Milk and supramammary lymph node samples were obtained from asymptomatic cows infected with Mycobacterium paratuberculosis at the time of slaughter. Of 81 supramammary lymph node samples, 22 (27%) were culture positive for M. paratuberculosis. Of 77 milk samples, 9 (11.6%) were culture positive. The prevalence of supramammary lymph node or milk infection was highest with heavy fecal shedding of M. paratuberculosis and lowest with light shedding. The serologic status of the cow was not useful for predicting the risk of supramammary lymph node or milk infection. Shedding of M. paratuberculosis occurs in the milk of asymptomatic infected cows but, apparently, less frequently than previously reported for symptomatic cows.

Sperm hyaluronidase has been implicated in sperm penetration of the extracellular matrix of the cumulus oophorus and may play a crucial role in gamete interaction and fertility in mammals. The objectives of this study were to characterize the enzyme activity of equine sperm hyaluronidase and to investigate its cellular distribution. Zymography of stallion sperm plasma membrane extracts was used to identify hyaluronidase activity in protein bands. Affinity-purified polyclonal IgG raised against equine sperm hyaluronidase was used to label fresh and capacitated stallion sperm, followed by indirect immunofluorescence. Equine sperm plasma membrane extracts displayed 3 major protein bands with potent hyaluronidase activity of approximately 54, 59, and 83 kDa. Under reducing conditions, a single protein band was observed at 62 kDa, although the reduced sample exhibited no enzyme activity. The polyclonal IgG labeled the postacrosomal region of stallion sperm and was redistributed over the acrosomal region during in vitro capacitation in a significant percentage of sperm cells. These studies suggest that a specific protein localized to the equine sperm head displays hyaluronidase activity, gets redistributed over the acrosomal region during capacitation, and may be important in fertility in this species.

The extent and persistence of Mycobacterium paratuberculosis environmental contamination on farms with a known history of Johne's disease is a commonly asked question by the agricultural community. Prospective buyers of farms following a dispersal sale often inquire about the possibility of newly acquired cattle becoming infected with M. paratuberculosis from the environment where Johne's cattle had previously been located. Thus, based on continuing inquiries from cattlemen, we developed a prospective research proposal to assess the extent of environmental contamination with M. paratuberculosis associated with known levels of infection in the herds as determined with whole herd fecal culture tests of adult cattle using a sensitive technique utilizing centrifugation1. Previous studies on the survival of M. paratuberculosis have been largely conducted under standardized laboratory conditions and not from samples taken from the immediate farm environment2,3,4. Those studies suggested that M. paratuberculosis is somewhat long lived in a variety of environmental conditions. Non-laboratory based studies have focused on the survival of M. paratuberculosis in slurry and no studies have focused on the extent of soil and environmental contamination on farms with Johne's disease. The frequency of occurrence of M. paratuberculosis in the environment of farms with known infection of cattle with M. paratuberculosis has not been reported. But, the survival of M. paratuberculosis in water, slurry, urine and other media has been published2,3,4,5. Previous authors often used laboratory-grown isolates then inoculated a variety of materials and monitored the recovery rate over time. Vishnewskii6 first reported that bovine urine markedly reduced the survival time of M. paratuberculosis to less than 10 days. The inhibitory effect of urine on tubercle bacteria growth has also been recognized for some time but the factor responsible for the inhibition has not been isolated7,8. Urine has a similar inhibitory effect on salmonella9.