There are many options for doing carnivore. I'll list both the easy and not so easy methods. Easy method 1, save scumming for pacu. Easy method 2, save scumming for shove voles, ranch them off dirt, block their movements with obsidian/pneumatic doors/1 tile-nowhere to jump to. Harder, but doable methods are shove vole hunting on the surface. It becomes a race to get there, but if you like to play on larger maps like neon eden then this method is much more difficult. The other method is ranching. Ranching doesn't take too much dupe time to get started, but it does take time for it to be a food source. The first dupe you print will have a skill point, invest that in farming. By cycle 13, he should get another skill point to invest in ranching. Actively ranch every wild critter you can. I have tried many times for a clean run preserving my wild critters, but this has proven very difficult to do even if you only ranch critters greater than 80% of their life cycle (they lay an egg after that). Pips are your friends for ranching dreckos, you will not forfeit the locavore achievement if you use wild mealwood. Wait until you've built up a supply of critters in your ranch and only kill critters when your dupes are starving and they cannot find any food. It is almost always a bad idea to have more than 3-4 dupes before you set up your ranch and incubators, instead rely on a method I call "ramping". You might have to do some math to figure out how many units of food your dupes need to eat based on how many cycles you have left. for a quick reference, not accounting for binge eating, bottomless stomach, or ravenous hunger, a normal dupe will eat 1000kcal/cycle or 1 unit/cycle. to simplify this, your dupes need to eat 400 (400000/1000) units by cycle 100. Use the mod "Achievement Progress" if you want to. The best thing to go for next after you have your ranches set up is to go for the Incubators which by themselves need to have a couple things to set up. Here is an example of the order of research you can do. You can always do research in a different order based on your map/needs.
You should get done with all of this around cycles 40-50, at which point you should look into ramping your consumption now that you have food and oxygen. You can always get dupes with binge eater to speed up the process, but sometimes this is not needed. Now for a math example. Starting with 5 dupes on cycle 51. Figuring out how many dupes you can add before cycle-100: 100-51/3 = 16.33 or just 21 total dupes. How many units will they consume: 3 * (5+6+7+8+9+10+11+12+13+14+15+16+17+18+19+20+21) = 663 total units of food. This exceeds the needed 400 by a bit. A few final notes. 1st, Always cook your meat. 2nd, baby critters cannot defend themselves when attacked and will drop the same amount of meat...I am not implying anything, that is just a fact.