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PubMed2003

Lysine-derived fluorophores formed by autoxidation of linoleic acid.

To obtain an insight into fluorophores formed in proteins during lipid peroxidation, a lysine residue analogue (N(alpha)-hippuryllysine) was exposed to autoxidation of linoleic acid catalyzed by iron(III)-EDTA and L-ascorbic acid. The reaction predominantly produced two fluorescent products, N,N'-bis[5-(N-benzoylglycylamino)-5-carboxypentyl]-2-hydroxy-2-pentyl-3-imino-l,2-dihydropyrrole (II) and N,N'-bis[5-(N-benzoylglycylamino)-5-carboxypentyl]-2-hydroxy-2-(7-carboxyheptyl)-3-imino-1,2-dihydropyrolle (I).

Ascorbic Acid↗
PubMed2004

Effects of supplemental rumen-protected conjugated linoleic acid or corn oil on fatty acid composition of adipose tissues in beef cattle.

Thirty-six Angus x Hereford heifers (365 +/- 60 kg) were used to determine the effects of supplemental dietary lipid sources on fatty acid composition of i.m., perianal (p.a.), and s.c. lipid depots. Lipid was supplied to diets as either corn oil or a rumen-protected conjugated linoleic acid (CLA) salt for two specific treatment periods of either the final 32 or 60 d on feed. Following an initial 56-d feeding period, heifers were fed one of three dietary treatments (DM basis): 1) basal diet containing 88% concentrate and 12% grass hay (CON), 2) basal diet plus 4% corn oil (OIL), or 3) basal diet plus 2% rumen-protected CLA salt (RPCLA) containing 31% CLA. The trans-10, cis-12 CLA concentration was greatest (P < 0.05) for heifers fed RPCLA and OIL diets and least (P < 0.05) for CON, regardless of time on dietary treatment. Heifers fed supplemental RPCLA had greater (P < 0.05) total CLA content than either CON- or OIL-fed heifers. Adipose tissue concentration of trans-11 vaccenic acid (TVA) was less (P < 0.05) for CON than OIL or RPCLA, which did not differ (P > 0.05). Percentages of C18:1 trans-10 were least (P < 0.05) in i.m. lipid compared with p.a. and s.c., which did not differ (P > 0.05). Following 60 d of lipid supplementation, heifers fed OIL and RPCLA had lower (P < 0.05) concentrations of oleic acid and total monounsaturated fatty acids (MUFA) compared with CON. The ratio of cis-9, trans-11 CLA:TVA was higher (P < 0.05) for heifers fed 60 vs. 32 d, but did not differ (P > 0.05) between adipose depots. Feeding OIL increased (P < 0.05) adipose concentration of C18:2 fatty acid, whereas feeding RPCLA increased (P < 0.05) total CLA isomers by 22%. Intramuscular lipid contained the lowest (P < 0.05) percentage of cis-9, trans-11 CLA, total CLA, C18:1 cis-9, C18:1 trans-10, and TVA. Total CLA and cis-9, trans-11 CLA isomers were increased (P < 0.05) in p.a. and s.c. adipose depots, whereas i.m. adipose tissue contained increased (P < 0.05) amounts of total PUFA. Results from this study indicate that short-term lipid supplementation to feedlot cattle can increase adipose tissue CLA concentrations, but only marginally (8.3 to 17.5%). Moreover, observed decreases in oleic acid and total MUFA concentrations of adipose tissues from heifers fed rumen-protected CLA or corn oil suggest that lipid supplementation may decrease delta9 desaturase activity in adipose tissues, which in turn would lower the conversion of TVA to cis-9, trans-11 CLA isomer.

Adipose Tissue↗
PubMed2006

Fiber but not conjugated linoleic acid influences adiposity in dogs.

Feeding obese dogs a high-fiber food with or without added conjugated linoleic acid (CLA) resulted in reduced caloric consumption, reduced body weight, and a 3.3% reduction in body fat, whereas feeding a low-fiber food resulted in a comparable increase in caloric consumption and a 2.4% gain in body fat. The addition of CLA did not significantly affect food intake, energy intake, final lean body percent, change in lean body percent, or final fat percent. These results suggest that the addition of dietary fiber but not CLA to foods may be helpful in the treatment of canine obesity.

Adipose Tissue↗
PubMed2005

Seasonal variation in conjugated linoleic acid and vaccenic acid in milk fat of sheep and its transfer to cheese and ricotta.

