MILTON KEYNES, UK, 20th September 2024 – Improved control of calf cryptosporidiosis is now within reach of all UK dairy and beef producers, thanks to the launch of practical disease management guidelines and a new vaccine from MSD Animal Health (a division of Merck & Co., Inc., Rahway, N.J., USA (NYSE: MRK)).
Dr Kat Baxter-Smith from MSD Animal Heath explained that the company’s new five-step calf cryptosporidiosis control planner tool will allow vets and their farmer clients to explore, record and score performance across the five fundamental best practice steps (Diagnosis; Colostrum; Environment & Management; Prevention and Treatment) required to unlock better control of the disease on farm.
“Working through a series of five key questions within each of these five basic steps allows both parties to quickly pinpoint any areas needing attention. A timeline-based action plan for better disease control can then be discussed and implemented,” she said.
- Diagnosis
Dr Kat Baxter-Smith stressed that accurate diagnosis was the first step towards better disease control of any cause of infectious scour on farm.
“When you are dealing with scouring calves, a veterinary consultation is important because treatment approaches differ depending on the pathogen(s) involved. It is unreliable to decide on the cause based on visual observation alone. What’s more, incorrect treatment can result in poor recovery, delayed recovery and inappropriate use of antibiotics. However, practical rainbow calf scour testing kits are simple to use on farm and will quickly identify whether the most common scour-causing pathogens (C. parvum, rotavirus, coronavirus or E. coli K99) are involved. Further testing to investigate coccidia and salmonella may also be recommended by your vet,” she said.
Calf cryptosporidiosis, caused by the protozoan parasite Cryptosporidium parvum, is now the most common cause of infectious scour in the UK1 (see figure 1). The disease is widespread on UK dairy and suckler cattle units and is prevalent throughout the year. The condition is mostly seen in calves 7-14 days of age, but can strike at anytime.
“Infection with the parasite causes blunting of the intestinal villi, reducing capacity for nutrient and water absorption. This has a significant impact on a calf’s future productivity. In a recent UK study2, cryptosporidiosis in the first 16 days of life significantly reduced weight gain over a six month period, with severe disease calves weighing 34 kg less on average than low disease calves. This equated to a £161 reduction in the calf sale price.”
2. Colostrum
Step two of the protocol focuses on colostrum. Dr Katie Denholm, an academic clinician at the University of Glasgow Veterinary School, explained that implementation of the 5Qs of colostrum management (Quantity, Quality, Quickly, Quietly and Quantify) is critical to setting calves up to have the best possible immunity.
What’s more, she added that calf rearers can derive a horde of animal health rewards by feeding high quality colostrum for longer. And according to a recent survey of 248 farmers from all nations of the UK, most say they are open to the practice if it were shown to be beneficial with adjustments to labour, equipment, and facilities3.
“Whilst each farm is unique and a tailored approach to extended colostrum feeding will be required, there is no doubt that the practice will reap calf performance dividends on units that implement it,” she said.
“For example, potential benefits include increasing calf serum immunoglobulin (IgG) concentrations, reduced antimicrobial use, increased immune protection for specific dam vaccinated pathogens (e.g. C. parvum, rotavirus, coronavirus and E. coli K99), the promotion of sound intestinal villi development (which will translate into better daily liveweight gain), reduced calfhood morbidity and mortality, and the improvement of reproductive and lactation outcomes in later life.”
Dr Denholm also stressed that it was important for farmers to recognise that colostrum provides so much more than just immunoglobulins to the calf.
“This liquid gold also contains immune modulators such as oligosaccharides, valuable enzymes, lactoferrin, cytokines, hormones, vitamins, and minerals – all of which are important for long term gut health, function and development.
“Whilst colostrum immunoglobulin concentrations and other immune modulators are highest in the first milking post-partum – so called ‘true colostrum’ – if practically possible, feeding this valuable first milk beyond the first feed over the first five days life and beyond will certainly be beneficial to the young calf,” she said.
