Imam al-Shafi'i (may Allah have mercy on him) said: "The masburah is a sheep that is tied up and then shot with arrows."
And Abu Ubayd (may Allah have mercy on him) said: "It refers to a bird or any other living creature that is tied up alive and then shot at until it is killed; the root meaning of sabr is to confine (and hold captive)."
Zahdam (may Allah have mercy on him) says: I saw Sayyiduna Abu Musa (may Allah be pleased with him) eating chicken, and he invited me. I said: I have seen this chicken eating filth. (He said:) "Come closer and eat, for I have seen the Messenger of Allah (peace and blessings be upon him) eating chicken."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19481