M. Wanner

The concentration of ionized magnesium in serum during the periparturient period of non-paretic dairy cows

Ion-selective electrodes have recently been designed for determining the ionized concentration of magnesium (Mg2+) in serum. This development may allow new insights into some metabolic diseases of cattle. For this report, the concentrations of Mg2+, total magnesium (Mgtot), ionized calcium (Ca2+), total calcium (Catot), and inorganic phosphate (Pi) were determined in sera from seventeen 3-to 16-year-old Brown Swiss and crossed Simmental/Red Holstein cows during the periparturient period. In each animal, a transient increase of Mg2+ and Mgtot serum concentrations was observed in association with the transient decrease in serum concentrations of Ca2+, Catot and Pi after parturition. On average, throughout the study, the serum Mg2+ concentrations were 68.5% of those of Mgtot, whereas the serum Ca2+ concentrations were 52% of those of Catot. The possible mechanisms involved in the transient increase of Mg2+ and Mgtot serum concentrations are discussed.

Comparative pharmacokinetics of aditoprim in milk-fed and conventionally fed calves of different ages.

Aditoprim body disposition was described after intravenous and oral administration of 5 or 10 mg kg-1 bodyweight to milk-fed and conventionally fed calves with bodyweights of 80 kg, 160 kg and 210 kg. After intravenous administration to conventionally fed calves, aditoprim total body clearance increased and elimination half-life decreased with age. Oral administration of aditoprim with feed was associated with a longer absorption half-life and consequently longer elimination half-life in the older calves, because the drug was deposited in a functionally mature rumen. The weak base aditoprim is slowly absorbed from the rumen according to the pH partition hypothesis and probable binding to dietary fibres and other macromolecules. The favourable pharmacokinetics of aditoprim indicate a potential use for this antimicrobial in bovine practice, pending further studies on residue depletion profile, safety and therapeutic efficacy.

Parathyroid hormone-related protein and calcium concentrations in milk and blood of ewes

Parathyroid hormone-related protein (PTHrP) and calcium (Ca) concentrations were measured 2 to 3 months postpartum in milk and plasma or serum of 22 ewes by the use of commercial radioimmunoassay kits for PTHrP concentration, colorimetry for serum total Ca concentration (Catot), and atomic absorption spectrophotometry for milk total Ca concentration. Scatter plots did not reveal dependency between milk Ca and Catot, Catot and plasma PTHrP, milk Ca and milk PTHrP, and milk PTHrP and plasma PTHrP. Thus, the systemic and mammary effects of PTHrP are not major determinants of the endocrine, paracrine, and autocrine regulation of Ca homeostasis during lactation in ewes.

Judgement of hygienic quality of roughage in horse stables in Switzerland.

In 46 horse farms all over Switzerland, the hygienic quality of the roughage (including silages) was investigated. Therefore, a macroscopic examination as well as the microbial counts (bacteria, yeasts and moulds) was carried out. Further, the contents of lipopolysaccharides (LPS) and the contamination with deoxynivalenol (DON) were determined. In all roughages, the dry matter (DM) content was measured and in silages additionally the pH was measured. Predominantly, the straw showed a lower hygienic quality than hay and silages. The LPS contents were significantly higher in straw than those in hay samples. The macroscopic examination and the microbial counts showed a tendency in the same direction. Eight straw samples and one hay sample with DON contamination were found. The silages showed a DM content with a median of 65.8%. The pH of those silages was between 4.3 and 5.9. Despite the high values of DM and pH, the silages showed mainly a high hygienic quality. In total, the hygienic standard of straw was worse than that of hay. This should be taken into account also in straw used as bedding as much as the hygienic quality of hay.

