Why do calves need milk?

Calves are born without antibodies in their system and must consume colostrum within the first 36 hours after birth – preferably in the first six hours.

Calves are also born with a non-functional rumen, which takes about 8–10 weeks to develop. The rumen is the main fermentation chamber which allows ruminants to digest fibrous plant feeds. The fermentation process takes place prior to feed moving to the abomasum (or ‘true stomach’). Calves must have milk or a milk substitute for at least the first six weeks of their life.

Cow’s milk is about 88% water and has an energy content of around 23–26MJ of ME/kg depending on fat, protein and solids content. This satisfies the requirements of a growing calf.

What is weaning?

Weaning is the process of removing a calf from its mother and her milk, and means the diet of the newly weaned calf may need additional supplements depending on its age and the pasture quality, if it is to reach target growth rates. Weaning provides benefits for both cows and calves, depending on the circumstances, and is an essential practice in Australian beef enterprises.

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