Scours is a health and welfare challenge for many UK dairy farms, but it also has serious implications for farm business and for its people. A survey, commissioned by Virbac UK and involving 324 dairy farmers across the UK, has shown the pressure it puts on farmers and their teams.
A total of 61% admitted to added anxiety from having calves sick with scours, while for others it was also the pressure on time it created 77% said the time spent nursing sick animals caused difficulties for them. For more than half (56%), the financial cost of mortalities, labour and treatments was a major worry. Scours is caused by infection from a number of pathogens, but of the farmers surveyed, cryptosporidia is the principal cause.
This has been identified as a pathogen on 57% of farms, while rotavirus is the second most common virus, with tests revealing its presence on 40% of farms. Other pathogens detected are e.coli, salmonella and coronavirus. But more than half of the respondents admitted to not actively testing scour in their herds and this could be a mistake, says vet Kate Ingram, ruminant technical adviser at Virbac UK. She says: "Testing samples from scouring calves and understanding which pathogens are involved in a scour outbreak can help decide the best approach to treating sick calves, but also, importantly, helps to guide the approach to prevention of future outbreaks." The farmers who responded to the survey ranged in size; the overwhelming majority (272) milk fewer than 300 cows, while for 37 respondents, their herds range in size from 300-599 cows.
There were larger herds too; 11 milk 600-899 cows and four milk 900-1,200. On those farms, about 13% of calves on each had been affected by scour in the last 12 months. For 90%, no more than five calves had died as a result of scours - nearly half had no losses at all. The survey revealed that different farms have different approaches to treating sick calves.
The use of electrolytes is the most common form of treatment, with 83% of farmers using this method to tackle scours. But worryingly, given increasing pressure from milk buyers and governments on farmers to reduce antibiotic use, a significant finding was that 59% of farmers resort to antibiotics to combat scours. Ms Ingram says vaccination can help to eliminate the need to use antibiotics. By vaccinating dams during the last trimester of pregnancy, the antibodies in their colostrum against some of the infectious causes of scour will increase.
Colostrum
Ensuring the newborn receives a sufficient quantity of good quality colostrum from a vaccinated dam quickly enough after birth will help protect their newborn calf against some of the most common infectious causes of scours. Ms Ingram recommends vaccination with Bovigen® Scour, a single-shot broad spectrum vaccine which protects against three major causes of scour: rotavirus; coronavirus; e.coli. Cryptosporidium is a protozoa and therefore not covered by vaccines. Ms Ingram says: "Irrespective of previous vaccination history, only a single injection of the vaccine given 12 to three weeks prior to calving is required to boost cow serum and therefore colostrum antibody levels against rotavirus, coronavirus and e. coli." Vaccinating against scours should be considered in every calf disease prevention plan, Ms Ingram advises. "Considering the potential investment made to ensure a cow is in-calf - feed intake, supplementation, artificial insemination and scanning - to lose a calf to scours is financially and emotionally draining. "Vaccination can help to reduce the likelihood of these costs occurring."
Importantly, it may also help to reduce antibiotic use on some dairy units, she adds. However, vaccination will only be effective when combined with good colostrum management to ensure effective transfer of that immunity to the calf. Calves should receive 10-12% of their body weight of clean and good quality (with a BRIX score of more than 22%) colostrum, ideally within two hours of birth to maximise the levels of antibodies absorbed. Nutrition also plays a role in ensuring calves have a strong immune system and are less susceptible to disease.
Deficiencies, even if only sub-clinical, can increase the risk of disease, particularly during high-stress periods, such as weaning or mixing of groups. Treating calves for scours can be demanding, taking up time in a dairy farmer's working day in an industry where labour is already a significant challenge. Most farmers surveyed said they spend up to three days treating scours among their calves, but for 6% it is three to five days and for 3% it is seven to 10 days.
There is a wide range in the time taken for treating and caring for calves on these farms. For 41% it is 15 minutes per calf per day, for 38% it accounts for 30 minutes and for 15% it takes an hour, but for 5%, that care amounts to three hours.
The impact of scours varies from farm to farm. For farmers with larger farm sizes, their concern centres on how the disease reduces calf growth rates, while for smaller operators it is its impact on their time and labour costs which is their greatest worry. Other concerns range from vet and medicines costs and the cost of replacing youngstock lost to scours, to lost future production.
Good stockmanship, biosecurity, ventilation and testing are all key to healthy calves, but vaccination is now playing an increasingly important role on dairy farms. New guidance on vaccination to improve cattle health in the UK prioritises scours as a disease which livestock should be protected against by default. Vaccinating pregnant cows and heifers annually to prevent scours in calves was included in the National Office for Animal Health's new Livestock Vaccination Guideline, published in 2022.
There is good reason for including it as a category one vaccine, those which are considered highly important in herds, as scours is one of the most common causes of disease and loss of growth in calves.
The guidelines on vaccination have changed as the industry moves forward towards preventative health and reducing reliance on antibiotics. Of the farmers involved in the survey, most said they would start vaccinating if it was on the advice of their vet or if there was evidence of a cost benefit.
