Tissue content of alpha-tocopherol and oxidative stability of broilers receiving dietary alpha-tocopheryl acetate supplement for various periods pre-slaughter.

1. The effects of dietary alpha-tocopheryl acetate on the alpha-tocopherol status of chicken plasma and tissues were investigated. The rate of iron-ascorbate-induced lipid peroxidation was also studied. 2. One hundred and forty four chicks were divided into 6 groups: one control group was fed a basal diet of 30 mg alpha-tocopheryl acetate/kg food for the duration of the trial. A supplemental diet of 200 mg alpha-tocopheryl acetate was fed to each of the other 5 groups for 1,2,3,4 or 5 weeks prior to slaughter. 3. Supplementation resulted in an increase in alpha-tocopherol in plasma and all tissues examined. Saturation levels of alpha-tocopherol were observed in plasma after 1 week of feeding and in tissues within 3 to 4 weeks of feeding. 4. Supplementation with alpha-tocopheryl acetate for up to 4 weeks pre-slaughter resulted in significant reductions in susceptibility to induced lipid peroxidation. 5. Overall, the results show that feeding 200 mg alpha-tocopheryl acetate/kg food to chicks for at least 4 weeks prior to slaughter is necessary to optimise muscle content and stability against lipid peroxidation.

An immunohistochemical study of the distribution of biotin in tissues of pigs and chickens.

An optimised indirect peroxidase-anti-peroxidase immunohistochemical technique was used to detect endogenous biotin in frozen tissue sections from biotin-supplemented and biotin-depleted pigs and chickens. A monoclonal anti-biotin antibody was used as primary antibody in this technique. Immunoreactive biotin was detected in many tissues of both species including liver, kidney, pancreas, adipose tissue, adrenal gland, testis, brain, choroid plexus, cardiac and skeletal muscle, epithelium of the respiratory and digestive systems, skin and lymphoid tissues. The specificity of immunostaining for biotin was confirmed by the finding of reduced staining intensities in tissues of biotin-depleted animals compared to those of biotin-supplemented animals. The results of this study suggest that biotin has metabolic functions in a wider range of tissues than previously known. They also indicate that endogenous tissue biotin should be considered as a source of false-positive staining when immunohistochemical or histochemical techniques which use avidin or streptavidin reagents or anti-biotin antibodies as components of the detection system, are applied to tissue sections.

Effects of vitamin E on mammary and blood leukocyte function, with emphasis on chemotaxis, in periparturient dairy cows.

OBJECTIVE: To determine the effect of vitamin E supplementation on the immune system of dairy cows. DESIGN: The following immune parameters were followed: production of chemotactic factors and superoxide by mammary macrophages and chemotactic responsiveness of blood neutrophils. ANIMALS: 16 healthy Holstein dairy cows. PROCEDURE: Dairy cows were assigned to 1 of 2 experimental groups: control (no vitamin E supplementation) and vitamin E supplemented. Supplementation of vitamin E started 4 weeks before and continued up to 8 weeks after parturition, and included oral supplementation of vitamin E at the rate of 3,000 IU/cow/d. In addition, the same group of cows received 1 injection of vitamin E (5,000 IU) 1 week prior to the expected date of parturition. Blood samples were collected weekly throughout the experimental period. RESULTS: Vitamin E supplementation enhanced by 30 to 83% (P < 0.05) chemotactic responsiveness of blood neutrophils beginning 2 weeks before to 4 weeks after parturition, compared with controls. There were no differences in production of superoxide or chemotactic factors by mammary macrophages between control and vitamin E-supplemented cows. CONCLUSIONS: Vitamin E supplementation prevents the periparturient inhibition of neutrophil chemotaxis. It is unlikely that vitamin E affects directly the function of mammary macrophages.

Color coordinates for assessment of dietary vitamin E effects on beef color stability.

