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February 10, 2005 Many Factors Can Lead to Hyperkeratosis in Dairy Cows
Teat-end hyperkeratosis is a thickening of the skin that lines the teat canal and surrounds its external opening. The condition commonly is described as teat rings, teat flowers, teat erosion, callous formation, callosity, cornification or teat-end roughness. Winter weather often is to blame for such aliments and most herds will have some cows with poor teat-end conditions. Major factors that can affect hyperkeratosis are teat-end shape, milk yield, peak milk-flow rate, duration of milking and overmilking, stage of lactation, parity and the interaction between milking management and the milking machine. The total time that the milk- flow rate is less than 2 pounds per minute appears to have a profound effect on the level of hyperkeratosis. In general, hyperkeratosis is more severe with long, pointed teats, slow-milking cows and higher producing cows. Problems peak three to four months postpartum and then decline as lactation progresses. The National Mastitis Council suggests the following risk factors increase levels of hyperkeratosis.
The large variation in levels of hyperkeratosis among herds with similar milking systems and comparable levels of yield suggests that there may be a considerable genetic influence, which should not be overlooked. It is normally accepted that most herds will have some cows with poor teat-end conditions or cows that are not responsive to changes in milking technique. When more than 20 percent of the teats evaluated have raised, roughened rings or worse, then evaluation of equipment may be in order. Hyperkeratosis often is associated with milking machine function, milking duration, milk-line vacuum and low milk flow. Milking duration is at least partially controlled by the milking unit take-off settings. Often, reducing the length of milking time by changing the factory settings will improve the teat-end condition. Milking rates of less than 2 pounds per minute are reportedly associated with decreased teat-end conditions and mastitis. Low milking vacuum may contribute to extended milking duration at a low milk-flow rate. The claw vacuum should be maintained between 10.5 and 12.5 inches of mercury under peak milk- flow conditions. Adjusting the milking system to 11.5 to 12.5 inches of mercury at peak milk flow will decrease milking duration and increase milk-flow rates. Under these conditions, udder preparation must stimulate adequate letdown and milking units must be removed when milk flow falls to a low level. Overmilking or milking at a low flow rate can occur shortly after the units are attached or at the end of milking just before removal of the milking units or at both times. Proper udder preparation takes 10 to 12 seconds of actual teat contact time to insure adequate letdown. With proper stimulation, the teats will become plump with milk within 20 to 25 seconds after preparation. For optimum results, the milking units should be attached between 45 to 75 seconds after the beginning of udder preparation. Proper stimulation will result in milk flow into the claw as it is attached and there with should be no decrease in flow. Routine milking machine evaluation is the key to keeping excessive numbers of cows ending up with poor teat-end conditions. See your dealer for regular maintenance. Then observe cows during milking for milk-flow rates at unit attachment and removal and perform routine assessments of teat-end conditions. ### Source: J.W.
Schroeder, (701) 231-7663, jschroed@ndsuext.nodak.edu |
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North Dakota State University |
