Since the mid-19th century, there have been continuous attempts to make milk harvest more efficient. And since that time, mechanized milking has been blamed for the development of mastitis in dairy cattle.
So where does the blame lie?
"Machine milking can lead to the development of mastitis, but poor management practices also result in reduced milk quality," noted Patrick Gorden, a veterinarian with the Iowa State College of Veterinary Medicine, at the National Mastitis Council annual meeting.
While a great deal of time is spent evaluating milking systems to troubleshoot mastitis problems, milking systems only cause 6 to 20 percent of all new intramammary infections. The majority of problems related to new infections come from milking time management and herd and farm management, continued Gorden.
When looking at the milking system's contribution to new infections, approximately half are caused by the machine moving bacteria to or inside the teat, or by irregular vacuum fluctuations in the claw. The remainder is related to teat issues caused by milking machines, such as congestion or the development of hyperkeratosis at the teat end.
Milking time tests should be used to evaluate the milking system's ability to maintain the average vacuum and the pulsation system's capacity to operate within specifications. When evaluating a milking system, tests should be undertaken while the highest producing cows are being milked.
Measurements to determine average claw vacuum, vacuum fluctuation and pulsation function should be taken. Milkline and receiver vacuum instability can also be measured to determine if slugging is occurring or if inadequate vacuum production or regulation is present.
To evaluate completeness of milkout, strip yields can be performed, but these must be completed immediately after unit removal. Note inconsistencies in milkout between the quarters. Cows are considered milked out if there is less than 100 mL in each quarter when hand stripping.
A complete evaluation of the farm needs to be completed to determine the underlying cause for a milk quality problem. While on-farm, several other observations, which are often more revealing than the actual equipment evaluation, should be made:
- Observe the milk harvest technicians and udder prep procedure
- Handling of cows and cow behavior
- Timing of procedures
- How quickly continuous milk flow begins
- Alignment of units and frequency of liner slips
- Quality of pre- and postmilking teat dipping
- Cow cleanliness
- Teat condition
- Completeness of milkout
The author , Amanda Smith, was an associate editor and is an animal science graduate of Cornell University. Smith covers feeding, milk quality and heads up the World Dairy Expo Supplement. She grew up on a Medina, N.Y., dairy, and interned at a 1,700-cow western New York dairy, a large New York calf and heifer farm, and studied in New Zealand for one semester.
