If you want to stand a chance in the show ring you really need to push a lamb from birth with the best of every thing , but the genetics need to be their in the first place . You don't say how old the lamb is , hopefully spring born off good grass 60kg ?? there are specialist ram feeds or lamb fattening pellets , soaked beet pulp , very good leafy grass , the best hay , yes chopped turnips /swedes /cabbage all good , regular min vit drench or boluses and all worm /fluke /heptavac up to date . To keep fleece /skin / body / bones as good as you can he requires no set backs and must always be improving