Untersuchungen zum Vorkommen von Histomonas meleagridis bei Mastelterntieren und Einfluss eines positiven Nachweises mittels Real-time PCR auf die Produktionsparameter der Herde
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Beschreibung
Investigations on the occurence of Histomonas meleagridis in broiler breeders and influence of positive detection by Real-time PCR on the production parameters of the flock
In the course of this work, 19 broiler breeder flocks located in Mecklenburg-Western Pomerania, Saxony-Anhalt and Thuringia were analysed by qPCR for the presence of Histomonas meleagridis DNA every four weeks from the day of housing into the production facility. These were nine farms with broiler breeders of breed A and ten farms with broiler breeders of breed B. Data on flock health (necropsy findings) and economic parameters (mortality and laying performance) were collected for all flocks and compared with the results of the qPCR
The first aim of this study was to investigate the extent to which broiler breeders become infected with H. meleagridis despite extensive biosecurity measures. The results of the tests showed that DNA was detected several times in all flocks during the production period. At the time of housing into the production facility, DNA of H. meleagridis was already detected in 31.6 % of the flocks. The latest time at which a positive DNA detection was achieved was the 36th week of life. Furthermore, it was investigated whether certain factors such as the season, the origin of drinking water or the region in which the farm was located influenced the probability of a positive DNA result in the qPCR. This was not the case for the first two factors, but with regard to the region, the Ct values of boot swabs from farms located in Mecklenburg-Wesern Pomerania were statistically significant lower than those from farms in Saxony-Anhalt and Thuringia. The reason for this difference in the Ct values remained unclear.
Another purpose of this study was to find out whether the probability of an infection with histomonads differs between two breeds. However, the examination of cecal and boot swabs did not yield any statistically significant result in this respect. The percentage of positive DNA detections of H. meleagridis was 51.6 % in breed A broiler breeders and 39.5 % in breed B broiler breeders. Furthermore, the use of two different sample materials, cecal swabs and boot swabs, was used to investigate whether the sample material influences the probability of a positive DNA detection. It was found that there was a statistically significant difference between the qPCR results at identical sampling times. DNA of H. meleagridis was detected in more than half of the boot swabs, while only a third of the cecal swabs tested positive. These results appear to be due to the fact that testing with boot swabs involved more animals than testing with cecal swabs.
Despite of a considerable number of positive DNA detections by qPCR, no connection to typhlitis could apparently be established. Only 3 out of 19 flocks were found to have typhlitides in the routinely performed necropsies during the study period, with the highest percentage being 3.0 %. Interestingly, DNA of H. meleagridis could also be detected in 36.2 % of macroscopically inconspicuous ceca. With regard to the diagnosis of polyserositis, in breed A there was a correlation between the sum of the Ct values (boot swabs) and the percentage of broiler breeders in which polyserositis was diagnosed. The results of the statistical analysis indicated that the percentage of broiler breeders with polyserositis decreases with increasing Ct values. Finally, further studies showed that infections with H. meleagridis detected by qPCR do not necessarily lead to a negative effect on laying performance or to an increase in mortality in broiler breeder flocks.
Autor*in
Monique Necke
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Prävalenz Zäkum Polymerase-Kettenreaktion Proben Histomonas meleagridis Fäkalien-Sammlung Masthähnchen broilers Typhlitis Serositis Sterblichkeit Legeleistung prevalence caecum faeces collection