Tips for Avoiding Summer Scour Syndrome

Summer scour may not affect all calves in the group. The severity of the disease tends to differ from year to year and farm to farm. It typically occurs in dairy calves within a month of turnout to grass and up to 12 months of age. It is characterised by scour and rapid weight loss, lethargy, lack of rumination, and weakness, which can be fatal for calves.

Summer Scour Syndrome

The cause is not definitively known and several theories exist as to what the most likely risk factors are. An infectious cause has not yet been identified and the disease is thought to relate to nutritional issues. For example when the rumen is insufficiently developed to digest forage, grazing is the common denominator in all cases.

Summer Scour Syndrome is more common in calves grazing ‘lush’ pastures, typically with a high crude protein (greater than 20%) and low fibre (less than 40%) content per kg of dry matter ingested. Calves are selective grazers and preferentially consume the top, leafier parts of the grass, which contain more nitrates and non-protein nitrogen (NPN).

The consumption of large quantities of nitrates and NPN by young calves with an immature rumen might lead to an excessive build-up of ammonia in the rumen. Papillae are the finger-like projections that line the inside of the rumen. Papillae are essential for rumen function as they increase the surface area for greater potential to absorb nutrients. Calves are born with undeveloped rumens and concentrates, long fibre and water intake are the most important factors for rumen development (papillae growth).

The excess nitrates and NPN from lush grass damages the papillae which has developed in the rumen since birth, reducing the overall surface area available for nutrient absorption and therefore reducing thrive and performance, i.e., resulting in scour.  Inadequate rumen development may also lead to an unstable pH for rumen bacteria to function properly, which may potentially contribute to the syndrome.

Tips to Avoid Summer Scour Syndrome

• Ensure calves have access to high levels of fibre from stemmy grass or older swards when first turned out to pasture
• Add an extra source of fibre (straw or hay) when first turned out to pasture
• Avoid grazing reseeded pastures, or leafy (lush) grass for at least 2 months after turnout
• Strip graze calves to encourage the consumption of both the leaf and stem of the grass
• Avoid pastures that have had slurry or nitrogen applied recently
• Continue feeding RumenCare Calf Nut, which includes a high level of digestible fibre

For more information on the benefits of GAIN RumenCare Calf Nut, please contact your local Tirlán FarmLife Representative.

First Published 29 May 2024