Color stability was investigated in longissimus lumborum (LL), semimembranosus (SM), and gluteus medius (GM) muscles from Holstein steers fed diets including doses of alpha-tocopheryl acetate that were 0 (EO), 250 (E250), 500 (E500), and 2,000 (E2000) mg.steer-1.d-1 for 42 or 126 d. Longissimus lumborum was aged for 14, 28, and 56 d and GM and SM were aged for 14 d. Effects of vitamin E dose on retention of redness (a*), yellowness (b*), color saturation (chroma), and proportions of redness and yellowness (hue angle) following an aging period of 14 d were E2000 > E500 = E250 > EO (P < .01). Effectiveness of dose duration on the color parameters was 126 d > 42 d (P < .01). Dietary vitamin E supplementation stabilized redness and color saturation, decreased yellowness, and extended color display life of fresh beef. A technique for estimation of color display life based on hue angle measurements of fresh beef is described. Color display life estimates based on hue angle measurements were more consistent with vitamin E supplementation effects on metmyoglobin percentage and hue angle than were estimates obtained from the metmyoglobin threshold method. Color display life across LL, SM, and GM stored until d 14 and then displayed under simulated retail conditions was extended (P < .01) 2.0 (E250) to 5.0 d (E2000). Coefficients of determination for regressions of color display life on muscle alpha-tocopherol concentration were .81, .64, and .63 in LL, SM, and GM muscles aged 14 d, respectively. Supplementation of 500 mg of alpha-tocopheryl acetate per steer daily improved (P < .01) the mean color display life of these three muscles by 2.3 d, or 100%.

Rapid determination of alpha-tocopherol in muscle and adipose tissues of pork.

A fast, sensitive and reproducible method for the analysis of alpha-tocopherol in pork tissues is presented. It combines saponification of the tissue and alpha-tocopherol extraction in a single vessel, followed by HPLC separation and fluorescence detection. Added alpha-tocopherol was recovered quantitatively. The reduction of lipid peroxides with potassium iodide before the saponification step did not alter the amounts of alpha-tocopherol detected. Membrane-bound alpha-tocopherol was not oxidized by lipid peroxides during the procedure. The coefficient of variation of alpha-tocopherol analysed using this method was +/- 4.2% for muscle and +/- 2.5% for adipose tissues.

Folic acid requirements of broilers.

1. Dietary folic acid requirements of broilers were studied in three experiments using wheat- and maize-based practical diets. Requirements were assessed on the basis of performance and metabolic criteria. 2. Growth and food conversion efficiencies were optimised with supplements of 1.5 mg folic acid/kg added to basal mash starter diets. The dietary folic acid requirement of broilers was estimated to be in the range of 1.7 to 2.0 mg/kg. 3. Red blood cell phosphoribosylpyrophosphate concentrations and dihydrofolate reductase activities did not show consistent changes over the range of dietary folate concentrations studied but plasma folate concentrations responded markedly to dietary folate supplementation. 4. Adding choline to diets in amounts greater than the normal requirement did not spare the requirement for folic acid. 5. It is suggested that minimum folic acid supplements for pelleted practical diets should be in the order of 2.5 to 3 mg/kg.

Modulatory effects of dietary beta-carotene on blood and mammary leukocyte function in periparturient dairy cows.

Beginning 4 wk prior to predicted calving, 14 Holstein cows per treatment were fed diets 1) unsupplemented (control) or supplemented daily with 2) 300 mg of beta-carotene, 3) 600 mg of beta-carotene, or 4) 120,000 IU of vitamin A. Blood was collected around calving on wk -4, -2, -1, 0 (within 24 h postcalving), 1, 2, and 4 for isolation of lymphocytes and neutrophils and for the analysis of plasma vitamins. Lacteal secretions were collected on wk 0, 1, 2, and 4 for the isolation of phagocytes. Cows supplemented with 600 mg of beta-carotene had higher concentrations of plasma beta-carotene and retinol than did unsupplemented cows. Supplemental vitamin A increased plasma retinol on wk 4 and decreased plasma beta-carotene on wk -1 and 0. Treatment did not affect concentrations of plasma alpha-tocopherol. Blood lymphocyte proliferation in response to concanavalin A, phytohemagglutinin, and pokeweed mitogen during the peripartum period was higher in cows supplemented with beta-carotene than in unsupplemented controls. Phagocytic activity of blood neutrophils was enhanced on wk 1 in cows fed 300 mg of beta-carotene. Intracellular killing by blood neutrophils was enhanced in cows supplemented with beta-carotene (wk 0) and vitamin A (wk 0 and 1). Iodine uptake and nitroblue tetrazolium reduction by blood neutrophils was stimulated in cows supplemented with beta-carotene. Phagocytic activity, iodine uptake, and nitroblue tetrazolium reduction by mammary phagocytes from all cows generally were lower postpartum than on the day of calving. The incidence of retained placenta and metritis was higher for unsupplemented cows than for cows supplemented with beta-carotene. Therefore, dietary beta-carotene can elevate peripartum concentrations of blood beta-carotene, enhance host defense mechanisms by potentiating lymphocyte and phagocyte function, and decrease the incidence of certain reproductive disorders.

