Nutrition and Rumen Development

Nutrition and Rumen Development

Follow these 3 principles to ensure your calves grow well!

In the mature cow a large percentage of carbohydrates and proteins in pasture and supplements are digested by microbes in the rumen to produce volatile fatty acids (energy) and protein for use in maintenance, milk production or pregnancy. Calves are born with an undeveloped rumen and large abomasum.

At birth the rumen is only around 25% of the total volume, while the abomasum is up to 60%. The large abomasum is important for digesting and obtaining nutrients from the highly concentrated milk or milk replacer. It is essential that within three to four months the rumen develops to being the main stomach where digestion takes place.

Profitable and successful calf rearing relies on weaning the calf at the youngest possible age without hampering growth rates. This means the calf must be provided with the proper ingredients for rumen development so it can utilize the most amount of grass at weaning.


The following are needed for rapid rumen development:

1. A high quality calf feed that contains high levels of starch
Dry calf feed does not stimulate the closure of the oesophageal groove so the feed is deposited in the rumen where it stimulates development. Starch promotes the growth of the population of microbes in the rumen, and in particular those that produce volatile fatty acids or energy. In turn these volatile fatty acids stimulate the development of rumen papillae, which are finger-like projections that absorb them. The longer and denser the rumen papillae, the more energy the calf will get from grass and pellets at weaning.


2. Good quality clean hay
Hay promotes the development of the muscles that surround the rumen, as well as rumen size. This is important for encouraging rumen motility, feed movement around the rumen for digestion and removal of feed from the rumen. A large amount of hay before weaning can result in a large rumen, but little papillae development, therefore it is not desirable.


3. Clean water
The microbes in the rumen require water to survive. Milk or milk replacer is not free water as it bypasses the rumen via the oesophageal groove. Water helps with the absorption of volatile fatty acids and stimulates the intake of calf feed. The water should be clean and fresh to reduce the risk of pathogens and disease.


Along with whole milk or calf replacer, calves should be provided with good quality calf feed, clean water and hay for rumen development.


Most calf meal sold commercially will contain 18-22% crude protein, 10-25% fibre and an energy level of 11.5-12.5 MJME/kg/DM. You can find this information on the packet, which shows why ordinary, adult cow feed may not be right for your calves.  


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