The goal of this research was to document the influence of Line 1 Hereford cattle, developed by the United States Department of Agriculture at its research facility in Miles City, Montana, on Hereford cattle in South Africa. Analytical approaches made use of both recorded pedigree and microsatellite marker information. Cattle with recorded performance data in South Africa were mated with Line 1 Hereford sires in silico and inbreeding coefficients were calculated for the resulting progeny. The relationship between South African and Line 1 Hereford cattle populations was estimated as twice the maximum inbreeding coefficient for the progeny of each South African animal. The calculated pedigree relationship of Hereford cattle registered in South Africa with Line 1 was 24%. Thirty-six South African Hereford cattle and a sample of 64 Line 1 animals were genotyped with 34 microsatellite markers. Based on a Bayesian model-based clustering method, the probability that the South African Hereford cattle were members of Line 1 was 0.38 ± 0.08. This research documents one aspect of the far reaching effects of the Line 1 Hereford population.
