As far as nutri drench, I don't see it as being a bad additive. The vinegar... I never understood why so many people use it to be honest. Does an acidic environment discourage the proliferation of the harmful pathogens? yes... however the vinegar isn't going to make it through the birds system without being neutralized. It will most likely end up getting neutralized by the contents of the crop and further down it will basically have no effect... except if it's overdosed, and then it can actually start leaching out minerals from the body. A lot of people will argue that it cures wet nests with youngsters, and while this may be true there is a reason for it. Parent birds will often drink a lot of water when they are lacking in salts and minerals trying to draw out the tiny amounts that may be available in the water supply. In turn they load the babies with water and you have very wet droppings and nests. Then they add vinegar to the water and the nests dry up... however this occurs because the birds don't like the taste of the vinegar in the water and in turn they drink less water. But this didn't solve the actual issue of the birds lacking in minerals (it's just a band aid in this instance that can actually make things worse). If one wants to acidify the water, and have it's benefits throughout the system of the bird without discouraging water consumption, I would recommend something like alltechs Acid-pak 4-way 2x ( https://www.alltech.com/acid-pak-4-way-2x ). It works and it's cheap, and you only use a 1/4 teaspoon per gallon of water. Another great organic acid product based on oregano is Siegel's ecol tonic ( https://www.siegelpigeons.com/product/ecol-tonic-gallon/ )... it's definitely more expensive but also a very nice product. To be clear though... all these products and methods are basically a preventative type measure. None of them are really meant to be a cure for any disease.
