[PCB concentration in hair, blood, tissues and secretions of chronically exposed dairy cows, fattening bulls and calves]. / PCB-Konzentrationen in Haaren, Blut, Geweben und Ausscheidungen chronisch belasteter Milchkühe, Mastbullen und Kälber. 2. Mitteilung: Verlauf der Konzentration hochchlorierter Biphenyle (PCB) in Haaren, Geweben und Ausscheidungen chronisch belasteter Bullen und trockenstehender Kühe bei PCB-freier Fütterung.

Fattening bulls (n = 8) and cows (n = 10) affected chronically with PCB were kept in barns on PCB-free feeding (silage, straw, concentrates). The cows were dried off. The kinetics of PCB-concentrations in hair, blood and feces were examined. Fattening bulls (mean 460 kg bw, german black and white and interbreeding german black and white and Simmental) with low (320 g) and medium (730 g) daily weight gain for a period of 5 months and 3 bulls with medium (640 g) weight gain within 18 months were examined. A drying off period of 3-5 months was recorded for the cows. The distribution of PCB in the carcass of some animals was registered in addition. The following results are to be emphasized: Reduction of PCB in the studied substrates in the fattening bulls depends on a high degree on daily weight gain. This is important in order to calculate biological half life times of PCB. By standardized weight gain of 10 kg in bulls, fed PCB-free diets for a 5 months period, a reduction of PCB-concentrations from 1 to 3% was found (hair and feces: 1%, blood 3%). Within a period of 18 months and with higher weights, in the examined substrates (blood, hair, feces) mean declines of the PCB-concentrations of 2% were found. On knowledge so far this value is an essential point to estimate biological half life times, because metabolic PCB-elimination is negligible.(ABSTRACT TRUNCATED AT 250 WORDS)

[PCB concentrations in hair, blood, tissues and secretions of chronically-exposed dairy cows, fattening bulls and calves. 1. Course and relation of some polychlorinated biphenyls in hair, milk and tissues in exposed nursing cows and conventionally raised dairy cows]. / PCB-Konzentrationen in Haaren, Blut, Geweben und Ausscheidungen chronisch belasteter Milchkühe, Mastbullen und Kälber. 1. Mitteilung: Verlauf und Beziehung der Konzentration einiger hochchlorierter Biphenyle in Haaren, Milch und Geweben bei belasteten Ammenkühen und konventionell gehaltenen Milchrindern.

20 cows contaminated chronically with PCB were kept as nurse cows or in a tie-stall. The contamination in different substrates (hair, milk, blood, feces) was examined for a period up to 8 months. The distribution of PCB in the carcass of some animals was registered in addition. The system of keeping nurse cows turned out to be useful in order to overcome a contamination situation. Drying off gravid animals in the first step helps solving problems of handling contaminated milk. With low contaminated animals a short dry off period is sufficient, so that the milk--after calving--is marketable (report II, in preparation). In case of nurse cows with two calves post partum a continuous decline of PCB-concentrations in the milk can be observed. With biological half life periods of 2-4 months, milk with PCB 153-concentrations of 0.15-0.20 mg/kg fat will be marketable within this period. Cows milked by milking-machines show a decline of PCB in the milk similar to nurse cows. Two animals had a limited increase p.p., probably caused by mobilization of fat in the high lactation stage. Over longer periods, the biological half-life-periods were comparable to nursing cows. Hair is easy to sample and store; it is useful as a diagnostic substrate beside the milk in order to estimate the degree of contamination in individual animals. The ratio of PCB-concentrations between perirenal fat and hair is 1:0.95 (s = +/-0.192); the ratio of PCB-concentrations between perirenal fat and milk is 1:0.77 (s = +/- 0.122).(ABSTRACT TRUNCATED AT 250 WORDS)

[The use of ELISA systems for control of epizootics: safety of test standards using batch assays]. / Der Einsatz von ELISA-Systemen in der Tierseuchenbekämpfung: Sicherung der Testaussagen durch Chargenprüfungen.

