I use excel, but because I have 30 snakes, I setup a page with the snakes in the first column and each day of the month in the following columns. I print it out to keep in the snake room, but enter the data in the computer at the end of the month. I have abbreviations for all the events (SH - shed,RW - rat weanling,PK - pinkie, etc.) and I record the mass of the food item. At the beginning of each month I weigh each snake and enter it in a separate spreadsheet. My feeding spreadsheet looks up that data and puts it in the appropriate column.
I use a separate worksheet for each month and a separate file for each year. I have been doing it this way for years.

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Chris Harrison
San Antonio, Texas