Guinea pigs make excellent pets. They love attention and become very attached to their owners, and they make an array of different sounds and noises to communicate with each other and with us. They are, however, not the easiest pets to care for. As with any cage animals they require some maintenance. In the end, it's well worth it, though!
One of the biggest mistakes Guinea Pig owners make is that they don't research the diet of their guinea pigs appropriately. They are by far one of the most difficult pets to feed, because there are 3 components to their diet, instead of just the usual one or two.
Mistake #1 is usually that people believe that feeding their pigs on a diet of rabbit pellets is sufficient. And while a lot of pigs will be ok on this they won't thrive, and will be more prone to health issues. Imagine only eating bread yourself, you could probably maintain your weight, but you would feel like crap most of the time, and your health would be compromised because you're not getting the vitamins and minerals you need to be healthy. The biggest problem with rabbit feed is that it doesn't contain Vitamin C - which guinea pigs are unable to produce on their own, so need in their diet. The other issue is that MOST rabbit pellets available in stores in SA contain a very high amount of antibiotics and other nasties that meat rabbit farmers add to the food to ensure that their animals, who are only required to live for a very short time, gain enough weight to get to slaughter.
So basically, you need to find a pellet that is guinea pig specific. It needs to be high in fiber, low in protein and contain Vitamin C.
Guinea Pigs have a digestive system very similar to those of cattle. Therefore, they need to graze all day long. If you had to make sure they had enough pellets to last them a whole day of non-stop eating you would very quickly sit with a pig that is grossly overweight, and very likely bloated because they haven't received enough roughage to clear out their intestines. It is of utmost importance that your pigs have access to unlimited amounts of fresh hay all day long. The most preferable hay available here is Oat hay, with Teff and Lucerne a close second.
Besides the above diet becoming extremely boring, pigs also need a variety of fresh fruit (limited) and vegetables daily.
As a rescue that takes in many adult male guinea pigs on a regular basis I face this question a lot. How do we introduce new guinea pigs to our existing herd without risking our dear pets' lives in the process?
Socializing female pigs is generally an easy task. Most sows are not nearly as territorial as males, and bond quickly with new inhabitants. I have only ever encountered one female who hated all but one other girl. It took me several months to find the right fit for her, but she was definitely the exception to the rule, but I did find a friend for her eventually, and they have lived happily since. Generally with sows, I do a brief introduction on neutral grounds, like a couch, the bed or the bathroom, to see how they react to one another. They usually show some interest, sharing some food is also a good way to bond them quickly. If it goes well there I will move them to their cage, which has been cleaned down properly, and I'll watch them for at least an hour to make sure they are ok. 99% of the time this works just fine.
Boys are a different story altogether.
If you have young boys, under 5 months of age (before they hit puberty) the above procedure for girls will work fine. However, you must keep in mind that boars require more space, so that if they do get into each other's hair they each have enough of their own space to cool down. I usually advise that you also provide them with 2 food bowls, 2 hay racks, and 2 water bottles, placed far enough away that one male isn't able to monopolize the supplies or that they are able to fight over it.
If you want to introduce 2 adult males it will take time, space, and patience. I have set up C&C cages in such a way that there are 2 cages directly next to one another, with only bars separating them. This gives them an opportunity to get to know one another without being able to get to one another and do actual damage. I keep them like this for about a week. I then start introducing them on neutral ground, with a towel and water squirter in hand in case something goes wrong. At first I do short sessions - 5 or 10 minutes, and then gradually work it up to longer periods of time. Once they are able to endure about an hour of being together without any issues at all I will move them into a neutral cage where neither of them has stayed, that also doesn't contain anything either of them are used to or carries their scent. Remember, boars need more space than sows, so make sure that it's a big cage. I will sit and intently watch them for quite some time to make sure that all is well, and remain vigilant thereafter.
It is easier to introduce a smaller/baby boar to an older boar. They are generally more accepting of each other, but I will still suggest a proper introduction process because the older boar may well do a lot of damage to the younger boy if he takes to disliking him.
And it is worth noting that some boars remain stubborn and refuse to pair up with another. In that case it would be best to neuter him, and introduce him into a female herd where he is the only boar.