At Milk Bar, our focus is to provide you with fact-based information about a calf’s digestive processes so you can reduce some of the common problems that can make raising calves stressful.

Troublesome calf behaviour is so common, its often seen as normal. However, if you know what you are looking for you will start to see the link between calf behaviour and how calves are fed.

More often than not, it’s not what your feeding, but how your feeding that can be causing the problem. 

How does the digestive system work?

When a calf suckles from a cow, she applies both positive and negative pressure (squeezing and suckling). The squeezing stimulates the cow’s teat, so oxytocin is released. Oxytocin causes cells in the udder to contract and eject milk from the alveolus into the cisterns above the teats. 

The suckling overcomes the sphincter barrier, allowing the calf to remove milk from the teat. Oxytocin does NOT cause milk to flow from the teat. The teat canal must be physically opened to remove milk.
She drinks slowly, up to 4 or 5 minutes per litre of milk and produces a lot of saliva.

The saliva that is produced by suckling slowly is rich in lactoferrin-lactoperoxidase, an enzyme system with antioxidant and antimicrobial properties that boosts the immunity and improves the protection of the calf. 
Salvia balances the pH in the abomasum so the milk can turn into a thick curd. The slow delivery of milk combined with saliva gives rennin and other enzymes time to curd the milk and lipase to digest fats. The milk lactose is digested and absorbed into the bloodstream.

The natural suckling action of using positive and negative pressure helps activate the oesophageal groove to close and form a tube so milk bypasses the rumen and enters the abomasum. 
The oesophageal groove is a curved muscle that lies at the base of the oesophagus. It ensures that everything that enters the calf’s mouth, ends up in the right place. 

The Oesophageal Groove and the Rumen

When a calf drinks water from a trough or eats meal and grains, the oesophageal groove stays relaxed and these food groups drop straight into the rumen for digestion.

The Oesophageal Groove and the Abomasum

When a calf suckles, the oesophageal groove closes and forms a small tube to direct the milk past the rumen and into the abomasum for digestion. Too much milk can cause it to overflow allowing milk to enter the rumen.

Milk in the rumen

Milk in the rumen is harmful to calves. The rumen has enzymes to digest grains and forage, but these enzymes are unable to digest milk, causing the milk to ferment and produce lactic acid. The lactic acid enters the bloodstream and can cause depression, anorexia and sometimes death. 

Put simply, in nature, the calf drinks with her neck long and low, and the cow lets the milk down slowly. With the speed of milk controlled, the rumen is bypassed, and the abomasum creates the curd to start the digestion process. 
The enzymes do their job and get cracking with digesting fats and lactose. Happy, healthy calves!     

Why do calves cross suckle

Cross-suckling is when calves suckle on each other or their surroundings after feeding. 
It’s worth taking the time to check after feeding for cross suckling as it can cause short term infections and long-term damage.

If you watch your calves after feeding you will see that the length of time they spend cross suckling is directly linked to the speed in which they drink.

Example: A calf fed 4L at ‘natures speed’ should take around 12 - 15 minutes to drink. After drinking she will be quiet and settled. Her suckling urge is satisfied, and she is content. If she drinks 4L in 8 minutes or less, then she will spend the next 4-5 minutes cross suckling to satisfy the natural suckling urge.

Why it’s a problem:

Short term problems like navel infections are a nuisance and take time and cost to treat. 

We are more interested in the long-term damage because cross suckling removes the keratin plug and leaves the developing teat canal open to infections.

Cross-suckling is strongly linked to mastitis and blind quarters in first lactation heifers.

How to fix it:

Some ‘fixes’ include nasal rings, spraying toxic concoctions (please don’t spray homemade hot chilli, ouch!!) or tying flax to calves.

These old-fashioned remedies don’t address the underlying problem which is fast feeding. 

Allowing calves to drink at the ‘natural speed’ resolves cross suckling almost immediately It really is that simple!

How are lactose and diarrhoea linked?

Nutritional diarrhoea can be linked to two major causes, poor digestion and stress.
Stress can result from a variety of causes. It could be due to irregular feeding, sudden changes in milk replacer concentration, or a poor-quality milk replacer. 
Environmental stress like sudden weather changes can also play a part. 

Digestive stress is a key factor. If the pH in the abomasum is not balanced and the acid secretion is reduced, then the ability of the milk to clot is compromised as is the digestion of milk protein.
Inadequate clotting allows excess sugar (lactose) to enter the intestines and produce a nutrient source for pathogens such as E.Coli who’s numbers multiply rapidly when in contact with raw milk or lactose. This is a leading cause of nutritional diarrhoea in young calves.

Long term impact:

Aside from the cost and added workload of treating calves with nutritional diarrhoea, studies have shown that calves who suffer from nutritional diarrhoea pre weaning have a reduced average daily gain which can impact future conception.
Further studies have shown that nutritional diarrhoea pre weaning has a negative impact on first lactation milk production.

Address the cause:

Alongside reducing environmental stress, improving digestibility and lactose absorption is key in reducing nutritional diarrhoea.
We know from studies that a controlled flow of milk into the calf has a positive effect on digestion by promoting good clotting and improving lactose absorption.
Saliva production helps to balance the pH to further ease stress on the digestive system.
Feeding the calf at a slow, natural speed will maximise saliva production and ultimately reduce your workload.

How do I get better average daily gain?

Average daily gain (ADG) is the grams per day in weight gain. Good ADG has positive outcomes such as better conception rates and increased first lactation milk production to name just a few. 

Improving ADG performance:

Improving lactose absorption is key for calves to fully benefit from good nutrition programmes. Lactose is released from the milk curd in the abomasum. It is broken down to glucose and galactose and these are absorbed into the bloodstream to form the major energy sources for young calves.
Using a fast flow or bucket system reduces the lactose absorption and so calves do not receive the full benefit of their food.

By controlling the flow of milk, the digestive system can fully function for maximum utilisation of feed and optimum growth.

What is breakaway behaviour?

When calves are fed from a fast flow teat they can struggle with the high flow of milk and will come off the teat (break away) and either drop their head and cough or try to find another teat that is more comfortable. 

Why is it a problem?

Breakaway behaviour disrupts the feeding time and can influence the milk volume the calf uptakes. For calves fed in groups this can lead to unequal milk intake. 
Breakaway behaviour can contribute to extra training time.

How to fix it:

When calves are delivered milk with a controlled flow, break away behaviour is reduced to the occasional repositioning.

Published Research

There’s lots of old wives tales and mysterious concoctions around calf rearing.

At Milk Bar we like to deal in facts. 

If you are interested in the science, click here to view our collection of research including peer reviewed and published research.

Learn more