Check this out. This is from chooks4life on the
Milk flush for coccidiosis thread.
I would just buy cheap garlic, around $1.50 p/kg, which equates to a lot of garlic bulbs/corms. (People say bulbs these days but they used to be called corms). At a pinch I've used granulated dried raw garlic, and if you must substitute fresh raw garlic, I'd guess the stuff in a jar is also of some use. I don't know, I haven't used that, but generally any garlic is better than none because some of the active ingredients can't be cooked or processed out of it by standard means. However for active virus protection raw and fresh is best.
The main known antibiotic property, Allicin, is created by the reaction of the enzymes released after crushing or cutting the garlic, and dissipates in around 12 or less hours. Less in my experience but it would depend on the breed of garlic too. The more ancient and non-commercialized the breed, the more potent, but even the cheap stuff works for me. Garlic is also high in sulfur which makes a chicken's flesh and blood parasite deterring, once it's been on regular garlic for a while to infuse all its tissues. Works for internal and external parasites and other nasties like bad bacteria. The Allicin in garlic has been used to treat humans with food poisoning that does not react to even very strong pharmaceutical antibiotics and because the enzyme reaction is unique it prevents viral adaption and enables garlic to kill viruses and bacteria that man made antibiotics and antiviral drugs can't touch.
Since I mixed their grain with fluid to bind kelp powder into it I would just throw the garlic into that once minced. Kelp's another thing I would strongly recommend. It's contains all the vitamins and minerals in the correct balance and is a powerful endocrine regulator. It restores correct coloration to feathers/eyes/legs/beak/skin etc, and also instinct, but not in a spacky way; rather they become very intelligent but so peaceful in their interactions. I used to feed whatever I could afford that wasn't layer pellets or crumble or mash, since once you crack a grain the nutritional value depletes severely and progressively. Just cracked is fine. After 30 minutes, an hour, a day, there are shockingly large measurable increments of degradation, so the animals eat more to make up for it. Anyway I'd give coarse grain which has corn, red sorghum, black suflower seeds, and barley or wheat, also stuff like copra meal, millet, bran, whatever I thought they could do with. Raw milk from cows or goats is great, I never had any problems with it even though I would give them as much as they could consume. Apple cider vinegar is great too. My feed wasn't the best but was what I could afford after making allowances for what I considered very important staples (kelp and garlic) which retrospect has shown me were definitely the most important.
Sort of off-topic, last year I caught a virus that had been killing people in their prime rather than old folks and babies as is expected; it got a lot of news coverage. It was a mix of a virus and a bacteria and fungal infection working in cohesion. I had a fever for two days and was a skeleton when I emerged. I was left with a lung problem I knew would kill me if I didn't fix it... I don't look after myself the way I look after my animals, lol! I've had pleurisy before so I've got an idea what's a serious warning sign. Anyway it was making pockets of trapped air in my lungs and getting stronger even though the virus itself had run through, and nothing was coming out, so after a day or two I just chopped a single clove of raw garlic and swallowed it with water. The lung infection died within about 15 minutes, and I've been fine since. Other people died in hospital with the same thing, usually in comas they never emerged from. I am sure raw garlic could also have saved some or possibly all of them. If there's one thing you take a chance on, please try raw garlic for infections, especially viral ones; I'm not saying don't go to hospital, I'm just saying it's more powerful than many people know. A lot of doctors are waking up to its potential now