I tried avi-culture and benebac for birds but they had no benefit. I was told that many products that are sold for pets are low quality that includes bird probiotic and it is best to go for the human grade probiotic.
I have been using Bio-k for myself since 2007 and that works very well for me. One of my local Avian vets said that it was a very good product and that I could give it to my birds. It has not seemed to work so well because parrotlets are so small and they have such a fast metabolism that the good bacteria does not work in a severely deprived or compromise gut.
For this reason, Dr. K in Florida uses healthy bird poop therapy but it may be done in a manner that has to be administered by the vet. Since I am not a vet, I don't want to take the risk of giving the wrong amount of bacteria that could harm him. I have been trying coconut butter and healthy food but he is fighting a long infection; fatty tumor disease and was a neglected rescue with genetic defects.
Little NuNu is a sweet boy and I have been trying to find the secret sauce to get his energy back.