I . Investigations were carried out to establish the total biopotency of the natural vitamin E isomers in barley compared with that of DL-a-tocopheryl acetate.2. The chick was used as an experimental animal. Prevention of nutritional encephalomalacia (NE) and chick liver-storage and plasma-storage assays of vitamin E were the methods used in the study. The individual tocopherols and tocotrienols, both in the tissue samples and in the grain and barley oil, were analysed using high-pressure liquid chromatography (HPLC) with fluorescence detection. The diagnosis of NE was based on careful clinical and histopathological observations.3. It can be concluded from the results that full protection against NE in the chicks was obtained with a supplementation level of 7.5 mg DL-a-tocopheryl acetate/kg diet (i.e. a total vitamin E content of 11.20 mg/kg diet) or with a supplement of 8.7 g barley oil/kg diet (i.e. a total vitamin E content of 22.99 mg from barley oil/kg diet). This gave a biopotency factor of 0.49 for barley for prevention of NE of the chicks, as compared to that of DL-a-tocopheryl acetate.4. Using regression analysis a statistically linear relationship could be observed between the total dietary vitamin E level and the response, as measured by the total vitamin E content in the liver and plasma, both in the groups supplemented with DL-a-tocopheryl acetate and in the groups supplemented with corresponding amounts of vitamin E in barley oil. The liver and plasma responses to the total vitamin E in the barley-oil diet compared with those of the DL-a-tocopheryl acetate reference diet gave identical values for the regression coefficients, i.e. in both liver-storage and plasma-storage assays the value for slopes of dose-response lines was 0.37. This means that the biopotency of the total vitamin E in barley was 37% of that of dietary DL-a-tocopheryl acetate. Thus, barley is not as rich a source of vitamin E as could be supposed on the basis of the chemical determination of its total vitamin E content.5. It was possible to verify this experimentally established biopotency of 0.37 for the total vitamin E in barley by converting the chemically determined amounts of the vitamin E isomers in barley into DL-a-tocopheryl acetate equivalents by multiplying them with internationally accepted potency factors for the individual natural isomers (DL-a-tocopheryl acetate 1.00, D-a-tocopherol 1.49, D-8-tocopherol 0.60, D-y-tocopherol 0.1 5, D-a-tOCOtrienOl 0.37).6. In spite of the high proportion of a-and p-tocotrienols in the barley-oil diets (about 60% of the total vitamin E content), only traces of these isomers could be detected in the plasma and none could be detected in the liver. On the other hand, calculation of the individual hiopotencies for the different isomers in the barley-oil diet by comparing the dose responses, diet: liver, separately for each isomer with those of DL-a-tocopheryl acetate, resulted in biopotency values for a-and 8-tocopherol which were twice as high as the internationally accepted conversion fac...

Summary Vitamin E requirements of adult Standardbred horses were evaluated by tissue depletion and repletion. All the horses used in the study were given the same basal feed low in vitamin E during the eight months of the experiment. After an initial depletion period of two‐and‐a‐half months the horses were divided into groups according to the amounts of DL α‐tocopheryl acetate given (0 mg, control; 200, 600, 1800 and 5400 mg, respectively) as a daily oral supplement. The supplement study was followed by a second depletion period. Total vitamin E content and individual natural tocopherol isomers and tocotrienol isomers were measured both in the feed (hay and oats) and in tissues (serum, liver, skeletal muscle and adipose tissue) using high performance liquid chromatography with fluorescent detection. Tissue vitamin E response to different dietary vitamin E levels were studied. The serum total lipid content remained unchanged during the experiment; serum vitamin E levels were expressed per gram serum lipid. The total vitamin E levels in serum, liver, skeletal muscle and fat reflected the supplement levels. The highest vitamin E levels were seen in fat tissue, followed by the liver and by skeletal muscle. In spite of the wide occurrence of the different vitamin E isomers in the feed, α‐tocopherol was almost the only isomer detected in the tissues. To ensure nutritional adequacy, 600 and 1800 mg of dl α‐tocopheryl acetate was suggested as an optimal oral daily supplement of vitamin E to adult Standardbred horses given feed low in vitamin E; this corresponds to 1.5 to 4.4 mg/kg bodyweight. In addition, it appeared preferable to give the supplement daily to maintain a constant level of vitamin E in the serum, liver and skeletal muscle, rather than occasionally to give higher doses.

