Prevalence of chromosomal aberrations in breeding pigs in Spain

Abstract

Contents The main aim of this study was to document the prevalence of chromosomal aberrations found to date on the pig population in Spain, a country in which this production sector has a critical role, being the fourth country in the world in pig production and the second one within the European Union. The total number of animals studied was 849, and the founded frequency of carrier pigs with chromosomal alterations was 3.8%. When only the structural alterations were considered, the prevalence in males was 3.3%. This percentage is far from the 0.5% of carrier boars that has been estimated in France, a country where there is a systematic cytogenetic screening of future breeding pigs since 1992. In order to avoid the productive and economic losses caused by karyotype alterations in breeding pigs, it would be important to establish a cytogenetic screening of breeding animals at artificial insemination centres and genetic selection farms.

A de novo reciprocal chromosomal translocation t(3;6)(p14;q26) in the black Lucano pig

“…The reciprocal chromosome translocations are associated to a reduced litter size caused by lethal embryonic aneuploidy (Ducos, Berland, et al, 1998; Ducos, Pinton, et al, 1998; Gustavsson, 1980, 1988a; King, 1980; Pinton et al, 2000), reduction of the fertility and malformations not always manifested (Sánchez‐Sánchez, Gómez‐Fidalgo, Pérez‐Garnelo, Martín‐Lluch, & De la Cruz‐Vigo, 2019). Although in most cases the carriers have no phenotypic disorders, they have problems at the gametogenesis for the formation of a quadrivalent, a structure made of two normal and two rcp chromosomes that can segregate in alternate way or in adjacent ways (type I or II).…”

Classical, Molecular, and Genomic Cytogenetics of the Pig, a Clinical Perspective

“…Chromosome abnormalities, particularly structural chromosome rearrangements, are remarkably prevalent in the domestic pig relative to other species, with over 200 distinct structural rearrangements in the pig genome being identified [ 1 , 43 ]. The prevalence of structural chromosome rearrangements is variable between countries ranging from 0.47% to 3.3% and is largely influenced by access to screening laboratories that identify carriers and removal affected boars from breeding eligibility [ 8 , 11 , 44 ]. A variety of chromosome rearrangements are known to occur in the pig, including reciprocal translocations, Robertsonian translocations, tandem fusions, inversions, and deletions of chromosomes [ 1 ].…”

“…As of 2017, the largest cytogenetic screening program for pigs is conducted at the National Veterinary School of France in Toulouse, with 31,000 boars having passed through this lab as of 2017 [ 50 ]. Other large cytogenetic screening programs take place in Spain, the Netherlands, Poland, and Canada, screening 800, 1000, 2000, and 7000 boars, respectively [ 4 , 11 , 43 , 44 ]. Clinical cytogenetics programs, although time-consuming, are effective at reducing the prevalence of rearrangements in herds and are cost-effective for breeders, with a cost-benefit ratio of 5.3/1 due to reduced losses from breeding carriers [ 9 ].…”

Breeding and Economic Aspects of Cytogenetic Screening Studies of Pigs Qualified for Reproduction

“…The monitoring results from the 1990s encouraged other breeding centers to launch cytogenetic testing of boars from the reproductive sector. In Spain, based on the initial results of these analyses, the frequency of chromosomal abnormalities and structural anomalies in a commercial herd of more than 700 sires was estimated to be 3.8% and 3.3%, respectively [33,34,48,57,98,99]. In Canada, the frequency of karyotype defects among almost 900 boars qualified for reproduction in 2016 was estimated at 1.64% (with 1.36% animals carrying a translocation).…”

“…It should be highlighted that the introduction of modern cytomolecular techniques into laboratory practice has considerably increased the diagnostic potential of the screening system, resulting in a marked increase in the number of karyotype abnormalities identified [92,103]. To date, cytogenetic screening of many pig populations around the world has resulted in the identification of over 220 structural karyotype defects, including almost 200 reciprocal translocations with a clear negative impact on fertility and economic efficiency of production [1,2,13,17,19,30,32,41,93,[98][99][100][103][104][105][106][107]. It seems that the elaboration and implementation of the next screening strategies will significantly intensify the detectability of reciprocal translocations, which are likely much more frequent in breeding populations than previously estimated.…”