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  • Author or Editor: F. Husvéth x
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Increasing awareness of the health benefits of n-3 fatty acids has led to studies related to the manipulation of the fatty acid composition of animal products. These fatty acids, especially eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3), are abundant in foods of marine origin. Fish consumption is, however, limited by seasonal availability, affordability and consumers' preference. Recent studies on the provision of n-3 fatty acid rich foods have therefore centred on the enrichment of products such as poultry meat through feeding fish oil diets. However, decreased quality (storage and flavour) has been associated with products from poultry fed such diets. Other dietary sources of n-3 fatty acids such as fish meal and plant seed oils result in minor improvement of the quality and low levels of EPA and DHA in the enriched product. Supplementation of high levels of vitamin E or other synthetic antibiotics in diets may increase oxidative stability and hence the storage quality of n-3 fatty acid enriched broiler meat. However, their reported influence on off-flavour is conflicting. Other methods of reducing off-flavour in enriched meat involving the use of processed n-3 PUFA sources although may reduce off-flavour, result in reduced deposition of EPA and DPA. Marine algae (MA) is an attractive source of n-3 fatty acids because it is a primary rich source of DHA and contains naturally occurring carotinoids, which are useful for their antioxidant activity. Investigations into the use of MA and identification of cheaper sources of n-3 PUFA for the enrichment of broiler chicken are needed. In addition, the search for viable methods of reducing off-flavour in n-3 enriched broiler meat should continue. The production of high quality and affordable broiler meat is essential for realising the full benefits associated with the consumption of n-3 fatty acid enriched products.

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Ten Holstein cows between 8 and 12 weeks in lactation were used to investigate the effect of feeding full-fat soybean, full-fat sunflower, and a Ca-soap source (Profat) on the conjugated linoleic acid (CLA) content of milk. Cows were fed the experimental fat sources in the dosage of 500 g crude fat daily. The results indicated that milk CLA content increased in relation to the linoleic acid concentration of experimental fat supplements, namely full-fat sunflower increased the most and Profat increased the least the CLA concentration in milk. The strength of the correlation was r=0.62 between the linoleic acid concentration in feed and the CLA content in milk. The strength of correlation increased to r=0.69 when both linoleic acid and linolenic acid concentration of feed were used in the calculation. Considering milk production and the daily production of CLA in milk, the following equation described the relationship between the linoleic acid content of fat supplements and CLA concentration in milk: x=167.52+0.483×y; where x=CLA mg l −1 milk and y=linoleic+linolenic acid content of fat sources, g/day. Along with milk CLA, the trans -C18:1 concentration of milk also increased, but the magnitude of the increase was smaller compared to that of milk CLA.

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In this experiment sunflower oil, soybean oil and fish oil were incubated in rumen-fistulated adult ewes (n = 5) to study conjugated linoleic acid (CLA) production in the rumen. The individual oils were incubated in nylon bags in the rumen on perlite carrier (40% oil, 60% carrier) over a period of 2, 4, 6, 8, 10 and 12 h for all treatments. During the incubation of each oil primarily the formation of the cis-9, trans-11 isomer of CLA could be observed. Both sunflower and soybean oils showed similar changes in the rumen. After the incubation of these two vegetable oils the proportion of linoleic acid decreased significantly as the duration of incubation increased in the rumen. These changes were accompanied by a significant increase in the amount of cis-9, trans-11 CLA. However, in the case of sunflower oil the rate of formation of the cis-9, trans-11 CLA isomer was significantly higher after the different incubation times as compared to soybean oil. Much lower amounts of CLA were formed when fish oil was incubated in the rumen. The level of cis-9, trans-11 isomer produced during these treatments was 10% less than the amount obtained with the other two oils of vegetable origin. Besides the cis-9, trans-11isomer, trans-10, cis-12 CLA could also be detected during the incubation of the different oils in the rumen. However, the level of this isomer was low and did not show consistent differences among the treatments. The results of this experiment indicate that the fatty acid composition of the oils and the duration of incubation collectively determine the amount of CLA produced in the first compartment of the forestomach of ruminants.

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This study was designed to determine the effects of calcium salt of palm oil fatty acids (CS), hydroxyethylsoyamide (HESA), butylsoyamide (BSA) and soybean oil (SO) on degradation of crude protein and fibre in vitro, and on the blood plasma lipid parameters in vivo. Five mature wethers (body weight 75 kg) were fed five diets in a 5 × 5 Latin square experiment. The control diet consisted of 50% meadow hay and 50% concentrate with no added fat. The control diet was supplemented with CS, HESA, BSA, or SO. Fat was added at 3.5% of dietary dry matter (DM). The final ether extract content of the ration was near 6%. Each period lasted 20 days. Fat supplements, except HESA, consistently decreased the in vitro DM disappearance of soybean meal as compared to control. In contrast to the effect of other treatments, crude protein degradation was greatest in the test tubes with inocula obtained from sheep fed diet with HESA. Fat supplements equally inhibited the DM and fibre breakdown of alfalfa pellet. CS and HESA seemed to be less detrimental to in vitro fermentation of neutral detergent fibre (NDF) than BSA and SO. All fat supplements increased blood plasma triglyceride, cholesterol and total lipid content. Plasma concentration of cholesterol and total lipid was highest with SO. The inclusion of CS in the diet increased 16:0, while all fat supplements increased plasma 18:0 and decreased 16:1 and 18:1 fatty acid content. Plasma 18:2n-6 was not changed by feeding CS and SO. However, compared to the control diet, 18:2n-6 increased with 12 and 41% in plasma fatty acids when sheep were fed HESA and BSA, respectively. The results showed that plasma concentration of linoleic acid was enhanced more when the amide was synthesised from butylamine than when from ethanolamine.

