How to feed milk and milk replacer

Find out how much to feed and whether milk or milk replacer is the better option for your farm. Plus, the importance of consistent feeding temperature, total solids and nutrient levels to help calves perform at their best.

Back to: Feeding dairy calves

How much milk to feed?

The traditional recommendation to feed calves at 10% of body weight – or 2 litres of milk – twice a day does not provide growing calves with sufficient energy.

Calves should be fed 15–20% of calf body weight in whole milk or a suitable milk replacer.

Remember, as calves grow, they will need more energy, so volume and energy must increase.

Benefits from feeding the correct energy and volume of milk include improved health, growth rates, feed efficiency and lifetime milk performance.

It is a legal requirement that calves less than 28 days old must be fed at least two liquid milk feeds per day.

Milk feeding hygiene

It is important to maintain high standards of hygiene to prevent biofilms developing on milk-feeding equipment. Once biofilms have formed, further milk residues will stick to them and create an environment which helps bacteria to thrive. It is then very difficult to reduce these bacterial populations. Biofilms release bacteria and contaminate milk every time equipment is used. To reduce biofilm formation, follow the six-step milk-feeding equipment washing protocol below:

Causes of biofilms

  • Initial rinse is too hot
  • Poor brushing, so not all organic material is removed
  • Washing water is too cool
  • Damaged plastic equipment makes it easier for bacteria to stick to cracks and rough surfaces

Using your on-farm milk

  • Use whole milk from cows that are healthy and disease-free
  • Know the disease status of your cows
  • Do not feed milk from Johne’s-positive cows
  • Do not feed waste milk (antibiotic-treated, mastitic or high cell count) to calves. Feeding this can increase the risk of disease transmission and antibiotic resistance in the calf
  • Teat feeding is more natural. Drinking from a teat helps the calf satisfy their urge to suckle

Calf milk replacers

Milk replacers are priced differently according to differences in ingredients, manufacturing technologies and nutritional quality. Understand these differences to make informed decisions.

Advantages of milk replacer

  • Reduces risk of disease transfer (e.g. Johne’s disease and BVD)
  • Consistent product when mixed correctly – less risk of digestive upsets and scours

Disadvantages of milk replacer

  • Lower energy content than whole milk
  • Products with plant-based proteins have lower digestibility in calves under three weeks old

Understanding the label

It is difficult to assess milk replacer quality from the label. The only legal requirement is for ingredients to be listed on the label in descending order of inclusion. Generally, higher-quality ingredients are more expensive.

The constituents usually listed are crude protein, crude fat, crude fibre, ash and sometimes moisture, as shown in the table below. Milk replacer should contain 20–26% crude protein and 16–20% fat to achieve optimal growth rates in early life.

Analysis (on dry matter)
Crude protein‚Äč 26% Calcium 0.8%
Crude oils and fats 16% Sodium 0.5%
Crude fibre 0% Phosphorous 0.7%
Crude ash 7%
Ingredients (in descending order of inclusion)
Fat-filled whey powder, whey powder, whey protein low in sugar, soya protein concentrate, hydrolysed wheat gluten, whey protein concentrate, L-lysine, HCI, trace element/vitamin supplement, citric acid, DL-methionine, emulsifier – lecithin
Additives per kg
Vitamins Trace elements
Vitamin A 25,000 IU Cobalt 0.2 mg
Vitamin D3 6,000 IU Copper 10 mg
Vitamin E 250 IU Iodine 0.25 mg
Manganese 30 mg
Selenium 0.3 mg
Zinc 50 mg

Skim and whey milk proteins

Protein is necessary for tissue growth. Protein sources in milk replacer can be milk-based (e.g. dried skimmed milk, dried whey, delactosed whey, casein), egg-based or plant-based (e.g. soya, wheat gluten, pea).

Skimmed-milk-based powders are typically around 80% casein and 20% whey. The casein forms a clot in the abomasum and is digested like whole milk. It is important to mix to the correct concentration to allow the clot to form.

Whey-based powders are digested in the small intestine and the absence of casein means they do not form a clot in the abomasum.

Traditionally, it was thought that non-clot-forming milk replacers were inferior and responsible for scours in young calves. Recent research instead suggests that the poor performance of calves on some milk replacers is more to do with the ingredients and the calf’s age. Vegetable fats (palm oil, coconut or soybean) have similar digestibility to milk fat in calves over three weeks old.


Fibre is an indicator of protein quality. Look at the ingredient list to determine the protein sources:

  • Products with less than 0.15% fibre contain milk or egg
  • Fibre levels over 0.20% indicate the inclusion of plant proteins


  • It is not always clear if the analysis is on a dry-matter or fresh-weight basis
  • If moisture is reported, the analysis is on a fresh-weight basis
  • If moisture is not reported, ask the manufacturer whether protein, fat, fibre and ash are analysed on a dry-matter or fresh-weight basis
  • If analysis is on a fresh-weight basis and moisture content is not stated, then assume 5% moisture


  • Ash indicates the overall level of minerals
  • The ash content should be less than 8%

Vitamin and minerals

Declared minerals and vitamins vary little between milk replacers and do not usually warrant routine inspection.

Other considerations

  • Reconstitute milk replacer at the concentration required to achieve target growth rates and clot formation
  • Consistency is key
  • Always read the label and mix to the manufacturer’s directions
  • Feed at least 6 litres per day, up to 150 g/L, during normal environmental conditions
  • Use only reputable, quality products, otherwise calves may experience health problems and poor growth rates
  • Maintain a high standard of cleanliness throughout the preparation and feeding process
  • Ad-lib clean water is essential from birth for good rumen development and feed intake
  • Calves have a higher energy requirement in cold temperatures

Useful links

Calf management guide

If you would like to order a hard copy of the Calf management guide, please contact or call 0247 799 0069.