Calves on a New Zealand farm
Advice Hub

Rearing calves with Milligans.

Before You Start — Shed Setup

Getting your shed right before the first calf arrives prevents more problems than any product can fix.

Housing — Dry, draught-free and sheltered. Calves cannot regulate body temperature effectively in the first weeks of life — warmth and dry bedding are not optional. Cover the floor with sawdust, shavings, straw or wood chip to at least 200mm depth and top up regularly. Ventilate across the shed rather than down its length, and make ventilation adjustable with boards or wind cloth.

Pen spacing — 10–20 calves per pen, with a minimum of 1.5m² of shelter space per calf. Separate age groups wherever possible — mixing ages spreads disease and complicates feeding management. Have a hospital pen ready for sick calves. Isolate promptly, deal with sick animals last, and disinfect all equipment before returning to healthy animals.

Water and feeders — Fresh water available from day one — checked and refreshed daily. Minimum 300mm of trough space per calf for dry feed. Keep meal feeders dry and clean. Keep milk lines short and free from stale milk between feeds.

Cleaning — Clean and sanitise all feeding equipment — buckets, teats, mixing utensils — between every single feed. Never use a high-pressure hose inside the shed — it aerosolises bacteria to other pens. Use a broom in laneways. Spray the rearing area with an approved disinfectant at least weekly, and daily during any disease outbreak.

Buying Calves — What to Check

Look for: Dry navel. Bright eyes — not sunken. Ears up and alert. No scours. Over 4 days old and at least 35–40kg (excluding Jersey and Jersey-cross calves).

Avoid: Twins. Freebies. Calves treated with antibiotics. Mixing different age groups in the same pen.

On arrival: If dehydrated after a long journey or from a sales yard, offer 4 litres of electrolytes as the first feed rather than milk. Dip navels in iodine again on arrival. Handle gently — transport stress compromises immune function. Always ask about the source farm's colostrum management.

Colostrum — The Most Important Feed

Before any milk replacer — colostrum first, always.

Calves are born with no immune system of their own. The antibodies (immunoglobulins, IgG) in colostrum provide the only protection against disease in the first weeks of life. The gut can absorb these antibodies for a short window only — declining rapidly after 12 hours, essentially nothing by 24. Miss this window and no product, supplement or management practice makes up for it.

How much: Feed 15% of bodyweight (2.5–4L) within the first 12 hours. Get 1.5–2L in within the first 4 hours, another 1.5–2L within 10 hours. Continue colostrum or transition milk for 4 days where possible.

Quality: A Brix refractometer is the best on-farm tool for checking colostrum quality — aim for a reading of 22 or above. First-milking colostrum is always best. Heifers and mastitic cows produce lower-quality colostrum.

If unavailable: Use ExcelPlus Colostrum immediately. Do not wait.

Storing colostrum: Refrigerate for up to 24 hours or freeze for up to 12 months. Thaw slowly in warm water — never microwave or use boiling water.

Navel care: Dip navels in iodine right down to the base — dip rather than spray for maximum penetration. Re-dip daily for the first 4 days.

Feeding Guide

Starting on CMR — from day 4

Introduce Milligans CMR from day 4. If transitioning from colostrum, do so gradually over 2–3 feeds.

Mixing steps:

  1. Heat clean water to 38–40°C
  2. Add powder to water — not water to powder
  3. Mix vigorously until completely dissolved — no lumps
  4. Check temperature before feeding
  5. Feed immediately via teat — never store mixed CMR

Need product-specific feeding rates?

Use the Mixing & Feeding Rates page for the latest product-specific guidance.

View Mixing & Feeding Rates →

Consistency is everything. Same time, same temperature, same volume — every single feed. Varying any of these is one of the most common causes of scouring and digestive upset.

Introducing dry feed — from week 1

Put a small amount of calf starter in front of calves from 5–7 days of age. Initial intake will be tiny — that is completely normal. Rumen development begins when calves eat solid feed, and the earlier it starts the easier weaning will be.

Fresh water must be available separately from day one. Add good quality hay or straw from week 2. A calf cannot eat enough meal to replace milk nutrients in the first 8 weeks — quality liquid feeding remains the priority throughout.

Weaning

Wean on dry feed intake — not age alone.

Criteria: Consistently eating at least 1kg of dry feed per day for 3 consecutive days, in good health. Target weights by breed: Jerseys 70kg, crossbreds 80kg, Friesians 90kg.

Use step-down weaning — reduce milk by 20–25% every 4–5 days. Never wean abruptly. For automatic feeders, a 5% linear daily reduction over 20 days works well.

Continue feeding 1.5–2kg of dry feed per calf per day for 3–4 weeks after weaning.

Hold back any calves not meeting the criteria — the growth check from early weaning costs more than the extra milk.

