Originally Posted by mayfieldk
hay is important; winter turnout does not provide enough nutrition.
That being said, don't get your horse 'fat' for the winter. I know a lot of people say that extra weight is alright during the winter, and I disagree. Horse's joints don't do well under excess weight, ever! Keep 'em healthy. ;)
If your horse is holding weight and looking healthy, then the feed is probably sufficient. :)
Hear, hear! Being a hoofcare practitioner & into equine nutrition, I can say it's not just the joints which are affected by excess weight.
Digestion of fibre is also far more effective for keeping a horse warm - & therefore keeping weight on in winter - than 'hard' feed. A horse's system needs near constant access to small amounts, so if those 2 haynets per day & pasture will give her enough, that's fine. If she is eating it all and going hungry for hrs in between, you may need to provide more.
You may want to consider a ration balancer or such tho, as she is unlikely to get the required nutrients from the feeds you listed(tho I'm not familiar with Spillers).