Concentrations of immunoglobulins and other colostrum specific immune regulators fall with time as the colostrum ‘transitions’ to whole milk in the first 6-8 milkings post-partum. This is known as ‘transition milk’ but is still enormously valuable.
Dr Denholm also pointed out that farmers tend to cite supply and storage problems as the main barriers to implementing extended colostrum feeding on farm.
“In the recent survey, farmers told us that it is difficult to harvest enough first milking colostrum to feed this alone in an extended way3, so transition milk is practically preferable for longer term feeding,” she said, adding that artificial colostrum replacers and/or supplements are often inferior to maternally derived colostrum and may lack farm specific immunity. These proprietary products can also be expensive.
It is possible to add chemical preservatives to both colostrum and transition milk (e.g. 1% of a 50% potassium sorbate solution) to keep it for longer, or it can be stored at a low temperature.
“In the UK, colostrum is often preserved using low temperature. Depending on initial contamination levels, refrigeration at 4°C for 2-5 days and freezing in two litre batches at -20°C for up to 12 months will keep bacterial concentrations low and IgG concentrations high. But don’t use a microwave to defrost your colostrum in case ‘hot pockets’ form, which could denature the IgG molecules. Better to warm the frozen colostrum to around 40°C using hot water baths. Then it will be ready to feed to your calves,” advised Dr Denholm.
3. Environment & Management
Dr Kat Baxter-Smith from MSD Animal Health stressed that the cause of any outbreak of infectious calf scour is often multifactorial, pointing out that there is not one ‘silver disease control bullet’ available.
“Good biosecurity, vaccination and nutrition policies will all help to minimise disease problems – and implementing scrupulous hygiene practices will also help.
“Muck out, steam clean, disinfect and leave to dry as often as you practically can. Many common farm disinfectants are not effective against C. parvum, so only use those that are licensed to control this pathogen. And leave disinfected pens to dry thoroughly because C. parvum does not like dessication.
4. Prevention
Vaccinating pregnant heifers and cows with the new BOVILIS CRYPTIUM® vaccine (licensed in Great Britain in August 2024) can provide protection for calves from birth at the start of colostrum feeding – when they are most vulnerable. Active immunisation raises antibodies in colostrum against C. parvum, which will help to reduce clinical signs (i.e. diarrhoea) when calves are fed this fortified colostrum.
The primary vaccination course is two doses (4 to 5 weeks apart, in the third trimester of pregnancy. To be completed at least 3 weeks before calving). Cattle that have had the primary vaccination course only need a single booster dose during subsequent pregnancies.
“The protection of calves depends on adequate ingestion of colostrum and transition milk from vaccinated cows. It is recommended that all calves are fed colostrum and transition milk during the first five days of life. At least three litres of colostrum should be fed within the first six hours after birth,” explained Dr Baxter-Smith.
She added that BOVILIS CRYPTIUM® can be administered to cattle during late pregnancy at the same time as the BOVILIS® ROTAVEC® CORONA vaccine.
“BOVILIS® ROTAVEC® CORONA boosts antibodies in colostrum for other important infectious scour pathogens; rotavirus, coronavirus and both E. coli F5 (K99) and F41. Calves gain protection against these pathogens by drinking the fortified colostrum from their vaccinated mothers.”
5. Treatment
Despite effective implementation of the preceding four steps, treatment of individual calves may still be necessary when pathogen infectious pressure is very high.
“Calves with diarrhoea are often dehydrated. Consequently, it is crucial to provide rehydration in the form of oral or intravenous fluids (in addition to the normal milk feed) – and, under veterinary guidance, pain relief and antibiotic treatment may also be required,” said Dr Baxter-Smith.
“Halofuginone lactate (e.g. HALOCUR®) is the only licensed, non-antibiotic solution for the control of cryptosporidiosis in calves. It is indicated primarily for prevention of the disease but can also be used for early treatment of infected calves.” Vets and farmers interested in the new five-step calf cryptosporidiosis control planner tool should contact their local MSD Animal Health account manager for further information.
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