Consider Biosecurity Steps When Expanding Herd
Dairy farms considering expansion will have to respect sound biosecurity
measures in order to maintain disease free herds and sustain maximum
production. Most farm expansion requires an infusion of capital, which
implies an increase in the debt load carried by the dairy enterprise. The
variability in production (and subsequently cash flow) induced by
disease cannot be tolerated. A five percent drop in production can be
the difference between realizing a profit or enduring a loss. As dairy
farm units become larger, the scope of the economic impact from disease
magnifies. Infectious diseases can enter a herd through purchased
additions or carried onto a farm by other animal species including
humans. Strategies exist for increasing herd resistance against and
decreasing herd exposure to infectious diseases.
Here is a partial list of infectious diseases commonly found on U.S. dairy farms.
- Bovine Leukemia Virus/Leukosis--BLV
- Bovine Respiratory Syncytial Virus--BRSV
- Bovine Viral Diarrhea Virus--BVDV
- Chlamydiosis
- Clostridial Diseases--Black Leg, Malignant Edema, Enterotoxemia, etc.
- Contagious Mastitis--Staphylococcus aureus and Streptococcus agalactia
- Haemophilus somnus
- Infectious Bovine Rhinotracheitis--IBR
- Leptospirosis
- Listeriosis
- Mycobacterium paratuberculosis--Johnes Disease
- Mycoplasmosis
- Neosporosis
- Papillomatous Digital Dermatitis--"Hairy heel warts"
- Parainfluenza-3 Virus--PI3
- Pasteurellosis
- Rota/Corona Virus--calf diarrheal agents
- Salmonellosis
- Winter Dysentery--bovine corona virus?
All of these diseases can decrease productivity--from lower milk
production to reduced milk quality, from impaired reproduction to reduced
calf survivability, from chronic debilitating infection to death. Any
one of these diseases can be introduced into a naive herd during the
expansion process.
Strategies to reduce the risk of impaired productivity from infectious disease.
Raise the level of resistance in the herd to infectious disease.
- Develop a strategic vaccination program with herd veterinarian.
- Reduce environmental stress by:
- providing clean, dry, comfortable housing for all animals on the farm,
- using heat abatement strategies in summer, windbreaks in winter.
- Reduce nutritional stress by:
- providing a transition between the dry period and early lactation,
- supplying high-quality forage to all lactating cows,
- maintaining a balanced ration with adequate levels on trace minerals and vitamins.
- Maximizing colostrum intake of newborn calves.
Prevent the introduction of infected cattle.
- Only purchase cattle from uninfected herds or herds with known health status.
- Only purchase animals from herds with a known effective vaccination program.
- Avoid purchasing cattle from unknown sources or from commingled sources.
- Transport purchased animals in farm-owned trucks or require that hired transporters start with sanitized truck.
- Isolate and monitor purchased cattle for 30 days before allowing contact with the herd.
- Test new herd additions for infectious diseases before introduction to the herd.
- Embryo transfer recipients can be a source on infectious disease, test appropriately.
- Test all calves from purchased cattle for persistent infection with BVDV.
Decrease the herd exposure to infectious disease.
- Isolate sick and diseased cattle with unusual clinical signs or cattle that do not respond to customary treatments.
- Have a veterinarian necropsy any animal that dies from undetermined causes and dispose of dead animals promptly.
- Utilize individual calf hutches for newborn calves. Thoroughly disinfect between uses.
- When selling cull cows and bull calves, identify a location outside of the barn for cattle buyers to pick up these animals without entering the barn.
- Reduce manure contamination of water sources, bunks, feeds and feeding equipment.
- Require hoof trimmers to sanitize their chutes, tables, knives, and other equipment before coming on the farm.
- Limit access to the dairy facilities from outside visitors.
- Lock the doors to the barn.
- Post a warning sign asking visitors to keep out. Leave a telephone number to call.
- Provide clean coveralls and boots for all visitors.
- Maintain a log book of all visitors--date, time and origin.
- Employ rodent and other pest control measures.
Source: Dr. Richard L. Wallace, Expansion Workshop, Phase II, April 2, 1996. For further information, contact Dr. Wallace, Dairy Extension Veterinarian, University of Illinois, College of Veterinary Medicine, 217/333-2907.
Illinois Veterinary
Bulletin