Most of us are familiar with the story of the Trojan Horse and how this large hollow wooden horse filled with Greek soldiers was allowed past the security gate of the Trojans and was left unchecked and unattended in their courtyard. Annals report that this Trojan Horse ultimately resulted in the destruction of the city of Troy. History is currently being repeated today with similar situation on many of our dairies. The scenario is only slightly different in that we now are dealing with a "Trojan Cow" that enters unchecked and ultimately creates havoc on the bottom line of the dairy.

It is interesting how cavalier and nonchalant most dairymen a "Trojan Cow" potentially brings on. According to the 1995 NAHMS Dairy Management Survey, 44% of dairies brought cattle onto their operation during 1995 with 20% of these animals being lactating cows and 18% bred heifers. Only 6% of the lactating cows and 15% of the bred heifers were isolated or quarantined upon arrival at the dairy. Of these animals that were quarantined, most were not isolated for the 21 day minimum period deemed necessary to reduce the introduction and spread of an active (possibly inapparent) illness that was harbored by the new stressed additions. Only 50% of the dairymen required an vaccinations before arrival and less than 16% tested for BVD and less than 10% tested for Johne's disease.(1,2) Sixty-six percent of the dairymen did not even test for Brucellosis or Tuberculosis. Regarding screening for mastitis, one of the most common and costly diseases on a dairy, it is safe to say that the majority (75%) of dairymen required no testing or records regarding the presence of mastitis pathogens in either the individual animal or from the previous owner of record.

The preceding statistics prove that the concept of the "Trojan Cow" is real and so are the consequences of ignoring this critical issue of security on your dairy. The term "biosecurity" has been coined to describe the management practices of protecting the health of the herd and the quality of the food produced. While "biosecurity is the new buzz word in the food animal health circles, many producers seem unfazed by its implications. Possibly a more visceral synonym would be effective such as "Economic Security" or "Wreck Avoidance" or possibly "Chapter 11 Virus."

Pictured here, Dr. Gregory Quakenbush, D.V.M,.Technical Services, Pfizer Animal Health.

Biosecurity, or the lack of, will often mean the difference between a profit and a loss for most dairymen. Expanding dairy herds often result in increased debt loads. This increase in debt is not compatible with inconsistent production (i.e., inconsistent cash flow). Dairymen cannot afford to allow production to suffer by allowing a disease access to his herd.(3) Maximum production and therefore maximum cash flow will not be achieved or maintained if biosecurity management practices are slack or ignored.

What would be the consequences of bringing Mycoplasma, BVD, BRSV, and Johne's Disease, Lepto, or a contagious mastitis onto your dairy, just to name a few. A 5% drop in production would not be a stretch of the imagination. Researchers at Ohio State University recently attempted to measure the economic impact of a BVD outbreak in a large Ohio Dairy. The preliminary results show an estimated $473,000 loss for this dairy or approximately $500.00 for each lactating cow. What is even more sobering is that the majority of this monetary loss is due to milk production losses as opposed to the more visible abortion or animal death losses. Other production losses created by biosecurity lapses may be totally unobservable and better described as a lost opportunity. Research recently conducted by Dr.Vic Cortese (Pfizer Animal Health) and Dr. Jim Ferguson (University of Pennsylvania) showed that heifers vaccinated for BRSV produced 3.06 lb. More milk per day (during the first 21 weeks of lactation) than their unvaccinated herd counterparts.(4) While none of the heifers showed any visible signs of illness, the BRSV vaccinated heifers brought in and additional $133.56 of income @$13.50cwt). These are just 2 small examples of an endless string of examples of how economic profitability are ultimately dependent upon aggressive biosecurity measures.

Pictured here, Dr. Victor Cortese, D.V.M,.Technical Services, Pfizer Animal Health.

Biosecurity Strategies
Biosecurity measures are not difficult to understand but seem to be easy for many dairymen to disregard or to ignore because they have not seen the value such a plan or consider the measures too much work and effort. A good security plan would involve the following:(5,6,7)

Raising the level of resistance in the current dairy population.

Have a comprehensive and aggressive (not excessive) vaccination program in place.

• Consult with your veterinarian regarding a strategic vaccination program custom designed for your dairy and your management setup.
• Educate yourself regarding vaccine types and usage (e.g. modified live vaccine (MLV) vs. killed vaccine, vaccine timing, etc.) and basic immunology concepts.

Increase herd resistance by reducing environmental stressors:

• Provide clean, dry, comfortable housing for all animals.
• Have facilities and management in place that reduces heat stress in summer and cold or camp stresses in winter.

Increase herd resistance by reducing nutritional stresses:

• Providing a transition between the dry period and early lactation.
• Supplying high-quality forage to all lactating cows
• Maintain a balanced ration with adequate level of trace minerals and vitamins.

