Possible Clues:

• Mimicked a cow
• Lowed (like a cow)
• Bellowed, as Bossy
• Sounded like Elsie
• Imitated a 29-Across
• Made a low noise like a cow
• Emulated a bovine
• How Hereford expressed its feelings?
• Spoke with a Jersey accent?
• Bellowed, as a bovine