After being on here so long and reading how different cats are on brands besides sd i figure i would switch(its 3-4 dollars cheaper a bag anyway-and using 6 bags a month...) I have always done the mixing thing-1/5 new..wait then increase it. well on the first week of 1/5 I have had 3 cats from one litter show issues(gas, BLOODY diarthea and puking) and a couple others are doing the same...does anyone know anything in nutro that is not in sd. the cats are misserable and house STINKS!!! like the 24 cats in it... I have replaced the litter twice and had to give a few baths. definatley getting off this nutro junk. now i am curious for things to look out for...these are cats who get treats of friskies with no problem. I bought the bag of nutro from petsmart and its a high turnover rate and no problems with other bags fo food from them thanks for any input