They are still new to your place so they are not eating. They will eat soon. I experience the same thing when 4 new birds don't want to eat. Two or 3 days later they will eat. With respect to rollers I think roller people give them 1 tablespoon a day or about 1/2 ounces. Homers eat about 2 tablespoon (1 ounce) a day. Add more depending on the weather or their activity. Just calculate how many total ounces that your birds eat in one day and perhaps multiply that with 30 or 31 days and use this online conversion.
http://www.onlineconversion.com/weight_volume_cooking.htm
It is just approximate. Then perhaps you can divide the 50lb or 800 ounces? by the total of your calculations so that you can know how many months that 50lb will last.
Example: 4 rollers eat about 2 ounces a day. If you multiply that with 30 days, then 2 ounces x 30 days = 60 ounces a month.
Using the online conversion and using wild rice as an example. I then put 50 lb on the convert what quantity and choose pound on the From This list and ounce[weight] of To This list. I ended up with 800 ounces as an equivalent for 50lb rice.
That 800 ounces will then last about 800 ounces/60 ounces a month = 13 months! I don't know whether this calculation is correct though. It seemed that 50lb of rice can feed 4 rollers in one year?!
Please verify! It sounds too good! Can someone check the calculations? I can't believe it myself.