A comprehensive review on carotenoids in foods and feeds: status quo, applications, patents, and research needs.

Carotenoids are isoprenoids widely distributed in foods that have been always part of the diet of humans. Unlike the other so-called food bioactives, some carotenoids can be converted into retinoids exhibiting vitamin A activity, which is essential for humans. Furthermore, they are much more versatile as they are relevant in foods not only as sources of vitamin A, but also as natural pigments, antioxidants, and health-promoting compounds. Lately, they are also attracting interest in the context of nutricosmetics, as they have been shown to provide cosmetic benefits when ingested in appropriate amounts. In this work, resulting from the collaborative work of participants of the COST Action European network to advance carotenoid research and applications in agro-food and health (EUROCAROTEN, www.eurocaroten.eu, https://www.cost.eu/actions/CA15136/#tabs|Name:overview) research on carotenoids in foods and feeds is thoroughly reviewed covering aspects such as analysis, carotenoid food sources, carotenoid databases, effect of processing and storage conditions, new trends in carotenoid extraction, daily intakes, use as human, and feed additives are addressed. Furthermore, classical and recent patents regarding the obtaining and formulation of carotenoids for several purposes are pinpointed and briefly discussed. Lastly, emerging research lines as well as research needs are highlighted.

Preparation and characterization of hydrophobic and hydrophilic amidated derivatives of carboxymethyl chitosan and carboxymethyl ß-glucan.

Chitosan and ß-glucan are substances that are very widely used in the pharmaceutical and food industries, medicine and other areas. These polysaccharides have immense significance in human metabolism. They are able to affect the levels of cholesterol and lipids. Chemical modification of these polysaccharides allows the support of these attributes. A main goal is to prepare a group of amide derivatives of carboxymethyl chitosan and carboxymethyl ß-glucan to obtain a new group of polysaccharide derivatives and increase the benefits and attributes of these polysaccharides. The aim of carboxymethylation and subsequent two-step amidation is to achieve a high degree of substitution in the prepared derivatives. The amidation consisted methyl esterification followed by amino-de-alkoxylation with amidation reagents (n-alkylamines, hydrazine and hydroxylamine). The purity and substitution degree of the prepared derivatives were monitored by vibration spectroscopic methods (FTIR and FT Raman) and organic elemental analysis. The main, which was due to the presence of a secondary component (chitin) of polysaccharides, was the calculation of the substitution degree, which was based on the organic elemental analysis in combination with FTIR spectroscopy. These analytic methods confirmed the preparation of the substituted N-alkylamides, hydrazide and hydroxamic acid of carboxymethyl chitosan and carboxymethyl ß-glucan.

Effect of amidated alginate on faecal lipids, serum and hepatic cholesterol in rats fed diets supplemented with fat and cholesterol.

The effect of octadecylamide of alginic acid on serum and hepatic cholesterol, and the faecal output of fat and sterols was examined in female rats fed diets containing cholesterol and palm fat at 10 and 50 g kg-1, respectively. Cholesterol supplementation significantly increased serum and hepatic cholesterol concentrations, and faecal output of cholesterol and coprostanol. Cholesterol and amidated alginate supplementations changed the profile of fatty acids in the faeces. Cholesterol increased molar percentages of saturated fatty acids and amidated alginate reversed this effect. Amidated alginate, supplied at 10, 20 and 40 g kg-1, significantly decreased serum cholesterol from 2.82 to 2.00, 1.95, and 1.63 µmol mL-1, respectively, and significantly decreased hepatic cholesterol from 13.8 to 9.33, 7.81 and 6.3 µmol g-1, respectively. Amidated alginate increased the faecal output of fat and neutral sterols in a dose-dependent manner. In contrast, the output of bile acids was significantly decreased. The faecal outputs of fat and serum cholesterol were negatively correlated. At the highest concentration tested, amidated alginate significantly reduced the serum concentration of triacylglycerols. It can be concluded that amidated alginate is an effective cholesterol-lowering agent and sorbent of dietary fat.

Effect of dietary fat type on intestinal digestibility of fatty acids, fatty acid profiles of breast meat and abdominal fat, and mRNA expression of lipid-related genes in broiler chickens.

