Effect of teatcup liner design on teat characteristics and udder health.

A 6-month field experiment was carried out to test effects of liner design on teats and udder health. 13 herds with 138 cows participated. The liners tested had mouthpiece and barrel diameters of 24/24 mm (A) and 20/21 mm (B), both were Alfa Laval products. Teat length and diameter measured on unstimulated teats between milkings, were significantly affected by the liner used. Liner A gave 2.6 mm longer and 1.4 mm wider teats than liner B at the end of the experiment. The choice of liner had no effect on the severity of teat canal eversions. CMT-score increased over the period, but no difference between liners was observed when data for all cows were included. For first lactating cows there was a different response in the liner groups, with lowest CMT-scores at the end of the experiment for the narrowest liner (B). Laboratory diagnoses of quarter milk samples revealed no effect of liner when all cows were included. The first calvers, however, had significant lower mastitis prevalence rate in the liner B group at the end of the experiment. A tendency towards lower new infection rate, and fewer clinical mastitis cases was also observed for the narrowest liner (B).