Abstract
Currently, mastitis is commonly treated with antibiotics, although in some cases the desired effect cannot be achieved when the causative organism is resistant to antibiotics. This study investigated the effect of a Sasa senanensis extract (SanSTAGE), which has shown immunostimulatory effects in humans, on chronic mastitis in Holstein cows. A total of 32 cows with mastitis caused by gram-positive bacteria were used in the study; SanSTAGE was fed to 26 cows for 2 weeks, while the remaining 6 cows were untreated as controls. Milk and blood samples were collected before and 1 and 2 weeks after the start of treatment and 1 week after the end of treatment (Weeks 0 to 3). For milk, somatic cell count (SCC), the modified California mastitis test and bacterial isolation/culture were performed. Udders were classified into two groups according to the pre-treatment SCC: a high SCC group (≧ 200,000 cells/mℓ; 26 udders in treated cows) and a low SCC group (< 200,000 cells/mℓ; 15 udders in treated cows). Seven udders from the control group were similarly classified. For blood, acute-phase protein levels (21 treated cows and 2 controls), leukocyte subpopulations and cytokine gene expression (12 treated cows) were analyzed. Pre- vs. post-treatment comparisons were performed for each parameter. In the treated group, cows with high SCC showed a significant decrease in SCC at Weeks 2 and 3, while cows with low SCC showed a significantly increased SCC at Week 1. No significant change was observed in SCC in the untreated group. The results of the modified California mastitis test did not change significantly in both groups. By bacterial isolation/culture from milk, the same bacteria were isolated throughout the study period in both groups. Among acute-phase proteins, haptoglobin significantly increased at Week 1 in treated cows. Among leukocytes, a significant increase was seen in the number of WC1-N1+ cells at Week 2 in treated cows. In the treated group, furthermore, MX2 gene expression was significantly upregulated at Week 1. These results suggest the possible use of 2-week continuous feeding of SanSTAGE as an adjunct therapy in the treatment of chronic mastitis, since the treatment led to activation of some immune components and, in cows with high SCC, a decrease in SCC.
