BLOOD SERUM TRANSFERRIN POLYMORPHISM AND MASTITIS

Abstract

Seven hundred and one cows representing 21 herds of the Dairy Herd Analysis Service of Macdonald College were studied. Out of these, 105 cows were in series 1 and the remaining 596 cows were in series 2. Of the 105 cows in the first series, 91.4% were California Mastitis Test (CMT)(+), 50.5% were Streptococcus agalactiae(+) and all the cows were hemolytic staphylococcic(+) at one or more tests in one or more quarters. The corresponding figures for quarters were 28.8%, 6.7% and 35.4%. In the second series, data for mastitis criteria were available for 533 cows only. The incidence of cows in this group with one or more CMT(+) quarters was 64.2%. The incidence of CMT(+) quarters in 2131 quarters from these cows was 39.2%. Out of these CMT(+) quarters, 29.1% were infected with streptococci and 30.7% with hemolytic staphylococci. In both series 1 and 2, the differences in percentage of CMT(+) quarters between transferrin genotypes were significant (series 1, X29 d. f. = 34.44, P < 0.005; series 2, X29 d. f. = 19.00, P < 0.025). In series 1, the percentage of Streptococcus agalactiae (+) and percentage of hemolytic staphylococci (+) quarters were also significantly different from genotype to genotype (P < 0.005). On the other hand, in the second series, only the percentage of streptococci(+) quarters were significantly different between genotypes. The Tf D1D1cows had a higher incidence of Str. agalactiae infection in series 1 and of streptococci in series 2. Tf D1D1cows also had a significantly higher (P < 0.05) mean CMT score and mean total somatic cell count per cow in series 1. Tf EE cows, however, were free of Str. agalactiae infection in series 1 and of streptococci in series 2. Tf EE cows also had a significantly lower (P < 0.05) mean streptococcal score per cow in series 2.