High SPCs, What to Do

Occasionally dairy goat producers will run into trouble with high standard plate counts (SPCs) in their bulk tank sample. This can occur either quite suddenly, or as a gradual increase in numbers on consecutive bulk tank tests. Either of these scenarios calls for immediate action by the producer to work on pinpointing a cause. As has been seen on many occasions, the initial cause of high SPCs can often have compounding effects that continue to worsen the problem. For this reason, quick action on the producer's part to respond to the first sign of an elevated bacteria count is critical.

While investigating quality issues during farm inspections, more than one potential cause of high counts has routinely been found. If your SPCs are on the rise, conduct a thorough review of your entire milking and milk handling operation including: the milking equipment condition; its' cleanliness and operation; milk cooling; milking procedures; and milk handling. Animal health should also be looked at. Following is a detailed checklist:

Equipment Condition, Cleanliness and Operation

Check all milk contact surfaces. Disassemble as much equipment as possible for visual inspection. Always use a good flashlight to see those dark areas.

• Rubber or silicone parts should be clean, smooth, free of cracks and deterioration (inflations, hoses, gaskets, valves, receiver jar plugs).
• Stainless surfaces should be clean and shiny when dry. Deposits or films often show up as a white or slightly bluish discoloration. Significant water beading (water droplets clinging to stainless surface) indicates a fat film.
• These films can be removed by using a specific power wash as outlined in the OMAF fact sheet Troubleshooting Films & Deposits on Dairy Goat Milking Equipment. If in doubt, contact one of the Raw Milk Specialists listed in the contact section of this newsletter.
• Inspect the bulk tank when empty, clean and dry. Check all interior surfaces including the agitator and shaft, dipstick, gaskets, and disassembled outlet valve. Use a strong light to readily see difficult areas.
• Observe automatic wash systems in operation - be aware of times, temperatures, chemical concentrations and wash solution flow.
• If wash system problems are suspected, contact your dealer.
  Increasing the amount of cleaning chemicals is not always the answer.

Milk cooling

Rapid cooling and maintenance of milk temperatures to between 1 and 4°C. is critical to quality.

• Does milk cool to between 1 and 4°C. within one hour of finishing milking?
• Optimum maintenance temperature of milk in the bulk tank is 1 - 2°C.
• Is there significant formation of ice in the cooler which can obstruct uniform cooling of milk?
• Does the compressor automatically start before milk temperature rises above 4°C.? It is preferable for compressor to start before milk temperature rises above 3°C.
• Is the milk temperature being monitored with an accurate thermometer?

Milking Procedures and Milk Handling

• Is all equipment sanitized and completely drained prior to use?
• Are animals clean prior to milking?
• Are udders clean and clipped of long hairs when necessary?
• Is a proper udder wash technique being followed?
• If milking unit drop-offs occur, are the inflations sanitized prior to being reattached?
• Is the correct vacuum level being used?
• Is the milk house water source potable? If water quality is suspect, collect a water sample from 'point of use' and submit it to your local health unit for testing.
• If a dipper is used to sample, check that it is clean and free of cracks or crevices that could harbour bacteria. Always sanitize the dipper before using it. Review cleaning and sanitizing procedures for dipper.

Animal Health

Although a less common source of high bacteria, recent investigations indicate that infected goats may shed enough bacteria to markedly increase the bulk tank SPC. Actions to be taken include:

• Screen all milking goats using the California Mastitis Test (CMT) three to five times over a one week period. Note that a slight gelling or graininess is a normal reaction for goats milk. Goats are suspect when one or both udder halves score a two or higher.
• Any goats scoring two or higher should be pulled out of the milking group and their milk kept out of the bulk tank.
• Consider using a strip cup as part of the pre-milking routine to more accurately detect abnormal milk.
• Watch for udder halves that slacken off in production. Slack halves are a common sign of infection.
• Examine teat ends for signs of damage. Like any open wound, damaged teat ends can lead to infection.
• Treat or cull the infected goat(s).
• Consult with veterinarian if necessary.
• Keep all milk from any infected goats out of the bulk tank until the goat(s) are cleared of infection and antibiotics.

The above guidelines are intended to give producers direction for where to start looking in the event they run into high SPC's on their bulk tank samples. If problems persist producers are advised to contact their equipment dealer or OMAFRA Raw Milk Specialists.