The seasonal variation in conjugated linoleic acid (CLA) and vaccenic acid (VA) concentrations in sheep dairy products and the extent of their transfer from milk fat to cheese and ricotta fat were investigated. Samples were collected from 2 sheep milk processing plants in North Sardinia (Italy) every 2 wk from March through June. Concentrations of fatty acids (FA) in fresh cheese and ricotta fat were primarily dependent on the fatty acid content of the unprocessed raw milk. The content of c9,t11-CLA averaged 1.73, 1.69, and 1.75 mg/100 mg of FA methyl esters (FAME), respectively, for milk, cheese, and ricotta, and differed significantly between cheese and ricotta. The content of VA averaged 3.40, 3.33, and 3.43 mg/100 mg of FAME, respectively for milk, cheese, and ricotta. The FA composition of dairy products was markedly affected by period of sampling: the mean c9,t11-CLA and VA concentration decreased from March (2.20 and 4.52 mg/100 mg of FAME) to June (1.14 and 1.76 mg/100 mg of FAME) in all dairy products. No differences in c9,t11-CLA and VA concentration of dairy products were observed between the 2 dairy companies obtaining milk from the same geographical origin. The seasonal changes in CLA and VA in milk fat were probably related to changes in pasture quality.

Animals↗
PubMed2005

Influence of dietary conjugated linoleic acid (CLA) on lipid and fatty acid composition in liver and flesh of Atlantic salmon (Salmo salar).

The aim of the present study was to determine the effects of conjugated linoleic acid (CLA) on lipid and fatty acid metabolism in Atlantic salmon. The overall objective being to test the hypotheses that CLA has beneficial effects in salmon including growth enhancement, improved flesh quality through decreased adiposity and lipid deposition thereby minimising detrimental effects of feeding high fat diets, and increased nutritional quality through increased levels of beneficial fatty acids including n-3 highly unsaturated fatty acids (HUFA) and CLA itself. Salmon smolts were fed diets containing two levels of fish oil (low, approximately 18% and high, approximately 34%) containing three levels of CLA (a 1:1 mixture of 9-cis,trans-11 and trans-10,cis-12. at 0, 1 and 2% of diet) for 3 months and the effects on growth performance, liver and muscle (flesh) lipid contents and class compositions, and fatty acid compositions determined. The diets were also specifically formulated to investigate whether the effects of CLA, if any, were more dependent upon absolute content of CLA in the diet (as percentage of total diet) or the relative level of CLA to other fatty acids. Dietary CLA in salmon smolts had no effect on growth parameters or biometric parameters. However, there was a clear trend of increased total lipid and triacylglycerol contents in both liver and flesh in fish fed CLA, particularly in fish fed the high oil diets. Finally, CLA was incorporated into tissue lipids, with levels in flesh being 2-fold higher than in liver, but importantly, incorporation in liver was at the expense of saturated and monounsaturated fatty acids whereas in flesh it was at the expense of n-3HUFA.

Animals↗
PubMed2001

Dietary conjugated linoleic acid reduces adiposity in lean but not obese Zucker rats.

Recent studies have demonstrated a reduction in body fat in growing animals fed conjugated linoleic acid (CLA). Two experiments were conducted to extend these observations to obese rats so that the mechanism of the actions of CLA might be more easily elucidated. In experiment 1, male lean and obese Zucker rats were fed diets containing either 0 or 0.5% CLA for 5 wk. There was no effect of diet on growth rate or food intake. Dietary CLA reduced retroperitoneal and inguinal fat pad weights in the lean rats but increased fat pad weights in the obese genotype (diet x genotype interaction; P < 0.05). Determination of fat pad cellularity indicated that these changes in fat pad weight were due to a reduction or increase in average fat cell size for the lean and obese Zucker rats, respectively. In experiment 2, we sought to reproduce these effects on fat pad size, as well as to determine the effect of dietary CLA on the catabolic response to bacterial endotoxin injection in obese Zucker rats. Growing female lean and obese Zucker rats were fed diets containing 0 or 0.5% CLA for 8 wk. On d 28, each rat was injected intraperitoneally with lipopolysaccharide from Escherichia coli serotype 055:B5 (1 mg/kg body weight) and body weight was determined over the next 96 h. There was a diet x genotype interaction (P < 0.05) for the body weight response to lipopolysaccharide 24 h postinjection. Lean rats fed CLA lost less weight than did lean controls, but obese rats fed CLA lost more weight than did obese controls. As in the first experiment, there was a diet x genotype (P < 0.05) for the effect of treatment on retroperitoneal fat pad weights determined at the end of the experiment. Lean rats fed CLA had smaller RP fat pads than did lean controls, but obese rats fed CLA once again had heavier RP fat pads than did obese controls. These results indicate that CLA reduces body fat and catabolic response to endotoxin injection in lean Zucker rats but not in the obese genotype. The observed interaction between diet and genotype warrants additional investigation into the specific mechanism(s) of the biological activities of CLA.

