Best practices for ranching?

No, and it's not close. You sell a 5 heart pig that finds you lots of truffles, only to buy a zero heart baby pig 18 days later, that will find fewer truffles in Spring. Per pig, you've made a net profit of 4,800g from the sale, and saved another 900g in hay, which is 5,700g to the good. But when an iridium truffle sells for 1,250g, your old pig would only need to find 5 more truffles than its potential replacement. And as the number of truffles a pig can find each day is closely linked to its friendship with you, its earnings will easily outstrip the 5,700g you "saved".

 

From my past experience, I know pigs are more profitable than sheep overall, but I plan to do both a sheep farm and a pig farm anyway.

One advantage sheep have over pigs, however (besides consistency), is that once you have Auto-Grabbers and a good pasture system going, there is literally no maintenance required. The Auto-Grabbers shear for you and eating grass offsets the friendship decay. So once the sheep are at 4.5 hearts, you can basically ignore them and then, when you want to cash in, you just pop into the barn, empty the auto-grabber, and be on your way. Pigs you need to pet often (since grass is counter-productive to truffle spawning) and run around picking up truffles (since letting truffles accumulate for too long gets in the way of new ones spawning).

Some other anecdotal observations: My experience has been that 3 truffles per pig per day is on the generous side. My last pig farm had 100+ pigs but I definitely wasn't getting 300 truffles per day; more like 100-150. I suspect that when you get that many pigs, they start getting in the way of each other and stunting their truffle spawning capacity. I wish I knew more about the game so I could examine what exactly was preventing my pigs from spawning as many truffles as they should.

Finally, as to wool quality, it definitely erred towards iridium at max friendship and I almost never saw silver wool. I think a fair assessment of the per-day profit from wool would be to average the gold and iridium wool values, at 714g/day, so 8,568g/day for a full barn. So with shepherd, I believe that a barn full of sheep will outperform a barn full of cows, even if you are aging cheese. Moreover, you max out at 125 casks, so you are only earning 644g/day/cow for up to 17 cows. Meaning sheep will always outperform cows once you get past 17 animals. Since my goal is to focus entirely on animals for profit, I am most interested in outcomes once I hit 100+ animals.

 

I agree, there's definitely a point where adding more pigs is pointless, probably because they run out of space to dig up truffles. I have a few pigs enclosed in a grassless area on one farm, I don't recall how big the area was but I'm guessing around 10x18, minus the area taken up by the barn, so maybe 150ish spaces total. When I had three pigs in there with full or close to full friendship, I was getting about 8 truffles a day. I got a fourth pig and even when it grew up and started gaining friendship, I was still getting about 8 truffles a day. So my probably very inaccurate guess based on this one piece of data would be about 50 spaces per pig.

 

So of course I was too impatient to wait until March so I went ahead and made my sheep farm soon after starting this thread. I wanted to share my results so far.

Welcome to Grazeland: https://stardew.info/planner/11-dangerous-squirrels-played-jovially/.

FARM SETUP & PROFITS
As of Summer Y2, I had 14 Deluxe Barns with 168 sheep at or near 5 hearts. (The barn and coop near the farmhouse are for personal use.) I make about 120,000g per day from wool. Around 75% of the wool is iridium quality. I get a little silver quality wool, which I spin into cloth. Other income streams include ancient fruit wine in the greenhouse, some honey, and eventually the crystalariums will be producing diamonds.

PETTING/GATHERING:
I don't pet the sheep or gather the wool every day, but when I do it takes me about 5 hours. I'm looking for ways to increase efficiency here; I'm tinkering with the idea of filling the inside of each barn with fencing or the like to force all the sheep to cluster in one area for easy petting. I'm also considering doing something similar with the pastures, because of the issues I've been having regarding the next topic.

FEEDING:
My sheep are like locusts when it comes to grass. Even in the quadrants with 2 barns per pasture, they chewed through full fields of grass in 1.5 months. I should probably resign myself to just buying hay from Marnie, but I would very much like some ideas on how to maintain some amount of grass-feeding. Maybe some sort of pasture rotation system? I'm not sure how that would even work. On the other hand, if I just embrace the hay, I can probably squeeze in a bunch more barns.

STRATEGY:
This is where I'm probably the weakest, since I'm not nearly as experienced or knowledgeable as many of you.
My Year 1 Spring strategy followed the sell-everything-and-fish method, funding my axe and pickaxe upgrades and barns with cows. While it was nice to focus on ranching from the beginning, I had to spend a lot of time fishing, even into Summer. It may well be more optimal to follow the typical Spring strategy toward quality sprinklers and then use cash crops to bankroll your ranching operation.

This time around, I didn't upgrade straight into Deluxe Barns. Instead, I would build fresh Barns on Sundays (so I could buy cows from Marnie when they finished on Wednesdays) and only upgraded into Big Barns (to enable births) after all the base structures were complete. I'm not sure if this was better than going straight into Deluxe Barns, but it seemed to make sense to prioritize building whatever would increase my animal capacity the cheapest.

I hit Farming 10 around mid-Fall, at which point I sold all but 12 of my cows and replaced them with sheep as I could afford them. I had all of my Deluxe Barns and auto-grabbers around the end of Winter Y1. I'm currently in the process of adding 2 more barns of sheep and switching my cow barn to pigs.

Any feedback or questions about my strategy and/or experience are welcome!

 

I loved your design!

When you reach farm lv10 you can purchase auto-grabbers from Marnie, on my farm take care of 5 barns don't take even 1h and it's kinda OP in terms of availability, we ranchers may not make the most money like the artisans, but surely we have more time for other things.

By your design you won't will be able to feed all your animais with grass, it is better to purchase from Marnie but you will want more Silos to be able to hang for at least one week (that's why I filled the other map with Silos), you will be surprised by how often Marnie shop is open but she isn't anywhere to be found.
Takes 108 titles to feed all the animals in one barn, that's why ranchers shold always stick with the basic layout if you want to feed them with grass (source).

The goal for a rancher is to have lv6 in farming for you to be able to make press cheese machines, I started with my cows in lv4 and took me a while for level up, so I wouldn't recommend. There's plenty of discussions here about how you can reach lv6 farming by day 13 and people will be more than happy for help since they love this kind of strategy.
I think that since you're not aiming for strawberries you can try a different kind of approach for rancher.

You should have your first barn fully upgraded and full of cows, then you build your second with the desirable animals, cows aren't that bad at make money, animals overall are good money makers, they just aren't broken as a artisan with 20 iridum sprinklers and kegs, so don't worry about the money, the cows will take care of it.