Guinea pigs need a good amount of vitamin C in their diet because they are prone to scurvy if they are deficient.
Oranges can cause problems if you feed them too much. Even though fructose is natural fruit sugar, it can upset the guinea pigs' digestive system.
Limit your serving Portions. Compared to a guinea pig, an orange is large. A single orange segment is more than enough for your pet and should be offered no more than twice a week.
Here's another healthy treat for your guinea pig! you can also provide your guinea pigs with a range of other healthy treats such as apples, broccoli, grapes, cherry, strawberry, etc.