Or HaChaim on Genesis 41:3/אור החיים על בראשית מ״א:ג׳

1 עולות אחריהן מן היאור, rising behind them from the river. This description corresponds to what we explained on the previous verse, that the cows' existence was due to the river. Although in this instance the river is not mentioned first, i.e. מן היאור עולות, the word אחריהן, behind them, makes it plain that both categories of cows had an identical origin.