Acta veterinaria Scandinavica. Supplementum最新文献

The objectives are to review results and experiences from interdisciplinary research projects in Research Centre for the Management of Animal Production and Health (CEPROS) concerning scientific content, organisation, and collaboration. The Centre has been founded as a result of an agreement between four institutions: the Danish Institute of Agricultural Sciences (DIAS), the Danish Veterinary Laboratory (DVL), the Danish Veterinary Institute for Virus Research (DVIV) and The Royal Veterinary and Agricultural University (KVL). CEPROS is a "research centre without walls" and is physically located as an integrated part of the four institutions named above. The Centre has close collaboration with the industry. The superior goals of the Centre are to co-ordinate fundamental and applied research and simultaneously integrate the veterinary and the production oriented livestock research within animal health and welfare, taking into consideration the production economics and reduced use of medication. The assignment of the Centre is to initiate and carry out research, aiming to investigate the influence of breeding and production systems on animal health and welfare as well as on production and product quality. The Centre has since 1997 established 16 interdisciplinary research projects dealing with cattle, pigs, poultry, or mink. The scientific content can be divided into three research clusters: A. Management of animal production and health in production systems, B: Pathogenesis of production diseases, and C. Animal health economics. In Cluster A, the physical environments of production systems have been investigated, broader definitions of the concept health have been established and used in identification of risk factors. Cluster B has investigated physiological, immunological and genetic mechanisms behind development of production diseases and how to apply this knowledge in disease prevention. The cluster in animal health economics has developed decision support tools for disease control in swine and cattle herds. The interdisciplinary research groups organised in a centre without walls are found very useful for dealing with complex issues. The initial phases in the projects may be long as it takes time for different researchers to define common goals and identify methods. The individual researcher must get some insight in other disciplines without loosing his/her own area of expertise. In order to reach a synthesis of the different parts of a project, it is important that the project is well organised and there is participation of researchers with both specialised insight and researchers with a more broad insight in the problems. It is also important that the integration process is balanced, and not too many research disciplines are included in the same project.

In a prospective, longitudinal study ten pregnant dry cows were randomly assigned as either experimentals or controls. The experimental period was from 28 days before expected calving until calving. Experimental cows were allocated 800 g of zeolite A daily during week 2 and 3 before expected calving. The zeolite A was given continuously via a feed dispenser. The daily calcium intake was calculated to be 60 g. Daily urine samples were obtained before, during and after the period of zeolite A supplementation. Urine pH was measured immediately whereas the remaining of samples was stored at C until analysis for calcium and creatinine. Urinary calcium/creatinine ratio was used as a measure of renal calcium excretion. Zeolite A supplementation did not affect urine pH. Renal calcium excretion peaked at the first day of supplementation, whereupon it decreased steadily to a level comparable to pre-exposure level. This could be explained by a sudden draw of calcium from the readily mobilizable pool in the bone. A commercial available water hardness test kit was evaluated as a possible cow-side test for monitoring renal calcium excretion. The repeatability of the analysis was acceptable (CV = 9.3). The accuracy of the test was good. When compared to laboratory derived urinary calcium/creatinine ratios of the same samples, a distinct linear relationship could be shown (Y = 7.9E-7 + 1.9E-8). It was therefore concluded that the water hardness test was able to monitor renal calcium excretion with an acceptable accuracy.

Neonatal mortality is very high in farm animals (approximately 10%) and disease resistance is greatly influenced by an adequate passive immunisation just after birth. In piglets, foals, calves and lambs, the intestinal absorption of immunoglobulins from their mother's colostrum occurs mainly by a non-specific endocytosis of macromolecules, but the details of the absorption process, and the mechanisms regulating its cessation after 1-2 days of colostrum exposure, remain poorly understood. In both normal and 'compromised' (premature, growth-retarded, hypoxic, lethargic) newborn farm animals, the intestinal capacity to absorb macromolecules is influenced by both diet- and animal-related factors. Thus, macromolecule uptake is severely reduced in response to premature birth and when macromolecules are to be absorbed from diets other than species-specific colostrum. On the other hand, fetal growth retardation, in vitro embryo production, or a stressful birth process are unlikely to reduce the ability of the intestine to absorb immunoglobulins from colostrum. More knowledge about the diet- and animal-related factors affecting intestinal immunoglobulin uptake will improve the clinical care of 'compromised' newborn farm animals. The present text gives a brief introduction to the process of intestinal immunoglobulin absorption in large farm animals and describe some recent results from the author's own studies in pigs, calves and lambs.

