Brown rice and prey model for dogs

Hi there, is brown rice good for dogs? My aunty is concerned about an older dog she wants to feed and I am researching for her, as a raw feeder myself. He does get canned dog food, but dislikes it. He can tolerate chicken, cooked. However, he is on his last legs, being over thirteen years old and has issues, such as joint pain. She wants to feed him raw, as she has seen me do it for my puppy, and understands that raw is better. I recommended chicken neck bones, for joint health, however he has no teeth and therefore would like to know how best to go about this, as I do not have a meat grinder.

With my next question, how does BARF differ from prey model and how do I work out the amounts needed to feed a growing puppy? My puppy is five months old, a large cross breed puppy. At the moment, she is over 14 kilos, about 16 I would say. She eats raw mince, chicken neck bones, raw eggs, olive oil, sometimes liver or heart. She gets brain. She gets yoghurt too and pure powdered colostrum. In a meal, she gets, mince and bones, with yoghurt sometimes. She does get a raw egg sometimes, and the olive oil, though not always together. Same with powdered colostrum. The offal is also not an everyday item. She also gets raw goats milk to drink, almost twice daily, with fresh water throughout.