The Rebbe reminds the recipient of the Previous Rebbe’s teaching that a shochet is not merely one who slaughters but has a duty to uplift his community spiritually. He highlights the transformative power of kosher slaughter, elevating the physical to the spiritual, and blesses him with success in his mission.
https://www.torahrecordings.com/rebbe/004_igros_kodesh/teves/876