Biosecurity for the Highland Herd
There has been a groundswell of interest in so-called biosecurity for agricultural interests, particularly the cattle producer. Relatively recent government sponsored programs in the control of Johne’s disease, increased cases of bovine tuberculosis in states previously classified a s TB-free, the association of mad-cow disease (bovine spongiform encephalopathy and human new variant Creutzfeld-Jacob disease, and the devastating outbreak of foot and mouth disease recently battled in Britain have all pushed this concept of biosecurity to the forefront.
“Biosecurity” is a term that is thrown around a lot lately, but it simply means excluding disease organisms from an animal’s environment. This includes limiting the spread of disease organisms presently on the farm, and preventing the introduction of new disease.
Biosecurity is critical to the well-being of the animals involved, as well as the financial health of the operation owning these animals. The adverse effects of infectious disease can range form decreased reproductive efficiency (open cows, abortions, congenital defects, weak calves) decreased production ( lower weaning weights, decreased daily gains) increase sick animals and increased numbers of deaths due to disease. What may be forgotten in the equation is the loss of marketability of your cattle due to a poorly planned or nonexistent biosecurity program. With the increased knowledge concerning the pathogenesis and transmission of disease such as BVD (Bovine Viral Diarrhea), Johne’s Disease, Transmissible Spongiform Encephalopathies, and others, the liability of selling infected animals, particularly for the seedstock producer, will increase. Slaughter-only marketing options would be absolutely devastating for the purebred breeder with known infected herds. Likewise, breeder’s burying their heads in the sand and refusing to be concerned with biosecurity will find that their liability is no less just because they can claim they do not know the status of their herd’s health.
Biosecurity is basically an insurance policy for the health and productivity of the herd. There is no one acceptable method, but rather a gradient of choices based on risk tolerance. Absolute prevention of disease can probably only be accomplished in specialized laboratories inhabited by workers in pressurized suites. Excellent management in a completely closed herd protected by peripheral boundaries large enough to prevent influx of disease by wildlife, contaminated water sources and airflow could provide close to the perfect biosecurity program, but most of us wouldn’t choose that scenario even if we could. Certainly we can each find a level of biosecurity with which we can be comfortable. That may range from the completely closed herd to the randomly purchased, open herd. The completely closed herd would allow no entry of new animals, and no reentry of herdmates. Show attendance would be possible only if all animals taken off the farm for shows were subsequently sold, and never reentered to the farm. A compromise situation would allow no introduction of purchased cattle, but reentry originating on the farm would be allowed. Obviously a strict quarantine area and time would have to be implemented for those animals coming home from shows for this to be effective. A program more workable for those with small herds, who do not plan to produce their own replacements is the purchase of new animals from farms with known medical histories, herd tests, vaccinations, etc.,. and strict quarantine before introduction to the herd. Easing these requirements could drop the isolation period while relying on the herd history and vaccinations for the owner’s piece of mind. The lowest level of biosecurity might involve the purchase of animals with unknown history and vaccination status, with no isolation period before exposure to the herd. Needless to say, this last category offers little in the way of protection for the existing herd, or the new arrival.
Regardless of your personal concerns on the introduction and/or reintroduction of animals, it is imperative to make management changes that minimize the spread of disease. Infectious disease can already exist on a given farm, or can enter a herd through purchased additions or literally carried onto the farm by other animal species, including humans.
Methods of biosecurity include such simply concepts as raising the resistance level to infectious disease by keeping your animals healthy. Herd members can be vaccinated for appropriate diseases; environmental stress can be reduced by providing clean, dry, comfortable housing for all animals, (including protection from excessive heat in summer and windbreaks in the winter); nutritional stress can be reduced by feeding a well-balanced ration with adequate levels of minerals and vitamins, and high quality forage to cows nursing calves, and growing youngstock; colostrum intake should be maximized in newborn calves (use colostrum only from Johne’s and Bovine leukemia-free dams).
Prevent the introduction of infected cattle by purchasing cattle from uninfected herds, or herds with known health status; purchase cattle from herds with a known effective vaccination program; isolate purchased cattle for at least 30 days before allowing contact with your herd; test new herd additions for disease before allowing contact with the herd (appropriate for at least BVD, Johne’s, BLV (bovine leukemia), and intestinal parasites); transport purchased animals in farm owned or sanitized trucks; remember to treat semen and embryos as potential sources of disease also.
Perhaps most important is to decrease exposure to infectious disease by keeping calving areas clean and dry; isolating any sick cattle; have autopsies performed on any animals that die of undetermined causes; reduce manure contamination of water and feed sources; require hoof trimmers to sanitize all their equipment before bringing it on to your farm; implement good rodent and insect control measures; insist on excellent medical protocol involving vaccinations, castrations, dehorning and pregnancy examinations. A sterile needle for each animal is a necessity to prevent the spread of bovine leukemia virus and wart virus. Likewise, do not contaminate an entire vaccine vial with a previously used needle. Tattoo kits should be disinfected between animals to prevent spread of the same. A new rectal sleeve should be used for every pregnancy examination, or at a bare minimum for every animal that is known to be free of leukemia virus and Johne’s disease. If the status of your herd is unknown, pretend the animal you just treated is contagious and the one you’re doing next is uninfected. If you have to treat or feed sick animals, leave them until last. then shower and change clothes before performing chores for the healthy members of the herd.
Remember that there are numerous sources of disease organisms that originate not only from newly purchased cattle. Feed concentrates can be a source of salmonella, as can forages if they are irrigated with contaminated water. Less than ideal ensiling can lead to listeriosis. Water sources can be contaminated with salmonella, E. Coli, cryptosporidium, leptospira and giardia. Contact with other cattle can occur across fencelines, at shows and fairs. Wildlife can be a source of salmonella (birds, coyotes, rodents) tuberculosis (deer) Brucellosis (elk, bison) leptospirosis (rodents, coyotes) and giardia (beaver fever, virtually any mammal including humans and dogs). Ticks and blood-sucking insects can spread anaplasmosis and other blodd borne diseases. Human visitors can carry disease organisms on their soiled clothes and shoes, and may harbor viruses in their respiratory systems for a short time. Dogs can be a source of Neosporum canis, which can cause abortion, and cats can contaminate feed concentrates with toxoplasma, an organism that probably won’t affect the cattle, but can seriously damage any human fetuses exposed by their mothers consumption of infected, and improperly cooked beef.