Análisis demográfico y genético de la raza ovina Mallorquina

Summary Demographic and genetic analysis of the Mallorquina sheep flockbook Information from 6273 registered in the flockbook of the Mallorquina sheep breed was analysed. Up to 34.3% of the individuals had registered parents and 7.6% registered grand-fathers. Average generation interval was 3.7 years. The effective number of founder herds (11.1) was roughly a quarter of the real one. The effective number of herds supplying rams was 8.8 for fathers and 3.8 for grandfathers. The equivalent number of founders was 4122 which was 66% of the total analysed animals. The effective number of founders was 704 (17% of the equivalent number of founders). The effective number of ancestors for the Mallorquina population was 90, and 50 ancestors would explain 50% of the total genetic variability of the population. Average values for inbreeding, average relatedness and equivalent to discrete generations were 0.24%, 0.17% and 0.43, respectively. Only 121 inbred individuals were found with average values for the former parameters of 17.93%, 0.92% and 1.91. A few within-flock bottlenecks have been detected and, as a consequence, inbred individuals appeared. However, no risk for the genetic variability of the breed arose.