Create a Slicer

wneiton - One possibility is to create a new Calculated Table and Calculated Column:

1. Calculated Table for the new filter (Note that it has a buffer to go up to 1,000):

Animal Counts = 
var __NumberList = GENERATESERIES(1, 1000, 1)
return 
ADDCOLUMNS(
    __NumberList, 
    "Farm Quantity Bucket", 
    SWITCH(
        TRUE(),
        [Value] < 10, "up to 10 Animals",
        [Value] < 50, "from 10 to 50 Animals",
        [Value] < 100, "from 50 to 100 Animals",
        [Value] < 200, "from 100 to 200 Animals",
        "more that 200 Animals"
    )
)

2. Create a new Calculated Column on the Farm table:

Farm Quantity = 
var __RowCount = COUNTROWS(RELATEDTABLE(Animal))
return MIN(__RowCount, 1000) //In case a farm has more than 1,000 animals, we still need the relationship to work.

3. Create a Relationship between the new table and the new column.

Now, you can filter on the new "Farm Quantity Bucket" to show only farms of certain sizes.

Hope this helps,

Nathan