Adipose Tissue↗
PubMed1993

Effect of linoleic acid hydroperoxide on production of matrix metalloproteinases by human aortic endothelial and smooth muscle cells.

The effect of linoleic acid hydroperoxide on the production of proforms of matrix metalloproteinase-1, -2, and -3 (proMMP-1, -2, and -3) in cultured human arterial endothelial and smooth muscle cells was investigated. Upon cultivation of the endothelial cells in the absence of the hydroperoxide, only proMMP-1 was detected, and its amount was increased by cultivation with the hydroperoxide. In the cultures of the intimal smooth muscle cells in the absence of the hydroperoxide, a large amount of proMMP-2 and small amounts of proMMP-1 and -3 were detected, and the hydroperoxide treatment increased remarkably the amounts of proMMP-1 and -3, but rather decreased the amount of proMMP-2. In the cultures of the medial smooth muscle cells, the same tendency was observed. However, the amounts of these proenzymes found in the intimal smooth muscle cells exceeded those found in the medial smooth muscle cells, both in the absence and in the presence of the hydroperoxide. Possible involvement of these phenomena in atherogenesis was discussed.

Aorta, Thoracic↗
PubMed2001

Conjugated linoleic acid does not inhibit development of aberrant crypt foci in colons of male Sprague-Dawley rats.

Conjugated linoleic acid (CLA) is a potent inhibitor of the initiation and promotion of mammary carcinogenesis in animal models, but its role in colon carcinogenesis remains unclear. The objective of this study was to determine whether CLA inhibits the promotion of colon carcinogenesis. Forty male Sprague-Dawley rats were given a single dose of azoxymethane (20 mg/kg body wt i.p.). After 1 wk, the animals were randomized into two groups (n = 20) and fed a control AIN-93G diet or the control diet supplemented with 1% CLA at the expense of the soybean oil. After 12 wk, the animals were killed, and their colons were stained with methylene blue for aberrant crypt foci (ACF) analysis by light microscopy. The total number of ACF per animal did not differ between the control (174 +/- 11) and CLA (170 +/- 10) groups. Furthermore, CLA did not affect the average crypt multiplicity (crypts/ACF) or the average number of ACF in any size category. However, rats fed the 1% CLA diet had significantly higher serum insulin levels at the time of sacrifice than those fed the control diet. Thus it is possible that the promoting effects of elevated serum insulin on colon carcinogenesis may have counteracted an inhibitory effect of CLA.

Animals↗
PubMed2004

Effects of two conjugated linoleic Acid isomers on body fat mass in overweight humans.

OBJECTIVE: To examine the effects of two different conjugated linoleic acid (CLA) isomers at two different intakes on body composition in overweight humans. RESEARCH METHODS AND PROCEDURES: Eighty-one middle-aged, overweight, healthy men and women participated in this bicentric, placebo-controlled, double-blind, randomized study. For 6 weeks (run-in period), all subjects consumed daily a drinkable dairy product containing 3 g of high oleic acid sunflower oil. Volunteers were then randomized over five groups receiving daily either 3 g of high oleic acid sunflower oil, 1.5 g of cis-9,trans-11 (c9t11) CLA, 3 g of c9t11 CLA, 1.5 g of trans-10,cis-12 (t10c12) CLA, or 3 g of t10c12 CLA administrated as triacylglycerol in a drinkable dairy product for 18 weeks. Percentage body fat mass and fat and lean body mass were assessed at the end of the run-in and experimental periods by DXA. Dietary intake was also recorded. RESULTS: Body fat mass changes averaged 0.1 +/- 0.9 kg (mean +/- SD) in the placebo group and -0.3 +/- 1.4, -0.8 +/- 2.1, 0.0 +/- 2.3, and -0.9 +/- 1.7 kg in the 1.5-g c9t11, 3-g c9t11, 1.5-g t10c12, and 3-g t10c12 groups, respectively. Changes among the groups were not significantly different (p = 0.444). Also, lean body mass and dietary intake were not significantly different among the treatments. DISCUSSION: A daily consumption of a drinkable dairy product containing up to 3 g of CLA isomers for 18 weeks had no statistically significant effect on body composition in overweight, middle-aged men and women.

