Changes in cow teat tissue created by two types of milking cluster

We have investigated the responses of con tests to machine milking in a stu dy of relatively newly installed commercial milking parlours fitted with on e of two types of milking cluster. The first was a common type with a large clam volume (> 200 mi), 15-16 mm i.d. long milk tube, 10 mm short pulse tu be, cluster weight < 3.2 kg and used alternate pulsation. The second was a more traditional type with a 150 mi claw bowl volume, 13.5 mm i.d. long mil k tube; 8 mm short pulse tube, cluster weight similar to 3.5 kg and used si multaneous pulsation. We scored similar to 50 cows in each of 20 herds, all within 60 s of cluster removal, for changes from the premilking teat condi tion: teat colour (creation of reddening or blueness), firmness, thickening at the base of the test associated with the position of the liner mouthpie ce, and whether the tent duct orifice was open. There were statistically si gnificant differences in the proportion of cows displaying these four alter ations in teat condition between herds using the two types of cluster. The more common type of cluster was always associated with better tent conditio n. The cause and effect of poorer teat condition hare not been fully establ ished and are likely to be multifactorial. The principal risk factors may b e cluster weight, overmilking, vacuum applied during the overmilking phase and the design of the liner mouthpiece.