Die Vermehrung der Pappeln durch Stecklinge

Ohne Zusammenfassung     

Gewitter und Forst

Ohne Zusammenfassung     

The incidence of agglutination and its influence on sperm quality and fertility of boar semen

The aim of this study was to examine the incidence of sperm agglutinations and their relationships with sperm quality and fertility. Semen samples of 40 boars of an AI-station were investigated. Nineteen of the 40 investigated boars showed a constantly low (< 10% agglutinated sperm), 3 an intermediate (10-20%) and 6 boars a high level (> 20%) of agglutination in raw semen. The degree of agglutination in sperm samples of 12 boars varied distinctly during the investigation period. During summer more (P < 0.05) agglutinated sperm were observed (11.0 +/- 11.6%) than during winter (6.2 +/- 7.3%). There was no association between bacterial contamination and incidence of agglutinations (P > 0.05). After dilution in extender the percentage of agglutinated sperm decreased from 6.2 +/- 7.3% to 1.1 +/- 1.4% (P < 0.0001). Twenty-four hours after dilution the percentage of progressively motile sperm was 7.4% lower (P < 0.05) in ejaculates with an initially high degree of agglutination (> 20% agglutinated sperm) compared to samples with an initially low degree of agglutinated sperm (< 10%). Plasma membrane integrity, mitochondrial membrane potential, acrosome reaction and chromatin structure were independent (P > 0.05) from the level of agglutination. Fertility data did not differ (P > 0.05) between boars with low and high numbers of agglutinated sperm in raw semen. The results show that there are individual, ejaculatory and seasonal variations in the incidence and degree of agglutination. Agglutinations have a negative effect on motility of sperm and disappear to a large extent after dilution in sperm extender. They have no negative consequences on fertility.     

The clinical diagnosis of BSE

Diagnosis of Bovine spongiform encephalopathy (BSE) is confirmed by specified laboratory methods on brain material. On the other hand clinical signs of manifest BSE are quite obvious. The first part of this paper describes case histories, clinical signs, laboratory findings and the most common differential diagnoses. On the basis of the data of actual prevalence in Germany, the role of clinical examination in eradication of BSE is dealt in the second part. Clinical diagnosis is a very sensitive and specific method when there is a high prevalence. According to the data from December 2000 to November 2001 prevalence in Germany was beyond 1 BSE case per 100,000 cattle or 3 cases per 100,000 cows. This very low prevalence decreases rapidly sensitivity and specificity of the diagnosis made by clinical examination. Therefore the main focus of field-diagnostics has to be laid on specified laboratory diagnostic methods. On the other hand prevalence of BSE-positive cattle is distinctly higher in the group of animals slaughtered in cases of illness or emergency than in cattle slaughtered on the regulatory bases. Nevertheless every veterinary practitioner should be aware of the clinical picture of BSE, clinical examination-routine and differential diagnosis, because occurrence of BSE is still possible in any dairy herd. At the moment it is not possible to make any statement if eradication of BSE can be reached in future.