Mowing only is fine if you intend to keep the pasture indolent. If you disc, zillions of dormant seeds in the 'soil seed bank' will germinate when sunlight stimulates them, giving no improvement.
If you intend to renovate the pasture, mow than disc periodically, after weed germination occurs but before weed seeds are produced. Seed or overseed the same day after discing and smoothing the ground when temperatures are appropriate for the seed you wish to dominate. Improverd seed varieties are highly productive but require fertilizer and water during dry periods to give high yields. Rolling in the seeds with a roller or cultipacker will improve germination rate of desirable seed. Most grass seeds require some direct sunlight to germinate.