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An experiment was performed to study the effect of different vegetable oils containing high proportions of PUFA (5% soybean oil, SBO; and sunflower oil, SFO; respectively, in the DM of concentrate) or grass silage (150 g DM/d/animal, GSL) on the level of conjugated linoleic acid (CLA) isomers and other C18 fatty acids in muscle and adipose tissues of growing lambs. Control animals were fed on the same diet as SBO or SFO groups; however, instead of vegetable oils hydrogenated palm oil containing low level of PUFA was applied. In both muscle and adipose samples tested c-9, t-11 C18:2 showed the highest levels among the CLA isomers, however, t-10, c-12 CLA could also be measured in lower proportions. Considering vegetable oil supplementations, only SBO resulted in a significantly higher level of c-9, t-11 CLA in the triceps brachii muscle as compared to the control. Such a difference could not be detected in either the gracilis muscle or in the adipose tissue samples. However, lambs fed on the GSL diet had significantly higher c-9, t-11 CLA levels in both the triceps and gracilis muscles and lower proportion of t-10, c-12 CLA in the adipose than those fed on the control, SBO and SFO diets, respectively. Concerning C18 fatty acids other than CLA, SFO lambs showed significantly higher proportions of C18:1n-9 than those of control animals in both muscles and perirenal fat tested. However, level of C18:0 in the adipose tissue of GSL lambs was significantly lower than that of the animals fed both control or vegetable oil supplemented diets. Results of this experiments show that different dietary fatty acid sources have various potential to increase CLA contents in the meat of lambs. In addition to vegetable oils rich in PUFA, grass silage may be good dietary source for nutritional manipulation of the fatty acid composition of lamb meat.

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Authors: G. Kovács, J. Schmidt, F. Husvéth, K. Dublecz, L. Wágner and E. Farkas-Zele
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The effect of supplementary methionine and fats of different saturation levels on the glutathione redox system of growing broiler cockerels was studied. The diet of three groups of chicks was supplemented with corn germ oil, beef tallow and fish oil at the levels of 30 g/kg and 50 g/kg of feed, respectively. The diet of further three groups was supplemented with methionine (5 g/kg of feed) in addition to the different fat sources. Control chicks were fed with a compound feed without methionine and fat supplementation. Reduced glutathione (GSH) and glutathione disulphide (GSSG) content as well as glutathione peroxidase activity in the liver were determined and GSH/GSSG ratio was calculated at day old and then at one and three weeks of age. Our results indicate that supplementary methionine stimulates both the synthesis of the glutathione redox system and glutathione peroxidase activity in growing chickens in the first period of postnatal life, when the risk of lipid peroxidation is high due to feeding unsaturated fats in the diet.

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Age-related changes of tissue lipid peroxidation (LPO) of liver and brain, as well as plasma antioxidant capacity of broiler chicken cockerels were investigated. Tissue LPO was characterised by the spectrophotometric assessment of thiobarbituric acid reactive substances (TBARS). Plasma antioxidant power was evaluated by the measurement of total antioxidant status (TAS). Newly hatched broiler chicks had similar TAS value (1.19 mmol/l) as newborns of mammalian species. Significant changes (p < 0.05) were observed in the time course of all parameters. Tissue TBARS concentration was higher in the brain than in the liver at hatching, while the latter organ was found to have more effective antioxidant defence during embryonic life. The concentration of TBARS increased up to the 10th day in the liver but only up to the 21st day in the brain, and the former was accompanied by an approximately 50% decrease of plasma antioxidant capacity. This suggests that the liver plays an important role in forming the antioxidant defence mechanisms of the blood plasma in broiler chicks.

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Authors: Tibor Gaál, L. Wágner, F. Husvéth, H. A. Manilla, P. Vajdovich, N. Balogh, I. Lóth and Katalin Németh S.

The influence of fish oil (highly unsaturated) and beef tallow (highly saturated) with vitamin E (100 IU/kg) supplementation on the antioxidant status of broiler chicken cockerels was investigated. Chicks were fed a control diet with no added fat, 40 g/kg each of fish oil and beef tallow diets, respectively, from 11 to 42 days of age. Tocopherol concentration and the rate of lipid peroxidation, thiobarbituric acid reactive substance (TBARS) in liver, fatty acid composition of the liver lipids, blood serum total antioxidant status (TAS), and reduced glutathione (GSH) content were determined. Vitamin E supplementation of the diet increased liver ?-tocopherol content in chicks regardless of the type of dietary fat. Fish oil diet resulted in higher liver TBARS value while beef tallow diet showed lower values compared to the control diet. Vitamin E supplementation reduced liver TBARS as well as serum GSH, and raised serum TAS for all diets. Serum GSH was the same for vitamin E supplemented diets regardless of the fat supplement. Fish oil diets resulted in a significant increase in hepatic lipid n-3 PUFA content. A significant positive correlation was found between liver TBARS and n-3 PUFA content. No relationships were established, however, between liver TBARS and n-6 PUFA or saturated fatty acids. The results suggest that feeding oils rich in n-3 PUFA increases tissue concentration of these fatty acids, consequently increasing tissue lipid peroxidation and reducing the antioxidative status of broiler chickens. Supplementing high levels of vitamin E with such oils may increase tissue oxidative stability. Serum TAS or GSH may be used as a measure of antioxidative status in chickens.

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