Dear MR. Vishal Goel,
You yourself can answer all these questions with some effort.
First check out the Dry matter requirement of the cattles.
Dry Matter intake depends on weight of cattle, milking or dry , milk yield, fat content of milk, Lactation stage, number of calvings etc.
Body Condition Score is also taken into account in deciding the feed.
Just fulfilling DMI is not enough…you should know what all nutrients to be provided CP (RDP, RUP), TDN, Net energy (for growth, lactation, body maintenance), mineral and vitamins etc etc. All these energy and nutrient requirements will come through the dry matter itself. Two or different combinations of different feeds with same DM doesn’t mean same constituent nutrients.
Next check out for the available feed (viz green fodder, dry fodder, concentrate feed) in your area or what you can grow on your fields. Try to know the DM% and nutrients etc. in those available feeds. Now you can calculate how much of what to be given for feed.
In this way you’ll know how much of green fodder, concentrate feed, mineral mixture, dry roughage to be fed.
Now it will be easy for you to calculate cost also.
Roughly half of the milk per day goes for feed…but can be optimized to a fair extent by practising good feed techniques.
Hope it helps!!!
Seniors and experienced person in farmnest community will help you in better way.