(Chicken Case)Please explain two pieces of evidence

The plaintiff-buyer in the Frigaliment case I posted (What is chicken?) claimed that "chicken" in the contract meant that chickens in the 2 1/2 - 3 lbs. category should have been only young chickens that were suitable for broiling and frying and excluded old chickens that were known as stewing chickens. The defendant-seller, however, claimed that "chicken" in the 2 1/2 - 3 lbs. category included the older or stewing chickens. Identify and explain two pieces of evidence in the form of the testimony of witnesses that defendant- seller relied on to establish that "trade usage" meant that an older or stewing chicken would be considered as a chicken falling in to the 2 1/2 - 3 lbs. category