Summary Runs of homozygosity (ROH) are recognized as potential inbreeding measure in studies on humans. Inbreeding coeffi cients derived from ROH (F ROH ) measure proportion of the genome arranged in long homozygous segments and highly correlate with those derived from pedigree (F ped ). From that we assumed that ROH represent an alternative to pedigree inbreeding levels in studies on animals too, because pedigree can be incorrect, incomplete and can not fully explain what happened in meiosis. To confi rm our premise we used pedigree and genotype data from 500 Austrian dual purpose Simmental bulls to determine correlation between F ROH and F ped . ROH were obtained using Fortran 90 soft ware created by the authors. Proportions of genome in ROH were calculated for lengths of ROH of >1, >2, >4, >8 and >16 Mb. Pedigree data were analyzed and inbreeding coeffi cients for complete pedigree (FpedT) and fi ve generations (F ped5 ) were calculated using ENDOG soft ware. We found low F pedT and F ped5 (means of 1.5% and 0.9%) while FROH for segments >1Mb suggested much higher values (9.0%) indicating old inbreeding that can not be traced using pedigree. Th e highest correlations were found between FROH calculated from ROH of length >4Mb and F pedT (0.68) that is consistent with studies on humans. We conclude that inbreeding coeffi cients derived from ROH are useful for measuring levels of inbreeding in cattle, because ROH are not subject to mistakes as pedigrees and calculations made from those.

Inbreeding results in identity by descent of maternally and paternally inherited alleles. Due to the process of recombination that combines maternal and paternal DNA in very large chunks during meiosis, inbreeding to a recent ancestor results in relatively long homozygous segments of the genome, "runs of homozygosity". High density genotyping renders the search for such homozygous segments relatively easy. Runs of homozygosity that are several megabases (Mb) long are due to inbreeding to a recent ancestor. We have searched for runs of homozygosity that are longer than 2 Mb, 4 Mb, 6 Mb, 8 Mb and 10 Mb, respectively, and expressed these segments as proportions of the total length of the autozygous genome, based on SNP positions available. Very long segments most likely result from recent inbreeding while shorter segments may have been caused by inbreeding to ancestors further in the past. The breeds involved in the study are Fleckvieh (dual purpose Simmental), Brown Swiss, Norwegian Red, 500 animals each, and Tyrol Grey, 213 animals. On long and informative pedigrees, inbreeding coefficients were calculated for the full pedigree available and for subsets including a maximum of 5 generations for each individual. Results indicate a high correlation (>0.80) of individual runs of homozygosity with pedigree inbreeding coefficients of animals when calculating correlations across breeds. Within breeds, correlations were smaller (~0.70) because of differences in inbreeding levels in these breeds. We conclude that the proportion of the genome arranged in long homozygous segments provides a good indication of level of inbreeding of an animal that is more informative than the probability of autozygosity derived from from pedigree data.

Health control of the mammary gland was conducted comparing results of CMT (California Mastitis Test) and bacteriological findings of milk samples during one year. A total of 3863 secretion samples of mammary glands were collected. There were 85.3% matches for CMT and bacteriological findings. The most frequently isolated causative agents were: staphylococci (52.4%), streptococcus bacteria (23.5%), mixed infections (13.1%), and enterobacteria (10.3%). Secretions disorder and inflammations of mammary gland are most common for the warm period of the year, and very rare for the winter period. With permanent use of these two methods it is possible to obtain satisfactory results in order to get better milk production and health condition of the mammary gland. .

With 268 heifers in farm breeding, udder examination has been performed for clinical mastitis during 14 days after calving. From each quarter we took secretion samples and performed bacteriological analysis. From total number of heifers, 56 of them had shown clinical signs of inflammation, and 12 were bacteriologicaly positive. By bacteriological analysis mastitis pathogens had been found, even in 14 heifers without inflammation signs, at least until the end of test period. From the total number of tested heifers in 3,35% of cases Streptococcus agalactiae have been found, 4,85% coagulase positive staphilococcae (CPS) and 1,49% Corynebacterium pyogenes. Because coagulasa positive staphilococci were the most present bacteries in the period of 14 days, we made opinion that the same are the most often mastitis pathogen. Heifers with intramammarian infections like these, represent source of infection fot other non-infected animals in herd.