One of the advantages of ELISA techniques is to achieve a higher degree of safety by standardization. Bases of these standardizations should be, if available, international or national standards in combination with cutoff definitions. The cutoff definitions should be expressed, separate for the main kinds of samples, defined as a dilution of the standard. Those definitions can replace the mostly awkward and involved test descriptions as usual in official regulations. To guarantee a high grade of reliability it is a matter of urgent necessary to test (if possible by the producer) each serial (lot) of ELISA and to describe their capacities with regard of sensitivity and specificity. Separate pretests may be done with the main kinds of samples with well known reactions (negative and weak positive). The results are to compare to those of the cutoff-related dilutions of the standard in the same matrix. These descriptions of the capacities of each serial (lot) are safe bases for use of the serial. Key concepts are the quotients of the minimum positive value divided by the maximum negative or alternatively the mean value of the positive minus the threefold standard deviation divided by the mean value of the negative plus the threefold standard deviation.

[Experiences in the control of brucellosis in cattle herds in the government district of Hannover]. / Erfahrungen bei der Bekämpfung der Brucellose in Rinderbeständen des Regierungsbezirks Hannover.

Caused by imported beef cattle new outbreaks of Brucellosis (subtype III) were observed in the government district of Hannover, which was "Brucellosis free" over a long period. With the aim to interrupt the series of infections from herd to herd it seemed to be necessary to introduce a herd screening system including frequent tests. It was not possible to screen the herds by the usual way of blood serum testing because of reasons of practicability and economy. A practicable alternative was the ELISA supported tank investigation. Four of the last six outbreaks were detected by this milk sampling. The other two infected herds were detected by only clinical symptoms because the lactating cows were not infected and had no contacts to the infected separately held heifers. The required test frequency in the dairy cattle herds could only be realized applying an ELISA supported highly sensitive tank milk test method. This method offered the chance of discovering infected herds as soon as possible and prevented greater economical losses and animal health risks. The tank milk screening of the dairy cattle herds to detect antibodies against Brucellosis (and additional EBL and IBR) has now become a standard method to continue the official status "free from..." This is a safer and a more economic alternative to the previous blood sampling of cattle older than two years with a three years interval because this method guarantees a safe information about the serological status of each cow which is now tested at least once a year, depending on the time of dry standing status.(ABSTRACT TRUNCATED AT 250 WORDS)

[Control measures in officially acknowledged brucellosis-free and leukosis unsuspected dairy herds on the basis of bulk milk samples in combination with ELISA tests]. / Kontrollmassnahmen in amtlich anerkannten brucellosefreien und leukoseunverdächtigen Milchviehbeständen auf der Basis von Tankmilch-Proben in Kombination mit ELISA-Tests.

1. EC- and National Regulations. Since 1988 the EC-regulations accept in addition to the on Agar Gel Immunodiffusion test (AGIDT) based blood serum testing of cattle herds that are filed as "free from Enzootic Bovine Leucosis" the use of ELISA for this purpose. The regular testings in dairy cattle herds can be done alternatively with single or pooled milk samples, in other herds with pooled blood sera using ELISA. General condition is only a minimal sensitivity of the test to detect the European EBL Antibody Standard ("E4") in a dilution of 1:10 in negative serum or 1:250 in negative milk. Adequate national regulations are in preparation. The present limitation of pool sizes, blood maximum 50 animals without preparation steps 20, and milk after concentration treatment 50 cows is neutralized by proceedings in development of higher sensitive ELISA tests. This limitation should be canceled. Herd bulk milk samples without size limitations are accepted to be tested with "Milk Ring Test" by EC for the regular testings in filed "Brucellosis Free Dairy Cattle Herds". The alternative use of more sensitive (and more specific) ELISA tests for this purpose including the technical conditions is in a final discussion. 2. Scientific-Technical Base for Using the Chances of the Proceeding in the EC-Regulations. The realisation of the EC accepted or final discussed ELISA based bulk milk testing to control filed "EBL- and/or Brucellosis Free Herds" depends on some basic conditions like sensitivity, specificity, and variability of the ELISA systems. Field trials of more than 20,000 bulk milk samples in case of Brucellosis and more than 2,000 in case of EBL show the feasibilities and the limits of the ELISA systems in defining the status of the herds. The Brucellosis respectively the EBL situations of the dairy cattle herds tested in this trail were well known by history and by investigation of single animal blood samples using conventional tests. Special test run variations of pretested assays demonstrated the possibilities to define the EBL status of dairy cattle herds up to 50 lactating cows without preparation of the bulk milk sample and up 100 after concentration of the antibodies by the rennet-ammonium sulfate method. The concentration limit for detection of Brucellosis antibodies is 100 lactating cows. The bulk milk of smaller herds can be tested without concentration. On principle the evaluation of the test values bases on defined relations to a "weak positive" reference.(ABSTRACT TRUNCATED AT 400 WORDS)