While pneumonia and scours are usually the main causes of mortality in dairy calves, rumen drinking is also very commonly diagnosed by SRUC Veterinary Services, either as the sole cause of death or, on the back of other health conditions, resulting in mortality.

Underlying disease such as respiratory disease or scours (which cause pain, distress, or weakness) can predispose calves to become rumen drinkers.

Rumen drinking is due to a failure of the oesophageal groove reflex, where groove closure is either incomplete, or it does not close at all. This allows milk to spill into the rumen where it undergoes bacterial fermentation, resulting in acidosis (see photo below).

The Scottish Farmer: Lorna MacPherson, SAC dairy consultant Lorna MacPherson, SAC dairy consultant

Acidosis is likely the main risk factor for continued poor groove closure, though the rumen lining can also become inflamed which may also affect groove closure. In severe cases, secondary bacterial and fungal infection can occur.

Recurring bouts of rumen drinking will lead to thickening of the gut wall, slower passage rates of milk through the digestive tract, and poorer nutrient absorption. Affected calves appear dull and lethargic and are often under conditioned with poor growth.

The Scottish Farmer: Rumen contents showing fermented milk (courtesy of SRUC Veterinary Services)Rumen contents showing fermented milk (courtesy of SRUC Veterinary Services)

Tell-tale signs to watch out for include:

• Appearance of pain and calves kicking at their flanks

• Bloat

• Poor/inconsistent appetite (with on/off drinking) and a weak suckle reflex

• Dehydration from scouring with grey coloured faeces

• Arched backs

• Teeth grinding and vocalisation

• Moving from one foot to another and poor co-ordination

• Hair loss

If the condition is detected early enough, it can be reversed. Calves can take a minimum of 10 days to fully recover but chronically affected calves are unlikely to get better.

The risk of rumen drinking can be minimised by allowing calves to drink from a teat versus an open bucket. Calves can consume milk very quickly once they learn to drink from an open bucket. When feeding with a teat, ensure the teat is at nose height.

Feeding management is also very important in prevention. Milk should be fed at the correct temperature (body temperature – 39°C) as cold milk carries a higher risk. Avoid feeding waste milk or poor-quality milk replacer, as taste also influences oesophageal groove formation.

Ensure consistency in feeding management; milk should be mixed at the correct concentration and regular feeding times adhered to. Be aware that under stressful conditions, the oesophageal groove is less likely to form. This includes things like long transport journeys, mixing of calves and changes in feeding management.

Affected calves can be treated by tubing them with a warm electrolyte solution containing bicarbonate to aid rehydration, as well as combat the ruminal acidosis.

Smaller volumes of milk should be fed more frequently (via a teat or nipple bottle) until the symptoms disappear. Offering affected calves a finger to suck prior to milk feeding can help trigger oesophageal groove closure, ensuring milk enters the abomasum and not the rumen. Feeding milk through a stomach tube for problem drinkers is likely to make the situation worse, depositing more milk in the rumen.

Early detection and treatment of calf diseases are vital for the prevention of rumen drinking, and by successfully treating the primary disease the calf should be able to regain normal function of the groove.