Top Tips

Priority Tip
1 Colostrum in the first 4 hours is non-negotiable. The window closes fast. Everything else in this guide comes second.
2 Temperature matters every single feed. 38–40°C every time. Use a thermometer. Cold milk causes digestive problems and growth setbacks. It takes 10 seconds and it is worth it.
3 Teat not bucket. Buckets risk milk overflowing into the rumen. Always use a teat.
4 Start dry feed earlier than you think. Week one, not week four. Early rumen development means easier weaning and better post-milk growth rates.
5 Have electrolytes in the shed before the season. Scouring calves deteriorate fast. Having ExcelPlus Electrolyte on hand before you need it means you can respond immediately — not after a trip to the stockist.
6 Clean equipment between every feed. Residue in feeders, teats and buckets is a leading cause of bacterial scours. Five minutes of cleaning saves a lot of headaches.
7 Weigh calves regularly. A healthy calf should gain weight steadily from the first week. Weekly weight checks are the earliest indicator that something is wrong — before visible symptoms appear.

Common Health Issues

Scouring

The most common issue in calf rearing. Dehydration is what kills scouring calves — not the scour itself.

Nutritional scours: Usually pale or yellow. Calf is still alert. Caused by incorrect mixing temperature, mixing rate too high, inconsistent feeding times or volumes, or starting CMR before day 4.

Infectious scours: Foul-smelling, may be watery or bloody, calf is dull with elevated temperature. More serious — contact your vet if there is blood present, the calf is under 5 days old, or it deteriorates quickly.

Treatment — same for both:

  • Introduce ExcelPlus Electrolyte immediately at the first sign
  • Feed 2L of electrolyte followed by 2L of milk — at least 4 hours apart, never mixed together
  • Reduce CMR volumes temporarily
  • Keep the calf warm and sheltered
  • Clean and sanitise all feeding equipment
  • If a calf stops suckling or cannot stand — call your vet now

Dehydration guide:

Signs Est. dehydration Action
Scouring only 5% Start electrolytes immediately
Eyes slightly sunken, skin slow to return, staggering but still suckling 7% Electrolytes urgently, monitor closely
Eyes sunken, gums sticky, calf depressed 9% IV fluids needed — call your vet
Eyes very sunken, skin won't return, calf cannot stand 12% Emergency vet required

Calf Bloat

Calf bloat is a digestive condition caused by excessive gas production within the digestive tract. It can occur in calves fed both calf milk replacer and whole milk and is often associated with bacterial fermentation, feeding practices, and digestive function rather than a single cause.

There are two main types of bloat:

Abomasal Bloat (Right Side Distension)

This occurs when gas builds up in the abomasum (the calf's true stomach). It is often associated with bacterial fermentation, delayed stomach emptying, overfeeding, or feeding highly concentrated milk. Abomasal bloat can develop rapidly and should be treated seriously.

Ruminal Bloat (Left Side Distension)

This occurs when milk enters the rumen instead of bypassing it through the oesophageal groove. Fermentation within the rumen produces gas which becomes trapped, causing the left side of the abdomen to swell.

Bloat is usually influenced by multiple factors including feeding concentration, feeding consistency, hygiene, additives, water quality, calf health, and environmental conditions. Successful troubleshooting often involves reviewing the entire calf-rearing system rather than focusing on a single cause.

Prevention:

  • Same volume, same temperature, same time — every single feed
  • Never overfeed — follow mixing guidelines strictly
  • Keep all equipment clean and sanitised
  • Add a probiotic supplement to milk
  • Ensure access to roughage from week 2

If bloat is suspected: Reduce volumes immediately, keep the calf moving, contact your vet promptly.

Read our complete article on Calf Bloat

Coccidiosis

Most common from 3–8 weeks of age, often triggered by the stress of weaning.

Signs: Watery scours often containing mucus or blood, straining, poor growth, dull coat.

Prevention:

  • Use a suitable CMR and follow your retailer, nutritionist or vet's advice on coccidiosis prevention
  • Feed a meal containing a coccidiostat after weaning
  • Calves should eat at least 1kg of meal per day before weaning off milk
  • Move meal feeders regularly to avoid contamination in wet areas
  • Avoid overcrowding

Navel Ill and Joint Ill

Prevention: Dip navels in iodine at collection — right to the base, not just a spray. Re-dip daily for 4 days. Avoid overcrowding during transport.

Signs: Swollen, warm or painful navel. Hot swollen joints and lameness indicate the infection has spread. Contact your vet early — treatment works best before the infection spreads to the joints.

Pneumonia

Signs: Raised temperature, nasal discharge, coughing, laboured breathing, dullness.

Prevention: Good ventilation without cold draughts. Dry clean bedding. No overcrowding or mixing of age groups.

Treatment: Contact your vet at the first sign — early treatment gives significantly better outcomes and affected calves are at real risk of permanent lung damage if delayed.

Infectious Agents — Quick Reference

Cause Age Key signs Action
E. coli Under 10 days Acute scour, high temp Rehydration + vet for antibiotics
Rotavirus 10–14 days Watery foul-smelling scour, high temp Rehydration. Vaccinate cows pre-calving
Cryptosporidiosis First 10 days Pale watery scour Rehydration, maintain energy
Campylobacter First 3 weeks Foul watery scour, short duration Rehydration, clean water
Salmonella Any age High temp, rapid deterioration Urgent vet — can be fatal fast
Coccidiosis 3 weeks+ Scour with mucus or blood, normal temp Rehydration, coccidiostat in meal