Modern milk replacers can be used to successfully rear healthy calves. Before deciding to use a milk replacer, farmers should weigh up the advantages and disadvantages for their calf-rearing system.
Ease of handling with automated calf feeding systems, high milk prices and minimal waste milk are reasons why milk replacers are favoured on some farms.
Only high-quality reputable products should be used otherwise health problems and poor growth rates may result.
Composition of milk replacers
Clot-forming or non clot-forming Traditional milk replacers are made from downgraded skim milk powders, and are digested like whole milk, forming a clot in the abomasum.
Early products varied in quality ù mostly due to the processing of casein ù and sometimes caused scouring.
The majority of milk replacers sold in Australia still contain significant percentages of skim milk powder.
Whey proteins are digested in the small intestine and do not form a clot in the abomasum.
The increasing value of casein and improvements in filtration and purification methods have seen whey-based milk replacers that can produce average daily weight gains and performance comparable to casein-based products.
Modern whey-based milk replacers lead the market in the United States and Europe and are gaining share in New Zealand.
Protein A newborn calf is better able to digest milk protein than plant protein sources.
Milk proteins are the best sources for growth and development of calves and should provide most of the protein in a milk replacer. With increasing age, calves develop better capacity to digest other proteins and so milk proteins become less important.
Other protein sources have been used in milk replacers with varying success (see Figure 1).
Soy protein is the most commonly used alternative to milk protein in milk replacers.
Processing of soy protein is required to make it more digestible and remove factors that may inhibit calf growth.
Wheat-based proteins may also support adequate calf growth rates and may mix better than soy proteins.
Crude protein levels in milk replacers commonly range from 18-25 per cent.
High levels of non-milk proteins are often used to compensate for low protein digestibility.
The sources of protein should be listed in the product ingredients, but the actual percentage each contributes to the overall protein content may not be listed.
Fat Fat can be derived from animal-based products such as tallow, or cheaper sources such as palm or coconut oils, all of which are highly digestible and suitable if properly dispersed into the milk replacer.
Levels between 10 and 20 per cent are suitable for calf growth.
Additives Vitamin, minerals and animal health medications are commonly added to milk replacers.
Ionophores such as lasalocid and monensin help control coccidiosis, and may also have a growth promotant effect.
The use of cocciostats in calves less than 2-3 weeks is of questionable value, and lasalocid is potentially toxic when given to calves less than 24 hours old.
Mixing of milk replacers Consistency is the key.
Always read the label and mix according to the manufacturer's directions. Many automated calf feeders are designed to handle powdered milk, making it easier to transport food to the calf shed.D
Contact: Dairy Australia, phone (03) 9694 3777, website www.dairyaustralia.com.au.
This is an edited extract of a Dairy Australia factsheet. It first appeared in the Australian Dairyfarmer May-June 2018 edition.