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Decrease weaned heifer pneumonia

Dairy Calf and Heifer Association Published on 03 February 2011

Respiratory disease is responsible for nearly half of all weaned heifer deaths on U.S. dairy farms.

New benchmarks for pneumonia treatment and mortality rates take aggressive aim at this troubling statistic from the National Animal Health Monitoring System’s Dairy 2007 study.

The benchmarks, established last year in the Dairy Calf and Heifer Association’s Gold Standards II, urge heifer growers nationwide to keep pneumonia treatment rates under 3 percent for heifers between six months old and 12 months old and less than 1 percent for heifers 12 months old to freshening.

The standards also advocate that death loss from all conditions, and particularly pneumonia, be less than 1 percent for heifers six months old to 12 months old and less than 0.5 percent for heifers 12 months old to freshening.

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Reducing pneumonia treatment and death loss in weaned heifers is not a walk in the park. Many risk factors threaten to derail heifer health and performance, but measures that prevent transmission and keep respiratory problems low are still worth fighting for on your operation.

Identify the risk factors
“Several very good studies have evaluated risk factors for (pre-weaned) dairy calf pneumonia,” says Amelia Woolums, veterinarian and associate professor at the University of Georgia College of Veterinary Medicine.

Unfortunately, there is very little published research that investigates the risk factors for respiratory disease in weaned heifers six months old and older.

However, “some of the factors that increase the chance of (young calves) developing pneumonia are also important for contributing to pneumonia in weaned heifers,” Woolums says.

According to Woolums, possible sources of infection include:

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• Housing weaned heifers in close contact with younger animals. This could make older heifers more susceptible to the viruses and bacteria that are “amplified” in the respiratory tracts of young calves. Infection is possible in this situation, especially if the older heifers’ maternal antibodies have disappeared.

• Housing weaned heifers in close contact with adult cattle.

• Housing heifers in areas with high numbers of airborne bacteria or poor air quality, particularly if weaned heifers are housed indoors.

• Recent transport

• Commingling of large numbers of cattle from different sources. This can occur if you add incoming heifers to an existing group, such as when heifers from more than one site are brought together in large groups at around six months old.

• Transmission through caretakers. Hands and clothing contaminated with viral respiratory pathogens can transmit pathogens from younger to older animals and vice versa.

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Inappropriate vaccination also can contribute to increased rates of respiratory disease in weaned heifers. For instance, this can occur when calves are vaccinated right before they move from hutches to group pens. In this situation, calves are not given enough time to develop an immune response to the vaccine before increased exposure to viruses and bacteria occurs, Woolums says.

Using the wrong antibiotic, using it too late, or giving too short a course of therapy also can contribute to chronic and increased rates of respiratory disease in older heifers.

Growers take aim at pneumonia rates
Don Gardner, DVM, and one of the founding members of DCHA, does his best to prevent pneumonia from gaining a foothold in weaned heifers that arrive at Gardner Heifers Inc.

“Early detection is critical. My philosophy is if they come in here and they’re not right, we’re going to jump on them with both feet and stay on them ’til they are straight,” says the contract heifer grower and veterinarian.

This firm commitment to early detection and intervention explains why Gardner and his son Sam have been able to keep mortality rates from pneumonia under 0.5 percent. “We have only lost two animals out of 750 in the last year for all causes. One was for pneumonia with lung hemorrhage and one from suicide in a board fence.”

The process begins shortly after five-month-old heifers arrive at the 750-head operation in Huddleston, Virginia. On entry, the heifers get a physical exam and, at that time, the Gardners record each animal’s temperature with an electronic thermometer.

“Except for the hot summer months, our cut-off point for treatment is 103ºF. If they are at or above that temp, we treat them with the appropriate antibiotic based on previous results. Some folks might think this is a little aggressive, but our low death loss and lack of respiratory problems later on show its value.”

In a group of 20 or so incoming heifers, it is not uncommon for them to detect elevated temperatures in at least five heifers – sometimes even half the group. From a distance, those same heifers may show few visible signs of illness. “We see more problems in the colder months of the year.”

Early identification of heifers with respiratory disease gives the Gardner family a jump on future problems associated with pneumonia. “Often these affected heifers are underweight for their age, which tells me they have had issues for a while. These animals’ growth rates are lower than unaffected animals after they straighten up. The cost of respiratory disease lasts long after the clinical problem is resolved.

“Continuing vigilance prevents a sick animal from going too far to recover. We check all groups daily and count heads to make sure everyone is up and eating in all groups. Treatment success is measurably better if it is started in a timely fashion. You can’t pick up sick animals by driving by with the mix wagon and only looking at the feed trough.

“We don’t want problems down the road with these animals and we don’t want them creating an issue with the cattle we’ve got here on the farm,” Gardner says.

Vaccinate for peak immunity
The Gardners also have instituted a pre-receiving vaccination program to minimize the impact of respiratory disease on weaned heifers.

“There are a number of vaccines that we want them to have six weeks prior to the move and (again at) three weeks prior to coming here,” Gardner says. “We try to do everything we can to make sure that (heifers are) vaccinated against all the (major respiratory) viruses” – IBR, BVD, BRSV, PI3 – with an MLV vaccine.

“After these vaccinations, I don’t think we’re seeing a lot of viral pneumonia problems,” Gardner adds. “I think most of the problems in these incoming calves are bacterial pneumonia,” such as pasteurella multocida.

“It is not as violent in appearance as manheimia hemolytica and will kind of sneak up on you if you aren’t checking calves closely. We use some core-antigen products to try to prevent (this type of) pasteurella.”

Work with your veterinarian – and in the case of custom-rearing operations, with the dairy owners – to develop a vaccination protocol for respiratory-disease challenges specific to your region or operation.

It takes commitment to a combination of factors – optimum nutrition, sound health protocols, proper housing and environmental conditions – to protect heifers against pneumonia-causing agents and achieve low treatment and mortality rates.

A sound vaccination program and attention to risk factors that threaten heifer respiratory health are good first steps toward decreasing pneumonia rates and mortality in adolescent heifers on your operation. PD

The Dairy Calf & Heifer Association is dedicated to serving the dairy calf and heifer industry. DCHA strives to provide information, education and access to leading research and technology to help its members be more profitable. DCHA members have the opportunity to network with producers, industry leaders and top academia to learn more about current issues affecting the dairy calf and heifer business. For more information about DCHA and the Gold Standards, visit www.calfandheifer.org or call 877-HEIFERS .

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