Experiments were conducted to examine the effects of dietary zinc (Zn) upon plasma vitamin E (E) concentrations to test the hypothesis that there may be a significant dietary interaction between these two nutrients. Weanling female Sprague-Dawley rats were fed diets that were (i) Zn-deficient (~0 . 9 pg Zn/g diet) ad libitum; (ii) Zn-adequate (50.9 pg Zn/g diet), pair-fed to the Zn-deficient group; and (iii) Zn-adequate (50.9 pg Zn/ g diet) ad libitum. Plasma E in Zn-deficient animals (4.02 k 1.20 pg/ml) was significantly reduced (P 5 0.05) compared with results in both Zn-adequate pair-fed (9.21 +. 0.70 pg/ 379 DIETARY Zn AND PLASMA 6
Experiments were conducted to determine the relationship of selenium-dependent glutathione peroxidase (SeGSHpx) activity to the onset of nutritional pancreatic atrophy (NPA) in chicks. Chicks produced from hens fed a low Se, low vitamin E practical diet had low activities of SeGSHpx in plasma and pancreas at hatching. The SeGSHpx activity remained at a low level before and during all stages of the onset of NPA. Selenium supplementation of the diet prevented NPA and resulted in significant elevations in SeGSHpx activity. Although the early stages of NPA are believed to involve mitochondrial swelling, no significant differences were found in rate of oxygen uptake, respiratory control index or adenosine diphosphate to oxygen ratio between pancreatic mitochondria isolated from Se-deficient or Se-adequate chicks. Improvements in maternal Se status significantly increased chick pancreatic SeGSHpx activity at hatching and delayed the onset of NPA in chicks fed a Se-deficient diet. A significant proportion of the second-generation Se- and vitamin E-depleted chicks used in these studies was found to grow at nearly normal rates when fed the Se-deficient diet. These chicks, designated as refractory to the growth-depressing effect of severe Se-deficiency, were biochemically deficient (i.e., had very low SeGSHpx activities) and showed NPA. It is concluded that the Se-responsive lesion which results in NPA in the chick is different from that which results in depressed growth.
Experiments were conducted to determine the initial effects of oral selenium administration on selenium-deficient chicks. Administration of 5 microgram selenium as seleno-DL-methionine increased voluntary feed consumption within 2-3 hours, whereas selenite did not have a significant effect until 3-4 hours. Spontaneous activity, body weight gain and plasma glucose concentration increased 6-8 hours after selenium administration. The earliest response in the specific activity of selenium-dependent glutathione peroxidase occurred in plasma at 8 hours and in liver at 24 hours after selenium administration. The onset of pancreatic atrophy, however, was not affected by the level of feed intake suggesting that the effect of selenium upon appetite may be distinct from the involvement of selenium in nutritional pancreatic atrophy and fibrosis.
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