Remember you are feeding the lamb breast raw - not cooked...
I know similar questions have been raised on COL but can I just ask specifically with lamb breast, is there no fear of splinters with these bones? Do your dogs automatically crunch them up? If I were, for example to offer Fern raw lamb breast with the bones, a seven year old, who has never been offered raw meat before and is used to swallowing everything offered her whole 
, is there no chance that she might try to swallow these whole too and cause her to choke? 
I am not trying to put anyone off BARF at all. The theory behind it makes perfect sense to me, I just wonder -would a pup perhaps take to BARF more readily and more sensibly than an adult?
This sounds stupid now I have written it down but she is so 'enthusiastic' with her food - doesn't know what 'being picky' is. .....perhaps I should start her off with a large cow shin bone 
Ruby's 5 months, but we switched her over to raw after she had been eating complete kibble, and so I can't speak for older dogs, but she certainly ate evrything without it touching the sides - her kibble, treats - once she swallowed a hard boiled egg (shelled, obviously) in one go without chewing!
So I was concerned she'd eat too quick and choke and kept a v.close eye on her when we switched her diet. It turned out not to be a problem really as she hadn't had raw bones before and at first looked at it as if to say 'What's this - do I eat it?' And so she ate very slowly, giving it a lot of licking first. Also, I would start with bigger bones, like a big chunk of oxtail maybe, and move on to chicken wings after she's learned to eat more slowly. You could also give it to her partly frozen - that will really slow down the eating speed! We did this as we thought it would be soothing whilst Ruby was teething, and also when it''s very hot. It'll occupy her for 45 mins.
There's an article in Dogs Today about raw feeding this month which I read with interest. They start by talking about a case where a poor dog died after choking on a chicken wing. Two things popped to my attention: the owner admits she listened to others who said 'BARF's good' and just started adding stuff to their diet without doing any further reading!!! Also, she just plonked chicken wings on top of their kibble, so of course he was used to bolting down the whole meal and swallowed a bit whole which damaged his insides and caused his death. It was so very sad, but I wouldn't have switched Ruby over without extensive reading and research - I bought 5 books from Amazon - and they each have chapters in which deal with making the transition in an older dog.
