[Machine] There is no harm in castrating horses, as leaving stallions together would result in them attacking and harming each other. This is also in line with the statements of Ibn Umar and Ibn Abbas, as well as the established Sunnah. With the help of Allah, it is possible to accept this if there is a valid purpose for it, as we have heard from the companions and recorded in the book of Al-Dhahaya the sacrifice of the Prophet ﷺ with two rams, which was done for the pleasantness of the meat.  

بَأْسَ بِإِخْصَاءِ الْخَيْلِ لَوْ تُرِكَتِ الْفُحُولُ لَأَكَلَ بَعْضُهَا بَعْضًا وَعَنْ عَطَاءٍ مَا خِيفَ عِضَاضُهُ وَسُوءَ خُلُقِهِ فَلَا بَأْسَ بِهِ وَمُتَابَعَةُ قَوْلِ ابْنِ عُمَرَ وَابْنِ عَبَّاسٍ ؓ مَعَ مَا فِيهِ مِنَ السُّنَّةِ الْمَرْوِيَّةِ أَوْلَى وَبِاللهِ التَّوْفِيقِ وَيُحْتَمَلُ جَوَازُ ذَلِكَ إِذَا اتِّصَلَ بِهِ غَرَضٌ صَحِيحٌ كَمَا حَكَيْنَا عَنِ التَّابِعِينَ وَرَوَيْنَا فِي كِتَابِ الضَّحَايَا تَضْحِيَةَ النَّبِيِّ ﷺ بِكَبْشَيْنِ مَوْجُوءَيْنِ وَذَلِكَ لِمَا فِيهِ مِنْ تَطْيِيبِ اللَّحْمِ