Herds are under constant risk of introducing new pathogens from different sources. In this article we describe biosecurity practices in Danish sow herds. Between December 1, 1999 and February 29, 2000, 121 sow units were interviewed regarding biosecurity on the site. The questionnaire contained 62 questions. The 121 units were situated in three areas with different swine densities. Sow units were described by their sizes (units with >110 sows were regarded as large herds) and health status (SPF herds or conventional herds). Of the 121 sow herds, 63 (52%) sold weaners. Most sow units (71%) used delivery facilities for the picking up of weaners, but half of these did not have a barrier between the loading area and the stable while loading. In 19% of the units, weaners were picked up directly from the stable, and in 10% the truck driver had access to the stables. Most units required the vehicle to be cleaned (16%) or cleaned and disinfected (48%) before the transport; large sites and SPF sites more often required stricter biosecurity measures, for example a quarantine period before the transport of weaners.

We consider 3 basic steps in a study, which have relevance for the statistical analysis. They are: study design, data quality, and statistical analysis. While statistical analysis is often considered an important issue in the literature and the choice of statistical method receives much attention, less emphasis seems to be put on study design and necessary sample sizes. Finally, a very important step, namely assessment and validation of the quality of the data collected seems to be completely overlooked. Examples from veterinary epidemiological research and recommendations for each step are given together with relevant references to the literature.

This paper summarise the development of the new principle of preventing parturient hypocalcaemia by reducing the bioavailability of ration calcium with calcium binders, based on the idea that a negative calcium balance would stimulate natural defence mechanisms against threatening hypocalcaemia. Synthetic sodium zeolite was selected as a first choice among the many calcium binders available commercially, such as polyphosphates, citrate, EDTA and it derivatives. Testing was done on non-pregnant rumen fistulated cows in the first place, followed by cows in late lactation. Encouraged by the tendencies seen in these animals, the final proof of concept was done on pregnant dry cows fed a supplement of synthetic sodium zeolite A from 4 weeks before expected calving until calving. By analysis of blood calcium levels, this supplementation was shown to have a stabilizing effect during the critical period shortly after calving.

The aim of our studies on parathyroid hormone dynamics were to establish standardized methods for induction of hypocalcaemia, sequential hypercalcaemia and normocalcaemia and sequential hypocalcaemia and hypercalcaemia suitable for careful and detailed evaluation of the PTH(1-84) secretion in vivo. We found that at least two distinctly different mechanisms of PTH(1-84) secretion serve to protect normal humans against hypo- and hypercalcaemia. First, an initial decrement of B-Ca2+ leads to a large transient release of preformed PTH(1-84) from the cellular depots, whereas, an initial increment of B-Ca2+ leads to almost immediate suppression of PTH(1-84) release. The change in PTH(1-84) release is rate dependent in either direction and demonstrable even at small decrements or increments of B-Ca2+. This mechanism of delta regulation provide a strong homeostatic mechanism for maintaining a stable extracellular calcium level during slow as well as rapid changes in B-Ca2+. Second, a mechanism of steady state regulation for continued secretion takes over, being dependent on the absolute B-Ca2+ concentration, which probably controls the synthesis of PTH(1-84) molecules. Selective investigation of the steady state response to hypocalcaemia demands elimination of preformed PTH(1-84). With this precaution, we described the inverse sigmoidal relationship in vivo between the steady state pairs of B-Ca2+ and S-PTH(1-84) in normal humans. The calcium set-points of Brown measured by this computer method were significantly lower than Parfitt's calcium set-points in normal humans, but strikingly well correlated. This observation supporting the view that Brown and Parfitt describe two different points on the same sigmoidal curve, corresponding to 50% and about 85% inhibition of PTH(1-84) in normal humans.

Strategies for the prevention of milk fever in the United States have made several 180 degree changes over the last several decades. During the 1950's and 1960's evidence suggested that low calcium diets could be utilized to stimulate the parathyroid prior to calving to initiate calcium homeostasis prior to the onset of lactation. High calcium diets were avoided and the strategy worked--for a while, until more concentrated farming practices changed the cation composition of the forages. Although Norwegian scientists presented evidence of a role for cations and anions in milk fever during the late 1960's, recent studies have more precisely defined the physiological link between high diet potassium and tissue sensitivity to parathyroid hormone as a leading cause of milk fever. Manipulation of dietary cation-anion balance has been growing rapidly as a means of controlling not only milk fever but sub-clinical hypocalcemia as well. A recent United States survey found that 45% of dairy operations feed dry cows a "low potassium diet" to reduce milk fever. In addition some use anionic salts. About 27% of dairy farms feed dry cows a diet with added anions to induce a compensated metabolic acidosis which has proved effective in reducing subclinical hypocalcemia. These diets are often high in calcium.