Inbreeding Coefficient in Simulated Open Nucleus Breeding Scheme in Egyptian Buffalo

Simulated Populations with one record were generated with assumed mean (0) and variance (1) milking Buffalo populations. Four different population sizes (z): 10,000, 25,000, 50,000 and 100,000 animals were generated. Populations were composed by four generations obtained by selection of sires and dams from the previous generation. Mating ratio (male: females) was designed to differ from 1:25 to 1:100 and from 1:1000 to 1:5000. The objective of this study was to evaluate the changes in the inbreeding coefficient according to some alter factors (generation, mating ratios, population size, fraction of total population in nucleus, proportion of all males born used as sires, fraction of base sires born in nucleus, and fraction of base dams born in nucleus) in simulated open nucleus breeding schemes in Egyptian buffaloes. The Inbreeding coefficient increased significantly (P<0.05) with the generation number. The inbreeding coefficient in the nucleus increased from 0.0012 in (G1) to 0.0057 in (G4) in the nucleus herd, and from 0.0008 in G1 to 0.0064 in G4 in the base herd. Moreover, the inbreeding coefficient increased by widening mating ratio in natural mating and artificial insemination. Significant differences (P<0.05) in inbreeding coefficient were observed between different mating ratios (MR). Inbreeding coefficient decreased significantly (P<0.05) by increasing population size (z). Increasing z from 10000 to 25000 resulted in a decrease of 43% in inbreeding coefficient in both the nucleus and the base. Increasing (z) from 25000 to 50000 resulted in an increase of 30% in inbreeding coefficient in both the nucleus and the base. Finally, there were no significant differences in the inbreeding coefficient when the population size increased from 50000 to 100000.