Tough times call for tough decisions. The University of Wisconsin's CULL.xls will allow you to make some of those tough calls, such as going to a separate TMR for low producers or when to cull an open cow.
Output values from CULL.xls are dollar contributions to fixed costs per cow per day. Daily returns are reported in a table based on level of production, and SCC level.
Given today's prices, for example, a cow milking 60 lbs/day with a 325,000 SCC only returns 30¢/day over the major variable costs. At $12/cwt milk, that same cow would contribute $1.50/day, and at $15/cwt milk, she would contribute $3.30/day.
CULL.xls requires only a few commonly known inputs to access your specific farm situation. Needed is your herd's average milk production per day in pounds, average butterfat, protein and SCC tests along with your latest base price for milk and value of components. The spreadsheet asks for dollar values per point of fat and protein, while today's market quotes values per pound of product (so just move the decimal point one place to the left).
Your nutritionist can help you with the average feed amounts and cost/cow/day. Feel free to use the standard values in the spreadsheet or your own labor costs/cwt/day and the value of miscellaneous (all other variable costs) supplies per cwt. Finally, enter your current feed levels and values and you're ready to roll!