To study their relationship to milk yield, the concentrations, in jugular venous blood, of thyroxine iodine (T 4 I), thyroxine (T 4 ), 3,5,3'-tri-iodothyronine (T 3 ), glucose, non-esterified fatty acids (NEFA), triglycerides, phospholipids, cholesterol, total protein, albumin, urea, haemoglobin and packed cell volume (PCV) have been measured in 36 cows (Simmental, Swiss Brown, Holstein and Simmental x Holstein) of different ages during a full lactation, pregnancy, dry period, parturition and 150 days of the ensuing lactation. Thyroid hormones and triglycerides were negatively, and total protein, globulin, cholesterol and phospholipids were positively, correlated with uncorrected or corrected milk yield during several periods of lactation, whereas glucose, NEFA, albumin, urea, haemoglobin and packed cell volume were not correlated with milk yield. The 10 animals with the highest milk yield (18-9 to 23-5 kg/day) exhibited significantly lower values of T 4 I, T 4 , T 3 and glucose, significantly higher levels of total protein and globulin and tended to have higher levels of NEFA than the 10 cows with the lowest milk yield (10-9 to 14-3 kg/day) throughout or during certain periods of lactation, whereas concentrations of triglycerides, phospholipids, cholesterol, albumin, haemoglobin and PCV did not differ. Changes in T 4 I, T 4 , T 3 , glucose and total jprotein during lactation were also influenced by age, presumably associated with an increase in milk production with age. T 3 was consistently lowest and cholesterol and phospholipids, during later stages of lactation, were highest in Holsteins, which had the highest milk yields of all breeds. Changes of blood parameters were mainly caused by shifts in energy and protein metabolism in association with level of milk production.

Chromium (Cr) absorption is low (<1%) and there is a need to find Cr compounds that are absorbed better than inorganic Cr salts. Therefore, the incorporation of nine different chromium (Cr) compounds on tissue Cr concentration of 6‐week male Wistar rats was investigated. Chromium compounds tested were Cr chloride (Cr chloride), Cr acetate (Cr acetate), Cr potassium sulfate (CrAlum), Cr trihistidine (Cr histidine), Cr triglycine (Cr glycine), Cr trinicotinic acid (CrNA), Cr dinicotinic acid dihistidine (CrNA‐HIS), Cr tripicolinic acid (Cr picolinate), and Cr dinicotinic acid diglycine cysteine glutamic acid (CrNA‐AA). Complexes were fed to weanling rats for 3 weeks at 5,000 ng of Cr/g of diet. Basal control diet was a cornstarch‐based diet containing 30 ng Cr/g. Chromium incorporation into the kidney was greatest for CrNA‐AA complex (850 ng/g dry wt) followed by CrAlum (407 ng/g), Cr acetate (397), CrNA‐HIS (394), Cr picolinate (368), Cr glycine (343), Cr nicotinate (166), Cr chloride (74), CrHIS (49), and control (23 ng/g). Chromium concentration of the liver was greatest for the Cr picolinate compound (50 ng/g) followed by CrNA‐AA and Cr acetate. Liver Cr concentrations of remaining complexes were not significantly different from those of the control animals that received no added Cr. Chromium concentrations were significantly greater in the kidney than those for the liver, spleen, heart, lungs, and gastrocnemius muscle. Supplemental Cr did not affect tissue zinc and copper but did alter tissue iron concentrations. Absorption of radioactive forms of Cr did not explain the differences in tissue Cr concentrations. Chromium absorption after 4 hours and retention after 24 hours were not significantly different for the forms of Cr tested. These data demonstrate that Cr concentrations are greatest in the kidney and that the form of dietary Cr significantly affects tissue Cr concentrations. Absorption of Cr does not correlate with tissue Cr concentrations and blood Cr is not in equilibrium with tissue Cr stores. © 1996 Wiley‐Liss, Inc. This article is a U.S. Government work and, as such, is in the public domain in the United States of America.

The goal of this article was to establish reference ranges of the concentration of trace elements in human serum and to compare these results with those reported by other authors. We describe the sample preparation and measurement conditions that allow the rapid, precise, and accurate determination of Al, As, B, Be, Cd, Co, Cu, Fe, Li, Mn, Mo, Ni, Rb, Se, Sr, and Zn in human serum samples (n = 110) by inductively coupled plasma-mass spectrometry (ICP-MS). Accuracy and precision were determined by analyzing three reconstituted reference serum samples by comparison with other methods and by the standard addition procedure.The advantages of the ICP-MS method include short time of analysis of the elements mentioned, low detection limit, high precision, and high accuracy. Disadventages include a high risk of contamination due to the presence of some of the elements of interest in the environment, the relatively delicate sample handling, and the high cost of the equipment.

Summary.We studied the effect of intravenous (i.v.) adminisration of 200 mg of iron sucrose following an i.v. bolus injection of recombinant human erythropoietin (r-HuEPO; 300 U/kg body weight) in seven subjects and compared it with seven subjects treated with r-HuEPO alone. Reticulocytes, serum erythropoietin (EPO) and ferritin levels were studied at baseline and daily for the following 8 d. Use of i.v. iron abolished the marked reduction in serum ferritin observed with r-HuEPO administration. Although the total number of reticulocytes was not affected by i.v. iron administration, the reticulocyte Hb content and retHb (a measure in g/l of the Hb contained in all reticulocytes) were increased in the i.v. iron/r-HuEPO group compared with the group who received r-HuEPO alone. Therefore i.v. iron significantly potentiates the haemopoietic response to r-HuEPO in normal subjects.

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