Scours Outbreak in the Calf Shed
On a 16-cow farm in Sonitpur, 14 calves aged 2–8 weeks are housed in a shed with a concrete floor and no bedding. Five calves developed watery yellow scours in three days; two died within 24 hours. The calves receive pooled milk from the bulk tank twice daily, about 2 L per feeding, and have free access to rice straw and water. Colostrum is given, but the owner cannot say how soon or how much. The calf shed is beside the adult shed, and boots are shared. A vaccine for rotavirus is not available. The owner wants to give oral antibiotics to all calves and to stop feeding milk for two days.
1. Assess the likely causes of the outbreak and critique the owner’s proposed plan. State the immediate priorities and explain why each one matters.
Read the worked answer
Likely causes
- Colostrum failure is highly likely because the timing and volume are unknown. Calves need adequate colostrum within the first hours of life; without it, they are vulnerable to rotavirus, coronavirus, E. coli and Salmonella.
- Pooled milk amplifies contamination: milk from many cows, including possibly mastitic or antibiotic-treated cows, is fed to all calves.
- Wet concrete and no bedding increase faecal contamination and chilling.
- Shared boots and proximity to the adult shed allow mechanical spread.
- The rapid deaths suggest a virulent enteric infection or severe dehydration, not merely a feed change.
Critique of the owner’s plan
- Oral antibiotics to all calves is not appropriate. Most calf scours are viral; antibiotics do not cure viruses and can worsen resistance and gut flora. Antibiotics should be used only for calves with systemic signs or confirmed bacterial infection, under veterinary direction.
- Stopping milk for two days is harmful. Calves need energy and fluid; starvation worsens dehydration and weight loss. Milk should continue in small, frequent feeds while oral rehydration fluid is given between feeds.
Immediate priorities
- Isolate affected calves and stop mixing groups.
- Start oral rehydration solution for scouring calves; give by bottle or tube only if trained.
- Continue milk feeds, smaller and more frequent.
- Clean and disinfect the shed; provide dry bedding; use dedicated boots and gloves.
- Call the veterinarian; collect faecal samples from untreated calves before antibiotics are started.
- Dispose of carcasses safely and keep children and visitors out.
2. Design a colostrum and calf-feeding protocol with measurable checks, and set out the biosecurity changes needed to prevent another outbreak.
Read the worked answer
Colostrum protocol
- Measure colostrum quality with a colostrometer or Brix refractometer if available; otherwise use thick, first-milking colostrum from healthy cows.
- Feed within 1 hour of birth, at least 10% of body weight in the first 6 hours. For a 40 kg calf this means about 4 L, split into two feeds if needed.
- Record calf ID, time of birth, time of first colostrum, volume fed and whether it was dam or banked colostrum.
- Keep a frozen colostrum bank from healthy cows; thaw in warm water, not boiling water.
- Check passive transfer indirectly by monitoring calf vigour, growth and disease; blood testing can be discussed with the veterinarian.
Milk-feeding protocol
- Feed 4–5 L/day in 2–3 feeds, using clean nipple buckets.
- Avoid pooled raw milk where possible; feed individual cow milk or pasteurised milk. Never feed milk from mastitic or antibiotic-treated cows.
- For scouring calves: continue milk, add oral rehydration solution between feeds, and weigh or monitor hydration daily.
Measurable checks
- 100% of calves receive colostrum within 1 hour and at least 10% body weight within 6 hours.
- Zero untreated clinical scours cases for two consecutive weeks.
- Daily record of faecal score, appetite and hydration for every calf.
Biosecurity changes
- Move calf shed away from adult shed or create a solid barrier.
- All-in/all-out grouping by age; clean and disinfect between groups.
- Dedicated boots and clothing for calf shed; footbath at entrance.
- Dry bedding changed daily; improve drainage.
- Restrict visitors; isolate any new or sick calf immediately.
- Keep a simple outbreak log to identify the source if scours recur.