304 



Journal nf Af/nculture. Victoria. 



[10 May, 1919. 



A CONTRIBUTION TO THE STUDY OF HEREDITARY 

 UNSOUNDNESS IN HORSES. 



P>;i ir. .1. N. Robertson. H.V.Sc, Chief Veterinarij Offirer. 



(Contimiod fruni jjage 69:1, Vol. X\'I.) 



f'riio systi'in of miniberiiiji that has been adopted in the tallies is to j^ive a 

 uiuiiIrt to the foundation member, 1. 2, .3, &c., and to use decimal points for the 

 subsequent generations, 1.1. 1.2, 1..3 representing the first, second, and third son 

 of 1 respectively. This arrangement does not refer to order of birth, Init merely 

 to first, second, or third son recorded, and so on. Another figure is used in the 

 next generation, 1.39 representing the ninth recorded son of the third recorded 

 son of the fouiider 1. When over nine sons are dealt with, the cypher is used in 

 front of the luiit of that generation, and represents 9, thus 1.04 is the thirteenth. 

 and 1.0004 is the thirty-first (9+9+9-|-4). Each of these refers to the first 

 generation ; the number of noughts preceding a unit being counted with the unit. 

 In this way the numbers 1.002,1,0,003 shows four generations from founder 1. 

 and, reading hackward, we get twenty-first son of sixth son of first son of twen- 

 tieth <on of 1. (The commas are introduced to show the meaning clearly.)] 



FAMILY 8. 



Only 56 meinbers of this family have been examined, and seven, or 

 12.3 per cent, were found unsound. The whole of the unsoundness runs 

 through 8.1, as shown in the following analysis of tlie family: — 



Thirty-four descendants of 8.1 were examined, and seven, or '2i)^ per 

 cent., were found unsound. Unfortunately the pedigrees of a grear 

 number do not trace through the female side to sires recorded in these 

 tables, and the unsound representatives are amongst these. But from 

 the facts Avhich can be gathered, it is apparent that by mating witli 

 sound mares the unsoundness has become a diminishing factor. 



S.U was undoubtedly unsound, yet six of his progeny were sound 

 when examined at five years of age or over — in all eleven sons Avere 

 sound, and only one unsound. 



An effort has been made to find the relation of the dams of the sound 

 animals To sires in the.se tables, with the following results: — 



8.111 was from a mare by 4.1261, a member of the sound fnniily 4. 



though with a taint of unsoundness. 

 8.118 was from a mare by 2.1, of sound family, and marcs by liim 



were much sought after. 