A group of 240-day-old Ross cockerels were used in a 4-week experiment to assess the effect of the fat type on the intestinal digestibility of fatty acids (FAs), the FA profiles of breast meat and abdominal fat, and the mRNA expression of six hepatic lipid-related genes. Experimental diets were supplemented with rapeseed oil, pork lard or palm oil at 60 g/kg. In the control diet, wheat starch was substituted for the fat source. The highest ileal digestibility of the fat and all FAs (except stearic acid) was observed in chickens fed lard. The content of fat in the breast meat of chickens was not significantly influenced by the fat supplements. The FA profiles of breast meat and abdominal fat reflected the FA composition of the diet. In the meat of chickens fed rapeseed oil, oleic acid was the predominant FA. Palmitic acid was the most abundant FA in the meat of chickens fed lard or palm oil. Oleic acid was the most abundant FA in the abdominal fat of all chickens. The highest mRNA expression of desaturases (Δ5-, Δ6- and Δ9-) was observed in chickens fed palm oil. The mRNA expression of hepatic FA synthase was higher in chickens fed palm oil or lard than in chickens fed rapeseed oil. The expression of HMG-CoA reductase was higher in chickens fed palm oil than in those fed rapeseed oil or lard. It can be concluded that rapeseed oil and lard are better sources of lipids than palm oil. These former two sources contain more digestible fatty acids and provide a lower concentration of SFAs in the meat and fat of chickens.

Comparative study of the hypocholesterolemic and hypolipidemic activity of alginate and amidated alginate in rats.

Alginate is a copolymer of ß-d-mannuronate and α-l-guluronate, which are present in the cell wall of brown algae. The hypocholesterolemic and hypolipidemic activities of alginate and its derivative, which is prepared by a reaction with octadecylamine, were compared in rats fed diets containing cholesterol and palm fat at 10 and 50g/kg, respectively. Amidated alginate at 20g/kg significantly decreased serum cholesterol from 2.93 to 2.00µmol/mL, serum triacylglycerols from 1.66 to 0.92µmol/mL, hepatic cholesterol from 17.5 to 5.9µmol/g, and total hepatic lipids from 67.4 to 51.7mg/g. Alginate at 20g/kg significantly reduced hepatic cholesterol to 13.1µmol/g, but did not influence serum cholesterol, triacylglycerols, and total hepatic lipids. Amidated alginate significantly increased the faecal concentrations of neutral sterols from 98.7 to 122.4µmol/g DM, but decreased faecal concentration of bile acids from 19.4 to 14.0µmol/g DM. In samples of intestinal contents, taurine-conjugated bile acids dominated glycine conjugates. The supplementation of diets with cholesterol significantly increased the expression of hepatic cholesterol 7α-hydroxylase, especially in rats that received cholesterol without alginate or amidated alginate. In conclusion, amidated alginate is an effective hypocholesterolemic agent that is more efficient than its parent polysaccharide.

Preparation and characterization of amidated derivatives of alginic acid.

Alginic acid is a suitable material for modification to prepare new derivatives because of presence of its carboxyl groups. The high content of carboxyl groups over the entire length of its chain renders it an easily modifiable material with a possibility of achieving a high degree of substitution in the prepared derivatives. The salt of alginic acid (sodium alginate) is readily commercially available and is widely used in many branches of chemistry. Alginic acid was thus selected as the substrate for amidation. The amidation used two-steps: methyl esterification followed by amino-de-alkoxylation. The aim of this study was to prepare highly substituted derivatives with different polysaccharide chain characteristics. As such, the alginic acid was modified by the two-step amidation based on the esterification of the alginic acid carboxyl groups by reaction with methanol and further amino-de-alkoxylation (aminolysis) of the obtained methyl ester with amidation reagents (n-alkylamines, hydrazine and hydroxylamine). The purity and substitution degree of the prepared derivatives were monitored by vibration spectroscopic methods (FTIR and FT Raman) and organic elemental analysis. These analytical methods confirmed the preparation of highly or moderately substituted N-alkylamides, hydrazide and hydroxamic acid of alginic acid.

Multilocus Sequence Typing of Cronobacter Strains Isolated from Retail Foods and Environmental Samples.

