Eating straw is usually ok as long as the straw isn't moldy and as long as they don't eat too much of it. To make sure they aren't eating too much, you would need to keep a close eye on their weight and body condition, and the amount of hay and pellets they are eating. You want your rabbits to maintain a healthy body weight.
Straw is pretty much devoid of nutrients(it's mostly fiber)j, so if they are eating too much straw and not enough of their higher nutrient foods(pellets, grass hay, veggies) and start to get too skinny because they aren't getting enough protein and the right nutrients, this wouldn't be good. So as long as they stay at a healthy weight and maintain this weight, eating the straw shouldn't be a problem. If they start to lose weight, the straw would need to be replaced with something else like grass hay or non edible rabbit safe bedding, so they will start eating their hay again. Increasing pellet rations might be an option as well(provided they eat the extra pellets), to balance out the increased consumption of straw and help increase their protein and nutrient consumption.
- eating some straw is fine
