Science behind medicated feed vs unmedicated for chicks?


10 Years
Dec 14, 2009
Carmichael, CA
Ok, heres the deal, i recently got a few chicks, i have a small back yard flock that i bought at 16 weeks last year, then i stumbled across BYC, you lot got me thinking/hooked/obsessed and now i have 4 chickens, 2 chicks and possibly meat birds next! So, i was at the feed store buying the chicks, the guy there had 4 dozen birds all raised from chicks on UNmedicated feed. He suggested i used UNmedicated feed because anything i feed them eventually gets into me via the eggs.

Now, i am no tree hugging hippy but environmentally conscious, i am relative rookie at this chickenry but feel like an aged old pro with the amount of info/advice i have consumed through this forum! So, one person likened using the medicated feed to our baby shots, they dont help increase the ferocity of bacteria and breed drug resistant illnesses, another likened it to the opposite and encouraged as "natural" raising as possible.

My question is, not about different peoples opinion on the medicated vs unmedicated but the science. Can we come to a conclusion that if you do not have a history of disease in your flock and you only introduce chicks to the flock, that it is safe to use unmendicated or is there compelling science (like that of our baby shots) that should encourage us towards using medicated?
I would think it would depend on the hatchery where they came from, and the store that purchesed them from the hatchery. I now my local feed and grain gets chicks from McMurray's and they do have them vaccinated. Other stores may not vaccinate do to cost. It would be a good question to ask when buying chicks. If they were not vaccinated and you want to vaccinate them, you can get the supplies to do it at home. I think Tractor Supply sells chicken vaccine.
The medicated chick feed is amprolium for coccidiosis, an intestinal parasite that most chickens have. As they get older they become tolerant of cocci in their digestive systems. As babies they can easily become overcome with cocci and die as a result of a massive infestation. Amprolium helps control the amount they have until they build an immunity to them. By 12 or 16 weeks, or until they start laying, they should be fed medicated feed and then be able to be weaned off the amprolium.

I have heard that amprolium doesn't cross the egg barrier and we can eat eggs from chickens on amprolium. When my girls were about 18 weeks old, I switched them to Flock Raiser, they started laying at 28 weeks, and I've had no problems with cocci ever.

The chicks I got from the feed store were vaccinated against Maraks, a viral disease quite different from cocci.

My recommendation: Get vaccinated chicks if you can and feed medicated feed as babies. It's really to their health benefit. I've read accounts of people who have had chicks die from cocci and it's not pretty.

Just my opinion, Mary
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thanks for your input Mary, I appreciate you sharing, i never ever want to do anything to harm the chicks or not do something that will benefit them either, thats why i am seeking input!

Is the vaccine that you can buy an injection? (a shot to all americans out there!) I cant imagine giving a chick a shot, but the wife is a nurse so i will get her to do it if it is!

You mentioned that cocci (Sp?) is in all chicks, if not vaccinated do they die 100% of the time or just more likely to die?
I've never used medicated chick starter nor have ever requested vaccine. If you keep the brooders clean it is not nessary. I dont want and meds in may chickens so I just keep them clean. I'm pretty sure cocci is in dirt. and unless they are on a dirt floor that is riddled with poo you shouldn't have worry. I've never had a sick chick or chicken
I learned the hard way about not using medicated feed. I raised my first batch of chicks without using medicated feed, and they did great. They went out to their new coop at around 12 weeks. (They went into a new coop where chickens had never been raised before.) I then ordered 25 new chicks the following spring. At 6 weeks they went into a new coop adjoining my older birds. It was very warm and rainy outside,but the coop was covered and dry. Hot, humid weather, nonmedicated feed, younger chicks with older birds= coccidiosis. POOF... I lost several to cocci. When you have younger birds (less than 16? weeks) on nonmedicated feed, and put them in a coop close to older birds, they can spread the cocci spores to your younger birds by scratching and flinging dirt into the other pen, if they are close enough. My young birds were overwhelmed and didnt have the immunity built up to fight it. I suggest you use medicated feed especially if you will have them near older birds, or will be putting them in with older birds. It isnt worth it. The medicated feed contains amprollium which helps them combat cocci. They WILL be exposed to spores, especially if you have older birds, and depending on the right conditions, it can get out of hand very quickly. I think it depends, too, on where you live. I live in Georgia, and it is super hot and humid here, which really makes the conditions perfect for coccidiosis. Hope this helps. As always, it is a personal decision on what you choose to do.
If you want the pure science...

Most medicated feeds contain amrpolium. This is a thiamine analog. In cocci, the incorporation of this thiamine analog prevents cocci from reproducing, and thus prevents chicks from getting sick from cocci. That said, vaccinated, medicated, and what not, if your native soils is high in raw oocyst numbers, your chicks may "get sick" from parasite load anyway if they do not have a slow introduction to the soil early in life.
IVe always considered medicated chick feed to be very benign, and so far (knock wood) Ive never had a problem with cocci with chicks...and Ive had a lot of chicks. That being said, I do not, nor have I ever, vaccinated any birds, but I keep a closed flock.

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