Biotin kinetics in serum of cattle after intravenous and oral dosing.

Single oral (p.o.) or intravenous (i.v.) doses of biotin were given to four cattle (400-450 kg body weight) in two consecutive tests two weeks apart. Dosages were p.o. 20, 40, 80 or 160 and i.v. 5, 10, 20, 40 mg biotin per 300 kg body weight. A three-compartment model was used to describe the course of serum concentrations with time. After i.v. administration, terminal half-lives of about 8 h were found. Areas under the curves were linearly related to both the p.o. and the i.v. doses. The systemically available fraction of the p.o. dose was 50 to 60%. On the basis of kinetic parameters, the biotin uptake via the feed was estimated to be 2.5 mg/day, which was about half of that estimated to be in the hay consumed. The data suggest that there was no relevant ruminal synthesis of biotin.

The bioavailability of supplemental biotin in cattle.

A trial using 12 yearling heifers was carried out to test whether biotin metabolism and bioavailability are influenced by continuous dietary supplementation with biotin. Six of these heifers received no biotin supplementation (controls), while six received a daily dietary supplement of 20 mg biotin over the whole experimental period of four months. During each of three test periods (on days 14 and 21, 56 and 63, and 118 and 124), single test dosages of 40 mg (oral) and 5 mg (intravenous) biotin were given to each animal in a crossover test design. Blood samples were collected up to 72 h after each of these single doses, and at approximately two-weekly intervals for the assessment of baseline values. Serum biotin levels were determined by an ELSA test. Areas under the curves (AUC) were calculated as the target parameter for the assessment of the bioavailability of orally administered biotin. Serum biotin baseline levels were 300-800 ng/l in the controls and 3000-8000 ng/l in the supplemented animals. In both groups, AUC values in the first test period (days 14 and 21) were significantly higher than in subsequent periods. However, the biotin supplementation showed no significant effect. There was no significant difference in elimination half-lives between groups with and without biotin supplementation. The range was 5-18 h. Furthermore, there was no significant difference in the bioavailability of biotin between the test periods or between the biotin-supplemented and unsupplemented animals. Overall bioavailability was 48%.

Effect of high concentrations of dietary vitamin E during various age periods on performance, plasma vitamin E and meat stability of broiler chicks at 7 weeks of age.

1. The effect of high concentrations of vitamin E (alpha-tocopheryl acetate) fed during various age periods on the performance and the oxidative stability (thiobarbituric acid [TBA] values) of the drumstick meat of 7-week-old broiler chicks was determined. The basal diets (for the age periods 0 to 3, 3 to 6 and 6 to 7 weeks) contained 60 g soyabean oil and 24 mg vitamin E/kg. The following five treatments were evaluated: (1) the basal diets from 0 to 7 weeks of age (control); (2) vitamin E, 100 mg/kg diet from 0 to 7 weeks of age; (3) vitamin E, 150 mg/kg diet from 0 to 3 weeks of age; (4) vitamin E, 150 mg/kg diet from 0 to 3 weeks of age and 100 mg/kg diet from 6 to 7 weeks of age; (5) vitamin E, 100 mg/kg diet from 5 to 7 weeks of age. 2. Food intake, weight gain and food efficiency were not significantly (P greater than 0.05) affected by the vitamin E treatments. 3. Plasma alpha-tocopherol (AT) concentrations in treatments 2, 4 and 5 were similar, and markedly higher than those in treatments 1 and 3, while those of treatment 3 were significantly (P less than 0.001) higher than those of treatment 1. Plasma retinol concentrations were not significantly (P greater than 0.05) affected by the vitamin E treatments. 4. TBA values of the meat were very low and not significantly affected by the vitamin E treatments. However, after incubation the TBA values were highly significantly (P less than 0.01) negatively correlated with the amount of vitamin E consumed during the experiment. The stability of meat of birds fed the various combinations of vitamin E (treatments 3, 4 and 5) was significantly (P less than 0.05) higher than that of birds which did not receive additional vitamin E (treatment 1), but it was significantly (P less than 0.001) lower than that of birds which received vitamin E continuously (treatment 2). 5. It is concluded that a high concentration of vitamin E fed during 0 to 3 weeks of age may significantly improve AT status of the broiler chick up to 7 weeks of age.

