according to the above situations, you can install a 420 feed production line or two 350 feed production lines. The differences lie in: (1) If you choose two 350T/H production lines, the two pelletizing machines can operate simultaneously to produce different feeds. The production demands are met at the same time and the output is higher than that of a single 420 production line. (2) A single 420 production line can only process one kind of material. You need to shut down the machine and change the ring die for changing materials. (3) From the point of cost, the expense for two 350 production lines is about 20000 yuan more than that of a single 420 production line. Therefore, we recommend customers to choose two 350 production lines if it is affordable. This includes a set of 110kw  grinder, a set of mixing machine with 1tons and two 350 pelletizing machines. But if the investment amount is limited, the 420 feed production line is also a good option.