Vet’s Voice by Dr. Dave Barz: Good biosecurity measures help prevent disease
This year it seems we are having a lot of wind. Fortunately, we have not had much snow in our area or we would be having blizzard conditions. Many of us have started calving and soon we will all be calving. The last few years we have seen an increase in respiratory problems in our suckling calves. We need to formulate a biosecurity plan to prevent disease in your herd.
From my swine days I remember the term “closed herd.” It meant that we raised all herd additions on the farm or ranch. This procedure meant no infectious agents would be added to the herd by the addition of heifers, cows, or bulls. Many of you quarantine herd additions for at least 30 days to assure they are no longer shedding pathogens.
We have used vaccinations to improve basic herd immunity. We vaccinate our cows so they provide immunity in the colostrum to enable the calf to withstand challenge from pathogens in early life. We vaccinate young calves to stimulate immunity to common pathogens as they mature. These vaccinations stimulate young calves to produce immunity to common pathogens on the ranch. Even if the herd and calves are extensively vaccinated, overwhelming exposure to pathogens can result in disease.
On the ranch cows and calves are exposed to pathogens every day. The animals are usually able to fend off the disease organisms, but environmental stressors suppresses the immune function. These may be wind, rain, blizzards – anything that weakens the animal. Nutrition and vitamin stressors may also result in decreased immunity. When one animal becomes sick it shed large amounts of the disease organism. This indicator animal usually is sick or treated 3-7 days before the remainder of the herd is affected. A close eye on exposes calves and early treatment or revaccination will help keep calves healthy.
Viruses are usually initially the primary cause of damage to the respiratory tissue. They usually bring on irritation and fever. The bacteria are secondary causes of infection, entering through the damaged tissue and causing disease. These infections may result in death of the animal.
The primary disease agents involved are:
· Infecteous Bovine Rhinotracheitis (IBR)
o Red nose, Bovine Herpes Virus
· Bovine Virus Diarrhea (BVD)
o Types I & II
· Bovine Respiratory Syncycial Virus (BRSV)
o Constantly cycles in herd commonly causing “summer pneumonia”
· Parainfluenza 3 Virus (PI3)
· Pasturella multocida
o Normal inhabitant of upper respiratory tract
· Histophilus somni
o Found in upper respiratory tract more common in colder climates
· Mannheimia hemolytica
o Normally in nasopharynx and releases a strong toxin when invading tissue.
· Mycoplasm bovis
o A chronic disease which can cause a more severe respiratory infection
Biosecurity is very important to the health of your beef herd. The most common cause of introducing disease to your ranch is through contact with new animals, strays and wildlife. Consult with your veterinarian or extension specialist to devise a sound vaccination and nutritional programs to form a strong foundation for the biosecurity program you choose. This will allow you to prevent disease while improving the efficiency of your herd.
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