Shelf life is that length of time that a perishable item is given before it is considered unsuitable for use. In the case of maternal colostrum, bacterial contamination is the measure determining suitability. The criteria using laboratory incubation methods are (cfu/ml = colony forming units per milliliter):

1. Total or standard plate count of less than 100,000 cfu/ml all bacteria
2. Coliform count of less than 10,000 cfu/ml

Least effective method
Storing colostrum at barn or milk house temperature – shelf life of less than 24 hours. If you sit a pail of colostrum in the milk house at 70°F, coliform bacteria will double hourly. Other bacteria species will grow, too, but at a slower rate. It is common at 12 hours to find bacteria counts of over one million in colostrum stored this way if parlor and equipment sanitation are compromised. In the name of good calf health, if you cannot feed the colostrum within one-half hour after collection, discard it.

Okay to feed for two days
If a bacterial growth inhibitor or preservative is added at the time colostrum is collected, the generation time (length of time needed to double the population) is ten times as long. If you start with reasonably clean colostrum and add potassium sorbate liquid preservative, then at milk house temperature the colostrum may be under 100,000 cfu/ml about two days later. However, if as harvested the colostrum is already at 10,000 cfu/ml, your colostrum is not likely to be suitable for feeding.

Or, if you chill your colostrum to 60°F within thirty minutes from collection and keep it in a refrigerator at 40°F, the bacteria count may be acceptably low for up to two days. To be on the safe side, it is a best management practice to regularly sample colostrum handled like this. Have it tested for bacteria in a laboratory.

Okay to feed up to six to seven days
Chilling colostrum rapidly immediately after it is harvested is one key to extended shelf life. The standard is down to 60°F within thirty minutes. At this temperature the generation time is extended out to 150 minutes. If you start with good cow preparation in the parlor and clean, sanitized milker cans, this can mean a really low bacteria count initially.

Then, add a preservative at collection time. One preservative with which we have considerable experience is potassium sorbate. A 50 percent solution added at the rate of 10 ml per 2 quarts and mixed in thoroughly extends the generation time ten times. At 60°F this means extending the time for coliform bacteria to double from 150 to 1500 minutes. Other preservatives probably will work to achieve acceptably low bacteria counts; I just do not have data on hand in order to describe their use.
The routine here is:

1. Clean teats
2. Clean collection bucket
3. Add preservative immediately
4. Chill to 60°F within 30 minutes
5. Store in refrigerator at 40°F or below

Okay to feed up to eight to 10 days
If you plan to push the shelf life of colostrum out to eight to ten days, accept that you will have to heat-treat it. Heat treating or pasteurizing drastically reduces the pathogens in colostrum. The keys to making pasteurization of colostrum work are:

• Start with clean colostrum
• Keep the pasteurizer clean and in good operating condition
• 60 minutes at 140°F with constant agitation
• Chill rapidly to 60°F
• Store in clean, sanitized containers
• Store at 40°F or less

Okay to feed at least eight to 10 days
Start with pasteurized colostrum that is processed according to the keys listed above. Then, add the preservative as it comes out of the pasteurizer, mixing it in thoroughly. These bacteria counts can be as low as 100 cfu/ml even at the end of a week.

Serious, big-time shelf life: Freeze it!
The keys to effectively freeze colostrum and have a low bacteria count when thawed and fed are:

• Start with clean colostrum
• Store in clean, sanitized containers
• Chill to 60°F within one-half hour – may require chilling before going into the freezer
• Store at 0°F for up to one year   PD

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