Cronobacter spp. are bacterial pathogens that affect children and immunocompromised adults. In this study, we used multilocus sequence typing (MLST) to determine sequence types (STs) in 11 Cronobacter spp. strains isolated from retail foods, 29 strains from dust samples obtained from vacuum cleaners, and 4 clinical isolates. Using biochemical tests, species-specific polymerase chain reaction, and MLST analysis, 36 strains were identified as Cronobacter sakazakii, and 6 were identified as Cronobacter malonaticus. In addition, one strain that originated from retail food and one from a dust sample from a vacuum cleaner were identified on the basis of MLST analysis as Cronobacter dublinensis and Cronobacter turicensis, respectively. Cronobacter spp. strains isolated from the retail foods were assigned to eight different MLST sequence types, seven of which were newly identified. The strains isolated from the dust samples were assigned to 7 known STs and 14 unknown STs. Three clinical isolates and one household dust isolate were assigned to ST4, which is the predominant ST associated with neonatal meningitis. One clinical isolate was classified based on MLST analysis as Cronobacter malonaticus and belonged to an as-yet-unknown ST. Three strains isolated from the household dust samples were assigned to ST1, which is another clinically significant ST. It can be concluded that Cronobacter spp. strains of different origin are genetically quite variable. The recovery of C. sakazakii strains belonging to ST1 and ST4 from the dust samples suggests the possibility that contamination could occur during food preparation. All of the novel STs and alleles for C. sakazakii, C. malonaticus, C. dublinensis, and C. turicensis determined in this study were deposited in the Cronobacter MLST database available online ( http://pubmlst.org/cronobacter/).

In vitro study and comparison of caecal methanogenesis and fermentation pattern in the brown hare (Lepus europaeus) and domestic rabbit (Oryctolagus cuniculus).

The brown hare and the domestic rabbit are mid-sized herbivorous mammals and hindgut fermenters, though their digestive physiologies differ in some traits. The objective of this study was to estimate and compare the caecal microbial activity in hares and rabbits via an analysis of the following end-products of in vitro caecal fermentation: methane, total gas production, short chain fatty acids and ammonia concentration. Hare caecal methanogenesis occurred at a much lower level (0.25 mmol/kg for samples incubated without substrate and 0.22 mmol/kg for samples incubated with substrate) than that of the rabbit (15.49 and 11.73 mmol/kg, respectively) (P<0.001). The impact of the substrate's presence on caecal methanogenesis was not significant, though its presence increased the total gas production during fermentation (P<0.001). Hare caecal microflora produced a lower short chain fatty acids concentration than did rabbit microorganisms (P<0.05). In unincubated hare samples, the short chain fatty acids concentration was 28.4 mmol/kg, whereas in unincubated rabbit samples, the short chain fatty acids concentration was 51.8 mmol/kg. The caecal fermentation pattern of the hare was characterised by higher propionate and isobutyrate molar proportions compared with those observed in rabbit caecum (P<0.01). No significant changes in the ammonia concentration in either rabbit or hare caecum were found. The results obtained indicate some differences in the activity of the microbial populations colonising the hare and rabbit caecum, particularly in regards to methanogenic Archaea.

Potential use of caprylic acid in broiler chickens: effect on Salmonella enteritidis.

The effect of dietary caprylic acid (CA) on Salmonella Enteritidis, as well as the surface treatment of chicken skin contaminated with Salmonella Enteritidis was evaluated. To evaluate the dietary effect of CA on Salmonella Enteritidis, the individually housed broiler chickens (n=48) were divided into 4 groups (positive control, negative control, 2.5 g/kg of CA in the feed, and 5 g/kg of CA in the feed). The feed of all groups, except the negative control, was artificially contaminated with Salmonella Enteritidis ATCC 13076 (10(7) colony-forming units/100 g of feed). Both concentrations of dietary CA significantly decreased counts of Salmonella Enteritidis in the crop and cecum of experimental chickens (p<0.05). The effect of CA in the crop contents was more pronounced than in the cecum. Surface treatment of chilled chicken halves with CA at 1.25 and 2.5 mg/mL significantly decreased Salmonella Enteritidis contamination of chicken skin (p<0.05). The sensory evaluation of the skin and meat showed that treatment of the skin with 1.25 mg/mL of CA worsened odor and appearance of the chicken skin, while sensory traits of chicken meat were not significantly affected. Taste and overall acceptability was not influenced by CA in both meat and skin. Treatment of the skin with 2.5 mg/mL of CA resulted in more pronounced changes of the skin odor and appearance. In conclusion, dietary CA reduced carriage of Salmonella Enteritidis in chickens, whereas surface-treatment reduced or eliminated Salmonella Enteritidis contamination in the processed bird.

Cholesterol and fat lowering with hydrophobic polysaccharide derivatives.

