Young pigs don't NEED alfalfa. They need extra calcium in their diets, and alfalfa is just a (sometimes) convenient way to give it to them. But alfalfa pellets will do the same thing, as will a few sprigs of parsley. They really need a grass hay, such as timothy, brome, blue, meadow, orchard, and they need it ALL the time. Alfalfa is a legume, like peas.
They need a plain hay pellet, no nuts, seeds or colored bits added. KMS Hayloft has excellent pellets. Oxbow is fine for young pigs, but older pigs have calcium issues because of the calcium source in Oxbow.
They need something with vitamin C in it, as they can't make their own. Bell peppers are good. A young pig needs half a cup or so of veggies a day, increasing to a cup or more when they're adults. See
https://www.guineapigcages.com/foru...vy-Nutrition-Charts-amp-Poisonous-Plants-List for what pigs can eat, and how often.