Followup : Understanding immunity in farming (and life)

There was a fair amount of interest and idea sharing from the last post and people offering their thoughts on what they thought the best solutions were to raising chickens naturally.  We also received several requests to share the results (which we were planning on doing - but it is positive reinforcement that what we are doing is useful) - so here's the highlights.  Out of dozens of responses, the overwhelming choice people made was to immunize their birds and let activity immunity play a role in keeping this particular disease out of their flock.  The second most popular choice was do nothing and let nature do it's own thing.  Nobody who responded thought antibiotics were a good solution towards prevention...  wonder how many folks would use antibiotics if there was an outbreak.  And then there were some pretty interesting "other" responses.  And it's there I'd like to spend a little discussion time.

One of the most common (and I think universally misunderstood) solutions offered was to "breed in immunity".  I hear and read about this concept all the time with regards to sustainable farming...  and while that's a noble goal there are a lot of reasons why it just doesn't work the way people "think" it works.  My favorite example of this comes from a large sustainable farm located in Georgia where they bought chickens from a hatchery, had one generation raised on their farm and then proclaimed - "We have bred in immunity to disease"...  even better, they brought in some animals from another farm, converted them to a grass based diet and then - proclaimed they had successfully "bred in immunity".  Huh - I thought breeding required reproduction...

The idea of breeding a more hardy (and hence disease resistance, healthier, able to fight things off better) breed is very common and has been practiced for centuries...  but when it comes to Cornish Cross meat chickens, or many other hybrids it's not a truly viable goal.  When you breed a hybrid (a cross between two different parent stocks where the end goal is to concentrate desirable characteristics in the offspring) one of the main characteristics the cross goes after is defined as hybrid vigor.  Hybrid vigor is the term used to describe (in plants or animals) the F1 (first generation) cross that can usually be, as an entire population of the "child cross", construed to be "healthier", "bigger", "faster growing", "more vigorous".  The one thing you DON'T get with a hybrid is the ability to breed them and have "true" offspring.  So let's look at the Cornish Cross chicken example.

The common, broad breasted, fast growing meat chicken many, many farms raise in both the pasture and the CAFO models are Cornish Cross broilers.  Contrary to the stories told by their detractors, they are created by the mating of male of a naturally double breasted Cornish strain chicken and a female of a tall, large boned strain of white Plymouth Rocks.  Their offspring, the Cornish Cross, are F1 hybrids...  their hybrid vigor is reflected in their massive breast size and their remarkable ability to convert food into flesh.  However, should they be bred the resulting offspring of the 2 F1 (Cornish Cross parents) would be very, VERY different.  (Breeding Cornish X birds is unlikely given their size, top-heavy nature and growth rates that make reaching maturity difficult).  The point is - IF you could breed them - you would have F2 chickens (second generational crosses) that genetically were all over  the place in terms of appearance, size and conformation - NOT the Cornish Cross bird you intended to have.

The point here is - should you want to try and breed for higher disease resistance you would first need to stick with lines that breed pure.  Then, you would have to find a way to select for the required "resistance"...  so - you would expose the birds to the pathogen and then breed only those that survived the experience.  Then, breed and repeat.  If you could find resistance (the inability to contract a pathogen) - you would then need to "test" for it in every new generation...  And all that pathogen exposure results in a lot of loss as you are selecting for resistance...  and resistance is NOT immunity.  Whew.

Not sure I got the point across or not - but immunity is an active biological process that is triggered by the presence of a pathogen.  Resistance is a genetic "change" whereby something about the resistant animal is different and the pathogen can't attack (great example Kelli gave - some people can't get HIV - their cells do not have the receptor the virus attaches to.  They are not immune because their body isn't doing anything - they are resistant.)

Bottom line - you can't really breed in immunity...  what you can try and do in pure lines is select for resistance.

