Farming operations are complex. The following pros and cons have not been factored into this calculator:

Less hay storage needed. If 30% less fodder is needed to be fed, this means that 30% less fodder needs to be stored, reducing the need or cost to invest in shedding or other fodder storage options.
Providing fodder on the ground can make it more likely that stock digest worms from faeces that the feed was placed on. This increases the expense of managing parasites.
Wasted fodder can prevent pasture from growing in that area in the future or needs to be cleaned up.