Understanding Digestion

A little understanding of how the digestive system of a calf works can help you rear the healthiest calves possible without the aid of expensive additives.


How the healthy calf works

In the natural state, as a calf drinks from a cow, it drinks slowly with its neck stretched out, and the calf produces a lot of saliva. This action closes the oesophageal groove so the milk bypass’s the rumen and enters the abomasum.

When milk enters the abomasum, rennin and other enzymes curd the milk. The whey is squeezed from the abomasum and into the intestine for digestion. Milk curd is then broken down by enzymes in the abomasum, before also passing into the intestine for absorption.


Saliva is a calfs best friend!


The saliva produced by suckling slowly, balances the pH in the abomasum to help curd the milk. Saliva contains
essentials enzymes like lipase, necessary for fat digestion, a vital energy source.
Saliva contains natural antibiotic properties, a calf’s first and main defence against infection.
When a calf is fed fast, it may not produce the saliva it needs to digest milk. This can cause the calf to suck on ears, navels and udders, as well as surroundings to try and make the saliva it should have produced while suckling. This is called cross suckling.
Fast feeding can lead to milk overflowing the oesophageal groove and entering the rumen where it will sour and ferment in the absence of enzymes, leading to digestive upsets.
Fast feeding and insufficient saliva can also result in a lack of curding, allowing whole milk to enter the small intestine. This leads to bacterial fermentation and nutritional scours.

E-Coli numbers multiply rapidly when in contact with raw milk. This is a leading cause of nutritional scours in young calves.


Check out the saliva produced by these calves drinking from Milk Bar Teats fitted into a Milk Bar 6.

Here is some interesting reading about Nutritional Scours from the Victoria Department of Primary Industries:

“Nutritional scours is normally caused by stress to the calf due to a breakdown in management routines. Nutritional scours often progresses to infectious scours, caused by a high population of pathogens.The initial digestion of milk occurs in the abomasum (or fourth stomach) and this progresses further in the intestines. 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 over supply of lactose in the intestines, caused by milk moving too rapidly out of the abomasum, so it cannot be broken down quickly enough. Pathogens use excess lactose as a nutrient source to increase in numbers. The rate in lactose digestion is then further reduced as a result of damage to the intestine walls by these pathogens. This damage also causes body fluids to leak into the gut, thereby increasing the rate at which the calf dehydrates”