Influence of high-altitude grazing on bone metabolism of growing sheep

The objective of this study was to identify the effect of high alpine grazing, associated with varying pasture grass qualities and more pronounced exercise on typically steep slopes, on bone metabolism by improving bone density and enhancing bone turnover in growing sheep. Twenty-four 5-month-old sheep were randomly assigned to two groups. One group was kept at high altitude (HA; 2000-2200 m a.s.l.) for 3 months, and the other group (C; control) remained in the lowlands (400 m a.s.l.). Both groups were kept in grazing pastures with access to good-quality swards. Before the start of the experiment, blood samples were taken, the sheep were weighed, and the left metatarsus of each animal was analysed by quantitative computer tomography. After 1 month, blood samples were taken and body weight was measured, followed by biweekly sampling. Finally, the animals were slaughtered, and the bones were collected for analysis of various bone parameters. Body weight development did not differ between the groups. Concentrations of 25-OH-Vitamin D, carboxy-terminal telopeptide of type I collagen and activities of bone-specific alkaline phosphatase were always higher in the HA group than in the C group, except on the last two sampling dates. Bone mineral content and density increased in both groups during the experiment, but more intensively in the HA group. In addition, the cortical thickness of the HA group increased. The present study demonstrates an increase in bone turnover and mineral content of the bones of the growing sheep grazing in high alpine pastures. The factors associated with HA grazing, therefore, clearly seem to improve bone composition.

Effect of vitamin E supplementation of sheep and goats fed diets supplemented with polyunsaturated fatty acids and low in Se.

Vitamin E (VitE) and selenium (Se) are an essential part of the antioxidative functions of metabolism. There are situations of low supply of both micronutrients. As VitE is involved in ruminal biohydrogenation of polyunsaturated fatty acids (PUFA) and their protection against oxidation in metabolism, diets supplemented with PUFA may challenge VitE to an extent making recommended supplies insufficient. Twelve goats and sheep each were fed a diet supplemented with PUFA and characterised by low Se and limited VitE contents during the last 2 months of gestation and the first 2 months of lactation. The basal diet consisted of hay and concentrate. Six goats and sheep received extra VitE, while the control groups received no extra VitE. Blood and milk samples were taken. In addition, liver, heart muscle and spleen samples were obtained from the offspring after slaughtering at an age of 8 weeks. No significant changes were observed in serum Se and VitE. A significant increase in serum VitE concentrations between 2 and 4 weeks postpartum (pp) was evident in the supplemented kids. In 4, 6 and 8 weeks pp, the serum concentrations of VitE in the supplemented kids were significantly higher compared to the unsupplemented group. In the kids, VitE was higher in liver of the supplemented groups. There were no significant differences in response to extra VitE between sheep and goat. The kids responded to serum VitE different from that of lambs, as a significant difference was observed between supplemented and unsupplemented animals in the goat kids, but not the lambs. In conclusion, goats and sheep have to be viewed differently and may not be considered alike relating to VitE/Se metabolism and requirements, especially in young animals.

Postparturient hypocalcemia of dairy cows: A model for the study of the interdependence of CA, Pi, and MG homeostasis

Disorders of calcium, phosphorus and magnesium homeostasis in ruminants provide natural models for the study of the physiology and pathophysiology of these minerals. The knowledge that can be acquired with a better understanding of the pathogenesis of these diseases could give useful clues in the puzzle of human osteoporosis. In the present study, the case of parturient paresis of dairy cows is reexamined with a newly developed technique for the measurements of serum ionized magnesium concentrations (Mg2+). The concentrations of total magnesium (Mgtot), ionized calcium (Ca2+), total calcium (Catot), and inorganic phosphate (Pi) were also determined in the sera of seventeen 3- to 16-year-old Brown Swiss and crossed Simmental/Red Holstein cows during the periparturient period. In each animal, a transient increase of Mg2+ and Mgtot serum concentrations was observed in association with the transient decrease after parturition of Ca2+, Catot and Pi serum concentrations. On average, throughout the study, serum Mg2+ concentrations were 68.5% of those of Mgtot whereas serum Ca2+ concentrations were 52% of those of Catot. The possible mechanisms involved in the transient increase of Mg2+ and Mgtot serum concentrations are discussed and the relevance of this data for osteoporosis is outlined.

