The alternative is commercial gerbil pet food. Always have a dish of dried food in the cage for your gerbil to avail itself. Gerbils are very active and need a constant supply of food. However, a sick gerbil may overeat or over-drink and become fat. For the sake of its health, you have to put it on a diet by restricting its amount of food.
Preventive medicine is the best medicine.
Cures for illnesses are expensive for these tiny rodents. Cleanliness and hygiene are preventive medicine measures. Overcrowding may compromise the gerbil's health by contagious spread of diseases. Symptoms of illnesses are diarrhea, runny eyes and nose, unhealthy skin, lethargy, excessive scratching and loss of appetite. Please bring your gerbil to the vet for diagnosis and treatment.