Adipose Tissue↗
PubMed1999

Conjugated linoleic acid rapidly reduces body fat content in mice without affecting energy intake.

Recent reports have demonstrated that conjugated linoleic acid (CLA) has effects on body fat accumulation. In our previous work, CLA reduced body fat accumulation in mice fed either a high-fat or low-fat diet. Although CLA feeding reduced energy intake, the results suggested that some of the metabolic effects were not a consequence of the reduced food intake. We therefore undertook a study to determine a dose of CLA that would have effects on body composition without affecting energy intake. Five doses of CLA (0.0, 0.25, 0.50, 0.75, and 1.0% by weight) were studied in AKR/J male mice (n = 12/group; age, 39 days) maintained on a high-fat diet (%fat 45 kcal). Energy intake was not suppressed by any CLA dose. Body fat was significantly lower in the 0.50, 0.75, and 1.0% CLA groups compared with controls. The retroperitoneal depot was most sensitive to the effects of CLA, whereas the epididymal depot was relatively resistant. Higher doses of CLA also significantly increased carcass protein content. A time-course study of the effects of 1% CLA on body composition showed reductions in fat pad weights within 2 wk and continued throughout 12 wk of CLA feeding. In conclusion, CLA feeding produces a rapid, marked decrease in fat accumulation, and an increase in protein accumulation, at relatively low doses without any major effects on food intake.

Adipose Tissue↗
PubMed2004

Physiological difference between free and triglyceride-type conjugated linoleic acid on the immune function of C57BL/6N mice.

Previous studies have shown the physiological significance of dietary conjugated linoleic acid (CLA) in various experimental animals and in human beings. One of the important problems to better elucidate is the difference between triglyceride (TG) and free (FFA) dietary CLA. Here, using splenocytes, this study assesses how TG- and FFA-CLA modulate immunoglobulin and various cytokine productions. In this study, C57BL/6N mice were fed an experimental diet containing 0% CLA, 0.1 or 1% FFA-CLA, or 0.1 or 1% TG-CLA for 3 weeks. The production of immunoglobulin tended to be up-regulated by 1% FFA-CLA. As a result of protein array analysis using the supernatant from splenocytes cultured with no CLA, 1% FFA-CLA, and TG-CLA, some cytokine production was shown to be remarkably regulated by dietary FFA- and TG-CLA. A total of 32 cytokines were examined, and 11-14 produced cytokines that were 2-fold up-regulated as compared with control for FFA- or TG-CLA, respectively. Especially, the production of IL-9 and MCP-5 and other cytokines was remarkably up-regulated by both FFA- and TG-CLA. In addition, seven cytokines were 2-fold down-regulated by TG-CLA. These data show that there is a slight but significant difference between the functionalities of FFA- and TG-CLA.

Animals↗
PubMed2004

Conjugated linoleic acid improves insulin sensitivity in young, sedentary humans.

BACKGROUND: Preliminary evidence in obese diabetic rats suggests that conjugated linoleic acid (CLA) may have antidiabetic properties, based on reductions in fasting glucose and insulin concentrations. However, in lean rats, CLA causes hyperinsulinemia. Furthermore, experiments in humans also suggest that CLA may worsen insulin sensitivity. OBJECTIVES: The present study examined whether CLA supplementation can improve insulin sensitivity in humans. DESIGN: : Sixteen young sedentary individuals (age, 21.5 +/- 0.4 yr (mean +/- SEM); body mass, 77.6 +/- 3.4 kg) participated in this study. Ten subjects received 4 g x d of mixed CLA isomers (35.5%cis-9, trans-11; 36.8%trans-10, cis-12) for 8 wk, whereas six subjects received placebo (safflower oil). Oral glucose tolerance tests were performed at baseline (0), 4 and 8 wk of supplementation. RESULTS: : After 8 wk of CLA supplementation, insulin sensitivity index (ISI) increased (14.4 +/- 1.0, 8 wk vs 11.3 +/- 1.3, 0 wk; P < 0.05), which corresponded to a decrease in fasting insulin concentrations. Six of the 10 subjects showed large increases in their ISI (range, +27 to 90%), whereas two demonstrated essential no change (+3 to 5%), and two had a decrease in insulin sensitivity (-12 to -13%). ISI was unchanged over 8 wk in the placebo group. CONCLUSIONS: Our results indicate that a common dosage of a commercially available CLA supplement can improve ISI in young, sedentary individuals. However, there is considerable individual variability in the response. Additional studies are required to identify underlying metabolic changes in human skeletal muscle.

