Bovine mammary immune response to an experimental intramammary infection with a Staphylococcus aureus strain containing a gene for staphylococcal enterotoxin C1.

Staphylococcal enterotoxin C (SEC), a superantigen, is the most frequently expressed enterotoxin by bovine strains of Staphylococcus aureus causing mastitis. To examine the possible impact of SEC on the immune response of the bovine mammary gland, we monitored changes in lymphocyte subpopulations in mammary glands of four lactating cows after intramammary instillation of S. aureus strain Rn4220 transformed with a plasmid containing a gene coding for SEC1.

Effects of premilking and postmilking teat disinfectants on teat skin condition.

An incomplete block split-plot design with repeated measures was used to test the effects of eight combinations of premilking and postmilking teat disinfectants on teat skin and teat end condition over a 6-wk period. These combinations included iodine, sodium chlorite, lactic acid, and orthophosphoric acid. Visual assessments of teat skin and teat ends were made on the teats of 101 cows.

A comparison of two methods of evaluation of teat skin pathology.

A split-plot design with repeated measures was used to test the relationship between visual teat skin condition score, the degree of transepidermal water loss from the skin, and the colonization by Staphylococcus aureus on experimentally chapped and inoculated teats of 20 lactating Holstein cows. Visual teat skin chapping score and the number of S. aureus colonies obtained from a teat skin swab were correlated (r = 0.