Genetic variability in three Italian beef cattle breeds derived from pedigree information

Abstract

The aim of the present work was to estimate genetic variability in Chianina (CH), Marchigiana (MC) and Romagnola (RO) breeds using pedigree information. Different approaches based on probability of identity-by-descent (effective population size through an increase in inbreeding Ne) or probability of gene origin (total number of founders f, effective number of founders fe, ancestors fa and founder genomes fg) were used. Reference populations were defined using female animals born between 1996 and 2000 where both parents are known. Generation intervals were 5.35, 4.93 and 5.15 years for CH, MC and RO, respectively. The total number of founders were 7092, 11947, 3928, for CH, MC and RO, respectively. Complete generation equivalent showed the relative high quality of pedigree information: 5.66 for CH, 4.54 for MC and 4.95 for RO. For CH, MC and RO, respectively, a fe value of 152.1, 70.9 and 89.8, a fa value of 73.6, 48.0 and 59.5 and a fg value of 39.5, 25.0 and 38.5, were calculated. When inbreeding was used effective population sizes were 138, 122 and 124 for CH, MC and RO, respectively. Parameters derived from the probabilities of gene origin were variable among the investigated breeds and the results for MC demonstrate the need to pay specific attention to breeding strategies

Pedigree analysis and inbreeding depression on growth traits in Brazilian Marchigiana and Bonsmara breeds1

“…Only 13 of these ancestors explained 50% of the genetic background of this population. In the study of Bozzi et al (2006) on Italian Marchigiana cattle, the number of ancestors explaining 50% of the gene pool was greater than in the present work (21). Because the animals of the present study probably descended from those studied by Bozzi et al (2006), this estimate is indeed expected to be reduced in Brazil.…”

“…In the study of Bozzi et al (2006) on Italian Marchigiana cattle, the number of ancestors explaining 50% of the gene pool was greater than in the present work (21). Because the animals of the present study probably descended from those studied by Bozzi et al (2006), this estimate is indeed expected to be reduced in Brazil. Similar results have been reported by Gutiér-rez et al (2003), Faria et al (2009), andPeixoto et al (2010) for different cattle breeds.…”

“…In the study of Groeneveld et al (2009), South African Bonsmara also presented the shortest generation interval (5.6 yr) among the breeds studied. According to Gutiérrez et al (2003) and Bozzi et al (2006), this finding is probably due to the early replacement of sires and dams when AI and ET were used.…”

“…The average level of inbreeding has increased over the years in different populations and has become one of the main concerns of researchers and producers because of its unfavorable effect on the maintenance of genetic diversity and production of domestic animals. Bozzi et al (2006) observed a significant increase in the average level of inbreeding in the Italian Chianina, Marchigiana, and Romagnola populations and concluded that the main cause of this increase was the intensive use of certain bulls. Mostert and Exley (2000) also reported significant increase in the average level of inbreeding over time in a South African Bonsmara population.…”

Evaluation of genetic variation in the international Brown Swiss population

“…For Danish Holstein, Danish Jersey and Danish Red populations, generation intervals between 4.6 and 5.2 years have been reported (Sorensen et al, 2005). Most of the Spanish beef breeds studied by Gutierrez et al (2003) had average generation intervals of between 3.7 and 5.5 years; and Bozzi et al (2006) reported generation intervals ,5.35 for three Italian beef breeds. The structure of the pedigree at the Interbull Centre, which is built primarily on the male side of the pedigree, can explain, in part, the long generation interval in our material: in that material the females without offspring are missing, and therefore the dam-daughter and sire-daughter generation intervals are overestimated.…”