We were asked to pick out the healthy ones and leave those that appear ill or very bruised. On the whole the hens that were eventually rehomed appeared fine health-wise. Those hens were already in a holding area for 2 days and given loads of food and water during that time. Short of employing a vet to check each bird , which is an extremely costly exercise (I think there's very little funding available because all participating in the rehoming exercise are really volunteering our day for these poor hens), I really cannot see what else more the BHWT could do for the birds before they are rehomed.
A vet once told me that if a bird is ill, it won't eat or drink anymore. If it stops eating or drinking for 1 day it is equivalent to a human not eating and drinking for 3 days. By the process of elimination the ill ones will probably die or appear quiet by the time the volunteers arrive to pick up and transport the hens to the adoption venue. So it is quite likely that the fairly healthy ones get rehomed.
Everyone seeking to adopt these hens is well aware of the potential health issues with the birds anyway. I do not think that anyone is that naive to think that they are getting a tiptop condition bird like that from a breeder‘s farm.
I do applaud you and other volunteers for helping to rehome these poor birds and I don't want to denigrate the the good work you have done or your compassionate motives. However your post does raise some issues of welfare that do concern me.
At one time I did consider adopting some exbatts and contacted several charities which did rehoming. I didn't go ahead as a result as I wasn't very happy with the replies I got concerning their understanding of health issues. However I was always under the impression and I think I was told by BHWT, that birds that were rehomed were first inspected by a vet. Of course I don't expect that every bird is going to get a full medical examination however I would have expected that if birds in a flock were showing signs of sickness that a sample examination of those birds would have been done to ensure that they weren't carrying an infectious illness. Maybe this happened prior to your arrival.
I'm afraid I don't share your confidence about the expectations of those adopting these birds. Not everyone will be aware of the issues or be experienced enough to cope with them. I doubt they will all understand the need and have the facilities to quarentine the birds. Sadly there's plenty of posts on this site and others from first time keepers who were given exbatts and were ill prepared for the problems they faced. It might well be reasonable to expect and I would have hoped, that they do a little more research before they take on exbatts however they often don't. It appears some rehoming charities (I don't know if BHWT is one) are quite willing to give the exbatts to inexperienced keepers.
In a flock if some birds have an infection it's almost certain that they all have been exposed and are potential carriers and will become sick in time whether they appear ill or not. Distributing such birds to inexperienced keepers just spreads disease puts healthy birds at risk and does the whole community of backyard keepers a disservice.
There are millions of layers slaughtered each year and only a small fraction are rehomed. Some are already kept in a "free range" environment and are more suited to rehoming. Given that some selection must occur it surely makes sense that only the most healthy ones should be rehomed and the sick ones should go for slaughter. It is therefore not unreasonable to expect that only healthy birds will be offered for adoption.
The poultry industry miight not be everything we might hope in terms of animal welfare but it is a "closed loop system". Birds raised for laying are contained and slaughted in "all in all out" batch system. The chances that any dangerous diseases can migrate from farms to backyard keeping was relatively low however rehoming open loops this and provides a direct path. Moreover rehoming, as far as I'm aware is largely unregulated so having self imposed tight procedures would seem very sensible. We all know about the lessons which were learned from BSE and this happened totally unexpectedly inside a seemingly well regulated and well understood industry. Rehoming is a relatively new thing and the potential for disaster I suspect is little understood.
If anyone has any first hand insights into how these charities operate and how they ensure that rehomed birds are healthy and aren't a source of disease for backyard poultry I'd be interested to hear.
HF