Welcome to the forum from Louisiana, glad you joined.
Hey guys I had a question regarding dual purpose birds and the best age to slaughter.. I’ve read it’s 16-20 weeks ideally for the rooster but is this also the case for any extra hens that I don’t want to keep over the winter for eggs? Thanks for helping a rookie
I eat dual purpose cockerels and pullets. They are different. My preference to process cockerels is around 23 weeks, though I start thinning them down at 16 weeks. One of my goals is to play with genetics and the way I do that means I almost always keep one cockerel to be my flock master every year. At 16 weeks I start processing the rejects and by 23 weeks I make my final selection. We all have our own different goals so what is best for one person is often not the best for someone else. I generally don't process most pullets until about 8 months. I keep some as replacements every year so I want to evaluate their laying before I make that final selection but some of the obvious rejects get butchered as young as 4 months.
One difference you will find between cockerels and pullets is fat. The boys are not going to have very much fat on them compared to the girls. The girls store up a lot of extra fat, it's what they mostly live off of if they go broody. If you haven't butchered yet don't let that fat make you think something is wrong. Just a warning.
To me the big difference in pullets and cockerels, other than size, is the hormones of puberty. Cockerels generally start puberty at 4 to 5 months but some can start at 3 or may not until 6 months. Those hormones can take over their behaviors but they also affect the meat. They flavor the meat. Some of us like that flavor, others call it "gamey" and don't like it at all. Another change is texture. The meat gets tougher or stringy. That affects the way you need to cook them. I bake mine slowly at a low temperature, it gets fall off the bone tender, but if you are going to fry or grill you need to butcher them earlier. A third effect of the hormones is the connective tissue. I skin mine instead of pluck so it is really noticeable. The cockerels grow connective tissue that connects the skin to the bones, bones to each other, and meat to bones. If you pluck them you probably won't notice, but the older they get the more tissue. If you try skinning a mature rooster you are in for a workout.
I haven't paid that much attention to when pullets really slow down growing. They will add some weight after they start laying but it is really slow. The pullets should be smaller than cockerels for dual purpose breeds. Size doesn't bother me, there are only two of us so the way I cook them I can get two meals out of a small pullet. For some people size is extremely important. I'd think that after 4 to 5 months their rate of growth is really slow. As they age the girls will develop flavor, texture, and connective tissue but it is nothing like the boys with the hormones. I can cook my 8-month-old pullets like I do the 16-week-old boys. They are just as easy to skin and have not developed that gamey flavor. Even two or three year old hens are as easy to skin as the 23 week old cockerels. They do develop texture and the flavor is not as "gamey" as the boys. Older hens are excellent for chicken soup or say chicken and dumplings.
When you butcher your pullets (and cockerels) will depend on your goals and maybe how you raise them. If you are buying most of what they eat you might want to butcher earlier. Mine forage for a lot of their food so I can afford to keep them longer.
For my goals, the way I keep them, and the way I cook them the best time to butcher my cockerels is in the 16 to 23 week window and around 8 months for my pullets. I have no idea what is the best time for you with your goals and such.