Effects of dietary retinol on hepatic retinol storage and on plasma and tissue alpha-tocopherol in pigs.

A feeding experiment was carried out with pigs to investigate the effects of graded dietary retinol supplements on hepatic and plasma retinol and on alpha-tocopherol in plasma and selected tissues. Four groups of twelve weanling pigs each with a mean body weight of 7 kg were fed a complete ration containing 54 IU vitamin E/kg and supplemented with 5, 10, 20 or 40 x 10(3) IU retinol/kg for Treatments 1 to 4, respectively. The feed was fed in restricted amounts for 150 days when the pigs were slaughtered at 105 kg body weight. Overall daily body weight gain and feed conversion ratio were 660 g and 2.49, respectively, without treatment differences (p less than 0.01). Hepatic retinol concentration (y, IU/g fresh weight) was linearly related to dietary retinol concentration (x, IU/kg feed) as expressed by y = -88.9 + 0.077 x [r2 = 0.94]. Total hepatic retinol (y, IU) and total retinol intake (x, IU) were linearly related as expressed by y = -194.9 x 10(3) + 0.4585 x [r2 = 0.98]. Hepatic retinol retention relative to intake ranged from 30.0% to 44.9%. Plasma retinol concentration was not affected by dietary retinol (p less than 0.01). Plasma alpha-tocopherol levels remained on a plateau for 42 days in all treatments. After 150 days plasma levels exceeded those at 42 days in Treatments 1 to 3, but not in Treatment 4. The effect of retinol on tissue alpha-tocopherol varied with tissues. While there was no effect on M. Longissimus and backfat, alpha-tocopherol levels in heart and liver showed an inverse relationship with dietary retinol.(ABSTRACT TRUNCATED AT 250 WORDS)

Bioavailability of ascorbic acid in horses.

The bioavailability of ascorbic acid administered to thoroughbreds by intramuscular injection was investigated. For intramuscular injection two preparations were studied, and the percentage bioavailability up to 24 h of 10 g of ascorbic acid was 95% +/- 22 in four horses and 60% in two horses with preparations A and B, respectively. Bioavailability at 24 h in three horses injected subcutaneously with 10 g of preparation B was 82%. Intramuscular injection of both preparations was apparently well tolerated while subcutaneous injection of preparation B (pH 6.0) was associated with marked irritancy. In a cross-over trial in seven thoroughbreds the effect of 13 or 15 days of oral administration of crystalline ascorbic acid (20 g) or ascorbyl palmitate (47 g) on plasma ascorbic-acid concentrations was investigated. Marked differences occurred between individuals. There was a greater increase in plasma ascorbic-acid concentration with ascorbyl palmitate compared to ascorbic acid at 6 and 24 h following administration. In two horses there was no increase in plasma ascorbic acid at 6 h following either oral preparation. The finding of lowered plasma ascorbic-acid concentrations following a period of supplementation warrants further investigation to assess its significance.

Biotin supply by large bowel bacteria in minipigs: evidence from intracaecal avidin.

The influence of a change of colonic availability of biotin on biotin status was studied. This was done by inhibition of biotin absorption by intracaecal avidin infusion. Five adult minipigs with a permanent caecal 'T' cannula were fed on a semi-synthetic, biotin-deficient diet for 4 months. Following an 8-week adaptation period there were nine sequential 1-week infusion periods with or without oral lactulose or antibiotics. Avidin infusion during weeks 2, 5 and 8 amounted to 18 mg/d (13 U/mg). Plasma biotin concentrations were not changed by avidin infusions. There was a significant average 84% rise in faecal biotin excretion during the avidin periods. Urinary biotin output following avidin decreased by 21%. This is taken as evidence that biotin synthesized by colonic bacteria is available for host metabolism. A rough estimate shows that under basal conditions 1.7-17% of the metabolic allowance may be covered by this metabolic route.

Clinical study on the effect of biotin on skin conditions in dogs.

