Abu Ubayd (may Allah have mercy on him) said: "Do not take from their choicest wealth; rather accept the old one, and the bakr, that is, a young camel." And this was at the beginning of Islam, before people had learned the Shari'ah.
The Shaykh (may Allah have mercy on him) said: This hadith is mursal. In our view, it is conceivable that when all the livestock are defective and male, the male, the young and the defective may be taken.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7311