Weaner dairy heifer health
Your calves have survived to weaning. Surely nothing can get them now? Wrong! The following diseases are all relatively common in weaners and at the very least will affect their growth and development. As with all diseases, the earlier they are detected, the less damage is done.
Coccidiosis
Coccidia are protozoan parasites that damage the lining of the gut, causing straining and scours. Immunity develops with age. Many calf meals contain a coccidiostat that controls coccidia numbers, allowing immunity to develop without disease. The stress of weaning can precipitate an outbreak. Faecal samples can be tested to confirm the diagnosis. Treatments are available. Calf feed containing a coccidiostat should be fed for at least a month after weaning.
Internal parasites
Gastrointestinal worms are the most common cause of slow weight gain and ill-thrift in young stock. The optimal parasite management plan will vary between farms. Most calves will need regular drenching from weaning until approximately 15 months of age with a combination oral or pour-on drench. Regular faecal egg counts can determine the need for drenching and reduce overall drench use. The same paddocks on dairy farms are often grazed by calves year after year allowing worm numbers to accumulate. Grazing these paddocks with other stock classes will help reduce the worm burden. Drench resistance is present on many dairy properties. Carrying out a faecal egg count reduction test is a good way of assessing what drench families will be most effective on your farm.
Clostridial disease
Clostridial diseases such as tetanus and blackleg are often fatal. Effective vaccines are available for these diseases. Routine vaccination of all calves from three months of age is recommended.
Bovine Viral Diarrhoea Virus
Bovine Viral Diarrhoea Virus (BVDv) causes scours and ill-thrift similar to parasites. BVD calves may also have ulcers in the lips and mouth. BVD virus suppresses the immune system, making calves more susceptible to other diseases such as pneumonia and yersiniosis. Testing last year by Totally Vets showed a high incidence of BVD in our region. Outbreaks of BVD in weaners can be a recurrent problem on some properties with devastating effects. Very good tests and vaccines are now available.
Polioencephalomalacia
Polioencephalomalacia (PEM), also known as vitamin B1 or thiamine deficiency, most commonly occurs in weaners and presents with signs of blindness,
incoordination and if untreated, seizures and death. Vitamin B1 is produced by bacteria in the rumen and in PEM, the process is disrupted. PEM has been linked to sudden changes in diet and high sulphur levels in the feed, but most of the time the cause is not known. Most cases occur over the late spring/early summer period. Call Totally Vets immediately if you suspect a calf has PEM. Most animals will recover if they are treated early.
Ryegrass staggers
Ryegrass staggers occur over the summer period and are caused by a fungal toxin (lolitrem B) present in ryegrass seed heads. The condition can look similar to PEM with cattle showing tremors and a staggery gait, especially when disturbed. However, at rest the calves are completely normal other than perhaps a slight head tremor. Often a large proportion of the mob will be affected.
Facial eczema
Facial eczema (FE) can have devastating effects on mobs of calves. Don't forget this group in your FE prevention plan.
Other conditions that can affect weaners include pinkeye, footrot, pneumonia, yersiniosis, Salmonella, bloat, lice and IBR (catarrh).
Most of the diseases that occur in weaned cattle will be prevented by feeding for rumen development pre-weaning, achieving optimal weaning weights, reducing stress at weaning time, good post-weaning nutrition to achieve target weights and the timely input of vaccinations and drenches.
