Fowls covert Nitrogen into Uric acid which doesn't not need as much dilution as urea(excretory product of mammals). This combined with the fact that they don't have a urethra and neither a seperate opening for urine to exit. This, the Uric acid is excreted put along with faeces through anus.
Fowl or birds do not have a separate urinary system like mammals, which is why they do not urinate. Instead, their kidneys filter waste products from their blood, which are then mixed with digestive waste and eliminated as solid excrement through their cloaca. This mechanism helps birds conserve water as they do not need to eliminate excess water in their liquid form. As fowl are adapted to their environment, their unique excretion system has evolved to suit their needs and make them efficient in their natural habitats.