Inclusion of oxidized fish oil in mink diets. 2. The influence on performance and health considering histopathological, clinical-chemical, and haematological indices

Effects of dietary vitamin E supplementation on the reproductive performance of yearling female mink (Neovison vison) fed wet fish-based feed

This study was conducted to investigate the effects of dietary vitamin E (VE) supplementation on the reproductive performance of female mink, preweaning growth performance of their kits, and antioxidative status and immune functions of dams and kits. Yearling mink dams (n = 180) were randomly assigned to five treatment groups (n = 36). The dietary treatments included a basal diet supplemented with VE at 0 (control), 80, 160, 320, or 640 mg/kg DM. Compared with the control, the addition of 160-320 mg/kg VE decreased (P = 0.0362) the percentage of pre-weaning mortality of mink kits. At weaning, the average body weight was greater (P = 0.0408) in kits fed 320 mg/kg supplemental VE. In mink dams, the addition of 80-320 mg/kg VE increased (P = 0.0125) serum SOD. Supplementation of 320 or 640 mg/kg VE decreased (P = 0.0260) serum reactive oxygen species (ROS). Furthermore, feeding a large dose of VE (640 mg/kg diet) resulted in increased (P = 0.0245) serum α-tocopherol. In mink kits, the addition of 320 or 640 mg/kg VE increased serum α-tocopherol (P = 0.0207) and IgG (P = 0.0464). Supplementation of 640 mg/kg VE decreased (P = 0.0471) serum ROS. The present results indicate that VE supplementation improved the antioxidative status of mink dams and enhanced the immune functions, decreased pre-weaning mortality and enhanced weaning weight of their kits. Taken together, the effective VE supplementation was 320 mg/kg of diet for yearling female mink.

Effect of antioxidant inclusion and oil quality on broiler performance, meat quality, and lipid oxidation

The objective of the present study was to evaluate the effect of antioxidant inclusion and oil quality on broiler performance, meat quality, shelf life, and tissue oxidative status. Ross 308 male broilers were allotted to a randomized complete block design in a 2 × 2 factorial arrangement. Factors consisted of antioxidant (ethoxyquin and propyl gallate) inclusion at 2 levels (0 or 135 mg/kg) and oil quality (fresh soybean oil, control diet peroxide value <1 mEq/kg, or oxidized soybean oil, diet peroxide value 7 mEq/kg). Each treatment included 12 pen replicates comprising 24 birds for a total of 1,152 birds on trial allotted to 48 pens. On the final day of the study, 1 bird from each pen was killed by cervical dislocation and used for determination of tissue oxidative status. Another 5 broilers from each pen were processed at a commercial slaughtering facility. Immediately after processing, carcasses were transported to the University of Illinois Meat Science Laboratory (Urbana) for further analysis. With the exception of 2 responses (liver vitamin A and serum vitamin A), no interactions were found between antioxidant inclusion and oil quality. Body weight and weight gain were increased by dietary antioxidant inclusion (P < 0.001) and fresh oil (P < 0.001). Feed intake was increased in broilers fed the antioxidant (P = 0.047) and fresh oil (P = 0.062). Antioxidant inclusion had no effect on G:F (P = 0.18). Antioxidant supplementation had no effect on carcass weight (P = 0.202), dressing percentage (P = 0.906), breast yield (P = 0.708), or breast ultimate pH (P = 0.625) and had minimal effect on breast color. Antioxidant supplementation (P = 0.057) reduced breast thiobarbituric acid reactive substances after 7 d of display. Fresh oil decreased liver thiobarbituric acid reactive substances, whereas antioxidant inclusion increased serum and liver vitamin A and E concentration. The presence of an antioxidant in the feed protects lipids from further oxidizing, therefore increasing broiler performance and improving shelf life when using oxidized oil.

Effect of dietary α -tocopherol concentration on performance and some immune responses in broiler chickens fed on diets containing oils from different sources

