Your cavies wheek because they are hungry!
I formerly fed my cavies morning and evening, but it became a problem in that it was almost impossible to have someone come in twice a day in the event that we were out of town for a couple of days. When we got our current boys, they were babies and knew nothing but hay and pellets. We decided to feed once a day in the late afternoon/early evening. By feeding at this time, they are quite satisfied and sleep through the night. We feed a large salad that generally consists of spring mix, peppers, green beans, and red cabbage or radicchio. They sometimes get a snack of corn husks, dandelion or other favorites around 3pm.
Because I feed veggies only once per day, I feel that they should have access to pellets 24/7 as well as unlimited hay. And, it's just too long for them to go overnight and half the day with no pellets. My boys maintain a stable weight and rarely wheek for food unless it is approaching the dinner hour. I'm not adverse to "tough love" and rarely feed them earlier than dinner time even if they are restless and begging. Cavies need a predictable routine and come to depend on a regular feeding time whenever possible. You probably should experiment and see what schedule works for both you AND your cavies.
