Yahya related to me from Malik from Thawr ibn Zayd ad-Dili from a son of Abdullah ibn Sufyan ath-Thaqafi from his grandfather Sufyan ibn Abdullah that Umar ibn al-Khattab once sent him to collect zakat. He used to include sakhlas (when assessing zakat), and they said, "Do you include sakhlas even though you do not take them (as payment)?" He returned to Umar ibn al-Khattab and mentioned that to him and Umar said, "Yes, you include a sakhla which the shepherd is carrying, but you do not take it. Neither do you take an akula, or a rubba, or a makhid, or male sheep and goats in their second and third years, and this is a just compromise between the young of sheep and goats and the best of them."
Malik said, "A sakhla is a newborn lamb or kid. A rubba is a mother that is looking after her offspring, a makhid is a pregnant ewe or goat, and an akula is a sheep or goat that is being fattened for meat."
Malik said, about a man who had sheep and goats on which he did not have to pay any zakat, but which increased by birth to a zakatable amount on the day before the zakat collector came to them, "If the number of sheep and goats along with their (newborn) offspring reaches a zakatable amount then the man has to pay zakat on them. That is because the offspring of the sheep are part of the flock itself. It is not the same situation as when some one acquires sheep by buying them, or is given them, or inherits them. Rather, it is like when merchandise whose value does not come to a zakatable amount is sold, and with the profit that accrues it then comes to a zakatable amount. The owner must then pay zakat on both his profit and his original capital, taken together. If his profit had been a chance acquisition or an inheritance he would not have had to pay zakat on it until one year had elapsed over it from the day he had acquired it or inherited it."
Malik said, "The young of sheep and goats are part of the flock, in the same way that profit from wealth is part of that wealth. There is, however, one difference, in that when a man has a zakatable amount of gold and silver, and then acquires an additional amount of wealth, he leaves aside the wealth he has acquired and does not pay zakat on it when he pays the zakat on his original wealth but waits until a year has elapsed over what he has acquired from the day he acquired it. Whereas a man who has a zakatable amount of sheep and goats, or cattle, or camels, and then acquires another camel, cow, sheep or goat, pays zakat on it at the same time that he pays the zakat on the others of its kind, if he already has a zakatable amount of livestock of that particular kind."
