Every little buff counts when it comes to DPS, so naturally your pet should be no exception. Don't leave your pet starved and weak when you take them into a raid. Give them the good stuff: Spiced Mammoth Treats. It's an often overlooked item. It provides a nice little buff for your pet, stacks with all other raid buffs (since it counts as well fed for your pet), and it really doesn't take that much effort to farm the materials. It requires 400 cooking and the recipe calls for 1x Chunk o' Mammoth and 1x Northern Spices.

You'll find that Chunk o' Mammoth on most servers is extremely overpriced in the auction house, so your best bet is to probably farm them yourself. I've found that the best location is just NE of the Glimmering Pillar in Sholazar Basin, since most of the mammoths there tend to drop 2 a piece. The Shattertusk Bulls have a very nice drop rate, and their spawn rate/quantity seems much higher than the Shattertusk Mammoths you'll find roaming around the northwest even though the Shattertusk Mammoths do have a higher drop rate. So stop neglecting your pets and get hunting!