Neighbors leaned out their windows to watch and cheer, or snap cellphone pictures. Little boys daubed their hands in the blood and spattered one another, and teenagers helped remove steaming entrails from the carcasses. Scores of people pressed forward to buy fresh meat for the ritual holiday meal, standing in puddles of clotted gore.

For most Muslims, the holiday, which ended Friday night, is a joyful time with a charitable theme: according to tradition, a third of the slaughtered meat is to be given to relatives, and a third to the poor. It is a welcome gift in Egypt, where the price of meat has been rising and many families cannot afford it.

What bothers Ms. Abaza and other activists is not the principle of Id al-Adha  the Feast of Sacrifice  which commemorates the biblical story in which God allows Abraham to slaughter a ram instead of his own son. Nor do they object to animal slaughter itself (Ms. Abaza is not a vegetarian).

Instead, they complain that many butchers fail to abide even by Islam’s own strictures: that the animal should not be mistreated, and should not see or hear other animals being killed.

Amateurs slaughter their own sheep at home in many Arab countries, with no special training on how to spare the animals pain. It is common to see men hurling terrified sheep into the backs of trucks, and beating the animals as they herd them to the killing grounds. In abattoirs, some workers sodomize the beasts with knives to drive them into the pens, Ms. Abaza and other activists said.