Malik said, "This is the best of what I have heard about this. "

حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ ثَوْرِ بْنِ زَيْدٍ الدِّيلِيِّ، عَنِ ابْنٍ لِعَبْدِ اللَّهِ بْنِ سُفْيَانَ الثَّقَفِيِّ، عَنْ جَدِّهِ، سُفْيَانَ بْنِ عَبْدِ اللَّهِ أَنَّ عُمَرَ بْنَ الْخَطَّابِ، بَعَثَهُ مُصَدِّقًا فَكَانَ يَعُدُّ عَلَى النَّاسِ بِالسَّخْلِ فَقَالُوا أَتَعُدُّ عَلَيْنَا بِالسَّخْلِ وَلاَ تَأْخُذُ مِنْهُ شَيْئًا . فَلَمَّا قَدِمَ عَلَى عُمَرَ بْنِ الْخَطَّابِ ذَكَرَ لَهُ ذَلِكَ فَقَالَ عُمَرُ نَعَمْ تَعُدُّ عَلَيْهِمْ بِالسَّخْلَةِ يَحْمِلُهَا الرَّاعِي وَلاَ تَأْخُذُهَا وَلاَ تَأْخُذُ الأَكُولَةَ وَلاَ الرُّبَّى وَلاَ الْمَاخِضَ وَلاَ فَحْلَ الْغَنَمِ وَتَأْخُذُ الْجَذَعَةَ وَالثَّنِيَّةَ وَذَلِكَ عَدْلٌ بَيْنَ غِذَاءِ الْغَنَمِ وَخِيَارِهِ . قَالَ مَالِكٌ وَالسَّخْلَةُ الصَّغِيرَةُ حِينَ تُنْتَجُ . وَالرُّبَّى الَّتِي قَدْ وَضَعَتْ فَهِيَ تُرَبِّي وَلَدَهَا . وَالْمَاخِضُ هِيَ الْحَامِلُ . وَالأَكُولَةُ هِيَ شَاةُ اللَّحْمِ الَّتِي تُسَمَّنُ لِتُؤْكَلَ . وَقَالَ مَالِكٌ فِي الرَّجُلِ تَكُونُ لَهُ الْغَنَمُ لاَ تَجِبُ فِيهَا الصَّدَقَةُ فَتَوَالَدُ قَبْلَ أَنْ يَأْتِيَهَا الْمُصَدِّقُ بِيَوْمٍ وَاحِدٍ فَتَبْلُغُ مَا تَجِبُ فِيهِ الصَّدَقَةُ بِوِلاَدَتِهَا قَالَ مَالِكٌ إِذَا بَلَغَتِ الْغَنَمُ بِأَوْلاَدِهَا مَا تَجِبُ فِيهِ الصَّدَقَةُ فَعَلَيْهِ فِيهَا الصَّدَقَةُ وَذَلِكَ أَنَّ وِلاَدَةَ الْغَنَمِ مِنْهَا وَذَلِكَ مُخَالِفٌ لِمَا أُفِيدَ مِنْهَا بِاشْتِرَاءٍ أَوْ هِبَةٍ أَوْ مِيرَاثٍ وَمِثْلُ ذَلِكَ الْعَرْضُ لاَ يَبْلُغُ ثَمَنُهُ مَا تَجِبُ فِيهِ الصَّدَقَةُ ثُمَّ يَبِيعُهُ صَاحِبُهُ فَيَبْلُغُ بِرِبْحِهِ مَا تَجِبُ فِيهِ الصَّدَقَةُ فَيُصَدِّقُ رِبْحَهُ مَعَ رَأْسِ الْمَالِ وَلَوْ كَانَ رِبْحُهُ فَائِدَةً أَوْ مِيرَاثًا لَمْ تَجِبْ فِيهِ الصَّدَقَةُ حَتَّى يَحُولَ عَلَيْهِ الْحَوْلُ مِنْ يَوْمَ أَفَادَهُ أَوْ وَرِثَهُ . قَالَ مَالِكٌ فَغِذَاءُ الْغَنَمِ مِنْهَا كَمَا رِبْحُ الْمَالِ مِنْهُ غَيْرَ أَنَّ ذَلِكَ يَخْتَلِفُ فِي وَجْهٍ آخَرَ أَنَّهُ إِذَا كَانَ لِلرَّجُلِ مِنَ الذَّهَبِ أَوِ الْوَرِقِ مَا تَجِبُ فِيهِ الزَّكَاةُ ثُمَّ أَفَادَ إِلَيْهِ مَالاً تَرَكَ مَالَهُ الَّذِي أَفَادَ فَلَمْ يُزَكِّهِ مَعَ مَالِهِ الأَوَّلِ حِينَ يُزَكِّيهِ حَتَّى يَحُولَ عَلَى الْفَائِدَةِ الْحَوْلُ مِنْ يَوْمَ أَفَادَهَا وَلَوْ كَانَتْ لِرَجُلٍ غَنَمٌ أَوْ بَقَرٌ أَوْ إِبِلٌ تَجِبُ فِي كُلِّ صِنْفٍ مِنْهَا الصَّدَقَةُ ثُمَّ أَفَادَ إِلَيْهَا بَعِيرًا أَوْ بَقَرَةً أَوْ شَاةً صَدَّقَهَا مَعَ صِنْفِ مَا أَفَادَ مِنْ ذَلِكَ حِينَ يُصَدِّقُهُ إِذَا كَانَ عِنْدَهُ مِنْ ذَلِكَ الصِّنْفِ الَّذِي أَفَادَ نِصَابُ مَاشِيَةٍ . قَالَ مَالِكٌ وَهَذَا أَحْسَنُ مَا سَمِعْتُ فِي ذَلِكَ .