While feed texture and particle size greatly influence the initial selection of feed, there are complex biochemical process which regulate the fact that a layer usually eats about 110g of feed each day, or that a 40-day-old broiler consumes around 250g daily. Gut fill has some effect on short-term feed intake of chickens. Anyone who has palpated the crop on a 15-week-old broiler breeder pullet 2 hours after feeding may think that filling of the crop has a satiety effect on the bird. However, there is little evidence that crop-fill has a meaningful effect on intake because there are virtually no nerve endings in the crop which would be necessary to initiate a control feedback mechanism. The effect of crop-fill on feed intake is therefore very minor.