NAHMS Dairy 2002

Fort Collins, Colo.-The National Animal Health Monitoring System (NAHMS) study shows that vaccination practices among the nation's dairy producers vary significantly by herd size.

Brian J. McCluskey, DVM, MS, dipl. ACVPM, tells DVM Newsmagazine that the study is meant to offer a snapshot of management practices for dairy producers on a vast array of management topics from animal health conditions to vaccination practices to biosecurity.

In fact, NAHMS, which is part of the United States Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS), just released the first part of its mammoth study on dairy management practices. The study incorporated results from 80,810 (82.8 percent) of U.S. dairy operations representing 7,790,000 (85.5 percent) of U.S. dairy cows.

Dairy 2002 was a cooperative effort between state and federal agricultural statisticians, animal health officials, university researchers, extension personnel, owners and operators. The data gathered in the study was from the Veterinary Services of APHIS.

Table 1

Top disease conditions

Clinical mastitis, lameness and infertility were the top reported conditions for dairy cows. According to the report, mastitis continues to be the most prevalent of the dairy cattle diseases during 2001, costing $102 to $162 per case with most of the loss attributed to lost milk production.

McCluskey says the numbers help remind both veterinarians and producers that mastitis, lameness and infertility continue to be problems faced by dairy producers (Table 1, p. 1F).

"Twelve percent of dairy in all operations had infertility problems, and they were not pregnant 150 days after calving. You have got to get them pregnant to start milking. What is happening is that as production goes up per cow, the infertility problems also go up. There has to be some balance of high levels of production and improvements and fertility."

Table 2

The results: Clinical mastitis has been the number one problem since producers have been keeping dairy records. Of the conditions reported, lameness is a costly disease for producers. NAHMS estimates that lameness costs producers $347 to $346 per case in lost productivity.

Vaccinations practices

Vaccination practices varied by size of operation. For example, in operations with less than 100 cows, 67.5 percent vaccinated for bovine viral diarrhea (BVD), while closer to 88.2 percent of operations with 500 or more cows did the same. (See Table 2.)

Table 3

The trend was actually very similar even if looking at prevention of infectious bovine rhinotracheitis (IBR), Parainfluenza Type 3, bovine respiratory syncytial virus (BRSV) and Hemophilus somnus.

McCluskey says of the results. "Larger operations, to maintain the higher levels of production, need to manage more intensively, so they are going to vaccinate more. Those kind of practices seem to go hand in hand. The larger operations are normally the ones that are more progressive."

McCluskey says that amount of brucellosis vaccination has decreased quite significantly, most likely because the country is almost brucellosis free. But even when the statistics where broken out by herd size, there were disparity in vaccination practices. For example, 47.8 percent of producers with less than 100 animals vaccinated against brucellosis. About 74 percent of operations with 500 or more animals vaccinated against the same disease. Overall, the numbers represent a 12.8 percent decrease in vaccine administration since the NAHMS Dairy '96 study. This survey showed a 63.8 percent of operations vaccinated heifers for brucellosis.

NAHMS says, "For dairy heifers, operations in the West region reported the highest percentage of vaccine usage across all vaccine types, with the exception of Hemophilus somnus, leptospirosis and clostridia, where usage was similar for the West and Southeast regions.

The survey adds, "Clostridial vaccine was used on the highest percentage of operations in the Southeast region. The Northeast region had the highest percentage of operations that administered no vaccines (23.3 percent), followed by the Midwest (14.7 percent), Southeast (6.1 percent) and the West (3.5 percent).

Culling practices

Culled dairy cows represent a significant income loss for producers. Udder and mastitis problems as well as reproductive problems accounted for more than half of the reasons producers culled dairy cows. NAHMS adds, "Producers and veterinarians must continue to focus on the major reasons for culling and look to improve strategies that reduce culling." (See Table 4.)

McCluskey says, "You look at that statistic and say one-quarter of the culling is due to mastitis and one-quarter is due to reproductive problems. Those are two areas that producers can do something about with the help of their veterinarian."

He adds, "It is a little bit disturbing that we aren't seeing greater improvements, but the higher levels of production you are going to see higher levels of mastitis and end up with more reproductive problems, unless you are working very, very hard at staying on top of udder and reproductive health. This is an area veterinarians can really step in and develop better programs with producers."

Table 4

In addition, poor production not related to listed problems and lameness or injury were top culling categories sited in the survey.

Overall, 25.5 percent of all dairy cows were removed permanently from their herds in 2001. Large operations had the highest percentage of cows removed.

McCluskey adds that the total numbers are low in comparison to DHIA statistics, which average about 30 percent.

He says that DHIA also counts dead cows as culls, which may represent the increased numbers.

McCluskey adds that the survey is producer-reported, which may also account for the variable.

Cow deaths

The survey shows that 19.8 percent of cow deaths were unattributed to any specific cause. McCluskey says that the statistic isn't that surprising. "When I was in practice, to get a producer to agree to a necropsy was pretty tough. The sentiment was, the animal is dead, 'why do we really need to know why it died?' "

Table 5

"I think it is a good area for veterinarians to point out to producers that 20 percent of cow deaths go unidentified. There can be some laboratory work or even just a necropsy to identify why.

Other key findings are that 17.1 percent of cow deaths are attributed to mastitis, while calving problems represent 17.4 percent, NAHMS says. (See Table 5.)

Biosecurity

The survey also explored biosecurity practices for the first time. Dairy 2002 reveals that a majority of operations are reporting either physical contact with female dairy cattle and/or contact with their feed by different species.

On average, 53.1 percent of operations cited contact with deer or other members of the deer family (elk, moose). In the Southeast, 68.7 percent of producers say there had been physical contact with deer, while in the West the percentage of operations dropped to 21.6. The results are significant, NAHMS adds.

"Contact of dairy cattle, their feed or their water sources with deer is of particular concern and should be avoided. Deer may be infected with pathogens transmissible to cattle (e.g. tuberculosis)."

Producers also cited contact with cats (87.8 percent) and dogs (70.6 percent).

While quarantining new additions helps prevent introduction of new diseases, only unweaned dairy or beef calves (37 percent) and weaned steers (40 percent) were quarantined on more than one-quarter of operations, NAHMS reports.

"For the most common classes of cattle brought onto dairy operations, bred heifers and lactating cows, only a small percentage of operations quarantined these new additions, 19.6 percent and 9.5 percent, respectively," the survey says.

When looking at vaccination practices for new additions on the farm, about 48.4 percent of operations did not normally require boosters. The top vaccination categories for new arrivals were for brucellosis, BVD, IBR, leptospirosis and neospora.