I too doubt whether vets know very much about nutrition - but at least the vet actually read the tin label, and this product has taurine, and vitamins A, D and E added, which suggests it is scientifically constituted - magnesium is 0.008%, and phosphorus 0.2% - I have to assume that as both are mentioned the manufacturers are aware they should be kept low
I guess we have to trust something, as the cats have to eat - I personally have concerns about a raw diet as so many additives are made to meat - I'd rather trust a made for cats food