There were a few other "other ideas" that were interesting but the last one I wanted to mention was a very informed response about homeopathy as a solution / alternative.  Certainly there are some really good homeopathic preventative and acute treatment solutions out there (for example - we add Apple Cider Vinegar to the chicken waterers every few months to help with any parasites they might have ingested).  The thing I though was really interesting was the proposed homeopathic solution for coccidiosis in chickens - various mercurial salts and sulfur.  Basically it's a cocktail for a sulfonamide antibacterial....  which is the same basic chemical that farm stores sell to treat the disease.  Sometimes homeopathic and "modern" medical solutions are the same chemicals - just a different name :)

(Before someone goes nuts out there - there are many different "meat breed" chickens that breed pure.  So you certainly could breed and select for higher resistance...  but they are different in taste, gain rates and conformation than the Cornish Cross.  Thus far we have found several of those meat breeds to be very good for stewing, soup and boiling but our search continues for a fast growing ,tasty, good textured breed that can compete on a dollar for dollar and taste basis with the Cornish Cross.)

Understanding immunity in farming (and life)

Likely you have heard of a vaccine.  Perhaps you have even heard they are "bad" and "cause autism" (which is absolutely not true).  What is almost always lacking is a clear and correct definition about the functionality of a vaccine - what it actually does.  And if you are in the camp who thinks that vaccines are categorically bad and are inherently evil - but at the same time believes that natural food production is the answer to all the world's woes...  get ready to confront some serious cognitive dissonance.  Since natural and organic farms don't use antibiotics - they typically more likely to vaccinate their herds and flocks against potential maladies (gasp).

What is immunity (not Survivor Island related)?

Before we can talk about a vaccine we need to understand immunity.  Basically there are two types of immunity that an animal (you included) can "have" or experience; active and passive.  Active immunity means the immune system is active and working to fight a pathogen (germ, bug, badness...  something that's "not self" - not part of the animal mounting the immune response) and build memory against that pathogen.  This can be induced by actually getting the disease, where then the body must fight off the invading pathogen, like you getting a cold and then getting better.  This can also be induced by vaccination where a non-disease causing version of the pathogen (or only a part of it) is introduced to the body, which makes the immune system actively respond and fight off the pathogen, like you getting a flu shot so you don't get the flu.  Both of these scenarios produce an active immunity and the immune system has worked itself to build that immunity.  Also important is that there is memory for how this fight was conducted - so this active immunity is long term and can even last a lifetime!  A great example is chickenpox - if you got it as a child your immune system remembers the virus it and you won't get it again.

Passive immunity is a little different.  It does not involve the immune system actively doing anything (hence the name passive - creative huh?).  The immunity, in this case, is simply received - via breast milk or through the placenta, for example.  Since the immune system of the animal is not involved in building this immunity, no memory of the act can be built and this type of immunity is not long term.  It also means that the immune system did not get the practice or the "workout" involved in building an immune response down the road.  Passive immunity is only temporary.

Is an antibiotic immunity or does it make immunity?

Not even close.  Antibiotics are chemicals that disrupt the ability for bacteria (not viruses - they are completely different) from growing...  but antibiotics don't "cure you".  If you have a bacterial infection antibiotics hopefully slow or stop the spread of the infection and actually let your own active immunity take over and clean the mess up.  If your immune system had been primed against the pathogen before you were exposed, the infection might never have gotten established and you might never have needed to take the antibiotic in the first place.  Ohh, and taking an antibiotic for every little cold you get - all that does (since colds are viral) is make the bacteria that live in the world around us more resistant to the antibiotic chemical...  which means, should you ever NEED an antibiotic it may not be effective in stopping the bacteria and letting your immune system finish the job...  that's bad.

So what does immunity have to do with local food production?

Actually quite a lot!  Since natural and organic farms don't rely on antibiotics to help fight off nasty bacterial infections in our animals we need to do things that allow our animals to be healthy enough to mount the correct immune response should the need arise.  For instance - we COULD overcrowd our chickens, have them live in stressful and dirty conditions and "prevent" infections from getting going in the flock by feeding them an antibiotic medicated feed every day - all day....  OR we could give them very clean spaces, extra room and lots of natural relaxation so their own immune system can take care of the low number of bad "bugs" they encounter just by running around in nature.  The fact is many CAFO operations rely on a constant low dose level of antibiotics all the time in their animals since they are perceived as a quick and easy way to deal with or prevent potential infections.   However, antibiotic use relies on the chemical antibiotics to destroy or control a pathogen, rather than giving the immune system a workout (and those organisms can and do develop a resistance to the antibiotic making it ineffective).  Vaccines induce the natural actions of the immune system to kick in and then build an immune response.  And this building of active immunity also means that memory is built, so this is not a one time thing - the immune system is now trained to effectively fight off this pathogen again and again.   This  might explain why many natural and organic farmers turn to  vaccinations to avoid use of antibiotics in their animal feed - since antibiotics use in animals has been shown to develop that bacterial resistance that in turn negatively effects human health.  The simple and cost effective vaccinations give the animals immune system the ability to build memory and protect themselves from infections throughout their lives - without ever needing antibiotics (just like in people)!

