I would say any liquid, either ingested or secreted, but in most part, peristalsis (the wavelike muscular contractions of the alimentary canal) of the gut does most of the contribution in allowing food to be passed through.
Fiber.
fibre helps prevent constipation.
fibre helps the feces to form bolus. Fibre is not at all digested in the gut. It moves all the way through the gut sticking to the feces and makes it bolus for easy passage.
digested food is just molecules. undigested food is far too big to pass through the intestine wall.
fud makes it digeste throught the gut
Food of fish does not enters gills but pass on to gut, while water passes through gills.
It is important to know what is being eaten. Roughage is indigestible material in vegetables, that helps the gut pass food and waste.
So the intestine can contract and son the food passed through the gut can pass on
It helps you digest your food
they helps on digesting the food you eat!
Fibre helps the gut muscles to move the food along the gut. It makes the gut muscles work.
An insect's pharynx works by contracting muscles to help push food downwards toward the esophagus. The pharynx also helps regulate the flow of air during respiration by controlling the opening and closing of the respiratory system. Insects have a tube-like structure that extends from the pharynx to the gut, allowing for both food and air to pass through.