If can, grow grass seeds in big seed trays standing in same size gravel trays ,so you never let it dry out, to feed to piggies, if you can place tray down for them when the grass is 3-4 inches high, and if it's taken away from them as they eat it, my lot about 1/2hour. you can water it to grow again, how many trays is up to how often you want t to give it. I only do this in winter time, as l forage fresh the rest of the year. Be carefull of the seeds you give as some have a fungicides added. I use grass, wheat and corn.