Hydrophobic derivatives of highly methylated citrus pectin, chitosan and cellulose were prepared and tested as potential cholesterol lowering agents. Elemental analysis and spectroscopic methods confirmed high substitution degree for all of them. Substitution with long alkyl/acyl groups led to significant changes in physical and thermal properties of modified polysaccharides. Sorption of cholate and cholesterol by these polysaccharide-based sorbents was estimated in comparison with the synthetic drug cholestyramine. It was found that modified polysaccharides have high affinity to cholesterol. By contrast, cholestyramine was effective only in cholate sorption.

Prebiotic effects of a novel combination of galactooligosaccharides and maltodextrins.

Prebiotics are used for stimulating the growth of beneficial microorganisms in the gut. However, it is very difficult to find a suitable prebiotic mixture that exclusively supports the growth of beneficial microbes such as bifidobacteria and lactobacilli. We tested the effects of a prebiotic mixture in vitro by incubating it with fecal samples and in vivo by administration of the prebiotic supplement to healthy adult volunteers, followed by analysis of their fecal microbiota. The effect of the oligosaccharides on bacterial metabolism was studied by analyzing short-chain fatty acid (SCFA) production in vitro and the SCFA pattern for the stool samples of volunteers. In the in vitro test, a higher proportion of bifidobacteria (25.77%) was seen in the total bacterial population after cultivation on a prebiotic mixture than on the control medium (7.94%). The gram-negative anaerobe count significantly decreased from 8.70 to 6.40 log CFU/g (from 35.21% to 0.60%) and the Escherichia coli count decreased from 7.41 to 6.27 log CFU/g (from 1.78% to 0.44%). Administration of a prebiotic mixture in vivo (9 g of galactooligosaccharides [GOS]+1 g of maltodextrins; daily for 5 days) significantly increased the fecal bifidobacterial count from 9.45 to 9.83 log CFU/g (from 40.80% to 53.85% of total bacteria) and reduced the E. coli count from 7.23 to 6.28 log CFU/g (from 55.35% to 45.06% of total bacteria). The mixture comprising GOS and maltodextrins thus exhibited bifidogenic properties, promoting the performance of bifidobacteria by boosting their growth and inhibiting the growth of undesirable bacteria.

Antibacterial activities of plant-derived compounds and essential oils toward Cronobacter sakazakii and Cronobacter malonaticus.

Cronobacter sakazakii and C. malonaticus are opportunistic pathogens that cause infections in children and immunocompromised adults. In the present study, the antibacterial activity of 19 plant-derived compounds, 5 essential oils, and an extract of propolis were assessed against C. sakazakii and C. malonaticus. The effects of most of these antimicrobials have not been reported previously. Both strains were susceptible to thymol, carvacrol, thymoquinone, p-cymene, linalool, camphor, citral, eugenol, and trans-cinnamaldehyde as well as cinnamon, lemongrass, oregano, clove, and laurel essential oils; their minimum inhibitory concentrations varied between 0.1 and 2.0 mg/mL. As an alternative treatment method, vapors of the volatiles were tested as an indirect treatment. Vapors of trans-cinnamaldehyde, eugenol, oregano, and cinnamon essential oils inhibited both tested strains, while vapors of linalool were only active against C. sakazakii. To our knowledge, this study is the first time that the inhibitory activity of the vapors of these compounds and essential oils has been reported against Cronobacter spp.

Dose-response efficacy and long-term effect of the hypocholesterolemic effect of octadecylpectinamide in rats.

The dose-response efficiency and long-term effect of the hypocholesterolemic effect of octadecylpectinamide was examined in female rats fed diets containing cholesterol at 10 g/kg. In our first experiment, amidated pectin supplied at 20 g/kg, 40 g/kg and 60 g/kg significantly decreased serum cholesterol from 3.32 µmol/ml (control) to 1.23 µmol/ml in a dose-dependent manner. In a second experiment, the hypocholesterolemic effect of amidated pectin supplied at 20 g/kg persisted after 3 months of feeding. In both experiments, the amidated pectin significantly decreased the concentrations of cholesterol in hepatic tissue and triacylglycerols in serum. The serum concentration of aspartate aminotransferase significantly increased in rats fed amidated pectin at 60 g/kg for 4 weeks, and at 20 g/kg for 3 months. In conclusion, amidated pectin at a low dose and used for a period shorter than 3 months might be considered as an effective hypocholesterolemic and lipid-lowering agent that may substitute typical antilipidemic drugs.

The simple and sensitive measurement of malondialdehyde in selected specimens of biological origin and some feed by reversed phase high performance liquid chromatography.

