Monday, April 18, 2016

The Truth About the Effects of Probiotics Given to Baby Chicks

"Giving probiotics to baby chicks reduces the risk of Salmonella in eggs and other diseases later in life."  - Statement found on a popular chicken related blog on March 22, 2016.

Not all of what is suggested in this statement is entirely wrong.  The blog page where this statement was pulled from does a good job of referring the reader to sound research on feeding probiotics to chickens.  However, where the blogger falls down is that they refer the reader to research on broiler chickens and not laying hens.  The statement above was specifically targeted to laying hens because it mentions eggs.  Yes, giving broiler chicks probiotics does help them, but a laying hen is a completely different management system and therefore their level of exposure, over a much longer lifetime, creates a completely different situation.  You cannot compare apples to oranges and needless to say, by throwing in backyard management systems you have tossed in a pineapple for comparison.

I will agree that giving chicks probiotics does help them to some degree in their gut microbiome.  You may also see improvements in their feed conversion and growth rates.  However, broiler chickens are raised to about 6-8 weeks whereas a laying hen may stay on this earth for years.  During that time, any protection that could be imparted by giving that laying hen chick probiotics is gone before it even reaches the age of laying its first egg. 

The only other thought process here is that you may wish to repeatedly dose the chicken with probiotics.  The beneficial effect of repeated exposure of probiotics for the long-term has yet to be proven.  Laying hens, with their longer lifespan, can be repeatedly exposed to Salmonella (there are several hundred strains to choose from) and each time they will need to eliminate it from their bodies.  Keeping your chickens as a backyard flock exposes them to stressors that are not the same as commercial birds.  Therefore, the performance of any probiotic used in commercial conditions will not apply to backyard birds unless specific research is done with the said probiotic on multiple backyard flocks to determine an average response.  So that should explain why I mention comparing apples to oranges, and even pineapples, above.

It takes a large dose of Salmonella to infect an adult bird.  And most often if a chick is infected, the likelihood that the chick is going to clear its system of Salmonella in a matter of a few weeks is far greater.  This means that, although it can happen, it is less likely that a chicken is going to shed Salmonella for many, many weeks or even a few months.  So by giving the chick probiotics, you are likely imparting protection for only a few weeks, at a time when the gut microbiome is just developing.  Yes, at that time, when their immune system is not as strong as an adult bird, you want to impart as much protection as possible and probiotics are a good idea.  But to claim that by giving a chick probiotics you are going to impart protection for the lifetime of the hen is wrong.  Since a healthy bird with a good functioning immune system can potentially remove Salmonella by itself then probiotics may not be needed.  If you are dosing a bird with probiotics as it is trying to eliminate any Salmonella from its body using its normal immune functions, then the real question becomes the following:  Are the probiotics doing the heavy lifting or is it the immune system doing its job?
Probiotics are likely displacing organisms within the gut that are moderately affecting things like feed conversion or nutrient availability.  It is the hope of probiotics to displace pathogens, which can, like other bacteria or microbiota, access the gut of the bird through different pathways.  Your goal as a chicken owner is to reduce the exposure of your birds to these different pathways.  Knowing that as your bird ages, they are being repeatedly exposed to different organisms, means that you will need to use good biosecurity and stay on top of your good management practices.  Probiotics are nice to have on hand, but are by no means a requirement to successful chicken keeping.

Unfortunately, the quote above also states that the risk of salmonella in eggs will be reduced.  No reputable research to that effect (within the egg) has been shown.  Sometimes research finds slight reductions in bacteria levels by feeding probiotics, and they may be statistically significant, however, the actual numbers are only slight and not at all meaningful for you, the backyard chicken owner.  Significance and meaningful can be two very different things.  You may see a reduction, but if the levels are not enough to have any real, true meaning in real-world circumstances, then one must understand that probiotics are not a replacement for using sound management practices within your flock.  I emphasize that bacteria on the inside of the egg in the discussion can be detrimental especially in sauces or dishes that are not cooked.  You can reduce bacterial levels on the outside of the shell which is good, but washing eggs before eating them can also do good in reducing bacterial levels.

Lastly, the quote also states that by giving probiotics, a reduced risk will be imparted against “…and other diseases later in life.”  This statement is too broad.  There is no indication of what diseases are being referred to and so that makes this part of the statement a red herring. The real topic being discussed is the Salmonella level in eggs being affected by probiotics given to the birds in the chick life stage.  As was stated previously, when birds are exposed to the right dose, or other stressors, probiotics given as a chick will not impart protection at later life stages.

Beware of broad claims when you are shopping the internet for information.  Most times, if it sounds too good to be true, then it often is.  Thankfully, in this case, we have teased apart the truth from the myth in the aforementioned statement so that you can better approach this topic with science in mind.

Response provided by Dr. Brigid McCrea, Ph.D.
Associate Professor and Extension Poultry Specialist
Delaware State University

* This is another fine example of how bad information can quickly spread across social media. Example:  How many people read this blog? How many times are readers now going to post on other chicken related blogs and forums, "Giving probiotics to baby chicks reduces the risks of Salmonella in eggs," spreading the bad information even further? Reading a study is one thing, having the knowledge to understand what the study means is another. ~ Andy Schneider (The Chicken Whisperer)