Under those circumstances, I'd probably work towards the alfalfa pellets being about 20-25% of her diet. [if she weighs 420#, she probably needs 9-12# feed per day (if she were in good weight, I'd probably suggest a little less, but since she needs muscle and seems small for her age and breeding I'm going to go with more), so I'd work towards 2-3# of alfalfa pelelts, give a bit of time and see what that does for her. Then increase or decrease accordingly. I'm not one to feed lots of alfalfa, so this might be a very conservative place to start.]