Take steps to protect sucklers from scours
One of the biggest risks to suckler calves occurs around calving as most beef calves are sired by well-muscled high growth rate bulls. Once a suckler calf is safely delivered, its survival chances greatly increase.
The next major threat to health comes from infectious scours and, to a lesser extent, pneumonia. The majority of calf scours are caused by six organisms: viruses such as rotovirus and coronavirus, bacteria such as E coli and salmonella, and protozoa, cryptosporidia and coccidia.
Reports from the veterinary laboratories indicate that cryptosporidium and rotovirus are the most frequently found organisms associated with calf scours.
While there are vaccines available to control rotovirus, no vaccine is available to combat cryptosporidium. All the same, if there is good control of viral and bacterial infections, through the use of good hygiene, management and vaccines, the effects of cryptosporidium infection will be less severe.
Cryptosporidium is a protozoan parasite similar to coccidium that is extremely common in the environment. It can affect a wide range of species but only causes problems in newborn animals, apart from humans, where it can cause serious diarrhoea in adults as well as infants, as the population of Galway will remember from a few years ago.
Outside the host animal, the parasite exists as a resistant spore called an oocyst which develops in the intestine. Sources of infection for the young calf are from the cow and the calving shed. Estimates from the US suggest that an adult bovine sheds 2.5 million oocysts per day in the faeces and that a scouring calf could shed up to 50 billion oocysts in a week.
Since there is no vaccine to control crypotosporidia and only a moderate response to medication, prevention assumes major importance on farms where the diseases have been a problem. A healthy calf with rapid development of immunity from maternal colostrum is a good start.
Appropriate management of the cow pre-calving in relation to feeding, body condition, mineral nutrition and parasite control should help. Control of BVD, which suppresses the immune system, will reduce the severity of calf scours. As the oocysts are carried in the faeces, make sure the cow's teats, udder and lower limbs are dry and relatively clean at calving. This will lower the infective load that can be ingested by the calf immediately after calving.
Adequate colostrum in the first hours of life will provide protection, especially at the local sites of infection in the gut.
The oocysts are resistant to most commonly used disinfectants. Strong, ammonia-based disinfectants are effective when used on clean surfaces.
These chemicals are corrosive and should be used on the manufacturer's instructions. It is useful to thoroughly clean calving sheds as soon as the calving season ends and leave them exposed to summer drying.
At the same time, I have come across cases of cryptosporidium infection in new sheds in their first season of use. Obviously, the infection came from elsewhere, most likely the cow.
As already indicated, vaccination to control other infections can help. The condition will be more severe where there are multiple infections coupled with poor conditions. Indeed, under good management the disease can be mild and self-limiting. There is evidence that the infection rate is much higher than the rate of clinical disease.
Diarrhoea causes the rapid loss of body fluid and electrolytes such as sodium, potassium and chloride. Oral rehydration is the first treatment. Fluid-replacement products contain water, electrolytes and an energy source.
Feed two litres, three times a day, or according to the manufacturer's recommendations; if the calf's temperature drops below 38°C, supply supplementary heat. There is no need to remove the calf from the cow. If the calf does not respond to treatment, consult your vet.
Antibiotics have no effect on cryptosporidia but, where scouring persists, there is likely to be multiple infections and antibiotics can be part of the treatment programme under veterinary supervision.
Halocur can be used for prevention and treatment where there is a known problem with cryptosporidia. It halts or greatly reduces the increase in the population of oocysts in the calf.
Calves get 2ml per 10kg body weight once daily for a week, starting within 24 hours of life.
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