Increase the resistance of newborns via aggressive colostrum management:

• Know the quality of the colostrum administered.
• Four quarts of high quality colostrum administered at first feeding or shortly thereafter. (Holstein calves) Colostrum volume and time of administration (first hours following birth are critical to the immunity and protection f the newborn.

Increase herd resistance by removing internal and external parasites:

• Parasites can pull the immune system down and increase the animals susceptibility to other diseases. External parasites such as lice and biting flies can cause blood loss and anemia, which can cause further stress and reduction in production.

Controlling and monitoring all cattle (even home raised cattle taken off site), livestock, equipment and people entering the dairy.

Know the history regarding the source of newly purchased cattle:

• Avoid purchasing animals from unknown sources or that have been mixed with other cattle before the sale.
• Get verification of the vaccination program on new arrivals. Know what type of vaccine was used and when it was given. Evaluate the effectiveness of this program and make any adjustments if necessary.
• Only purchase cattle from herds with a known health status. Require a health history on purchased cattle. Ask for the DHIA somatic cell count information on milking cows. Check for evidence of contagious mastitis in current and previous lactations.

Heifers are preferable to lactation cows.

• They are easier to quarantine and less likely to have contagious mastitis. Open heifers are an even better choice, since they allow you more control and options in vaccinations over bred heifers.

Test and quarantine new herd dditions.

• Test all purchased cattle for BVD virus, Johne's disease, bovine leukosis, and mastitis caused by Staphylococcus aureus, Streptococcus agalactiae, and Mycoplasma bovis.
• Quarantine alone will not protect your herd against the above mentioned pathogens.Consult with your veterinarian regarding other disease testing such as Brucellosis, Tuberculosis, etc.
• Quarantine new and returning animals for 21-30 days. Have a designated quarantine area where new arrivals will not come in contact or share air space or equipment (feeders, waterers, etc.)with resident cattle. Avoid carrying diseases on boots, coveralls, etc. between quarantined cattle and resident cattle.

Control access by people equipment

• Transport purchased animals in farm owned trucks and trailers. If an outside hauler is used, require a sanitized truck.
• Limit people's access to the barn. Post a warning sign asking visitors to keep out.
• Make sure visitors wear clean boots and coveralls in the barn
• Use your own halters and ropes.
• Keep the livestock rendered away from your barn and from coming in contact with your animals. Move any dead animals to a specific location for pick up and avoid the possible contamination that the rendered could bring onto your dairy.
• Keep any dealers or transporters out of your barns when picking up cull cows or bull calves. Have an outside location for this type of transaction or take these animals off the premises yourself
• Require hoof trimmers to sanitize their chutes, tables, knives and other equipment before coming onto the farm.

Reduce exposure of the herd to on site diseases and pathogens.

• Have your veterinarian necropsy all animals that die from undetermined causes.
• Isolate sick and diseased cattle so their illness will not affect the health of others in the herd. Removal to a sick pen should allow frequent observations and treatment.
• Pay attention to good sanitation measures. Keep exposure to disease causing organisms to a minimum. Keep water sources, bunks, feeds and etc. free from manure contamination.
• Utilize individual calf hutches for newborn calves. Thoroughly disinfect between uses.

1.  "Biosecurity On Dairy Operations," Thomas J. Fuhrmann, Proceedings of 3rd Western Dairy Management Conference.
2. 1997 Dairy Management Practices: NAHMS, USDA, 555 South Howes, Fort Collins, CO 80521
3. Dr. Richard L. Wallace, Expansion Workshop, Phase II, April 2, 1996 (Dairy Extension Veterinarian University of Illinois).
4.  Dairy Herd Management/May 1997
5.  Biosecurity for Dairy Farms, Wisconsin Department of Agriculture, Trade and Consumer Protection (http://www.wislink.org/wisvet7/htm).
6.  First National Professional Diary Heifer Grower's Proceeding, Atlanta,Georgia, April 10-12, 1997, "Co-mingling--A Herd Health Time Bomb?," David Tomsche, LDVM, pgs. 173-181.
7.  "Worms and Germs: How helminthic parasitism suppresses bovine immunity, and the implications for de worming and vaccination," Gasbarre and Stromberg, Topics in Veterinary Medicine, Vol 5 No l 1994, pgs. 4-15

Dr. Quakenbush holds the title of, "Senior Technical Service Veterinarian, Technical Service-Cattle" with Pfizer Animal Health. This article was submitted by Pfizer Inc. with permission granted by Pfizer. If you need further information regarding this article, please contact Pfizer Animal Health at 1.800.829.5589.

This article reproduced with permission from Midwest Dairy Business.