A method for the determination of malondialdehyde (MDA) concentrations in specimens of animal tissues and feed has been developed using high performance liquid chromatography. The MDA concentration in acidified urine samples was determined after its conversion with 2,4-dinitrophenylhydrazine (DNPH) to a hydrazone (MDA-DNPH). Samples of blood plasma, muscle, liver and feed were prepared by saponification followed by derivatisation with DNPH to MDA-DNPH. The MDA concentration in chicken and hen feed samples was analysed after saponification and derivatisation followed by extractions with hexane. The free MDA in plasma samples was determined after deproteinization followed by derivatisation of MDA with DNPH. The chromatographic separation of MDA-DNPH samples was conducted using Phenomenex C(18)-columns (Synergi 2.5 µm, Hydro-RP, 100 Å, the length of 100mm) with an inner diameter of 2 or 3mm. MDA in processed biological samples was analysed using a linear gradient of acetonitrile in water, and the photodiode detector was set to 307 or 303 nm for detection. The current method that was utilised was based on the high-efficient derivatisation of MDA and was more sensitive compared to previously used methods. The selective and sensitive photodetection of the column effluent was found to be suitable for the routine analysis of MDA in urine, plasma, muscles and liver of animals and some feed samples. Because urine or blood plasma samples can be derivatised in a simple manner, the proposed method can also be suitable for the routine, non-invasive evaluation of oxidative stress in animals and humans.

Effect of feeding growing-fattening rabbits a diet supplemented with whole white lupin (Lupinus albus cv. Amiga) seeds on fatty acid composition and indexes related to human health in hind leg meat and perirenal fat.

A total of 20 weaned rabbits (33 days old) (10 per treatment) were fed one of two diets that included 150 g of sunflower meal (SF)/kg of diet or 120 g of whole white lupin (WL)/kg of diet for 42 days. The WL diet contained less saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) but more monounsaturated fatty acids (MUFA) than the SF diet. The WL diet significantly decreased SFA and PUFA content, as well as the PUFA n-6/PUFA n-3 ratio and saturation, atherogenic and thrombogenic indexes in hind leg meat. The fatty acid composition in perirenal fat was similar to that of hind leg meat; however, significantly higher MUFA levels were observed in rabbits fed the WL diet. Thus, feeding rabbits the WL diet affected the fatty acid profile of hind leg meat and perirenal fat in a favourable manner.

Inhibitory effect of organic acids on arcobacters in culture and their use for control of Arcobacter butzleri on chicken skin.

The inhibitory effects of 17 organic acids (C2-C16 fatty acids, sorbic, benzoic, phenylacetic, fumaric, succinic, lactic, malic and citric) on Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii were investigated by determining their IC50 values, defined as the concentration of acid at which the target DNA sequence was expressed at 50% of the positive control level in cultures incubated at 30°C for 24 h. DNA was analysed by real-time PCR. The Arcobacter strains tested were inhibited by all the organic acids, with the sensitivities in the order A. skirrowii > A. cryaerophilus > A. butzleri. Eight acids with IC50 values of <1 mg/mL against A. butzleri were tested for their effects on A. butzleri inoculated on chicken carcasses at a concentration of 5 log CFU/g of skin. Inoculated halved carcasses were immersed in solutions of the acids at 5 mg/mL for 1 min. Samples of skin were collected from carcass halves after storage at 4°C for 0, 1, 2 or 3 days for enumeration of arcobacters on Muller-Hinton agar. All eight tested acids suppressed bacterial proliferation. The highest inhibitory activities were observed for benzoic, citric, malic and sorbic acids. Subsequent sensory analysis revealed benzoic acid to be the most suitable organic acid for chicken skin treatment.

Changes in the bacterial population of the caecum and stomach of the rabbit in response to addition of dietary caprylic acid.

The effect of caprylic acid, either in its pure form, or as Akomed R, on the microbial community of the stomach and caecum of farmed rabbits was investigated. This fatty acid, which is often added to the diet of farmed rabbits to reduce mortality rates was shown to reduce the number of coliforms isolated from both the stomach and the caecum. Moreover, it led to a reduction in the total number of anaerobic bacteria isolated from the caecum, but not for those isolated from the stomach. Its mode of action remains unclear, but here it is shown by use of both DGGE and TRFLP analysis that these changes are not confined to one specific group of bacteria, but rather affects a number of species.

Bifidobacteria in the digestive tract of bumblebees.