1. An investigation was carried out into the effects of dietary α-tocopherol (α-T) concentration and source of supplemental oil on performance, activity of anti-oxidative enzymes and some immune responses in broilers from day-old to 41 d of age. 2. Three dietary concentrations of α-T (10, 50 and 100 mg/kg) with three sources of supplemental oil (sunflower - SFO, palm - PMO and safflower - SAO) were provided using a 3 × 3 experimental design. 3. Body weight gain and food conversion efficiency were not affected by either interaction or concentrations of α-T and sources of oil in diet. 4. Concentrations of total protein, globulin, triglycerides and cholesterol in sera increased significantly with dietary α-T concentration irrespective of the source of oil. Significantly higher concentration of serum albumin was evident in broilers fed on the SFO-based diet and the concentration of globulin was higher in groups fed on those diets containing PMO and SAO. 5. The lipid peroxidation (LP), measured as MDA release, decreased with the concentration of α-T in a dose-related manner with SFO- and SAO-based diets, although not with the PMO-based diet. With different oil sources, LP was significantly lower with the PMO-based diet compared to the others. Activities of glutathione peroxidase and RBC catalase increased and heterophil: lymphocyte ratio was reduced with concentration of α-T for each source of oil tested. 6. Assays for humoral and cell-mediated immune responses indicated no effect of the source of dietary supplemental oil or interaction, although an increasing concentration of dietary α-T improved cell-mediated immune responses. 7. It is concluded that sunflower oil, palm oil and safflower oil can be used as sources of oil for broiler diets without having any effect on performance, immune responses or the activity of anti-oxidizing enzymes. Higher concentrations of dietary α-tocopherol (50 or 100 mg/kg) reduced lipid peroxidation activity and enhanced activities of anti-oxidative enzymes, they also improved the cell-mediated immune responses in commercial broilers.

Effect of partial replacement of oats with sugar beet pulp and maize oil on nutrient utilisation in horses

The objective of the present work was to assess the influence of partial replacement of oats with dried unmolassed sugar beet pulp (SBP) and/or maize oil on nutrient utilisation in horses fed a traditional hay and concentrate diet. The total tract digestibility of nutrients, urinary excretion and plasma parameters were studied in a 4 x 4 Latin-square design experiment with purebred Arabian geldings. Horses fed the SBP diets responded with a reduced (P<0.05) apparent digestibility of crude protein and feeding of maize oil resulted in an increased (P<0.05) apparent digestibility of crude fat. The apparent energy digestibility was unaffected by the replacement of oats with SBP, but increased (P<0.05) when maize oil replaced part of the oats. The urinary excretion of nitrogen increased (P<0.05) when maize oil replaced oats and the excretion of energy was higher (P<0.05) on the diets where oats were replaced by maize oil and SBP. There was a significant (P<0.05) effect across treatments of postprandial blood sampling time on plasma glucose and insulin concentrations. Also, plasma concentrations of glucose and insulin tended to be higher on the oats than on the SBP diets. In conclusion, the limited effects on the digestibility of nutrients and energy suggest that it should be possible to partially replace oats with maize oil and/or SBP in diets for horses without any impairing effects on the overall nutrient utilisation. However, the dietary-induced changes in the urinary excretion of energy and on plasma glucose and insulin levels, indicate a possible influence of dietary carbohydrate composition on nutrient utilisation at the organ level, which requires further study.

Plasma thyroxine and cholesterol concentrations of miniature pigs are influenced by thermally oxidized dietary lipids

To investigate the effect of a dietary oxidized oil on thyroid hormone status and circulating cholesterol, we conducted a study with 16 male miniature pigs fed a nutritionally adequate diet with 15% of either fresh or thermoxidized oil for 35 d (n = 8/group). The thermoxidized oil was prepared by heating sunflower oil at 110 degrees C for 48 h. The fresh oil consisted of a mixture of sunflower oil and lard (94:6, v/v) which had a fatty acid composition similar to the thermoxidized oil. At the end of the study, there were no differences in body weight gains and plasma clinicochemical variables between groups, suggesting that the thermoxidized oil did not induce general toxic symptoms. However, pigs fed the thermoxidized oil had significantly higher plasma concentrations of total and free thyroxine (P < 0.05) and a tendency for a higher plasma concentration of thyroid hormone-stimulating hormone (P < 0.1) than pigs fed the fresh oil. Additionally, pigs fed the thermoxidized oil had lower concentrations of cholesterol in plasma, LDL and HDL (P < 0.05). There were significant negative correlations between the plasma concentrations of total (r = -0.29) and free thyroxine (r = -0.40) and that of cholesterol (P < 0.05), suggesting that there is a causal relationship between the changes in thyroxine concentration and the reduction of plasma cholesterol. Our results indicate that there is a close relationship between alterations of thyroid hormone status and cholesterol metabolism in pigs fed a thermoxidized oil, and dietary oxidized fats should be considered in thyroid hormone disorders.

