Heritability of Production Traits

Correct Answer: Medium

From the notes: Heritability classification of traits:

• Low h² (<0.2): Reproductive traits — fertility, litter size, hatchability, calving rate. These traits are governed by non-additive gene action and show HIGH heterosis.
• Medium h² (0.2–0.4): Productive/Production traits — milk yield, egg production, growth rate, fat%. Most economic traits fall here.
• High h² (>0.4): Growth/Carcass traits — body weight, feed efficiency, fat thickness, fleece weight.

Key Relationship (from notes)

Traits with low h² show high heterosis and vice versa. This is because low-h² traits are governed by non-additive gene action (dominance, over-dominance, epistasis), which is the same mechanism driving heterosis.

Formula

• h²(narrow sense) = VA / VP
• H²(broad sense) = VG / VP
• Narrow sense ≤ Broad sense always