Adult↗
PubMed2003

Short communication: Postruminal infusion of conjugated linoleic acids negatively impacts milk synthesis in Holstein cows.

In view of the potential of rumen-protected conjugated linoleic acid (CLA) as a means to increase the CLA content of bovine milk, a study was undertaken to evaluate the effect of synthetic CLA on milk production and composition. Four Holstein cows received abomasal infusion of: 1) control, no lipid infusion, 2) 150 g/d of synthetic CLA, 31.7% cis-9, trans-11; 30.4% trans-10, cis-12, 3) 150 g/d of safflower oil, and 4) 150 g/d of tallow. Infusion was carried out for 20 to 22 h/d for 11-d periods in a 4 x 4 Latin square design. The milk fat concentration of cis-9, trans-11 and trans-10, cis-12 isomers of CLA was significantly increased with infusion of CLA. However, CLA infusion had other unexpected effects on milk production and composition. Milk yield dropped significantly during the period of CLA infusion. Furthermore, as well as the typical depression in milk fat reported with trans-10 isomers of CLA, other negative effects specific to CLA infusion were observed including a drop in lactose concentration and yield, a drop in protein yield, and an elevated somatic cell count. The important difference between synthetically produced CLA and CLA produced naturally in the cow is the much higher proportion of trans-10 isomers of CLA in the former. The results of this study suggest that the extent of enrichment possible for trans-10 isomers of CLA, and hence the usefulness of synthetic CLA for this purpose, may be limited because of unacceptable effects on milk yield and composition.

Abomasum↗
PubMed2001

Effect of dietary conjugated linoleic acid on the in vivo growth of rat hepatoma dRLh-84.

We examined the effect of dietary conjugated linoleic acid (CLA) on the growth of injected hepatoma dRLh-84 in Donryu rats. After experimental diets containing 0% or 2% CLA were given to male Donryu rats for 3 wk, dRLh-84 cells were injected into the left lobe of the hepatic capsule, and the experimental diet was continued. The cells formed a solid tumor > or = 1 wk after the injection, and thereafter the tumor grew with feeding duration. In a morphological study, this tumor appeared to be a low-differentiated hepatoma, and there was no remarkable difference in the morphology of the tumor between 0% and 2% CLA groups. Tumor weight was significantly higher in the 2% CLA group than in the 0% CLA group throughout the feeding period after the injection. Serum glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase activities were significantly higher in 2% CLA-injected rats than in 0% CLA-injected rats at 3 wk after the injection. CLA upregulated acyl-CoA oxidase activity, especially 1 wk after the injection. However, dietary CLA did not activate carnitine palmitoyl transferase II, which is a rate-limiting enzyme in the mitochondrial beta-oxidation pathway. Natural killer cell activity in the spleen tended to be higher in injected rats, but a significant effect of dietary CLA was not recognized. Serum interferon-gamma and tumor necrosis factor-alpha levels were higher in injected than in sham rats. Moreover, these levels were higher in 2% CLA groups than in the respective 0% CLA groups.

Adipose Tissue↗
PubMed2006

Dietary conjugated linoleic acid has limited effects on tissue protein anabolism in sedentary and exercising adult rats.

The effects of conjugated linoleic acid isomers (CLA) and endurance training on lean body mass are expected to result from their action on tissue protein metabolism. The aim of this study was to analyze their effects on protein metabolism in 2 muscles, the small intestine and liver of adult rats. Four-month-old male Wistar rats were fed diets containing either no CLA, cis-9, trans-11 CLA isomer (1 g.100 g(-1)), trans-10, cis-12 CLA isomer (1 g.100 g(-1)) or both isomers (1 g.100 g(-1) each) for 6 weeks. Half of the rats were subjected to endurance training by running on a treadmill. At the end of this period, the rats were injected with a flooding dose of (13)C-valine to determine protein synthesis rates in the post-absorptive (experiment 1) and in the post-prandial (experiment 2) states. No effect of CLA or endurance training were detected in the small intestine. Training reduced food intake and protein synthesis rates in the liver but no effect was found on the protein synthesis rates in muscles. In the post-absorptive state, protein synthesis rate was increased by feeding the trans-10, cis-12 CLA isomer alone in the liver (+9%) or in combination with the cis-9, trans-11 isomer in the gastrocnemius (+30%), mostly in sedentary rats. In the post-prandial state, the cis-9, trans-11 CLA isomer tended to reduce the protein synthesis rate in the gastrocnemius muscle. However, no effect of CLA was found on muscle protein amounts. In conclusion, CLA isomers would have limited but differential effects on tissue protein metabolism in adult rats.

