Effects of Novel lntramammary Device Models on Incidence of Mastitis After Experimental Cha.pdf

Effects of Novel lntramammary Device Models on Incidence of Mastitis After Experimental Challenge S. C. NICKERSON, R. L. BODDIE, W. E. OWENS, and J. L. WATTS MastiUs Research Laboratory Hill Farm Research Station Louisiana Agricultural Experiment Station Louisiana State University Agricultural Center Route 1, Box 10 Homer 71040 ABSTRACT Firstcalf heifers were fitted with five different intramammary device models prior to, or within 2 mo after parturition. Each model represented an increase in the weight of the device to be supported by the epithelial cells of the gland cistern. Each model was tested in four animals by placing devices in two quarters while re- maining quarters served as controls. Fore- milk and stripping quarter secretion sam- ples were collected prior to device placement and weekly thereafter and ana- lyzed for total and differential cell counts, bacteriologic status, and NAGase activity. During the prebacterial challenge treat- ment period, foremilk and stripping SCC as well as percentage of neutrophils and NAGase activity in most device-fitted quarters remained significantly elevated over controls. Frequency of naturally oc- curring intramammary infection during the prechallenge period was lowest in quarters fitted with Models 2, 4, and 5. Frequency of infection with coagulase- negative staphylococci also tended to be lower in quarters fitted with Models 2,4, and 5. Approximately 4 mo after device placement, all quarters were challenged by intracisternal inoculation with about 565 cfu Streptococcus uberis. Results across all models combined showed that although mean foremilk and stripping SCC and percentage of neutrophils were Received March 5, 1990. Accepted May 14, 1990. lApprovcd for publication by the Director of the Louis- iana Agricultural Experiment Station 89 Uannscript Num- ber 90-804012. significantly elevated in device-fitted quarters immediately prior to bacterial challenge, only Model