Animal Genetics and Breeding- ICAR JRF/SRF 2024

• Inbreeding Defined: Inbreeding is the mating of individuals that are more closely related to each other by ancestry than the average relationship of individuals within the reference population.
• Genetic Consequences of Inbreeding:
• Increases homozygous genotype frequency ($AA$ and $aa$) while decreasing heterozygosity ($Aa$) at a rate of $F$ (inbreeding coefficient).
• Exposes detrimental recessive alleles, leading to inbreeding depression (reduced fertility, viability, and production).
• Distinctions:
• Pure breeding: Mating of animals within the same established breed.
• Crossbreeding: Mating of animals from two or more distinct pure breeds.
• Outbreeding: Mating of unrelated individuals within a breed (outcrossing) or between breeds.

Correct option: (3) Inbreeding

• Assertion (A) is True: In animal breeding, the rate of inbreeding per generation ($\Delta F$) is inversely proportional to effective population size ($N_e$):

• Reason (R) is True: For a population with unequal numbers of males ($N_m$) and females ($N_f$), the effective population size is given by Sewall Wright's formula:

Because far fewer breeding males (sires) are maintained compared to dams (e.g., in artificial insemination where $N_m \ll N_f$), $N_e$ is almost entirely constrained by the number of the less numerous sex ($N_e \approx 4 N_m$).

• Relationship: (R) is indeed the underlying demographic principle explaining why inbreeding rate is driven by the less numerous sex.

Correct option: (2) Both (A) and (R) are true but (R) is NOT the correct explanation of (A).

• Game / Draught Sports Cattle of South India: In Tamil Nadu, traditional games like Jallikattu (bull taming) and cattle racing specifically rear fierce, agile indigenous draught breeds:
• Pulikulam (A): Also known as Palingu maadu or Jallikattu maadu, native to Madurai, Sivagangai, and Dindigul districts of Tamil Nadu; specifically bred and trained for Jallikattu.
• Kangayam (C): Indigenous to Coimbatore, Tiruppur, and Erode districts of Tamil Nadu; renowned for extreme draft power, compact body, and participation in Jallikattu and cattle festivals.
• Other Breeds:
• Kankrej (B): Dual-purpose breed native to Gujarat/Rajasthan (Western India), known for 'Sawai Chaal' gait.
• Hallikar (D): Premier draught breed of Karnataka, known for working endurance.

Correct option: (1) (A) and (C) only.