Doc's Corner

Doc's Corner Article 115

August 28, 2006

“Who or What is Causing the Mastitis Problem?”

First - do you have a mastitis problem and what can you do about it?
The cost of mastitis in the dairy operations I work with on a monthly basis run from $5,000 to $60,000 per month with an average of $25,000 per month or $4 to $24 per milking cow with an average of $12 per milking cow per month (calculations based upon an estimated $300 loss each time a cow has mastitis). This, I would consider a problem and perhaps give some thought in attempting to correct. What can the dairyman afford to spend monthly to correct this problem - certainly the $250 per dairy per month that I presently charge for services - I would hope? Without question, costs of correcting the problem cannot exceed monthly losses. Specific dollars must be spent monthly to assure time is spent to make certain the so-called routine tasks are completed on a regular basis.

Let’s quickly determine how many cows are milked daily within a dairy operation. Dairies, which I work with, vary in parlor size from 20 to 100 milking units with an average of 60 milking units. Dairy size runs from 500 to 4000 milking cows (excluding dry cows) with an average of 2000 milking animals. Depending on shifts per 24-hour period, one could milk from 30 to 120 cows per milking unit per day. Assuming one milking unit operates improperly for a 24-hour period, 30 to 120 cows could be exposed to a potential mastitis problem. Assuming only 10% of those animals develop mastitis, this would provide a potential of 3 to 12 cows per day or 90 to 360 mastitis cases per month, certainly more than any dairyman would like to cope with. The dairies, which I routinely work with, experience about 15 to 250 cases, with an average of 90 cases per month - this reflects a percentage per month of 1.2% to 8.9% with an average of 4.8% per month. Approximately 50 to 60% of reported cases are new cases per month. Somatic cell count (scc) averages on test day are 120,000 to 450,000 with an average of 260,000 scc.

Who or what do we blame? Most likely the easier one to blame is the milking equipment or perhaps the milkers. More often the problem lies with the owner or the one who pays the bills. It is very easy to tell someone what they are suppose to do, but how often are we absolutely certain that the task is accomplished at a specific time on a routine basis? Most often other problems routinely arise and the so-called simpler routine tasks are often neglected.

Assuming the above data represents the averages for Tulare County, it is apparent that mastitis remains a major and costly problem in spite of all control efforts. What often happens? Very simple - quite often we blame the milking equipment or the milkers. Who or what else is there to blame? As I have stated, the one to blame, in my opinion, it is owner or the guy who pays the bill.

Without question, faulty milking equipment and poor milkers can cause a problem (In not making certain that all milking equipment is maintained in a proper and routine manner and that milkers are routinely supervised in the optimum milking procedures for the specific dairy), but more likely the problem is in faulty milking management. Certainly this is unusual in many cases, but there is always this possibility. Often orders are given to accomplish specific tasks, but are we absolutely certain that these tasks are performed on a regular basis within a specific time frame? Unfortunately, because of the many unforeseen problems that arise in normal daily dairy operations, the more simple and seemingly less important maintenance procedures are relegated to a “will do later” attitude, and suddenly, not done in the required routine and timely manner.

My major concerns are the following, assuming the milking equipment is performing in a normal manner:

1) Cluster vents and liner vents must be unobstructed at all times during milking
2) Every milk hose closure valve must close completely at all times when milk flow stops from each cow
3) The milk flow sensor, milk line closure valve and retract cylinder must be performing properly at all times to assure the milking cluster is not removed from teats under abnormal vacuum conditions (under load or vacuum higher than 1.5"hg).

The big question is how often must one be certain the above is happening?

1) Vents must be open at all times:

• obstruction of the vent depends on how dirty the equipment becomes during the milking period

• milkers must be aware of milk flow and immediately correct if unit not removing milk from cow in timely manner

• must be checked minimum once or twice daily

• cleaning apparatus must be same size as vent hole (0.041")

2) Milk hose closure valve:

• must be checked minimum weekly and more often if numerous leaks found each time valve evaluated

• to check - remove milk hose from cow side of valve and hold Ping-Pong ball to cow side of valve

• if the ball snaps to the valve - obvious leak and must be corrected immediately

3) Cluster vacuum:

• periodically graph vacuum within milking cluster at the time of removal from teats to assure vacuum has decayed to at least 1.5"Hg before milking unit pulled from teats

• often visually noted when the milking units quickly pulled from udder latterly to retract cylinder

• perhaps one of the foremost factors in causing mastitis

As previously noted, mastitis is considered to be caused by many factors, but it is my opinion that the above are most neglected on many dairies. Maintenance of described areas must be done on a routine and timely basis without fail.

Doc's Corner is a contribution of Lionel H. Brazil, DVM (1928-2007). Dr. Brazil offered dairy consultation services worldwide for many years. His services covered the following areas: milking management, vacuum system evaluation; and all management procedures relating to mastitis control and SCC reduction.