis-12 CLA isomer. Over the 7-d treatment period, 21 and 22% reductions in milk fat yield were observed for the amide-protected and lipid-encapsulated supplements, respectively. Transfer of trans-10, cis-12 CLA into milk fat was also similar for the amide-protected (7.1%) and lipid-encapsulated (7.9%) supplements. Overall, the amide-protected and lipid-encapsulated CLA supplements were equally effective at reducing milk fat synthesis and had no effect on milk yield or dry matter intake.

CLA isomers in milk fat from cows fed diets with high levels of unsaturated fatty acids

The concentrations of CLA isomers were determined by Ag+ -HPLC in the milk fat of cows fed a control diet consisting of hay ad libitum and 15 kg of fodder beets or this diet supplemented with oilseeds containing either high levels of oleic acid (rapeseed), linoleic acid (sunflower seed), or alphalinolenic acid (linseed). Highly significant (P < or = 0.001) correlations were found between the daily intakes of oleic acid and the concentration of the CLA isomer trans-7,cis-9 in milk fat; of linoleic acid and the CLA isomers trans-10,trans-12, trans-9,trans-11, trans-8,trans-10, trans-7,trans-9, trans-10,cis-12, cis-9,trans-11, trans-8,cis-10, and trans-7,cis-9; and of alpha-linolenic acid and the CLA isomers trans-12,trans-14, trans-11 ,trans-13, cis,trans/trans,cis-12,14, trans-11 ,cis-13, and cis-11 ,trans-13. CLA concentrations were also determined in the milk fat of cows grazing in the lowlands (600-650 m), the mountains (900-1210 m), and the highlands (1275-2120 m). The concentrations of many isomers were highest in milk fat from the highlands, but only three CLA isomers (cis-9,trans-11, trans-11 ,cis-13, and trans-8,cis-10) showed a nearly linear increase with elevation. Therefore, these three CLA isomers, and particularly the CLA isomer trans- 11,cis-13, the second-most important CLA in milk fat from cows grazing at the three altitudes, could be useful indicators of milk products of Alpine origin.