Sixty common carp in groups of five in four tanks per treatment were given three diets containing different increasing amounts of methionine. The aroma extract dilution analysis (AEDA) of the boiled carp fillets resulted in 32 odorants, of which 26 were identified. Ten compounds were quantified using an internal standard (IS), and the very low concentrations of 2-acetyl-1-pyrroline, (Z)-1, 5-octadien-3-one, and methional were calculated by the nasally determined detection limit. The concentration of methional seemed to increase with increasing methionine in the diet. Because the unstable methional could be converted by beta-elimination into methanethiol, the impact resulting in an off-flavor was investigated by headspace analysis. The investigation revealed no difference in the methanethiol contents between the treatments with the lowest and highest methionine supplies.

The influence of age and sex on the intestinal in vitro absorption of the trace elements zinc and manganese was studied with SPF-Sprague-Dawley-rats. For this purpose the absorption was measured with animals of both sexes starting at once after the weaning period (17 to 20 days) until an age of maximal 80 days. The measurements were made continuously in periods of a few days. The results of a total of five experimental series show that the transfer to the serosal solution and the uptake of the intestinal wall of both elements decrease permanently with increasing age. The most severe decrease occurs, however, at an age of the rats between 20 and 40 days, that is shortly after the weaning period. The previous change of the diet, however, cannot be the main explanation for the significant alteration of the absorption. In order to test this possibility the rats were only fed with the milk of their mothers up to an age of 36 days, while the control groups received already a pelleted casein diet starting with an age of 18 days. The results of these experiments were that the milk-fed rats absorbed only somewhat more zinc or manganese than did the corresponding control groups. There were no significant differences in the amounts of Zn absorption between male and female rats.

In two experimental series the absorption of zinc was continuously studied during gravidity and lactation with Sprague-Dawley rats of the same age. The absorption was measured in vitro with isolated, everted intestinal sacs. During the first third of gravidity the absorption of zinc--based on the intestinal Zn transfer to the serosal solution and the Zn uptake into the intestinal wall--rose at first slightly, during the second third it continued to increase, whereas there was a highly significant increase during the last third of gravidity in comparison to nongravid, nonlactating control animals (P less than 0.001). Shortly before parturition the absorption already started to fall and continued to do so during lactation. Therefore, Zn absorption was higher only in the first days of lactation in comparison to the controls (P less than 0.05). Reasons were discussed for these changes in the absorption during gravidity and lactation.

This paper examines the effect of different fatty acid composition, together with varying dietary vitamin E contents on fatty acid composition and tocopherol and tocotrienol contents of carp, and compares with other species of fish and the storage quality of the fish produced. Dietary fatty acid composition affected fatty acid patterns of tissues of carp significantly, but this was correlated with the fat content of the diet. Varying the vitamin E content results in no or only very slight variations in the fatty acid pattern of the tissues. The content of alpha-tocopherol in the tissues was affected significantly by dietary alpha-tocopheryl acetate content and by dietary fat source. There was a negative correlation between (n-3) fatty acids and the storage of alpha-tocopherol, while this was positively correlated with (n-6) fatty acids. The content of alpha-tocopherol in fish affected the stability during storage with the content of malondialdehyde used as a parameter for measuring the extent of fat oxidation. Other relationships, e.g. with sensory qualities and S-containing substances in the edible part of the fish, are discussed.

Imbalances in the supply with trace elements may be caused by the excessive administration of one or several elements or the insufficient administration in relation to other trace elements. This article deals with the interactions between the trace elements zinc and copper resp. zinc and iron under the conditions of the insufficient supply with Zn (6 mg per kg dry matter of the fodder) and the supply according to the demand with other trace elements (14 mg copper resp. 83 mg iron per dry matter of the fodder). For this purpose we investigated the copper, iron and zinc content of the milk and the serum of cows that were first depleted of zinc through a semi-synthetic zinc deficiency diet and then repleted with extra allowances of zinc. The closest connections exist between the copper and zinc content of the milk. Thus extreme Zn-deficiency feeding conditions the decreased Zn-content on the one hand and increased Cu-content on the other. In contrast to this, the cows' Zn-excretion in the milk increases after Zn-repletion whereas the Cu-content decreases. This shows a distinctly negative correlation. A loose connection could only be detected for the Cu- and Zn-content of the serum. Though the Zn-content changed considerably in dependence on the Zn-supply, the Cu-content remained largely uninfluenced. The Fe-content of both milk and serum shows no interaction with the nutritive Zn-supply. Only after 19 test weeks of extreme Zn-deficiency could a slight increase of the Fe-concentration be indicated.