> Grass actually grows year-round in England....and horses and cows can be left out year-round becase of this.

Don't forget that although it continues to grow, there isn't much goodness in the grass in the winter, which is why extra fodder has to be provided. In the spring, the flush of new growth is extremely rich in sugar and certain types of horses (and particularly ponies) can be subject to laminitis (inflamation of the sensitive laminae of the hoof) as a result.

Christabel