Goats are pretty simple too feed, or at least I like to keep it simple, but some feeds are a better pick than others. Ultimately, with any feed you choose, you’ll want to make sure you’re buying high quality fresh feed that is mold free. 
Hay
If your goat doesn’t have access to pasture, they’ll need to have hay. I think the best overall hay to feed any age or gender of goat is going to be a grass/alfalfa mix. With a mixed hay they’ll get a variety of nutrients. I prefer a ratio of 40% alfalfa and 60% grass hay like Bermuda, Brome, or Timothy.
For kids and pregnant does you’ll want to increase the amount of alfalfa for those extra calories to help increase milk production in your does and growth with young kids’ up to about 6 months of age. There’s controversy on whether or not feeding pure alfalfa is actually dangerous for bucks and wethers. Personally, I think too much of anything can be a bad thing. I think that straight alfalfa is too rich for bucks and wethers, and that they don’t really need it unless it’s breeding season or you do a lot of work with your boys like packing or shows. Otherwise, I think doing a mix should be just fine. Alfalfa pellets are a good no waste option as well. 
Chaffhaye is becoming a popular feed referred to as “pasture in a bag”. It’s alfalfa (non GMO) that’s been sprayed with molasses and then bagged where if ferments and breaks down. This makes it easier to digest and can offer some nutrients that traditional alfalfa may not. Personally, I like the product itself but wish it was just a little cheaper. I haven’t done the math but it’s supposed to be more economical due to “no waste” which is supposed to justify the cost. I’ll have to look into that. In general, I use it as a treat of sorts to mix things up for the goats. Otherwise I’ll also use it for pregnant does, as many have said that it increases milk production, and for young growing kids. It may also be a good choice for senior animals for easier digestion. UPDATE: I purchased a 50 lb bag of Chaffhaye, which costs about $15.50 where I get it, and found that it lasted for about 6 meals, or 3 days . A bale of hay for me costs $11.25-12.25 per bale, and I use 1.5 bales in 3 days which would be about $16-18. So at the current high cost of hay, I am saving roughly $.50-2.50 every 3 days or $60-300 per year. Should the cost of hay come back down to $10 per bale or less, than it would be more expensive to feed the Chaffhaye.
How Much To Feed: When it comes to hay, most will free feed their goats. Personally, unless they are in milk, I like to monitor what they eat. A normal 60-70 lb bale lasts my 8 dwarf goats about 2 days. I just look at what condition my goats are in and either increase or decrease their feed from there. Otherwise, the general rule of thumb is about 2-4 pounds of hay per goat. With Chaffhaye, according to their website, you’ll feed about 1 pound per 50 lb goat.
Grain/Pellets
The only time I ever use grain is for pregnant does or young kids. Otherwise, it’s a rare treat about 1-2 times per month. I like to mix my own grain mix of barley and oats with some BOSS and pumpkin seeds. I don’t use pellets as I see those as crap feed. I’ve never liked the list of ingredients on bags of pellets so at best I would consider mixing a little in with my own grain for a picky doe.
How Much To Feed: Many breeders go by feeding 1 pound of grain per 3 pounds of milk produced. I figure roughly 2 cups per day for a regular sized goat in milk, ½ cup per day for babies, half of each of those for miniature breeds.
Supplements
Loose Mineral: You’ll want to provide loose mineral to all of your goats so that they can get whatever minerals they may be missing in their feed. They’ll know how much they need. Avoid buying the blocks you may see for sale in the store for goats, they will not obtain what they need through licking a mineral block as lose interest in it.
Baking Soda: Baking Soda is another good one to provide free choice to your goats. I’ve heard mix things on giving it to bucks so I just give it to them occasionally. It’s mainly good for goats getting grain to help aid in digestion.
Additional: 
BOSS: Otherwise known as black oil sunflower seeds is mainly used to shine up your goat coat and has the added benefit of some trace minerals in it.
Kelp: This can give your goat some added iodine or selenium in their diet. A small amount goes a long way. They should only need a pinch or so in their feed.
Pumpkin Seeds: These act as a natural dewormer, containing a certain characteristic that paralyzes parasites, and keeps them from clinging to the walls of the digestive track.
And there you have it, it can be as easy or complicated as you make it.
