Rapid rumen development with Wynnstay AdVance Starter Feeds.

The main goal for rearing healthy calves successfully and economically is to encourage development of the calf’s rumen, enabling digestion of solid feeds and reducing their nutritional dependence on milk. (1)

As the calf learns to adapt to different feeds the changing environment in the digestive tract causes changes to the 4 stomach compartments as shown below:

Rumen Development Guide
Image credit: Sarah Alderton,’Weaning: Get it right to avoid calf disruption,’ Farmers Weekly 11.11.11

The abomasum occupies 60% of the digestive tract initially, and is the most important compartment in the first few weeks of life, as the milk flows directly to the abomasum via the oesophageal groove. At this stage milk by-passes the rumen, reticulum and omasum.

Feeding from a teat, rather than a bucket, helps the oesophageal groove to function naturally and promotes well digested milk. As cereals are introduced into the diet the volatile fatty acids produced by digestion cause the rumen papillae to develop, and the surface of the rumen appears to become rough, with a large surface area to absorb nutrients. The photos (far right) below show the difference after introducing cereals into the ration.

What is a healthy calf rumen? (2)

  • Dark colouration, caused by increased tissue mass and large blood vessels.
  • The papillae are numerous and visible without magnification.
  • The rumen maintains an anaerobic environment for bacterial growth.
Rumen Development in calves
Credit: The Pennsylvania State University, ‘Photos illustrating the process of rumen development in dairy calves,’ PennState Extension 8.8.17

Feed conversion efficiency (3)

A calf’s milk feeding period is a golden opportunity to maximise growth. Feed efficiency is the animal’s relativeVolac's Feed for Growth ability to turn feed nutrients into growth. It peaks around this period, at around 50%.

i.e. 100g of feed = 50g of growth

An animal’s ability to use feed efficiently declines with age. Prior to puberty, heifer growth focuses mainly on bone and muscle growth, whereas in later life heifers gain more fat, demonstrating poor efficiency.

Both the quality and quantity of ingredients can affect the efficiency of a feed product. The more digestible the feedstuff, the more efficient. When buying a milk replacer or starter feed the digestibility is influenced by the quality of protein and fat sources used combined with the manufacturing process. It pays to buy from a respected manufacturer.

Research shows the total cost of rearing a heifer to 24 months old was less when feeding extra milk in the first 8 weeks. Heifers fed lower volumes of milk had to catch up later in life, by which time feed conversion had declined, costing more to reach the same body weight at first calving.

How can our market leading 18% starter nut help maximise rumen development?

  • Wynnstay have 30 years of experience with calf starter feeds.
  • Wynnstay Start ‘n’ Wean is specifically formulated for rapid rumen development.
  • Designed to be fed from 3 days old to 12 weeks of age.
  • Palatable wholesome ingredients, providing a balance in starch,
    high quality protein and fibre.
  • Wynnstay Start ‘n’ Wean exclusively contains N.I.S as a main source of digestible fibre.
  • Nutritionally Improved Straw prevents acidosis and enhances appetite.
  • A bespoke health package helps stimulate natural immunity.
  • A coarse alternative to Start ‘n’ Wean nuts is Wynnstay Super Krunch + Alfalfa. Designed as an extremely palatable 18% protein, sticky, coarse starter feed. With the inclusion of N.I.S and Alfalfa for a natural, high-quality source of digestible fibre.

Check list for encouraging early rumen development (1)

  • Encourage early intakes of a high quality starter feed from a few days of age – provide small amounts and keep it fresh.
  • Good quality straw and clean, fresh water should always be available.
  • Ensure the calf is eating a minimum of 2kg of starter feed for 3 consecutive days before weaning.
  • Calves should have doubled their birthweight by weaning (use a weigh band)
  • Calves to be weaned should be healthy and free of disease.
  • Minimise growth check post weaning by gradual development of rumen papillae.

Please do not hesitate to contact your local calf specialist for further information on feeding programmes, in order to optimise your calves’ growth and development for future profitability.


  • Calf rearing guide – S.J Charlton
  • AHDB – Calf to Calving
  • Volac / Feed for Growth – Feed conversion efficiency

Millie Hendy
Calf Specialist

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