This is solid advice. If you start your loft with ferals, I would administer a broad spectrum all purpose antiobiotic, a dewormer as well as treat for external parasites. I would do this as follows:
1. Dust all birds with something like diatomaceous earth powder (food grade) and/or offer them a bath with good pigeon bath salts that are made to kill parasites, such as this: https://www.foyspigeonsupplies.com/dr-pigeon/7031-dr-pigeons-bath-salts. I would do both with ferals.
2. Before and after you administer the dewormer and the antiobiotics, offer good probiotics. This is especially important after the administration of anti-biotics, as they will kill all the good bacteria and fauna in their gut and leave their gut health susceptible to issues.
3. Use a dewormer such as levamisole, such as this: https://www.foyspigeonsupplies.com/medications/worms-wormers/2546-all-in-one-100-grams.
4. Use an all in one broad spectrum anti-biotic that covers the common issues with pigeons such as Salmonella/Paratyphoid) E-coli, Coccidiosis and Canker. This is a good example of a product like this: https://www.foyspigeonsupplies.com/medications/multiple-use-medications/2507-avio-4-1-powder.
5. Thereafter, for maintenance of good health and to avoid the issues the aforementioned treatments seek to remove, offer a bath at least once a week with the bath salts, which they love anyways (but not when it's too cold out). Keep fresh water treated with organic apple cider vinegar (about 2 tbs / gallon of water)--this prevents canker and other illnesses, and is also very good for the birds, and they like the taste. Adding garlic makes it even better, and the birds will love the taste (when I buy the large gallon bottles of applie cider vinegar, I take one full bulb of garlic and juice the entire thing and add the juice to the large bottle of apple cider vinegar and it lasts for a very long time, since the large bottle of apple cider vinegar is then treated with garlic so you don't have to add the garlic each time). Continue to offer probiotics about weekly, but at least once a month. If you use pro biotics that go in their water, I would not add the apple cider vinegar to the water with the pro biotics, I would keep them separate.
The products above can be found at online vendors other than Foy's, such as Jedd's.
Great advise. If OP follows this he will have no problems.
The feral birds are MUCH HARDIER and resistant to disease than some of the fancy breeds, or even pedigree homers. This is because only the toughest ones survive in the wild.
I found the domesticated pigeons from some lofts to be very weak when it comes to diseases... I suspect people have been overmedicating their birds for generations of pigeons and now they are not genetically resistant to even the common mild diseases.