Digestive challenges in calves

Every dairy farmer has to deal with digestive challenges in calves. This is – unfortunately – a common challenge on-farm. As a result of these challenges, calves may have impaired growth and for the  farmer it  means  lots  of  work  and costs caused  by potential value  and  money  loss. As  an  example,  a calf with  digestive challenges will demonstrate a decrease in growth rate.  Cornell University research showed that for every 500 g increase in daily gain, milk production increased in first lactation up to 57 kgMS (or up to 224 kgMS extra over the first 3 lactations).​ This means an extra $399.00 per cow in the first lactation on a $7.00/kgMS payout (or $1,197 per cow extra over the first 3 lactations).

In addition, from ‘Heifer rearing to optimise farm profitability’ – John Roche​:  undersized heifers have more calving difficulties, produce less milk and have greater difficulty getting back into calf. When lactating, they compete poorly with older cows for feed and because they are still growing, will use feed for growth rather than for producing milk. They are more likely to be culled for poor milk yield and/or infertility. Heifers that were 68 kg heavier at first calving reported a 5-7% increase in milk, milk fat, and milk protein production during the first lactation (Macdonald et al. 2005)

Causes of digestive challenges

The  cause for digestive  challenges  varies  from farm to farm,  and is often  a  combination  of  factors and can have different causes. One cause includes unfavourable bacteria. In others, disturbed protein or fat digestion and/or poor environmental hygiene can play a role.  Digestive  challenges  caused  by  bacteria can  result  in  a damaged intestinal  wall, as  unfavourable bacteria at gut level affect and damage the intestinal epithelial cells. This results in a decrease of the  intestinal surface area which in turn reduces the ability to absorb nutrients. Calves with digestive challenges caused by unfavourable bacteria  are therefore prone to having reduced growth rates. See Figure 1.

Figure 1: Intestinal wall lining(1).

Normal gut villae(2), responsible for surface area enlargement are irreparably destroyed or made impenetrable due to scarring by unfavourable bacteria(3).

Measure of proactive approach

A number of factors play a major role in taking a proactive approach to prevent digestive challenges due to unfavourable bacteria in calves.

Hygiene and housing

It is important to ensure that calves are born in a clean environment. After calving, calves can come into direct contact with bacteria from the environment and ingest these bacteria, that will end up in the intestines and can cause challenges. A proper environment after birth means that the calf is placed in cleaned, dry pen with a sufficiently thick layer of straw or sawdust. This thick layer  of  bedding  ensures  that  the  calf can  create its  own  microclimate that  safeguards  it  from  environmental influence.

The importance of colostrum

After the calf has been housed, the most important thing comes into play: the first colostrum. Optimally, calves must  have  ingested  200  grams  of  immunoglobulins  within  6  hours  of  birth (4 litres of colostrum, contain 50 grams of immunoglobulins per litre): the 3 Qs: Quantity, Quality, Quick! Immunoglobulins  are  antibodies that give calves their passive immunity. The so-called Brix-value of the colostrum, which can be measured using a refractometer, must be at least 23 in order to have 50 grams of Igg/litre. Shortly after birth, the absorption capacity of the intestinal wall is 100 percent, however after 6 hours this is halved. A calf’s passive immunity  is  obtained  via the  colostrum.  It can take 10 days to 4 weeks for the calf’s active immunity (their own immune system becoming active) to kick in. Between the passive and active immunity, a ‘gap’ exists, where a calf is extra vulnerable for digestive and other challenges.

Supporting the development of the immune system

Because of this immunity gap, the first weeks of life are particularly critical for the calf. The passive immunity from the colostrum is slowly lost and  calves  have  to  build up their  own immune  system.  In  the immunity gap,  calves  are  especially sensitive  to  digestive  challenges. Just  like  after  birth, hygiene during  the rearing period  is important. To achieve this, pens must be clean and preferably disinfected, farm boots and overalls, and drinking materials should  be  clean  and  of  good  quality.  It  is  also  important  to  ensure  the  correct  preparation  of  the  milk and/or milk replacer.

Providing milk and milk replacer

If milk or the milk replacer are not properly prepared; when damaged or incorrectly attached drinking materials are used, the calf’s oesophageal reflex may not work properly, and the milk ends up in the calf’s developing rumen instead  of  the  abomasum (so-called ‘rumen drinking’). In the rumen milk undergoes bacterial breakdown and produces lactic acid and other volatile fatty acids, resulting in acidosis.  This damages the lining of the rumen causing inflammation, as well as inhibiting curd formation of milk in the abomasum. This will case digestive challenges and can even cause death in calves.

Normally,  a  fold  in  the stomach,  called  the  oesophageal  groove, allows  for  milk  to bypass  the rumen  when  the  calf  drinks.  However, when  a  calf  does  not  have  the  correct  drinking  position, or when the  teat  is  of  poor  quality, the  milk  not  at  the  right  temperature  or  has  an  incorrect  composition,  this system will  not  work  optimally.  As  a  result, milk  will  flow  into  the  rumen. The quality  of drinking  teats should  be  checked;  they  should not be broken, ruptured or otherwise compromised and should be placed in the right position and at the right height. The correct position of the teats is illustrated in figure 2.

Figure 2: Teat position.

The correct way of positioning the teats, in a ‘+’ shape allows for proper milk flow. An ‘x’ shape hinders or blocks milk flow.

The teat should be in a ‘+’ shape to allow for a proper flow of milk out of the teat. In contrast, when placed in an ‘x’ shape, milk  flow  is  blocked  or  hindered. If  not  properly  monitored, it  could  then appear  that  a  calf is  not drinking and is suspected of having underlying health challenges, whilst in reality it’s being underfed. In addition, bad quality teats can lead to air sucking, also impairing the oesophageal reflex, once again resulting in milk to end up in the rumen. It is also important the teat is above the stomach level of a calf to activate the oesophagal reflex. E.g. when calves drink water with their heads down, this water will end up in the rumen, not in the abomasum.

Weaning

After the  milk feeding period, weaning is best done gradually to avoid calves from getting into a weaning dip. During  and  after  weaning, calves  gradually  learn  to  process  roughage  as  milk  provision  is  gradually  reduced. During the milk feeding period, quantities of solid feed will be provided so the rumen can already slowly develop. This will mitigate a potential weaning dip. In case of a weaning dip, growth may be impaired or even completely stagnated, hence it is worthwhile avoiding this as much as possible.

About AHV

AHV (Animal Health Vision) is the global leader in quorum sensing-powered animal health solutions and advisory services, giving #PowerToTheFarmer to optimise their animal health. Since opening in New Zealand February 2022, AHV has tailored a range of protocols to New Zealand farming challenges to power herd longevity, productivity and profitability. Reach out to your local Territory Manager or call AHV New Zealand at 0800 424 869 to learn more about how AHV can support your farm.