Question

Which of the following statements are true:
(A) Cornish and Plymouth rock are commonly used female lines for producing commercial broiler chicken hybrids.
(B) Broiler breeding exploits the principle of heterosis that results in high yielding commercial offsprings.
(C) Australorp, Newhampsire and Rhode Island Red are being used as female line, while White Leghorn as male line for the production of tinted egg shell layers.
(D) Crossbreds are expected to be more uniform and more influenced by environmental factors than parental lines.
Choose the correct answer from the options given below:

• A. (B) and (D) only
• B. (A), (B) and (C) only
• C. (A), (B), (C) and (D)
• D. (B) and (C) only

Hint:

Remember the classic broiler cross:
\[ \text{White Cornish (Male Line)} \times \text{White Plymouth Rock (Female Line)} \] This combines excellent meat conformation from the male with good reproductive performance from the female.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Commercial poultry breeding uses specialized crossbreeding systems to exploit hybrid vigor (heterosis) and combine the complementary strengths of different purebred lines.
Detailed Explanation:
Let us evaluate each of the statements to determine which are true:
- Statement (A): Cornish and Plymouth Rock are indeed the foundation breeds of the commercial broiler industry.
However, the White Cornish is used as the male (sire) line because of its exceptional breast muscling, while the White Plymouth Rock is used as the female (dam) line because of its superior egg production and maternal qualities.
Since the statement incorrectly describes both as female lines, it is false.
- Statement (B): Broiler breeding crosses distinct parental lines to exploit heterosis (hybrid vigor).
This process improves traits such as growth rate, feed conversion efficiency, and disease resistance, resulting in high-yielding commercial offspring.
This statement is true.
- Statement (C): To produce layers that lay tinted eggs, heavy brown-egg breeds (such as Australorp, New Hampshire, or Rhode Island Red) are crossed as the female line with a light white-egg breed (White Leghorn) as the male line.
This cross combines high egg production with a desirable tinted shell color.
This statement is true.
- Statement (D): F1 crossbreds are genetically uniform, but they are typically more buffered against environmental fluctuations (exhibiting developmental homeostasis) compared to inbred parental lines.
Therefore, they are less influenced by environmental factors, making this statement false.
Thus, only statements (B) and (C) are true.

Step 2: Final Answer:
The true statements are (B) and (C) only.