Best Selection Basis for Carcass Quality

The best basis of selection for estimating carcass quality in livestock is:

Correct Answer: Sib Selection

From the notes: Sib selection is the best basis of selection for estimating carcass quality. Since carcass traits require slaughter of the animal, the candidate itself cannot be measured and then selected. Instead, sibling (sib) records from slaughtered littermates are used.

Why Not Individual Selection for Carcass Traits?

Carcass traits (dressing %, fat depth, eye muscle area, lean meat %) can only be measured AFTER slaughter — by which time the animal is dead and cannot contribute to the next generation. Therefore, the individual's sibling is slaughtered for measurement while the candidate is evaluated based on its sib's performance.

Sib Selection is Also Best For (from notes)

• Carcass traits ✔
• Sex-limited traits
• Traits with low heritability

Note from Q39 Match

In the notes match column answer key: Progeny testing = 'Best aid for carcass traits in sheep' — note this refers to progeny testing as an alternative when breeding stock must be evaluated over multiple generations, but sib selection remains the direct practical choice for carcass quality selection within a generation.