Mycobacterium avium subsp. paratuberculosis (MAP) is the cause of paratuberculosis mainly in domestic and wild ruminants; paratuberculosis is also known as Johne’s disease. This disease is endemic all over the world generating significant economic losses, especially in dairy herds, although, MAP is the cause of infection in many other species including primates. Currently, MAP mycobacteria are recognized as pathogens transmitted by food. They are a potential threat to animal and human health. Infected animals excreting mycobacteria with faeces are the main source of MAP. The development of control strategies and disease control are based on determi- nation of the genetic diversity of the MAP strains causing Johne’s disease. This study describes 43 strains isolated from a herd of dairy cows located in northern Poland. The types of MAP were determinted based on the polymorphism analysis of two insertion fragments: IS900 and IS1311. The polymorphism of IS900 was analyzed with the use of a PCR multiplex according to Collins’ method and the IS1311 polymorphism with the use of the PCR-REA method. Based on the diffe- rences observed, the strains isolated were classified into two MAP types, cattle (C-type) and sheep (S-type), with the predominance of the cattle type.

This study analyzed the internal and external quality traits of eggs derived from hens of different breeds, including Silkie, Sultan, Cochin Bantam, Brahma and White Leghorn. The highest mean weight was noted for eggs originating from the White Leghorns breed, and the lowest was for eggs from the Cochin Bantams. Simultaneously, both a positive correlation between the egg weight and the percentage of albumen (r = 0.876) and a negative correlation between egg weight and the percentage of yolk (r = - 0.842) were found. The eggshell composition varied significantly in mean phosphorus amount, whereas the calcium content did not differ significantly. Despite this, eggshell strength varied significantly between breeds. Regarding cholesterol and fatty acid levels, the highest amount of cholesterol was noted in the Cochin Bantam breed, and the lowest was in the White Leghorn, although Leghorn was the breed characterized by the highest saturated fatty acid levels, and Cochin Bantam was the lowest. Regarding the polyunsaturated fatty acids (which have been proven to positively influence the cardiovascular system), the highest levels were obtained by Leghorn eggs, and the lowest were obtained by Silkie eggs. In conclusion, the study indicates that ornamental chicken breeds are a source of high-quality products, which could be attractive to consumers, additionally supporting traditional farming and animal genetic resources.