The effects of intramammary administration of liposome-wrapped recombinant bovine granulocyte-macrophage colony-stimulating factor (rbGM-CSF, 400 μg/5ml control solution per quarter) on the California mastitis test (CMT), chemiluminescence (CL) activity, somatic cell count (SCC) and Staphylococcus aureus (S. aureus) count in milk were investigated and compared with the effect of liposome-unwrapped rbGM-CSF, using 12 Holstein dairy cows with S. aureus-induced subclinical mastitis (average count of SCC in pre-injection time; 700,000 cells/ml). The animals were divided into a liposome-wrapped cytokine group (LWC group, 6 cows) and a liposome-unwrapped cytokine group (LUC group, 6 cows). CMT and CL levels had peak increases at 6 hr and decreased on days 7 and 14 after the injections of LWC and LUC. The decrements were higher in the LWC than the LUC group. The SCC level had a peak increase at 6 hr and decreased thereafter following the administration of LWC. On the other hand, administration of LUC caused the level to gradually increase on days 1 and 2, followed by decreased levels thereafter. The decrement was higher in the LWC than the LUC group. The S. aureus count decreased drastically to minimum levels at 6 hr and 24 hr in the two groups, respectively. The present study indicates that the LWC has more potential as a therapeutic agent for S. aureus-induced subclinical mastitis of dairy cows than LUC.
(Research Team for Production Disease, TEL +81-29-838-7708)
Reference:
- Takahashi et al. (2007) Proc. Heifer Mastitis 1 : 58-59.
- Takahashi et al. (2007) Proc. Jpn. Mastitis 11 : 15-20(in Japanese).
- Kiku et al. (2007) Proc. Jpn. Mastitis 11 : 21-26(in Japanese).
