Making sense of mastitis
When bacteria invade, follow these simple rules to keep trouble at bay and still make profit
When an outbreak of mastitis occurs on a farm, very often we resort to fire brigade treatments as we scramble from medicine to medicine until the outbreak settles. This is often the least effective way of dealing with bacterial invasions of the cow. It is far better that we take a step back from an acute outbreak and just follow some simple rules.
Taking a milk sample for analysis is a good starting point. But one sample from one quarter of one infected cow can give a misleading result. What we should do is identify the cows with the high somatic cell count (SCC) levels. High somatic cells mean those cows are fighting an infection that's causing a lowering of the quality of the milk from that quarter.
The high somatic cell cows are losing you money and a lot of our sampling should begin with this group of cows. Ask yourself why that cow is so high in her SCC. Then kill it, cure it or cull it. Don't just hide it by dumping her milk.
The ICBF report gives us our big offenders and using the California Milk Test (CMT) we can identify the problem quarter of each cow. Sampling these cows from these quarters gives a more accurate guide as to what bacteria is causing mastitis on the farm. Correct taking of the sample is vital and is discussed later.
The sampling of the high SCC cows can be greatly enhanced by also sampling any future new cases before any treatment starts. Such samples will arise late on Friday evening or early on Sunday morning when laboratories are closed. These samples can be frozen and when five or more are collected they can be analysed as a group. This helps to keep the cost down, while still keeping a handle on any active infections.
The laboratories use very scientific methods to identify the type of bacteria and also the sensitivity pattern of the bug. Naming or identifying the bacteria can act as a compass to guide us to where the likely problem is in the herd. Some bacteria are commonly associated with parlour spread and others are associated with the sheds and bedding areas. The names can be confusing so I sometimes give them nicknames to help concentrate my attention.
Staphlacoccus aureus is a common find but we must remember that he is very commonly found on skin. Therefore, our own hands or the skin of the cows' teats may be the source and the bug may be inadvertently introduced as a contaminant during sampling. So depending on how many times this crops up in samples, we can either rule it in or out as the main cause.