POPULATION STRUCTURE AND PEDIGREE ANALYSIS OF THE GROOTFONTEIN DOHNE MERINO STUD

 

  W.J. Olivier# & M.A. Snyman 

Grootfontein Agricultural Development Institute, Private bag X529, Middelburg EC, 5900, South Africa

#Corresponding author: Willem Olivier

 

 

Background: The wool industry in South Africa requested Grootfontein Agricultural Development Institute in 2001 to establish a fine wool dual purpose flock. The Grootfontein Dohne Merino stud (GDS) was established through the purchase of the top genetic material from the industry. The establishment of a reference population is an important part in the implementation of genomic selection for any breed. In light of the good genetic ties with industry flocks, as well as the large amount of phenotypic information, the GDS will be an ideal flock to include in a reference population. However, the creation of a reference population is dependent on the genetic relationships among the animals and the effective population size.

 

Aim: Determine if the GDS will be suitable to form part of the reference population for South African Dohne Merino, as well as woolled sheep by analysing the population structure and pedigree

 

Methodologies: The POPREP software system via the website http://popreport.tzv.fal.de provided by the Institute of Farm Animal Genetics (FLI) in Germany was used to analyse the pedigree data of the stud. The data uploaded to the website included the sires, dams, birth dates and gender of 7072 animals born from 2001 to 2015 in the stud. The POPREP output and data files provided information on the completeness of the pedigree, generation interval, inbreeding coefficients, additive genetic relationships and the effective population size.

 

Results: The average completeness of the pedigree born over the past 10 years for one to six generations deep were 99.8%, 89.2%, 76.3%, 63.6%, 52.5% and 43.9% respectively. The average generation interval for the GDS was 2.9 and that of the males and females 2.3 and 3.8 respectively. The average rate of change of the additive genetic relationships (∆f) per generation of 0.01137 was calculated from the ∆f of 0.003921 per year. The corresponding inbreeding coefficients (∆F) values were 0.007828 and 0.002699 per generation and year respectively. The 2015 born lambs average inbreeding coefficient was 1.11% with the corresponding values for the sires and dams used during the 2015 mating seasons were 0.8% and 0.6% respectively. The effective population sizes for GDS were 44 and 64 based on ∆f and ∆F respectively.

 

Discussion: The lower degree of completeness of the pedigree from the third to the sixth generation can be ascribe to the way that the flock was established and the use of sires to link the GDS to other studs in the industry. However, these genetic ties that have a negative effect on the pedigree completeness will be beneficial when this resource flock will be part of a reference population. Currently, inbreeding coefficients is relatively low for most of the animals, but care must be taken to ensure that there is not a drastic increase in the inbreeding coefficients.

 

Conclusions: This stud would be suitable to be included in a reference population, especially when the phenotypic data recorded on this flock, as well as the genetic ties with other studs is taken inconsideration. A similar analysis with the complete pedigree data of the Dohne Merino breed would also be beneficial in establishing a reference population for the breed.

 

Published

Proceedings 49th SASAS congress, Stellenbosch