Genetic aspects of mastitis resistance in cattle
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Cattle breeding program for improvement of milk traits is accompanied by intensive changes in the structural and functional specificity of the animal organism. Assuming the hypothesis that the biological role of the female is to rear her progeny, it may be concluded that the extremely high milk productivity of the modern cow many-fold exceeds the physiological normal range. The mammary gland as a milk-producing highly effective bioreactor is exposed to the particularly strong influence of external and internal factors. Therefore, susceptibility to udder dysfunction generally called 'mastitis' causes great economical losses in highly productive cows. Mastitis is usually induced by a bacterial infection conveyed through the teat canal. The high variability of pathogens and diversity of environmental conditions cause difficulties in mastitis treatment. Antibiotic therapy does not give satisfactory results. Scientific research aims to recognize the heritable specificity of organism defence systems. Still, the currently used breeding selection procedures cannot be successful because natural resistance treated in categories of quantitative genetic variation shows a very low heritability and non-additive genotype-environment interaction. To overcome this problem, an alternative approach to detect a single gene with a high protective expression can be effective. The topics presented in this review include expression of lysozyme and lactoferrin in mammary gland tissue regarded as candidate gene for mastitis resistance as well as BoLA histocompatibility complex and milk protein polymorphic systems proposed as potential genetic markers of natural resistance in cattle.
Publication order reference
K. Walawski, University of Agriculture and Technology, Department of Animal Genetics, ul. M. Oczapowskiego 5, 10-719 Olsztyn-Kortowo, Poland