What is the Chidush 'T'reifah Lo Heveisi Elecha... Genuvsi Yom u'Genuvsi Laylah'? A Shomer Sachar (paid watchman) is liable for theft or loss!
Seforno: Yakov meant that even when Lavan demanded payment following an Ones (irrespective of whether it was torn by an animal, or stolen by a human by day or by an animal in the night), 1 he paid up. Ohr ha'Chayim, Malbim
Bearing in mind that, for the first fourteen years that Yakov worked for Lavan, he was working for Rachel, how did he manage to pay for the losses in Lavan's flocks?
Refer to 29:18:1.5:1 & 2.
What is "Achatenah"?
Rashi: I would remove [from my animals to pay for it].
Tosfos ha'Shalem (5): If a lion came to tear from the flock, I seized the prey from the lion, 1 (for I knew that you would demand that I pay you for it).
Tosfos ha'Shalem (6): There was a lion that used to eat from Lavan's flock every day, before I came (Bereishis Rabah 74:11). I "sinned" through depriving the lion of its sustenance.
Ha'Emek Davar: I would fight off a wolf or lion (even though a Shomer is not obligated to do so), and if I did not, you asked me to pay (and I did)..
Why did he say both "'Anochi Achatenah mi'Yadi Tevakshenah"?..
Ohr ha'Chayim: If one wolf makes an animal Tereifah, this is not Ones; I paid by myself. A lion is Ones; I should have been exempt, but you insisted that I pay (and I did).