DIRECT SIRE LINE or  TAIL MALE LINE
AND
TAIL FEMALE  LINE BREEDING

     To  explain these terms a few simple facts about heridity and sex are necessary.  Canines have 39 chromosome pairs.  One pair determines the sex of the animal.  This pair is usually denoted as XX,  or XY.  When both chromosomes are type X, the canine is female. When both are different type, denoted XY, then the dog is a male. When dogs mate, one sex chromosome comes from the female and one from the male to determine the sex of the offspring.  Thus the male always determines the sex of the offspring, depending on whether the offspring gets his X or his Y.  The  female   has no determination of the offspring sex since she can only contribute  an X or an X. Each parent contributes 50% of the genetic material to the offspring.
     By making use of these facts,  one can develop breeding strategies to preserve or concentrate genes of the parents and ancestors.  The table below shows a pedigree of a dog named Pup.  Pup's sex is either XX or XY, i.e. female or male.
 
 

 

XY=  male sex chromosomes
XX=  female sex chromosomes

 

The DIRECT SIRE LINE is often called the TAIL MALE LINE,  What is a tail male  line?  On the pedigree chart above the tail male  line is represented by the following line of sires.   It is the top most line of males in a chart showing the males on top and females on the next box down. 

DIRECT SIRE LINE= TAIL MALE LINE  = Dynamite, Brumy, Dixie Blair, Boulder Brook's Blazing Lee

   The Y chromosome is passed from father to son down the unbroken male line.  It is the same Y as there is no   Y chromosome available from  the mother.  The X chromosome in XY comes from the  mother as she only has X's to contribute.

Dynamite started  the direct  sire of National Hunt champion Dixie Blair, National Hunt Champion Mr. Mick,  and Intermediate Hunt Champion Sydney of Woodbine,  i.e. they have the same Y sex chromosome.  These other Boykins are not shown on the chart but a review of their pedigrees would show this fact.

Similarly the TAIL FEMALE  LINE  is  Patty,  Southern Sass, King's Curlee Gurlee,  Boulder Brook's   Justa  Rose.  This is the string of females along the bottom line of the pedigree chart.  

Each daughter  has two X chromosomes,  XX.  One from her sire and one from her dame.  The X  passed from the sire comes from his mother,  who is  the paternal grandmother of his daughter.    The dame gets one of  her XX pair from her mother and the other X from her father who inherited it from his mother, i.e. the dame's  paternal grandmother.  For the female we can not determine which of the X chromosomes she gets from her dame. There is 50% per cent of which is passed to her.

How can we use this information in breeding?

To develop good brood bitches, use  only sires out of great dames since the X of the sire will be passed onto  the daughters of the sire. This X will be an  X of the great dame.  This is one of the few ways a breeder can have direct control of the chromosone the puppy gets.

In the illustration below  we see the sex chromosone passed from ancestors to SUPER BROODER BITCH.  The possible sex chromosomes are color coded for marking purposes in the example. The lower case comes from the female and the Upper case from the male.  There are two possible final results in SUPER BROODER BITCH.  One female would be  X x. The other female possibilty is X x.  In both cases the capital X from   SIRE occurs.  The one fact we do know is that the sex chromosone of SUPER-BITCH has continued and been passed to SUPER BROODER BITCH.
 

 
 

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NHC=Boykin Spaniel Society National Hunt Test Open Champion
INHC=Boykin Spaniel Society National Hunt Test Intermediate Champion

HR = Hunting Retriever Title, UKC
UH = Upland Hunter Title, UKC
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