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0609 PD: Mycoplasma may improve with colostrum replacer feeding

Dr. Stephen Acres, DVM Published on 09 April 2009

Several dangerous diseases can be transferred from dam to calf through infected colostrum, Johne’s disease being the most notable. However diseases caused by Mycoplasma species (Myco), including mastitis, are another group of infections transferred through colostrum. Myco diseases can be sinister, difficult to detect and economically devastating.

How common is Myco mastitis?
The National Animal Health Monitoring System (NAHMS) Dairy 2002 study looked at the prevalence of Myco species in bulk tank milk of 871 herds in 21 U.S. states. That study found that 7.9 percent of dairies tested positive, but the prevalence increased with herd size and was an alarming 21.7 percent in herds with 500 head or more. These figures are likely an underestimate of the real prevalence because only one sample was tested from each herd.

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Myco infection can be difficult to detect and may not be obvious when it first shows up in a herd. Myco species can infect animals of all ages. Some of the more common clinical signs are described below, but a diagnosis should be confirmed by growing the organism in a diagnostic laboratory from samples taken from one or more suspect animals.

Calves that become infected from drinking colostrum from a cow with Myco mastitis or by aerosol transmission can show a number of clinical signs, including the following.

• Inner ear infection – This can be seen in calves as young as 4 days old. Affected calves may have paralysis of the face that will be revealed by one or two droopy ears, head tilt and excessive tearing. Pus may also be present in the ear canal and on the external ear.

• Arthritis – This is shown by swelling of joints and lameness.

• Pneumonia – Respiratory signs can show up as early as 2 weeks old and later into adulthood. The disease can be difficult to detect in the early stages, and some calves are not noticed until 50 percent or more of the lung tissue is damaged. While they may survive, the chances of them becoming a productive milking cow are low.

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• Infection of the mammary gland – This has been reported in calves as young as 7 weeks old. It often goes undetected, but it can be found when replacement heifers are inspected for extra teats at several months of age.

Infected calves can serve as a reservoir and maintain the infection until they enter the milking line and develop mastitis themselves. This is one method of spread that completes the cycle of transferring mastitis infection from one generation to the next. The new cases can also become a major source of spreading the infection to other cows.

Cows with Myco mastitis are highly contagious and the spread of the disease can be rapid.

• Trademarks of Myco infection in individual cows are that multiple quarters are often affected and response to treatment is poor. This can result in an increase in death as well as culling rates because damage to the mammary gland is usually permanent.

• Cows with Myco mastitis usually do not show systemic signs of disease such as loss of appetite or high fever, but milk production can drop suddenly and dramatically.

• Carriers may not show any clinical signs. This can mean that infection is being spread to the next generation of newborn calves through the colostrum without the dairyman being aware of it.

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• Infection can spread from cow to cow during milking. There may be changes in the appearance of the milk, but it varies between cows and through the course of the infection.

• New infections can occur after the herd has experienced an outbreak of pneumonia.

• Infection without clinical signs (subclinical infection) can occur with or without increased somatic cell counts.

• Early detection and segregation or culling of the infected animal is essential.

• Laboratory culturing of bulk tank milk is a good way to monitor a herd for the presence of Myco mastitis. Individual cows with mastitis, as well as new entrants to a herd, should also be cultured.

Herds infected with Myco should strongly consider using good quality colostrum replacers because they can provide two benefits.

1. Colostrum replacers can help break the spread of Myco infection from generation to generation. Baby calves are most likely exposed to Myco infection by drinking colostrum or waste milk from cows with Myco mastitis. Feeding a colostrum replacer in place of colostrum from infected cows can help break the cycle of infection.

2. However, as with Johne’s disease, colostrum replacer feeding is not a total preventative program, but it can be an essential part of a broad Myco biosecurity plan designed by the herd veterinarian. Good quality colostrum replacers contain antibodies that will help protect calves against infection with Myco or other infectious organisms that indirectly make calves more susceptible to Myco infection.

In summary, feeding good quality colostrum replacers can be an important part of an overall Myco control program.

They can help to break the transmission cycle and ensure newborn calves have high IgG levels that will help prevent Myco infection and disease. PD

Stephen D. Acres
President
Saskatoon Colostrum Company Ltd.
(306) 242-3185

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