Which measurement is NOT part of assessing quantity in livestock sales?

The correct answer is maturity age, as it does not directly assess the quantity of livestock involved in sales. In livestock management and sales, quantifying animals typically focuses on measurable metrics related to sales performance and productivity.

Lambing percentage indicates the reproductive efficiency of sheep, showing how many lambs are born compared to the number of breeding ewes. This is a vital metric for determining flock productivity but it provides data related to reproduction rather than the direct sale of livestock.

The number of head sold is a straightforward measurement of the quantity of animals that have been sold, making it essential for evaluating sales volume and revenue generated.

Feedback c/kg pertains to the price earned per kilogram of livestock sold, representing the financial outcome of sales and thus a measure of economic quantity.

Maturity age, however, refers to the age at which livestock reaches reproductive capability or market weight. While it is an important factor in livestock management, it does not quantify the number of animals sold or reflect the volume of sales, making it unrelated to the assessment of quantity in the context of livestock sales.