DEFINING CANDIDATE GENES FOR MASTITIS RESISTANCE IN CATTLE - THE ROLEOF LACTOFERRIN AND LYSOZYME

We summarize our previous and ongoing efforts to characterize two pote ntial candidate genes (lactoferrin and lysozyme) for mastitis resistan ce and examine their relevance for an improvement of udder-health in c ows. The genes encoding lactoferrin (Lf) and lysozyme (Lys) have been isolated and characterized at the DNA-sequence level, besides the alph a S1-casein gene. Starting from these data, two different strategies a re being persued to analyse their relevance in breeding for mastitis r esistance. First, based on the molecular characterization of their nat ural variants Ne are searching for high-performance alleles of both ge nes in the active breeding population. A first trend for the implicati on of a Lf-gene variant in mastitis-resistance is seen in the Norwegia n breeding population. Second, we want to assess experimentally the va lue of these genes for mastitis resistance under physiological conditi ons in transgenic experiments, under expression control of the bovine alpha S1-casein gene promoter. Based upon extensive molecular and cell biological characterizations of the bovine alpha S1-casein gene and i ts regulatory elements, a vector cassette has been constructed for tra nsgene expression in the mammary gland. Postitive expression of a lact oferrin expressing transgene in the mammary gland of mice has been dem onstrated.