Hungry sheep

These sheep are in the field behind my mothers house, I was amazed when I took something out to the garden, that they all perked up when they saw me & charged across to the fence- one of them tried to climb the fence. Usually they ignore you or run away. There was nothing to eat but icy grass so I went into Montrose & bought some neeps, chopped them in big bits with a spade & chucked them onto the field. They went mad for them, two of them were fighting over a chunk. Now I know nothing about animal husbandry, but I'm worried about these sheep. I find it odd they behave like that, anyone out there able to enlighten me? Should I have phoned the SSPCA ? Am I over reacting?