No abstract

Abstract. Four groups of blue fox (Alopex Lagopus) were fed from weaning to pelting with feed of two different proteinlevels. The metabolizable energy (ME) from protein amounted to 35/30 % in the control group and to 22/18 % in three low-protein groups during the early and late growth period, respectively. One of the low-protein groups received an unsupplemented diet. The second low-protein diet was fortified with methionine, and the third with methionine and lysine to the same level as in the control diet. Hematological values, urea and creatinine were lower in all low-protein groups as compared to the control group. The activities of amino acid metabolizing enzymes ASAT, ALAT and GOT in plasma were lower in the lowprotein groups although the relative sizes of the liver and kidneys were greater. The lowered protein content in the feed was sufficient for growth, and only a slight negative effect on fur characteristics was observed. The dietary supplementation of methionine and lysine yielded no improvement in the fur quality or other parameters as compared to the unsupplemented low-protein feed, indicating that there was no deficiency of these amino acids in these lowprotein feeds.

Finnish Fur Brecders Associorion, Box 5 , SF-01601 Vniiruo, Fiirlniid ntrd 'Finnisli Fur Breeders Associntiorr. Box 92. SF-6SlOl I'nnsn. Fiirilnird Tyopponen. J. (College of Veterinary hledicine. Department of Biochemistry, Box 6, SF-00551 Helsinki), Valtonen. hl. (Finnish Fur breeders Association, Box 5 , SF-01601 Vantaa) and Berg, H. (Finnish Fur Breeders Association, Hox 92. SF-65101 Vaasa). LOWprotein feeding in mink: Effects on plasma free amino acids, clinical blood parameters, and fur quality. Received June 9, 1986. Acta Agric. Scand. 36:321128, 1986. Four groups of mink were fed from \veaning to pelting with feed of different protein levels. The metabolizable energy (hlE) from protein amounted to 40/36% in the control group and 36/31, 31/27, and 27/23% in thc medium, medium-low. and low-protein groups during the early and late growth period, respetively. Weight gain and hemalological parameters were within normal range in all groups, but the loa.est values \\.ere observed in the lo\vest dietary protein groups. There were no significant differences in plasma urea or creatinine concentrations between the groups. Plasma albumin and total protein increased with age and were highest in the low-protein group. The activities of transaminases, ASAT and ALAT, in plasma were also highest in the low-protein groups. The plasma content of total free amino acids !\as higher in the low-protein group as compared to the controls, especially essential amino acids. These changes a s \\.ell as the individual plasma amino acid concentrations indicated a metabolic response to conserve nitrogen and amino acids in mink on low-protein diet. Plasma free amino acid concentrations can hardly be used a s diagnostic means but their ratios may be a useful aid in determination of protein and amino acid requirements in mink. Fur size and colour \vere not affected by lowprotein feeding, but the quality of fur was louered in mink fed with the low-protein diet. INTRODUCTIONProtein constitutes the most expensive part of mink feed and a lo\vered content of dietary . protein for fur-bearing animals has therefore been a subject of several investigations in recent years. Under conditions that nutritional requirements are satisficd, any possibility of lowering the protein content in the feed \vould lead to considerable savings in feeding expenses.hloderately decreased dietary protein content during the feeding period has in previous experiments been shown to give good growth and fur quality in mink (Glem-Hanscn, 1980a; Berg et al., 1983). With the dietary protein content reduced below 30% of total metabolizable energy (hlE) in the feed a decreased fur quality has been observed. although nitrogen balance studies have shown 17 to 195'0 of h1E from protein sufficient for growth (Glem-Hansen, 1980b; Berg et al., 1984). It is obvious that in low-protein dicts the importance of well balanced amino acid composition becomes a matter of great significance.The natural diet of mink and other carnivores contains a high proportion of energy as protein, a...