KittenGro Milk Replacer Powder Newborn Kittens by Grober Pets. KittenGro milk replacer by Grober Pets is the only milk replacer on the market Made in Canada. KittenGro contains natural bovine colostrum to support early immune system development, is made from high quality human grade ingredients, and is extremely palatable and easy to mix. This milk replacer powder does NOT require refrigeration once opened, and is shelf stable at room temperature until expiry. This can also be used as a treat or meal topper for adult cats.