The effects of a dietary oxidized oil on lipid metabolism in rats

This study was carried out to investigate the effects of a dietary oxidized oil on lipid metabolism in rats, particularly the desaturation of fatty acids. Two groups of rats were fed initially for a period of 35 d diets containing 10% of either fresh oil or thermally treated oil (150 degrees C, 6 d). The dietary fats used were markedly different for lipid peroxidation products (peroxide value: 94.5 vs. 3.1 meq O2/kg; thiobarbituric acid-reactive substances: 230 vs. 7 micromol/kg) but were equalized for their fatty acid composition by using different mixtures of lard and safflower oil and for tocopherol concentrations by individual supplementation with DL-alpha-tocopherol acetate. In the second period which lasted 16 d, the same diets were supplemented with 10% linseed oil to study the effect of the oxidized oil on the desaturation of alpha-linolenic acid. During the whole period, all the rats were fed identical quantities of diet by a restrictive feeding system in order to avoid a reduced food intake in the rats fed the oxidized oil. Body weight gains and food conversion rates were only slightly lower in the rats fed the oxidized oil compared to the rats fed the fresh oil. Hence, the effects of lipid peroxidation products could be studied without a distortion by a marked reduced food intake and growth. To assess the rate of fatty acid desaturation, the fatty acid composition of liver and heart total lipids and phospholipids was determined and ratios between product and precursor of individual desaturation reactions were calculated. Rats fed the oxidized oil had reduced ratios of 20:4n-6/18:2n-6, 20:5n-3/18:3n-3, 20:4n-6/20:3n-6, and 22:6n-3/22:5n-3 in liver phospholipids and reduced ratios of 20:4n-6/18:2n-6, 22:5n-3/18:3n-3, and 22:6n-3/18:3n-3 in heart phospholipids. Those results suggest a reduced rate of desaturation of linoleic acid and alpha-linolenic acid by microsomal delta4-, delta5-, and delta6-desaturases. Furthermore, liver total lipids of rats fed the oxidized oil exhibited a reduced ratio between total monounsaturated fatty acids and total saturated fatty acids, suggesting a reduced delta9-desaturation. Besides those effects, the study observed a slightly increased liver weight, markedly reduced tocopherol concentrations in liver and plasma, reduced lipid concentrations in plasma, and an increased ratio between phospholipids and cholesterol in the liver. Thus, the study demonstrates that feeding an oxidized oil causes several alterations of lipid and fatty acid metabolism which might be of great physiologic relevance.

Effect of oxidized fish oil and alpha-tocopherol on the peroxidation of erythrocyte membrane phospholipids in rats

The effects of dietary oxidized fish oil and alpha-tocopherol on the thiobarbituric acid (TBA) values and phospholipid hydroperoxide levels of the erythrocyte membrane were studied in rats. No significant differences in the TBA values or phospholipid hydroperoxide levels of the membrane were observed between groups fed either oxidized fish oil or control diets. Furthermore, there were no marked differences in these values whether or not the groups were administered diets containing added alpha-tocopherol. These results suggest that the intake of oxidized fish oil and the supplementation with alpha-tocopherol do not influence the level of lipid peroxidation in the erythrocyte membrane.

Inclusion of oxidized vegetable oil in broiler diets. Its influence on nutrient balance and on the antioxidative status of broilers

Over a period of 4 wk, 24 10-d-old broiler hens were fed diets containing 11% vegetable oil (9% rapeseed oil, 2% soybean oil), which was added either fresh (1 meq O2/kg oil) or oxidized (156 meq O2/kg oil). The effects of the dietary treatments on nutrient digestibility were examined in a balance experiment. The antioxidative status of the animals was evaluated using plasma concentrations of thiobarbituric acid-reactive substances (TBARS), erythrocyte hemolysis in vitro, selenium-dependent and selenium-independent activity of glutathione peroxidase in liver cell cytosolic fractions, and concentrations of tocopherols and other fat-soluble compounds with antioxidative properties (lutein, beta-carotene, and retinol) in plasma and various tissues (skeletal muscle, cardiac muscle, liver, and abdominal fat). Compared to the fresh oil, the concentrations of linoleic and linolenic acid were slightly lower in oxidized oil. The concentration of alpha-tocopherol in the diet with fresh oil was an average of 80.8 mg/kg diet, whereas the diet with oxidized oil only provided 44 mg/kg. The dietary selenium content averaged 0.48 mg/kg in both diets. During the experiment, none of the animals showed symptoms of diarrhea or vitamin E deficiency. The intake of oxidized oil caused a growth depression after 2 wk. The retention of fat (P = 0.07), energy (P = 0.09), and alpha-tocopherol (P < 0.01) was lower in the group fed oxidized fat. Furthermore, these animals showed significantly higher plasma concentrations of TBARS (P < 0.01), and lower concentrations of tocopherols, lutein, beta-carotene, and retinol in plasma and tissues.