Bifidobacteria and other bacterial groups (lactobacilli, facultative anaerobes, anaerobes) from the digestive tract of three bumblebee species (Bombus lucorum (34 samples), Bombus pascuorum (18 samples) and Bombus lapidarius (9 samples)) were enumerated and characterised. Counts of facultative anaerobic bacteria and lactobacilli (5.41+/-2.92 and 2.69+/-3.02 log CFU/g of digestive tract content) were lower than those of anaerobes (7.66+/-0.86 log CFU/g). Counts of bifidobacteria were determined using two selective media: MTPY (Modified Trypticase Phytone Yeast extract agar) and a new medium with pollen extract. There was no significant difference between the counts of bifidobacteria from both media, 5.00+/-2.92 log CFU/g on MTPY and 5.00+/-2.87 on the pollen medium. Subsequently, 187 bacterial strains of the family Bifidobacteriaceae (fructose-6-phosphate phosphoketolase-positive) were isolated from three different localities and from all three species of bumblebees. Bifidobacteria were found in 42 out of 61 specimens (69%). Twenty-three (38%) specimens had counts of bifidobacteria higher than 7.0 log CFU/g. Bifidobacteria represented the dominant group of anaerobes (>70% of total anaerobes), i.e., the principal group of bacteria in the bumblebee digestive tract, in only fourteen specimens (23% of total). For the first time, bifidobacteria were isolated from the digestive tract of bumblebees. In addition, we suggest, on the basis of biochemical tests (API 50 CHL and RAPID ID 32) and genetic methods (PCR and DGGE), that these bacteria may represent new species within the family of Bifidobacteriaceae.

Inhibitory activity of rabbit milk and medium-chain fatty acids against enteropathogenic Escherichia coli O128.

Colibacillosis represents a major cause of diarrhea in young rabbits. In order to elucidate protective effect of milk, in vitro and in vivo experiments were carried out. In the in vitro experiment, rabbit milk treated with lipase significantly decreased the number of viable cells in cultures of Escherichia coli, O128 serotype, from 10.3 to 6.2-7.3log(10)/(cfuml). The lipase effect was the same with heat-treated (100 degrees C/10min) and raw milk. Raw milk without lipase decreased the number of E. coli only marginally. In the in vivo experiment, weaned rabbits received feed contaminated with the same bacterium. The course of the infection was moderate, only 2 out of 36 infected rabbits died. Seven days after inoculation, caprylic acid at 5g/kg feed and triacylglycerols of caprylic and capric acid at 10g/kg feed decreased faecal output of E. coli from 10.2log(10)/(cfug) to 5.8 and 6.1log(10)/(cfug), respectively. The number of E. coli in faeces of non-infected rabbits averaged 4.0log(10)/(cfug). The growth of infected rabbits was slow for 2 weeks after infection. In the third week a compensatory growth was apparent. At the end of the experiment, average body weights of rabbits receiving caprylic acid and those of non-infected rabbits were not significantly different. It can be concluded that (i) lipids rather than proteins seem to be responsible for the antimicrobial activity of rabbit milk; and (ii) this activity was lipase-dependent. Caprylic acid or oils with high a concentration of it may be used as feed supplements for weanlings.

Performance and tissue fatty acid profiles in veal calves fed diets supplemented with conjugated linoleic acids.

Three groups of six calves each were fed a milk replacer at 0.8 kg and a starter concentrate ad libitum. Calves of the control group received the basal diet supplemented with rapeseed oil at 10 g per kg of feed solids. Calves of treatment groups were fed diets supplemented with a synthetically produced oil containing 62.3% methyl esters of CLA. The CLA-oil was added to milk at expense of rapeseed oil and fed at 5 and 10 g x kg(-1) feed solids for 63 days. Calves were slaughtered at 115 days of age. There was no significant effect of CLA on growth, intake of starter, feed conversion, chemical composition of meat and its oxidative stability. Dietary supplementation with CLA at 10 g x kg(-1) significantly increased CLA content in m. longissimus dorsi (MLD) from 5.6 to 19.3 mg x 100 g(-1), in liver from 13.1 to 68.8 mg x 100 g(-1), and in perirenal fat from 0.37 to 3.17 g x 100 g(-1). Dietary CLA decreased the ratio of cis-9, trans-11 and trans-10, cis-12 isomers of CLA in tissues, concentration of monounsaturated fatty acids in the MLD and fat, as well as the concentration of fatty acids with 20 and 22 carbon atoms. It can be concluded that in veal calves unprotected CLA apparently escaped ruminal hydrogenation, but was preferentially incorporated into depot fat.