Effects of EDTA-Induced Hypocalcaemia and Stress on Plasma TNF-α, IL-1-ra, G-CSF, GM-CSF and S-100 in Dairy Cows

The pathophysiology of postparturient paresis is still not completely understood. Knowledge recently acquired in immunology, endocrinology and cell physiology has still to be integrated in order to elucidate the aetiopathogenesis of the disease. For that purpose, the effect of the EDTA infusion model on the plasma concentrations of selected cytokines and growth factors, and of a calcium binding protein was examined in dairy cows. Six 6- to 11-year-old Brown Swiss cows in mid lactation were infused with a 5% solution of Na2EDTA in one jugular vein over a period of 5 h. Blood samples were collected from the contralateral side daily two days before, and then hourly for five hours during the infusion, hourly for five hours after the end of the infusion, and once daily for 10 days thereafter. The plasma concentrations of cortisol, tumour necrosis factor-α, interleukin-1 receptor antagonist, granulocyte colony-stimulating factor, granulocyte and macrophage colony-stimulating factor, and the calcium binding protein S-100 were determined. Before the EDTA infusion, during the infusion and for two days thereafter, the mean plasma concentrations of cortisol were significantly higher than those from days 4 to 10 after the infusion. The plasma concentrations of tumour necrosis factor-α and interleukin-1 receptor antagonist followed a similar profile. At the end of EDTA infusion, low concentrations of granulocyte colony-stimulating factor were detected in one cow only. On days 3 and 4, the mean plasma concentrations of granulocyte colony-stimulating factor were significantly higher than the pre-infusion values, but this was followed by a significant decrease on post-infusion day 5. From day 4 to 7, the plasma concentrations of S-100 were significantly lower than the pre-infusion values. The importance of these findings in the pathophysiology of postparturient paresis remains to be established.

Mineral content of hay harvested in Bavarian and Swiss horse farms. Predictive value of cutting time, number of cut, botanical composition, origin and fertilization.

Hay samples from 29 horse farms in Southern Upper Bavaria and 31 horse farms in Switzerland were taken and analysed for minerals such as calcium, magnesium, phosphorus and potassium. The content of herbs and legumes in the hay was determined and the Weende analysis was performed. Comparison between Bavaria and Switzerland resulted in comparable calcium contents of approximately 4 g Ca/kg dry matter (DM) in grass hay. Hay with more than 10% of herbs and legumes found only in Switzerland showed higher Ca contents of >7 g Ca/kg DM in hay. The mineral contents of phosphorus and potassium were lower in hay from Switzerland (P: 1.8 +/- 0.7 g/kg DM, K: 15.4 +/- 5.1 g/kg DM) than from Bavaria (P: 3.8 +/- 0.6 g/kg DM, K: 20.0 +/- 6.0 DM), whereas the magnesium content of the hay showed no difference between the regions ( approximately 1.5 g Mg/kg DM). Very late first grass hay cuts showed low magnesium and calcium (<4 g/kg DM) contents. Further minerals in the hay for horses differed from those in dairy cattle in the same region. Fertilization showed only small effects on the mineral contents of the hay produced for horses. Therefore, in calculation of ration and production of supplements for horses, these differences should be taken into account.

Parathyroid hormone-related protein in the colostrum of paretic post parturient dairy cows

detected more infected individual pigs (82 per cent) compared with selective culture (69 per cent). In contrast, the uninfected group (sD-) was negative by both methods with the exception of one pig which demonstrated a marginal false-positive result with the ELISA. Although on a herd basis 100 per cent of the herds that were asymptomatic (SD+/-) were positive by the ELISA, only 75 per cent of the pigs tested within these herds were positive as compared to 82 per cent of pigs from herds displaying clinical dis-