I'll second on selecting a reputable hatchery within moderate shipping distance for a source.
As far as age to butcher, Welp Hatchery has, on their site, a chart, showing the typical feed to weight conversion of CornishX cockerels and pullets, by week. Take a look at their charts http://www.welphatchery.com/cornish_rock_care.asp and you'll see that the maximum conversion typically occurs in week 7, dropping off just slightly in week 8, and more so in week 9, which is as far as the chart goes. It's the efficiency of the creatures that make the meatbirds so remarkable, and that peak at week 7/8 is the FIRST reason for that being the customary age for butchering. So, for economy/efficiency in feeding a large family, you'll be better off buying and feeding more birds to butcher at that age than in feeding fewer birds for another several weeks.
If it's a matter of a 5-6# bird being one serving short of making a meal for your brood, then going that extra week or so may make more sense. If you need to go that route, that comes to the OTHER reason. I'd strongly recommend the 12-on/12-off feeding regimen and provide conditions that avoid any stress such as heat or crowding that would tend to exacerbate the congestive and other issues that are a characteristic of the CornishX's. Between their nature and any stresses, you could start losing them after that 8-week point, sacrificing any efficiency you hoped for from that extra 2-4 weeks. I've never tried to push them to 12 weeks, so can't offer any experience, but it strikes me as a pretty dicey proposition on the agggressive feeding program that gets them to weight at 8 weeks.
There are no end of stories of folks who have raised them to an age where the pullets start to lay, and the cockerels start to crow, but their feed has to be restricted even more than the 12/12 program, and they're just not the efficient meat -makers that they are when grown on the 8-week program.
Bottom line, for economy 8 weeks is prime. For an extra serving per bird, 9-10 weeks can be done with good and attentive care. Feeding them for efficiency beyond that point may be counter-productive.
As far as age to butcher, Welp Hatchery has, on their site, a chart, showing the typical feed to weight conversion of CornishX cockerels and pullets, by week. Take a look at their charts http://www.welphatchery.com/cornish_rock_care.asp and you'll see that the maximum conversion typically occurs in week 7, dropping off just slightly in week 8, and more so in week 9, which is as far as the chart goes. It's the efficiency of the creatures that make the meatbirds so remarkable, and that peak at week 7/8 is the FIRST reason for that being the customary age for butchering. So, for economy/efficiency in feeding a large family, you'll be better off buying and feeding more birds to butcher at that age than in feeding fewer birds for another several weeks.
If it's a matter of a 5-6# bird being one serving short of making a meal for your brood, then going that extra week or so may make more sense. If you need to go that route, that comes to the OTHER reason. I'd strongly recommend the 12-on/12-off feeding regimen and provide conditions that avoid any stress such as heat or crowding that would tend to exacerbate the congestive and other issues that are a characteristic of the CornishX's. Between their nature and any stresses, you could start losing them after that 8-week point, sacrificing any efficiency you hoped for from that extra 2-4 weeks. I've never tried to push them to 12 weeks, so can't offer any experience, but it strikes me as a pretty dicey proposition on the agggressive feeding program that gets them to weight at 8 weeks.
There are no end of stories of folks who have raised them to an age where the pullets start to lay, and the cockerels start to crow, but their feed has to be restricted even more than the 12/12 program, and they're just not the efficient meat -makers that they are when grown on the 8-week program.
Bottom line, for economy 8 weeks is prime. For an extra serving per bird, 9-10 weeks can be done with good and attentive care. Feeding them for efficiency beyond that point may be counter-productive.
