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Question
Explain codominance in colour coat in cattle with checker board method.
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Solution
- Coat colour in cattle is a classic example of co-dominance.
- There are two types, one with a red coat (skin with red colour hair) and the other with a white coat (with white hair).
- When red cattle (RR) is crossed with white cattle (WW), F1 hybrids (RW) have roan colour. Roans have a mixture of red and white colour hair.
- Thus, both traits are expressed equally. In F2 generation (produced by interbreeding of roans), red (RR), roans (RW) and white (WW) are produced in the ratio 1: 2: 1.
Phenotypic ratio → 1 : 2 : 1 (1 Red coat : 2 Roan : 1 White coat)
Genotypic ratio → 1 : 2 : 1 (1 RR : 2 RW : 1 WW)
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