Thanks everyone for your helpfully suggestions. My objective in asking this question was to find out the least stressful and quickest way to do the deed to minimise any suffering for the bird and I finally decided, as there were three of us available, to use a very sharp knife and a quick beheading. The procedure I used for anyone in a similar quandary was
- keep the birds in from the night before, deprived of food for 12 hrs
- Catch each bird in turn and hood with an old sock
- carry them the 80metres to the stable and hang them up by their feet. They were completely calm once hooded and hung up
- One held the wings in a bear hug while one used the knife from the side so as to not cut through the windpipe first, the third held a paper feed sack for the blood and we first spread shavings to soak up any spillage
- The heads were severed very quickly even before the bird reacted so I was very satisfied they didn't suffer
.
This might not have been the least messy method and some blood was obviously spilt and the socks were a write off but it was quick and that was the only object not to make it the most convenient for us. We did consider the air rifle method but decided that had some potential pitfalls such as ensuring the shot hits the brain and the potential danger of a ricochet. The broom handle method is obviously viable for a single operator but is not going to be as quick and we thought therefore was potentially more stressful.
I do find with a small flock of free range turkeys slaughtering them is personally stressful as they are such communicative birds, trusting and gentle for such powerful animals. After looking after them for 4 months you do develop a bond. Maybe a larger flock which you didn't get to know so well individually would be easier.
HF