A disease in calves caused by the protozoan parasite Cryptosporidium parvum, has been shown to result in significant longer term weight loss and appreciable economic impact for farmers, highlighting the importance of developing a vaccine.
A study led by researchers at the Moredun Research Institute in Midlothian and the University of Edinburgh’s Roslin Institute was carried out to address a knowledge gap on how the parasite Cryptosporidium parvum
affects the long-term growth of calves, as well as to provide data to help evaluate its impact on the efficiency of beef production.
Cryptosporidiosis, a disease of primarily young calves caused by the parasite Cryptosporidium parvum is a concern for beef and dairy farmers worldwide. The clinical signs of disease is a watery and profuse diarrhoea mainly in calves under three weeks old, causing dehydration, depression and in some cases death. It is very difficult to control as there are currently no vaccines and only two licensed products in the UK to treat infection. These treatments can reduce symptoms and shedding of the parasite in faeces, but will not cure the disease. An infected calf will shed millions of parasite oocysts (eggs) into the environment and transmission of the infection is mainly from calf-to-calf with only a few oocysts. The oocysts are very hardy due to their tough outer shell and can survive in the environment (sheds, pasture or water) for years.
The study, led by Dr Hannah Shaw (now based at Harper Adams University), took place during the spring calving of 2017 on a commercial beef suckler farm in Scotland where there was a history of clinical cryptosporidiosis in neonatal calves. Calves were weighed at birth, and scored for severity of cryptosporidiosis every second day until they reached sixteen days of age. This was followed up when the calves were weighed again at four, five and six months old.
The results show that those calves which are affected with severe cryptosporidiosis in the first 16 days of life have a significantly reduced weight gain over a six month period. On average, a calf with severe disease weighed 34kg less than a calf which showed no clinical signs of cryptosporidiosis. The direct losses associated with this reduced weight gain related to sales in that year were calculated to be approximately £130 per affected calf. However, further costs incurred from increased feed and husbandry to get cattle to market weights, additional labour to look after sick calves and extra veterinary treatment, make cryptosporidiosis a significant economic burden to the cattle industry.
Dr Beth Wells of Moredun Research Institute says: “Management strategies to help reduce the impact of cryptosporidiosis are important and should be applied to improve the health and welfare of cattle, increase production efficiency and reduce contamination of the farm environment with infectious Cryptosporidium oocysts. Further research is also required working towards a vaccine to prevent this disease.”
