TEAT CANAL INFECTION OF DAIRY-COWS DURING THE DRY PERIOD - COMPARISON OF 2 METHODS OF CANNULA INSERTION FOR INTRAMAMMARY ANTIBIOTIC-TREATMENT

The study involved thirty cows either in late lactation of during the dry period, of which ten cows were treated with intramammary antibiotics at drying off. The teat ends were cultured bacteriologically. The same sampling procedure was applied at the last milking before drying off and at weekly intervals subsequently, but with milk samples being taken for the two weeks after drying off. There were no significant differences in the bacterial isolation rate from the swab culture samples taken before and after fore-milking and after milking, indicating the adhesive properties of mastitis pathogens, notably S. aureus. After the cessation of normal milkings, the incidence of teat canal colonisation increased markedly. The number of positive cultures from teat canal swabs was approximately 50% greater than that from milk samples form the same teats. The study indicated that dry cow antibiotic therapy reduced teat canal colonisation of S. aureus during the dry period, and that modified short cannulas for dry cow therapy, had a positive effect.