The reality is a vaccination applied correctly to any animal can impart a totally natural defense against the pathogens that are known to cause disease in that species.  For farming operations where those pathogens can become concentrated enough where the animal is at risk for acquiring the disease a farmer must make a choice in prevention - do nothing, vaccinate or apply antibiotics.  When it comes to vaccinations you need to look past the fear inspired bad statistics, big money payouts and super helpful "medical science" narratives by former Playboy bunnies from the most un-notable corners of the internet and stick with the scientific facts.

So - with a basic understanding of immunity it's your turn to make a decision that small sustainable farmers make every day.

Would you vaccinate your chickens?

So how would you tackle this in the role of a local farmer.  Let's say you have really clean conditions for brooding and lots of pasture.  You are raising a bunch of broiler chickens over the course of the summer in several different batches back to back.  Now, the summer is supposed to be damper than normal and you know that adds an element of stress to the chickens you can't control.  You also know that there's a particular bug that lives naturally in the soil young chicks can consume resulting in a disease called coccidiosis that can wipe out an entire flock in 24 hours.  So let's look at your options and see where your principles for healthy local food meet economics and science fact:

The economic cost of a coccidiosis outbreak is usually considered a total loss.  Your investment in the flock of 150 birds is $200 + time and feed...  and boy do they eat a lot.  Depending on when an outbreak occurs (usually around week 4) you could have $200 dollars in feed already consumed.  You can prevent a total flock loss with an immediate application of medicine when the outbreak starts - cost is $20 and at that point 40-60% flock loss.  Should there be an outbreak - the subsequent risk to any other chickens living on the farm becomes VERY high and can have farther economic impacts.  Also, you should then notify your customers you had to medicate the chickens...  and they are thusly no longer organic.

So what would you do?

Option 1) Do nothing special and let nature run it's course.  Do your best to create conditions where the chickens will be minimally exposed (as best you can tell) to coccidia which exists in the soil, on plants in the soil and other bird droppings.  Hope that the weather will be on your side. Probability of an outbreak is maybe 20% or less using good flock management techniques.  An outbreak would reduce your gross profits to a level where that flock would not generate any profit, potentially a loss, and you would have many customers loose their deposit and receive no bird.  There should be no impact on bird weight gain using this approach.  Prevention Cost = $0 / $150 birds

Option 2) Have your chicks vaccinated before they arrive on your farm.  This means before they are shipped that are sprayed with a killed version of coccidia.  This allows their young immune systems to learn what the nasty pathogen looks like and be primed to fight it off should it encounter it.  Basically generate active immunity (see above).  Then, still provide the best conditions you can to the birds so their stress levels stay low and their primed immune systems can respond naturally if needed.  Probability of an outbreak is less than 3%, since the chickens are immunized already, providing you are using good flock management techniques.   Should there be an outbreak it's likely to spread much slower because of natural immunity so the losses would be much smaller.  There should be no impact on bird weight gain using this approach. Cost = $25 / 150 birds

Option 3) Offer your chicks a medicated feed over the first 6 weeks of their life.  Since broilers are processed around 7 weeks of age, you stop with the medicated feed 7-10 days before processing and allow for a washout period.  Since they are always being "protected" by the medication in the feed the conditions they are raised in are not super important, the medication deals with any coccidia the birds encounter.  Some people can be allergic to the medication in the bird meat - but the washout period should take care of that.  Probability of an outbreak is less than 10% assuming the flock is not maintained in utterly inhumane conditions BUT you can have more chickens per unit of space so overall you can have a flock that generates more revenue for the same amount of space... so let's a dd a few more birds, if that stresses all of them, the medication will still protect them.  If the birds do contract coccidia during the washout period they will likely not be symptomatic but their last week of weight gain may be slightly less.  Cost = $20 / 200 birds

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