Dairy Channel: Have you cleaned your ‘refrigerator?’


My mother visited recently, so the timing was right for a quick search-and-destroy mission into the refrigerator.

While Mom is very forgiving of my less than perfect housekeeping, a standing family joke is our refrigerator and the leftover food that occasionally gets lost in the nether regions. Typically, the items look like a penicillin test site, others are just ready for the compost pile, but usually there is no question that the item in question is not fit for human consumption.

What does this have to do with a dairy column? In a sense, the dairy also has to keep the “refrigerator” clean for many of the same reasons.

Dairy “refrigerator.”

The “refrigerator” in this case includes not only the bulk forage, grain and supplement storages, but also the mixed feeds as they are delivered to the varying animal groups and how refused feed is handled.

At this year’s Tri-State Dairy Nutrition Conference held in Ft. Wayne, Ind., Dan Grooms from MSU’s Veterinary Department presented a nice summary of the “Feed Borne Pathogens of Cattle.” In a nutshell, you are unlikely to have problems if:

1) feed is harvested and stored properly

2) rodents are controlled around the farmstead

3) cats and dogs are not allowed to mess in the feed

4) cattle manure is kept away from the feed

5) visibly moldy feed is not a mainstay of the diet

6) high-risk feeds are avoided.

Nothing particularly new or exciting here, but the stakes are high when a slip might occur.

Disease risk.

Recently, the popular press has been loaded with stories about BSE, more popularly known as “mad cow disease.”

This disease is transmitted by a feed-borne pathogen via the feeding of rendered by-products from infected animals. The ban on feeding ruminant byproduct feeds to ruminant animals was put in place to avoid this particular disease.

Fortunately, we have not had any cases of BSE in the United States, but the devastating impact on the British farm economy is painfully clear. This is certainly a vivid example of the potential impact of a feed-bourne disease, showing the impact on the animal, the individual farm operation, product safety, consumer confidence and the entire industry.

Other pathogens.

While BSE and foot and mouth disease are major concerns, they have not been documented in the United States. What are the pathogens we should be aware of?

Salmonella – Carrier animals can shed large numbers of salmonella bacteria. As with many diseases affecting cattle, there are many different strains with several in particular being the primary culprits if an outbreak in dairy cattle occurs.

Salmonellosis usually causes severe diarrhea that can “… lead to fever, dehydration, shock and death. Salmonella has also been associated with abortions, arthritis, and pneumonia.”

Route of infection: Cattle become infected by ingesting the bacteria in contaminated feed, water, bedding or licking it off of an object contaminated with infected manure.

Prevention: Grooms recommends reducing the risk of spreading salmonella through feedstuffs by:

* routinely clean and disinfect feeding equipment

* avoid using the same equipment to feed and handle manure

* control rodents

* provide clean water supplies protected from fecal contamination

* keep feeds dry as salmonella likes moist conditions to survive and reproduce

* avoid irrigation of forage crops with lagoon water or manure slurry right before harvest.

Grooms also suggests that supplemental animal and vegetable fats used in dairy diets may have a higher risk of salmonella contamination. A quick check with OSU Dairy Nutritionist Bill Weiss revealed that at this time, there is not a clear relationship or consensus on this point where dairy cattle are concerned.

Listeriosis – The bacteria Listeria mycogenes is commonly present in the environment on plants and soils. Generally, a cow can ingest the bacteria and it will pass through her digestive system without causing any adverse effects. Scientists are not entirely sure why a cow contracts a listeria-caused infection, but think that perhaps a break in the lining of the digestive tract creates an opportunity for bacteria to enter the cow’s system and cause illness.

“Circling disease,” the symptom most commonly associated with a listeria infection, is only one of several possible outcomes of an infection. Others include: encephalitis, abortion, keratitis and/or mastitis. The uncontrolled circling symptom is actually a neurological syndrome resulting from encephalitis caused by the listeria bacteria.

Prevention: Outbreaks of listeria are most frequently associated with poor silage. Listeria bacteria can … “survive in silage at low pH (<4.0) and multiply in poorly fermented silages where the pH is greater that 5.0 ... Listeria is more likely to be found in silage with a pH of greater than 5.6 as well as silage that is moldy."

Minimize soil and manure contamination of feeds at all times.

Johne’s Disease – Another bacteria, mycobacterium paratuberculosis, causes Johne’s disease. Johne’s is difficult to monitor in a herd as animals are most likely to become infected when they are less than 6 months old, but are unlikely to show symptoms until they are several years old.

Typical symptoms include chronic diarrhea and dramatic weight loss that do not respond to treatments. Infected cows may shed the bacteria in their manure as well as in colostrum and milk. Prevention: It is critical that contamination of feed by potentially infected manure is avoided, especially for young stock.

* routinely clean and disinfect feeding equipment

* avoid using the same equipment to feed and handle manure

* do not feed refused feed from older cows to young heifers

* feed only colostrum from cows who have tested negative for Johne’s

* do not feed waste milk to calves unless the herd has tested negative.

Preventing breakouts of feed-bourne illnesses typically do not require extreme practices, but come down to many of the basic good management practices that should be in place on every dairy operation.

Harvest and store good quality forages, keep manure out of stored feed, feed available for animals to eat and water sources; control rodents, keep feeds dry, evaluate carefully how you are feeding colostrum and waste milk.

All of these practices will have multiple payoffs for the dairy.

What is growing in your “refrigerator”? Take a quick inventory and fix any potential problems before your Mother comes to visit.

(The author is the northeast Ohio district dairy specialist with OSU Extension. Send comments or questions in care of Farm and Dairy, P.O. Box 38, Salem, OH 44460.)


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