Feeding Milk


3 min read

How often to feed calves? Is whole milk or milk replacer best? Choosing a milk replacer Choosing your method

What calves are fed early in their life will determine how well they grow and whether they will thrive as heifers entering the milking herd. Selecting the best system for your farm will help to reduce the stress of calf rearing, and ensure your calves get the best start to life. Here we answer a few common questions that farmers ask when choosing which rearing system to implement on their farm.

How often to feed calves?

Feeding strategies should ensure calves get enough energy for growth, are regularly monitored for signs of ill-health, and that their behavioural needs are met. Much of the research on calf rearing in New Zealand was conducted several decades ago and was based on weaning calves early by feeding less milk once-a-day and providing more solid feed.

Recent research has shown that feeding calves once a day for the first two-to-four weeks while they cannot digest solid feed, does not fully provide for their nutritional needs. They cannot ingest enough milk in one sitting for nutrition and will experience hunger later in the day. Calves can tolerate OAD feeding but it isn’t optimal for their welfare.

Feeding milk twice daily for two-to-four weeks, allows the calf to consume and digest adequate amounts of milk, and therefore energy, to maintain good health and growth. More energy also supports positive behaviour such as running and playing. Ad lib feeding systems also provide these benefits while conserving labour.

Some farms in New Zealand opt to use automated calf rearing systems, which allow the calf to choose when and how often they feed. This mimics the natural feeding behaviour of a calf on a cow. Properly managed, automated systems have been found to reduce nutritional or non-infectious scours and the need for additional labour.

The National Animal Welfare Advisory Committee (NAWAC) consulted on proposed changes for the Dairy Cattle Code of Welfare from April to June in 2022. This proposed several new minimum standards for feeding calves:

  • Ensuring calves receive gold colostrum soon after removal from the dam (i.e. within 6 hours)
  • Feeding twice a day for the first three weeks at 15-20% of a calf’s body weight in milk
  • Weaning no earlier than six weeks of age

It is unknown when the updated Dairy Cattle Code of Welfare will be released. Until then, the Dairy Cattle Code of Welfare (2019) remains in effect. Read more about DairyNZ's sumission on the proposed Dairy Cattle Code of Welfare here:

Is whole milk or milk replacer best?

Calves can be reared economically on both whole milk or high quality, reputable milk replacers. In seasonal dairy systems there is often an abundance of surplus milk over spring, and many farms cannot justify the use of milk replacers on economic grounds.

Important: Raw milk is the highest risk in the spread of M. bovis. Ensure any milk you sell or purchase is traceable by filling out/checking feed declaration forms.

There may be other drivers for farmers to use milk replacers, including:

  • Surplus milk is not readily available
  • Milk prices are high
  • Prevent infection from the herd
  • Control of diseases such as M. bovis and Johnes
  • Automated calf feeding systems

When choosing to use a milk replacer, calves need time to adapt to the new diet by initially mixing replacer with colostrum/whole milk to let them adjust between the two feeds. Consistency is key to the success of milk replacers. Always read the label and mix according to the directions.

Automated calf feeding systems can achieve good results with milk replacers, as the preparation and mixing is consistent. Delivery to the calf often seems to work better than with fresh milk and cleaning the system is easier too.

Choosing a milk replacer

Protein and fat are two key components of your feed that should be considered when comparing milk replacers.


Protein content and protein source of milk replacers can vary significantly. Calves respond best to dairy-based proteins, when compared to plant-based proteins. Not all milk replacers will state the protein source, so ensure that you use reputable products that have proven results when feeding young calves.

Calves will require around 22-25% protein on a dry matter basis to support growth and development. The faster your growth plan, the higher the protein content required.


Milk replacers commonly provide less fat than whole milk, ranging between 18-22% on a dry matter basis. Higher fat products may be valuable under ad-lib, or high growth situations. Higher fat diets can also be beneficial to calves during colder conditions as they provide added energy.

Choosing your method

Whole Milk Milk Replacer

✅ Low cost

✅ No need to mix milk – can go directly from dairy shed to calf pens

❌ Storage of excess fresh milk can lead to contamination/reduced quality

❌ Risk of disease transfer between cow and calf

❌ Changes in consistency day to day based on cow diets & production levels

✅  Consistency of product – less risk of digestive upsets and scours

✅  Can be stored and handled more easily than fresh milk

✅  Easily fortified with additional minerals & vitamins

✅ Not required to take any saleable milk out of the vat for calves

✅ Less risk of disease transfer from cow to calf

✅ Well suited to automated calf feeding systems

❌ Cost compared to feeding unsaleable milk (e.g. colostrum)

❌ Labour required to mix 

❌ Need space & facilities for dry storage

❌ Risk of spoilage by rodents

Last updated: Sep 2023
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