牛粪是牛的粪便，其中有许多未消化的植物残质，含有丰富的矿物质，颜色由绿色到黑色不等，在和空气接触后颜色会变暗。

干牛粪可用来做燃料、肥料。是可再生能源之一。蚯蚓及蜣螂可以清理牛粪，若牛粪没有被这些昆虫清理，牛粪会干掉。

牛粪也可以用来产生生物气体，可用来发电或产生热量。

干牛粪是很好的燃料，可再生能源，亦可以用于建房筑墙，「捡牛粪」在早期的乡村是一种副业／工作。

Cow dung, also known as cow pats, cow pies or cow manure, is the waste product of bovine animal species. These species include domestic cattle ("cows"), bison ("buffalo"), yak, and water buffalo. Cow dung is the undigested residue of plant matter which has passed through the animal's gut. The resultant faecal matter is rich in minerals. Colour ranges from greenish to blackish, often darkening soon after exposure to air.