Risk. What comes to mind when you hear this word? Bungee jumping? Playing the options or futures market? Russian roulette? Dairy Expansion? All of these entail some amount of risk. However, some are more dangerous than others, primarily because of unknown and uncontrolled factors that could come into play and result in painful consequences. Obviously the risk takers who survive are the ones who prepare ahead of time to stack the deck in their favor and reduce the chances of failure.

The way many dairy producers handle the risk of expansion and/or the introduction of outside cattle to their resident dairy herd sometimes makes Russian roulette look safe! All it would take is the introduction of one or two animals shedding a contagious but not necessarily visible, disease to financially bring down the entire dairy.

Recent National Animal Health Monitoring System (NAHMS) reports have confirmed an increased incidence of mastitis (clinical and subclinical) and outbreaks of acute diseases associated with Bovine Viral Diarrhea (BVD) following the introduction of cattle onto dairy operations. Either one of these conditions could spell huge economic losses for any dairy producer. Imagine what could be possible if you introduce both or other diseases at the same time-especially during the time of dairy expansion and critical cash flow. Maximum production requires, among other things, minimal exposure to disease-causing organisms.

Table 1 represents just a partial listing of infectious diseases that can be found in dairy operations. If your herd is currently free of any of these problems, the only way that the disease can gain access to your herd is by introduction from the outside. These diseases can be introduced by not only newly purchased animals, but also by resident animals returning from the veterinary clinic or show ring, human carriers (veterinarians, hoof trimmers, livestock hauler, etc.).

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

Diseases = Lost Milk Production and Reduced Cash Flow
To illustrate this concept, take the increasing and aggravating situation of hairy heel warts or Papillomatous Digital Dermatitis (PDD). In 1985, 99% of the dairies in the U.S. had never seen or even heard of hairy heel warts. Just 10 years later, 43.5% of all dairies had reported PDD, and 80.3% of dairies with 200 or more cows had PDD. The cost for each case of PDD has been estimated at $128/case, and is primarily a result of reduced milk production.

Considering the NAHMS data that approximately one in five cows is affected on positive PDD dairies, that represents a loss of $2,560 per 100 cows. While this loss could be considered small, this represents the economic impact of just one disease introduction. Imagine what the losses would be if two or three diseases were simultaneously present causing similar or greater economic losses. Unfortunately, this is often the case.

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

Establishing a Biosecurity Program
Considering that the introduction of a disease situation can undo years of hard work and create financial loss or even financial ruin, dairy producers need to become passionate about biosecurity measures and a non-negotiable biosecurity program in place. The first order of business is to reduce the necessary risk of introducing the problem into the herd is to establish an isolation, quarantine and testing program that will be required for all animals entering the resident herd. This includes the isolation of home-raised animals who go off the premises for any reason.

The 1996 NAHMS survey of biosecurity practices in the U.S. indicates that few dairy operations quarantined or isolated new arrivals from those animals already present on the farm. Approximately 94% of introduced lactating cows and 85% of introduced bred heifers brought into the U.S. dairies were not quarantined, but immediately co-mingled with the resident dairy population. It is practices like these that make bungee jumping or Russian roulette look safe!

The generalized lack of understanding of the importance of isolation or quarantine of al animal arrivals on the dairy readily accounts for the rapid spread of such diseases as hairy heel warts, mastitis, and other production-sapping conditions. These diseases then result in a shrunken milk check. Many dairy producers just figure that it is the cost of having livestock and unknowingly give away 1-10% or more of their production and profit potential.

Isolating and Quarantining New Animals
Nearly 43% of the readers of Midwest Dairy Business say they plan to add, enlarge, or somehow change their dairy facility in 1998. Any dairy plan that has not included an isolation or quarantine area would have to be considered incomplete and short-sighted. The quarantine and isolation areas should adequately separate new arrivals from the resident herd and insure that feed, air space, manure/urine exposure, and equipment (feeders, waterers, etc.) would also remain separate.

In addition, planning for this isolation area should reduce the chance that workers would carry the disease organisms on their boots, coveralls, etc. between the quarantined cattle and the resident cattle. The flow of people, livestock, and traffic on the dairy needs to be designed with biosecurity in mind.

The timing of the isolation and quarantine period is also critical. Quarantined animals should be separated for a minimum of 21-30 days. This time frame is necessary to get past the incubation period for most diseases of illnesses that new arrivals might be shedding. While new additions often look healthy the day they arrive, many break with an illness several days or even a week(s) later as a result of the suppression of the immune system brought on by the stress of relocation. The quarantine period also gives the dairy producer and veterinarian a chance to completely examine the animals from head to toe and bring them up to date on vaccinations, deworming, etc., in preparation for their release into the general dairy population.

Quarantined animals should be separated a minimum of 21-30 days.

Test Incoming Animals
Testing of new herd additions is another critical biosecurity measure that should be completed during the isolation period before the new animals are released. BVD, Johne's Disease, BLV, mastitis caused by Staphylococcus aureus, Streptococcus agalactiae, and Mycoplasma bovis are not stopped by quarantine alone. These diseases can be spread by carrier animals (Trojan cows) which appear to be perfectly healthy and have no outward signs of disease.

It is doubtful that most dairy producers would go out and buy a used truck solely on how it looks from the outside. Usually there would be a lot of questions asked and they will want to see the repair and service records, possibly speak with a mechanic, and take a look under the hood. Why do we go to so much trouble regarding such a purchase? To reduce the risk of buying a lemon or someone else's problems.

Why should a dairy producer do any less regarding the purchase and introduction of cattle onto his dairy? Cattle look absolutely normal on the outside, but on the inside be carrying or shedding a pathogen that will create an unseen, slow economic leak, or be a potential time bomb. Isolation, quarantine, and testing are just part of the overall biosecurity program designed to stack the deck in the dairy producer's favor, increase profit potential, and reduce risk.

Economic loss

Losses occur by

Spread via

Stopped by quarantine

Tests Required

High economic losses possible, but rare due to state and federal control measures. (Human health concerns exist.)

• Reduced milk production
• Abortions
• Still birth

• Milk
• Uterine discharge
• Aborted fetuses

No

• State and federal laws require vaccination and blood testing

Losses of $475-$665 per lactating cow have been reported. (Ohio State University)

• Reduced milk production
• Abortion
• Still Births
• Reduced conception rates
• Suppression of immune system

• Persistently infected (PI) animals (carrier or shedding animals

• Body secretions
• Body excretions
• Direct contact
• In utero (dam to calf)

No

• Blood Tests

Higher losses possible.

For every visible case (clinical), there are 15-40 invisible (subclinical) cases.

• Reduced milk production (70%)
• Medication costs (8%)
• Discarded milk (8%)
• Culling and death (14%)

• Milk

(infected udders, milking equipment, poor hygiene, poor parlor procedures)

No

• Bulk tank culture from the dairy of origin
• 6-12 mos. SCC from dairy or origin
• 6-12 mos. bacterial counts from dairy of origin
• Milk culture from each quarter
• Physical exam of udder

A strong dairy industry concern.

• Reduced milk production
• Increased culls and cull rate
• Increased replacement needs

• Milk
• Feces

No

• Blood test
• Fecal cultures

Low loss to individual dairy, but higher loss to industry due to decreased exports.

• Culling affected animals
• Reduced export of animals and semen

• Insects
• Dam to calf

No

• Blood test (optional)

• Reduced productivity
• Culling of affected cattle

• Respiratory tract
• Milk
• Other body fluids

No

• Skin testing mandated by state and federal laws

This article reproduced with permission from Midwest Dairy Business.