Animals↗
PubMed2003

Effects of dietary conjugated linoleic acid isomers on several functional properties of macrophages and heterophils in laying hens.

1. Effects of dietary conjugated linoleic acid (CLA) on various functional properties of macrophages and heterophils in the laying hen were determined. 2. Seventy two 28-week-old-ISA brown hens were randomly assigned to one of two experimental groups and were fed diets containing 0 or 1% CLA for a total period of 18 weeks. Blood samples were collected from 6 hens per diet group every 3 weeks and macrophages and heterophils were isolated. The following variables were determined in resting and phorbol myristate acetate-activated (65 microM) macrophages and heterophils: total cell-associated urokinase plasminogen activator (u-PA), membrane-bound u-PA, free u-PA binding sites and superoxide production. 3. There were no significant differences between diet groups throughout the whole experimental period in total cell-associated u-PA, membrane-bound u-PA, free u-PA binding sites and superoxide production by resting macrophages and heterophils. 4. Activated heterophils and macrophages isolated from hens fed the CLA-supplemented diet had higher membrane-bound u-PA activity compared with the corresponding values for activated heterophils and macrophages obtained from hens fed the basal diet. These differences were significant for heterophils during weeks 6, 12, 15 and 18 and for macrophages during weeks 6, 9 and 12 of the experiment. 5. Macrophages and heterophils from hens fed the CLA diet had lower superoxide production compared with the corresponding cells from the control hens on weeks 12, 15 and 18 of the experiment. 6. Dietary CLA modulated certain aspects of the immune system in the laying hen. The increased quantity of u-PA on the membrane of macrophages and heterophils isolated from hens fed the CLA diet may facilitate the ability of these cells to reach the point of a potential inflammation (pro-inflammatory effect). 7. In contrast to the effect on the u-PA system, dietary CLA reduced superoxide production by activated macrophages and heterophils during the second half (last 9 weeks) of the experimental period suggesting that CLA may exert an anti-inflammatory effect in the laying hen.

Animals↗
PubMed2001

Conjugated linoleic acid and other beneficial fatty acids in milk fat from cows fed soybean meal, fish meal, or both.

Twelve multiparous Holstein cows at 48 +/- 8 DIM were used in a 4 x 4 Latin square with 21-d periods to determine the effect of replacing soybean meal with fish meal on feed intake, milk yield, and milk composition. Fish meal substituted for soybean meal on an isonitrogenous basis at 0, 25, 50, and 100% of supplemental protein. Total mixed diets were (DM basis) 25% corn silage, 25% alfalfa hay, and 50% concentrate mix. Intake of DM (27.9, 27.8, 26.1, and 25.8 kg/d for diets 1 to 4, respectively) was similar for all diets. Milk yield (37.5, 37.8, 37.2, and 37.7 kg/d) was not affected by diets. Milk protein percentages (3.23, 3.24, 3.31, and 3.35) increased with 100% fish meal supplementation and tended to be higher with 50% fish meal supplementation compared with 100% soybean meal diet. Milk fat percentages (3.18, 2.99, 3.04, and 2.87) and yield were lower with the 100% fish meal than with the 100% soybean meal diet. Concentration of n-3 fatty acids in milk fat (0.54, 0.56, 0.63, and 0.72 g/100 g fatty acids) increased as the proportion of fish meal in the diet increased. Concentrations of c9,t11 conjugated linoleic acid (CLA; 0.39, 0.44, 0.46, and 0.72 g/100 g fatty acids) and transvaccenic acid (TVA; 1.09, 1.19, 1.28, and 1.54 g/100 g of fatty acids) were higher with the 100% fish meal diet than with the 100% soybean meal diet. A total replacement of soybean meal with fish meal in the diet of lactating cows increased milk protein percentages and the beneficial fatty acids (CLA, TVA, and n-3 FA) in milk fat.

Animal Feed↗