Well, I said I'd tell it all... And this has been an experiment.
The ISA x malay cockerels were at the right age to process today. And as they were beginning to square up to one another, it was time to make a move.
I locked them in their night roost last night, so they couldn't come out foraging this morning. Then at 7am I went in, captured the four that were going for the pot, and put them somewhere dim and quiet away from where it was all to be done (chickens are highly visual and recognise death, even from a distance). Since this is all about being as humane as possible, I made sure each bird was done quickly (I use the neck dislocation method). Each bird was processed fully, and the area cleaned up, leaving nothing that could upset the next one.
The only difference to my usual method was in skinning instead of plucking, because I was pressed for time. This results naturally in a slightly lighter carcass. Still, the leghorn malay crosses I've processed in the past have been over 2kg at 16 weeks. These ISA crosses were mostly in the 1.5kg range, not a great result. All but one of the birds were in good health with clean, deeply coloured livers, normal organs, thick gizzard walls, and no signs of worms in the digestive tracts.
The last cockerel weighed only 1.1kg dressed, but this little one obviously had a problem processing food. When I looked at the carcass, I saw no signs of ill health except a bit of a hunched back (probably a congenital deformity). Then I studied his insides further and found the oddest thing of all: complete absence of a gall bladder! His other organs were normal. It was an unusual find.
So the two remaining cockerels, which are nicely grown and would probably weigh around 1.6-1.7kg if processed, will perhaps not be worth keeping as breeders after all. Looking at the other birds of this cross, the frames are simply too small to make decent table birds at 16 weeks, when other factors (like crowing, fighting and treading hens) come into play.
This wasn't a bad experiment, as the pullets from this cross should make excellent layers (I'll be watching for age of onset and production levels, as well as broodiness, quickness of moulting and other influences on egg count). But for table birds, I think 16 weeks should be sufficient time to have 2.2kg dressed weight. Earlier malay-leghorn crosses were around that mark.
Back to the drawing board!