Genetic gain in open nucleus breeding scheme to improve milk production in Egyptian Buffalo

Populations of buffaloes with one milk record for each buffalo were generated with assumed mean (0) and variance (1). Four different population sizes (z): 10,000, 25,000, 50.000 and 100,000 animals were generated. Four generations of progeny were obtained by selection of sires and dams of the next generations. Mating ratio (male:females) was designed to differ from 1:25 to 1:100 in natural mating (NM) and from 1:1000 to 1:5000 in artificial insemination (AI). The objective of using different mating ratios was to compare between different selection intensities among males. Genetic gain per generation and annual genetic gain were calculated. Genetic gain increased significantly (P<0.05) with the increase in generation number (G) being 282, 389, 457 and 488 kg milk for generations G1, G2, G3 and G4, respectively. The average annual genetic gain ranged from 48 kg for Cl to 83 kg for G4, while it was from 64 kg for z = 10,000 to 73 kg for z = 100,000. Increasing nucleus size as a fraction of total population in nucleus (p), from 0.05 to 0.10 increased genetic gain significantly (P<0.05) from 390 to 418 kg milk. Non-significant differences in genetic gain among different proportions of males born used as sires (a) were found. The main variables affecting the fraction of base sires born in nucleus (w) were z, p and a. Annual genetic gain ranged from 50 to 66 kg milk in NM and from 80 to 82 kg milk in AI. Applying open nucleus breeding scheme (ONBS) for many generations of selection could accelerate the rate of genetic gain of milk production in Egyptian buffalo and increase the average milk yield by 15% in G1 to 26% in G4. (C) 2010 Elsevier B.V. All rights reserved.