Feeding milk

Feeding frequency

Feeding strategies should provide calves with enough energy for growth and play, ensuring they can mount a strong immune response, and also meet behavioural needs.

Research shows that feeding calves once a day (OAD) for the first two weeks, does not fully provide for their daily nutritional needs. Calves cannot consume enough milk in one sitting to meet their nutritional needs and they will experience hunger.

Feeding milk twice daily for two weeks, allows calves to consume and digest adequate amounts of milk. This provides the energy they need to maintain good health, growth and supports natural behaviour such as running and playing. Ad lib feeding systems also provide these benefits while conserving labour.

Some farms in New Zealand 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) are currently reviewing the Dairy Cattle Code of Welfare.

It is unknown when the updated Dairy Cattle Code of Welfare will be released but it is likely to include changes to calf rearing requirements. Until then, the Dairy Cattle Code of Welfare (2019) remains in effect. Read more about DairyNZ's submission on the proposed Dairy Cattle Code of Welfare here:

Whole milk and milk replacer

Calves can be reared economically on both whole milk and, 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.

Raw milk is a high-risk pathway for the spread of Mycoplasma Bovis (M. bovis) and certain other infectious diseases. Ensure any milk you sell or purchase is traceable by completing a feed declaration form.

There may be other reasons to use milk replacers, including:

• Surplus milk is not readily available.
• High milk price.
• Infection prevention (from herd).
• Disease control e.g. M. bovis and Johne's.
• Automated calf feeding systems

When choosing to use a milk replacer, calves need time to adapt to the new diet. This can be achieved 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 and cleaning of the system is often easier and works better with freshly mixed milk powder.

Choosing a milk replacer

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

Protein

Protein content and source of protein in milk replacers can vary significantly. Calves respond best to dairy-based proteins 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% of protein on a dry matter basis to support growth and development. The faster your growth plan, the higher the protein content required.

Fat

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.

Making raw milk safe for calves

Feeding infected milk is high risk for spreading diseases such as M. bovis. Milk that has the lowest risk of containing M. bovis bacteria comes in these forms: calf milk replacer powder, acidified milk, or pasteurised milk.

If you’re feeding whole milk, consider the following:

• Discard milk from cows under treatment for mastitis or other illnesses.
• Aim for a pH level of 4.5 to reduce the risk of M. bovis. At a pH level of 4, the milk is unpalatable, and the calves will refuse to drink it.
• Pasteurisation will kill M. bovis if the machine is working correctly and the proper procedures are followed.
• Adding yoghurt to milk is a less reliable way to reduce the pH, as this process takes more time and is temperature-dependent to get the culture growing.
• If the pH doesn’t drop below 5 for at least 8 hours, M. bovis will not be killed.
• The addition of potassium sorbate preservative does not kill M. bovis.

Acidifying milk

Do not acidify below pH 4 as this will result in thickened milk and risks complete coagulation. Calves will not drink milk with a pH of 4 or below.

• Milk must be less than 24°C to minimise coagulation or clot formation.
• Always add acid to milk, not milk to acid.
• The rate is 5.5g citric acid per litre of whole milk, or 550g per 100 litres of whole milk, or 5.5kg per 1,000L of whole milk. Sprinkle acid on top of the milk while it is being agitated.
• Milk at pH 5 and below separates, but with gentle mixing goes back into a homogenous solution.
• Gently mix the milk twice a week (continuous or vigorous mixing causes coagulation).
• The target pH is 4.5 for a minimum of eight hours to kill M.bovis bacteria.
• Test the pH of milk half an hour after the addition of citric acid and again just prior to feeding calves.
• Use pH strips or an electronic pH meter. Keep meters clean and calibrated.
• Systems that pipe milk may have coagulation in the pipes/tubes, causing blockage of lines and nipples. This may result in the feeding of “whey” to calves.