In a collaborative study with small-animal veterinary surgeons, dogs with fur and skin conditions were treated with biotin (approximately 5 mg biotin/10 kg body weight/day) for 3 to 5 weeks. In total 119 cases could be treated which were reported to show symptoms such as dull coat, brittle hair, loss of hair, scaly skin, pruritus or dermatitis. Cases requiring other treatments with e.g. glucocorticoids, were excluded from the study. In 60% of the cases all symptoms were reported to be cured after the biotin treatment and in a further 31% an improvement was noted; in only 9% no effect was recorded. All breeds responded but to a variable extent: e.g. in Poodles the response was lower (no response in 6 out of 11 cases) than in Alsatians where all improved and 14 out of 29 were completely cured. The results confirm the favourable effect of biotin for treatment of fur and skin conditions in dogs.

Dietary biotin requirements of young rainbow trout (Salmo gairdneri) determined by weight gain, hepatic biotin concentration and maximal biotin-dependent enzyme activities in liver and white muscle.

The objective of the present work was to determine the dietary biotin requirements of young, rapidly growing rainbow trout according to independently measured parameters. Two experiments were conducted with a purified diet which had a basal biotin level of 0.01-0.02 mg/kg. A third study was done with a nonpurified diet with or without a supplement of 1.0 mg biotin/kg. Each study was initiated with fry weighing less than 2 g/fish, and was continued for 16-20 wk at 15 degrees C. The first experiment, a cross-over design with pair-feeding, showed that the unsupplemented purified diet produced a biotin-specific deficiency condition in the trout. Dietary requirements could therefore be estimated (expt 2): maximal weight gain and maximal liver biotin concentration, 0.08 mg/kg; maximal activity of hepatic pyruvate carboxylase and acetyl CoA carboxylase, 0.05 mg/kg; and maximal white muscle pyruvate carboxylase activity, 0.14 mg/kg. No differences were found between fish fed the supplemented nonpurified diet and fish fed its unsupplemented counterpart (expt 3). The biotin requirement of the trout for growth does not exceed that of other vertebrates. These results also raise a question as to the level of supplementation which may be necessary for trout diets under field conditions.

Incompatibility between lasalocid and chloramphenicol in broiler chicks after a long-term simultaneous administration.

Two growth experiments were conducted to evaluate in broiler chicks the compatibility between lasalocid medication in the feed (at 90 or 125 ppm) and a long-term administration of chloramphenicol either via the feed (500 ppm) or via the drinking water (500 mg/liter). The simultaneous administration of lasalocid and chloramphenicol generally caused severe growth depression, decreased feed intake and impaired feed conversion. Several chicks showed evident symptoms of intoxication, such as ataxia, leg weakness and paralysis. The development and frequency of these symptoms were dependent on the dosage of lasalocid and on the duration of the simultaneous administration. Biochemical examinations (Experiment 2) revealed in the affected chicks significant changes in several parameters, in particular a markedly increased activity of creatine kinase and GOT in the plasma. It confirmed that the observed leg weakness and paralysis were caused by myodegeneration.

Available biotin content of various feed ingredients.

The availability to the chick of the microbiologically determined biotin in various feed ingredients was assayed using a standard curve methodology. The chicks were grown up to 28 days of age. Ingredients of the standard diet were partially replaced by the test ingredient. Each test mixture was also supplemented with 200 micrograms biotin/kg and fed to a control group. The percentage of growth of the test chicks compared with the controls proved to be a suitable parameter for the assessment of biotin availability. Availability of biotin was expressed in percentage of the biotin determined microbiologically. In the tested cereals availability was distinctly low, whereas in some other feed ingredients the availability was reduced less.

Relationships between vitamin A and vitamin E in the chick.

Plasma levels of vitamins A and E were analysed during the dietary administration of two levels of vitamin A (10 000 or 50 000 IU/kg) in combination with four levels of supplemental vitamin E (0, 50, 100, or 150 mg/kg) and with or without a supplement of oil to the diet. Tocopherol levels in plasma were markedly decreased by the higher vitamin A supplementation. In contrast, the various vitamin E intakes had no influence on plasma retinol levels. The addition of oil to the diet did not affect this interaction. The absorption, distribution and elimination of labeled 3H-dl-alpha-tocopheryl acetate after an oral or intravenous administration, in combination with a high oral dose of vitamin A (100 000 IU/chick), were studied. The high oral single dose of vitamin A reduced the levels of radioactivity in all the analysed tissues and organs, when both vitamins were administered orally. However, vitamin A did not affect distribution and elimination of radioactivity, when an interaction in the gastro-intestinal tract was avoided by different routes of administration.