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Here is a simple
Genomic pedigree chart. 2 separate
chromosome segments are shown for each ancestor. (During meiosis , they
divide-recombination). The earliest generation, are all one color for
illustrative purposes. Dairy cattle
have 30 chromosomes, including the X
and Y. On average each chromosome
carries millions of base pairs, and thousands of genes.
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1)For the first segment, the sire has inherited ½ from each
piece. In the second segment, the
majority was inherited from one piece (both of these are an example of a
crossover). The individual has
received portions of the first segment that are traced back to the
grandparent generation.
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2) The dam has
inherited most of one segment from one portion of her sire’s piece, and a
mixture (double crossover) from her dam’s piece. The individual has segments that can be
traced to all grandparents.
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In this
example…. Say the light green
segment from the paternal grand dam was one that was high milk
production; the offspring, inheriting
a large segment from her, could mean that through this recombination, this
animal would have a higher PTA for milk that a full sib.
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