Question

Heritability of fat percentage as compared to fat yield is

• A. Less
• B. More
• C. Equal
• D. Very less

Hint:

Heritability Hierarchy in Dairy Cattle:
High $h^2$ ($> 0.45 - 0.55$) = Fat %, Protein %, Type conformation.
Moderate $h^2$ ($0.20 - 0.30$) = Milk Yield, Fat Yield, Protein Yield.
Low $h^2$ ($< 0.10$) = Fertility Reproductive traits, Calving interval.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Quantitative genetics of dairy cattle traits: milk composition percentages (fat % and protein %) exhibit high heritability ($h^2 pprox 0.50$), whereas absolute yield traits (milk yield, fat yield) exhibit moderate heritability ($h^2 pprox 0.25 - 0.30$).
Key Formula or Approach:
\[ h^2 (\text{Fat \%}) \approx 0.45 - 0.55 \text{ (High)} \quad \gg \quad h^2 (\text{Fat Yield}) \approx 0.25 - 0.30 \text{ (Moderate)} \]

Step 2: Detailed Explanation:
In dairy cattle quantitative genetics:
- Heritability ($h^2$) measures the proportion of total phenotypic variation attributable to additive genetic differences:
1. Milk Composition Percentages (Fat % and SNF %): Have High Heritability ($h^2 = 0.50 - 0.55$), being governed predominantly by intrinsic additive genetic loci with minimal environmental fluctuation.
2. Yield Traits (Total Milk Yield, Total Fat Yield in kg): Have Moderate Heritability ($h^2 = 0.25 - 0.30$), being heavily influenced by management, feeding, lactation stage, and season.
- Therefore, the heritability of fat percentage is More (higher) than fat yield.

Step 3: Final Answer:
Thus, heritability of fat percentage is More, matching option (B).