Erzsébet Berta

EFFECTS OF HIGH DIETARY MOLYBDENUM IN RABBITS

To study the effects of high dietary molybdenum (Mo) content, rabbits were fed with commercial pellets and carrots containing 39 mg Mo/kg dry matter (DM) [Experiment 1] and with a commercial diet supplemented with 40 mg Mo/kg DM [Experiment 2] for 14 days. The high dietary Mo contents failed to reduce the growth performance of rabbits. Moreover, supplemental Mo given in a dose of 40 mg/kg non-significantly decreased the apparent digestibility of crude protein (CP) and crude fibre (CF) compared to the control (73.63 +/- 2.49 and 18.56 +/- 5.10 vs. 74.31 +/- 3.03 and 21.38 +/- 6.48, respectively). Molybdenum ingested with feeds was mainly excreted (57%) via the urine. The highest Mo levels were found in kidney and liver samples (3.464 +/- 0.872; 5.27 +/- 0.95 mg/kg DM [Experiment 1] and 1.878 +/- 0.283; 1.62 +/- 0.16 mg/kg DM [Experiment 2], respectively), and Mo could also be detected in limb meat (0.336 +/- 0.205 mg/kg DM). It was stated that the testes were more sensitive to Mo exposure than the female reproductive organs because the number of germ cells was reduced. Due to the high dietary Mo intake free radicals could be generated, resulting in a marked increase of creatine kinase (CK) activity.

Evaluation of mercury and lead content in the liver of the cormorant (Phalacrocorax carbo sinensis) population of Kis-Balaton, Hungary

Mercury and lead concentrations were measured in the livers of cormorant (Phalacrocorax carbo sinensis), an aquatic bird species living and nesting in the special, highly protected nature conservation area of Kis-Balaton, Hungary. The measurements of metal concentrations were performed by atomic absorption spectrometry using the cold vapour method for mercury and the electrothermal method for lead. Mercury concentrations in the livers were significantly higher in the adult population (4.479 ± 3.336 mg/kg dry matter, DM) than in the juvenile birds (2.682 ± 2.087 mg/kg DM), indicating an increase of bioaccumulation with age. A similar pattern was not observed for lead. There were no statistical differences between males and females either in mercury or in lead concentrations. The average levels of mercury (3.580 ± 2.906 mg/kg DM) and lead (0.746 ± 0.499 mg/kg DM) were statistically different in the liver. No correlation was found between the concentrations of the two heavy metals. Recently, the wild birds have been chronically exposed to subtoxic amounts of metals which have a tendency to accumulate especially in the soft tissues.

Effect of fulvic and humic acids on iron and manganese homeostasis in rats

The objective of this study was to investigate the effects of fulvic acid (FA) and humic acid (HA) as the two main compounds of humic substances, separately on Fe and Mn homeostasis. Seventy-two male Wistar rats were randomly divided into 9 experimental groups. The control diet (AIN-93G formula) and diets supplemented with 0.1%, 0.2%, 0.4% and 0.8% HA or FA were fed for 26 days. Fe and Mn concentrations of the large intestinal content, liver, kidney, femur and hair were determined. No significant differences were observed in the production parameters. The effects of FA and HA on iron homeostasis were significantly different. FA proved to be a good iron source, and slightly increased the iron content of liver and kidney, but - up to a dietary iron level of 52.7 mg/kg - it did not influence the efficiency of iron absorption. Above a dietary iron level of 52.7 mg/kg down-regulation of Fe absorption can be assumed. HA significantly stimulated the iron uptake and there was no down-regulation of Fe absorption up to 0.8% dietary HA supplementation level (61.5 mg Fe/kg diet). In the HA groups the iron content of the liver and kidney decreased significantly, suggesting that in spite of the better Fe absorption, the HA-Fe complex does not provide iron to the investigated organs. Neither FA nor HA supplementation influenced the Fe content of the femur and hair and slightly decreased the Mn concentration in the large intestinal content. This effect was significant (with a 22.7% Mn concentration decrease) only at the HA supplementation rate of 0.8%. Neither FA nor HA influenced significantly the Mn concentrations of the liver, kidney and femur. The Mn concentration of the hair in rats receiving FA- or HA-supplemented diets was higher than in the control rats; however, this result needs further confirmation.