L. Haak

Effect of linseed feeding at similar linoleic acid levels on the fatty acid composition of double-muscled Belgian Blue young bulls

The effect of including linseed [extruded (EL) or crushed (CL)] instead of whole soybeans (S) in the finishing diet of double-muscled Belgian Blue young bulls on the fatty acid composition of the longissimus thoracis, triceps brachii and subcutaneous fat was investigated. The dietary supply of C18:2n-6 was similar in the three diets, while in the EL and CL diet the supply of C18:3n-3 was equal. No effects of diet on the saturated, monounsaturated and branched chain fatty acids were found. Including linseed in place of whole soybeans increased the total intramuscular n-3 fatty acid content significantly, mainly as C18:3n-3, while no significant effect on the total and individual n-6 fatty acid incorporation was observed in the intramuscular fat. As a consequence of the higher n-3 content, the n-6/n-3 ratio was decreased by linseed feeding. In contrast with the intramuscular fat, the subcutaneous fat showed a significantly increased C18:3n-3 proportion accompanied by a significantly decreased C18:2n-6 proportion when linseed was fed. Diet did not influence the c9t11CLA content in the intramuscular or the subcutaneous fat.

Lipid and Protein Oxidation of Broiler Meat as Influenced by Dietary Natural Antioxidant Supplementation

Natural tocopherols (TC), rosemary (RO), green tea (GT), grape seed, and tomato extracts were supplemented in single and in combinations at total concentrations of 100 and 200 mg.kg(-1) of feed in a 4% linseed oil-containing diet to investigate the oxidative stability of broiler breast muscle. Supplementation with 300 mg.kg(-)1 of synthetic antioxidants alone and synthetic antioxidants with alpha-tocopheryl acetate at a concentration of 200 mg.kg(-1) (100 IU) feed was used as a control. Fresh patties were prepared and stored under light at 4 degrees C. After freezing for 8 mo and overnight thawing, 3 other patties were prepared and similarly stored under light at 4 degrees C. During display, samples were evaluated for oxidative stability measurements. For lipid oxidation, the treatment with synthetic antioxidants and 200 mg.kg(-1) of alpha-tocopheryl acetate yielded the lowest TBA reactive species (TBARS) values. For TC, grape seed, and tomato extracts, TBARS values for 100 mg.kg(-1) were higher (P < 0.05) than 200 mg.kg(-1) treatments, whereas no differences (P > 0.05) in TBARS values were observed for RO between 100 and 200 mg.kg(-1). In contrast, GT showed higher TBARS values at 200 mg.kg(-1). Administration of combinations of TC, RO, and GT did not reveal synergistic effects but confirmed the increase in TBARS values with increasing doses of GT. No differences (P > 0.05) among the different antioxidant treatments were detected for protein oxidation. The muscle alpha-tocopherol content linearly responded to the feed alpha-tocopherol content and thus there were no indications for a sparing effect on alpha-tocopherol from other antioxidant treatments. In summary, dietary natural antioxidant extracts were less effective than the treatment with synthetic antioxidants combined with alpha-tocopheryl acetate for protecting against oxidation, but there were marked differences between different natural antioxidant extracts.

Fatty acid profile and oxidative stability of pork as influenced by duration and time of dietary linseed or fish oil supplementation1

In this experiment, the effect of duration and time of feeding n-3 PUFA sources on the fatty acid composition and oxidative stability of the longissimus thoracis (LT) muscle was investigated. Linseed (L) and fish oil (F), rich in alpha-linolenic acid and eicosapentaenoic and docosahexaenoic acid (EPA and DHA), respectively, were supplied equivalent to a level of 1.2% oil (as fed), either during the whole fattening period or only during the first (P1; 8 wk) or second (P2; 6 to 9 wk until slaughter) fattening phase. All diets were based on barley, wheat, and soybean meal and were fed ad libitum. Crossbred pigs (n = 154; Topigs 40 x Piétrain) were randomly allotted to the 7 feeding groups. In the basal diet (B), only animal fat was used as the supplementary fat source. Three dietary groups were supplied the same fatty acid source during both fattening phases (i.e., group BB, LL, and FF). For the other 4 dietary groups, the fatty acid source was switched after the first phase (groups BL, BF, LF, and FL; the first and second letter indicating the diet in P1 and P2, respectively). Twelve animals per feeding group were selected based on average live BW. The LT was analyzed for fatty acid composition; lipid stability (thiobarbituric acid-reactive substances) and color stability (a* value, % of myoglobin pigments) were determined on the LT after illuminated chill storage for up to 8 d. The alpha-linolenic acid, EPA, and docosapentaenoic acid incorporation was independent of the duration of linseed feeding (1.24, 0.54, and 0.75% of total fatty acids, respectively, for group LL). Supplying fish oil during both phases resulted in the greatest EPA and DHA proportions (1.37 and 1.02% of total fatty acids; P < 0.05), but the content of docosapentaenoic acid was not affected. The proportion of DHA was greater when fish oil was administered during P2 compared with P1 (P < 0.05). There was no effect of diet on meat ultimate pH and drip loss or on lipid or color oxidation.

Effect of dietary antioxidant and fatty acid supply on the oxidative stability of fresh and cooked pork

The effect of dietary oil (linseed or soybean oil) and antioxidant treatment (α-tocopheryl acetate (AT; 40ppm) versus a cocktail (AOC; 200ppm): α-tocopheryl acetate+rosemary+citric acid+gallic acid) on colour, lipid and protein oxidation of fresh and processed pork was investigated. No effect of oil source on different parameters of oxidation was seen. No effect of antioxidant treatment on colour stability of fresh longissimus thoracis (LT) or cooked cured ham (CCH) was observed. For both antioxidant treatments, lipid oxidation in fresh LT and CCH was well controlled during display. However, lipid oxidation increased significantly in pre-frozen uncured cooked meat under aerobic conditions. No unambiguous effect of antioxidant treatment on protein oxidation was observed. There seemed to be no clear link between colour, protein and lipid oxidation. At the dose used in this study, no additional or synergistic effects of the extra components of the AOC on the different oxidation parameters was found.

Effect of dietary rosemary and α-tocopheryl acetate on the oxidative stability of raw and cooked pork following oxidized linseed oil administration

The effect of a 2% dietary administration to pigs of oxidized linseed oil (targeted level of 150mEq.O(2)/kg oil after heating at 50°C and exposure to air for 3-4 days following addition of 10ppm CuSO(4)), either or not in combination with antioxidants, on the oxidative stability of raw and cooked pork during illuminated chill storage was assessed. The antioxidant treatments were: 40ppm α-tocopheryl acetate, 40ppm rosemary extract, 40ppm rosemary extract+2ppm gallic acid, and 40ppm α-tocopheryl acetate+40ppm rosemary extract. A total of 20ppm of α-tocopheryl acetate (ATA) was added to all diets in order to meet the physiological requirement of the animals. The antioxidant treatments did not exert any effect on colour and protein oxidation. Lipid oxidation was only decreased by dietary ATA when comparing the ATA supplemented groups combined versus a control treatment group for raw but not for cooked meat. This was due to a higher content of α-tocopherol in the meat and subcutaneous fat. The lipid oxidation results suggested a lack of antioxidant effect for the rosemary extract. No evidence for a synergistic effect of the antioxidant combinations was observed.