Abstract:

 To explore the relationships of the degree of mastitis, total bacteria count, and bacterial infection pattern with milk composition and somatic cell count, the identifying medium and plate counting method were used for identification of bacteria and total bacteria count, and subclinical mastitis and dairy herd improvement (DHI) were also tested in 187 dairy cows with different degree of mastitis in this experiment. The results showed that: 1) Patterns of bacterial infection exerted insignificant effects on somatic cell count, milk protein and fat rate (P＞0.05), but had significant impact on the determination of daily milk yields (P<0.05); 2) Total bacteria count had no significant effect on protein content (P＞0.05), but had extremely significant effect (P<0.01) on daily milk yield, milk fat content and somatic cell count; 3) Under the same bacterial infection pattern, total bacteria count had significant impact (P<0.05) on the determination of daily milk yields, somatic cell count, milk protein and fat content; 4) the degree of mastitis had significant effect (P<0.05) on somatic cell count, daily milk yield, milk fat and protein content, and the total bacteria count; 5)The somatic cell count had extremely significant effect (P<0.01) on daily milk yield milk fat and protein content. These findings demonstrated that pattern of bacterial infection exerted insignificant effects on somatic cell count, and the degree of mastitis and somatic cell count had significant effect on milk component. We could use somatic cell count and the total number of colonies to monitor the mastitis risks and the possible changes in milk composition.