A digestive system in harmony


As farmers we try to do the very best for our animals but artificial feeding can cause problems with raising calves.

The biggest issue calves battle with is fast teat feeding or bucket feeding. These systems are very common but they put a calf’s digestive system under huge pressure resulting in nutritional diarrhoea, poor weight gains and suckling each other or surroundings post feeding. For farmers, it is easy to think these problems are normal, but they are the result of the feeding system working against the calf and not with the calf.


So, why do these systems work against the calf and not with her?

If we look to nature we can find the answer.

In a lactating cow Milk Let Down occurs when stimulation releases oxytocin into the blood stream. Oxytocin causes cells in the udder to contract and eject milk from the alveolus into the cisterns above the teats.

Oxytocin does NOT cause milk to flow from the teat. The teat canal must be physically opened to remove milk.

When a calf suckles from a cow she applies both positive and negative pressure (squeezing and sucking).

Calf drinking from a cow

The squeezing stimulates the cow teat causing the oxytocin to be released while the suckling overcomes the sphincter barrier, allowing the calf to remove milk from the teat.

She nurses slowly, up to 4 or 5 minutes per litre of milk and produces a lot of saliva.

The saliva that is produced has several key benefits to the calf

  1. It contains natural antibiotic properties which is the calf’s first and main defence against infection.

  2. It balances the pH in the abomasum so the milk can curd correctly. 

  3. Saliva contains essential enzymes like lipase for fat digestion.

The controlled flow into the abomasum gives the milk time to curd and for lactose to be absorbed. The curded milk is then passed into the intestines for absorption.


It is vital that lactose is primarily digested in the abomasum and not passed through to the intestines. The E-Coli present in the intestines multiply rapidly when in contact with raw milk or lactose. This is a leading cause of nutritional diarrhoea in young calves.    

Research Tip! Lactose and nutritional diarrhoea are linked

‘The initial digestion of milk occurs in the abomasum (or fourth stomach). Scours can usually be traced back to a failure of adequate milk digestion in the abomasum. Nutritional scours is simply the end result of an oversupply of lactose in the intestines, caused by milk moving too rapidly out of the abomasum, so it cannot be broken down quickly enough. Nutritional scours often progresses to infectious scours. Pathogens use excess lactose as a nutrient source to increase in numbers.

Source- Victoria Department of Primary Industries. 

The slow, controlled delivery of milk allows the oesophageal groove to function correctly.


The oesophageal groove is often overlooked but its correct function is critical to calf health!


  1. It protects the rumen by directing milk to the abomasum.

  2. It protects the trachea and lungs from milk.


The oesophageal groove is a curved muscle that lies in the throat of the calf. It ensures that everything that enters the calf’s mouth, ends up in the right place.


When a calf has her head down and drinks water from a bucket or when she eats starter ration or forage, the oesophageal groove stays curved and open to direct these foods to the rumen for digestion.


The natural suckling action of using positive and negative pressure activates the oesophageal groove to close and form a tube so milk bypasses the Rumen and enters the Abomasum. This tube is small, so it is essential that milk delivery speed is slow so it does not overflow and enter the rumen or lungs. 


Milk in the rumen can be catastrophic to calf health.

The rumen has enzymes to digest grains and forage. These enzymes have no ability to digest milk which ferments producing lactic acid as a by-product. The lactic acid enters the bloodstream of the calf and can cause depression, anorexia and occasionally death.

This demonstrates the Oesophageal Groove when relaxed.

When a calf is drinking water from a trough or eating grain or forage the Oesophageal Groove muscles are relaxed and the water or food drops into the Rumen for digestion.


This demonstrates the Oesophageal Groove when relaxed.

When a calf is suckling from a teat, the Oesophageal Groove muscles tighten to form a tube so milk bypasses the rumen and enters the abomasum.


Research Tip! Milk in the rumen is linked to acidosis

It is vital to the health of the calf that all the milk goes into the abomasum. If milk enters the rumen through fast feeding, tube feeding or bucket feeding, it can cause gut ache, as the enzymes in the rumen cannot digest milk. Milk in the rumen is a key contributor to rumen acidosis and ill thrift.

Source - Dr. Jim Quigley

Through, slow controlled suckling and saliva production, the digestive system is in harmony and the calf is heavier and healthier! 

When we designed the Milk Bar Teat we have followed the principles of nature as closely as possible so the calf can squeeze and suckle the teat and the teat delivers a nice controlled flow of milk that the calf can easily digest.


Photo courtesy of Eile van der Gaast