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Asian-Australas J Anim Sci > Accepted Articles
DOI: https://doi.org/10.5713/ajas.20.0401    [Accepted] Published online August 30, 2020.
Genetic diversity evolution in the Mexican Charolais cattle population
Ángel Ríos-Utrera1  , Moisés Montaño-Bermúdez2  , Vicente Eliezer Vega-Murillo3  , Guillermo Martínez-Velázquez4,*  , Juan José Baeza-Rodríguez5  , Sergio Iván Román-Ponce6 
1Campo Experimental La Posta, Centro de Investigación Regional Golfo-Centro, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Medellín, Veracruz 94277, México
2CENIDFyMA, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Colón, Querétaro 76280, México
3Facultad de Medicina Veterinaria y Zootecnia, Universidad Veracruzana, Veracruz, Veracruz 91710, México
4Campo Experimental Santiago Ixcuintla, Centro de Investigación Regional Pacífico-Centro, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Santiago Ixcuintla, Nayarit 63570, México
5Campo Experimental Mocochá, Centro de Investigación Regional Pacífico-Sur, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Mocochá, Yucatán 97454, México
6Campo Experimental La Campana, Centro de Investigación Regional Norte-Centro, Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Aldama, Chihuahua 32910, México
Correspondence:  Guillermo Martínez-Velázquez,Email: gmv1us@yahoo.com
Received: 13 June 2020   • Revised: 22 July 2020   • Accepted: 16 August 2020
Abstract
Objective
The aim was to characterize the genetic diversity evolution of the registered Mexican Charolais cattle population by pedigree analysis.
Methods
Data consisted of 331,390 pedigree records of animals born from 1934 to 2018. Average complete generation equivalent, generation interval, effective population size (Ne), and effective numbers of founders (fe), ancestors (fa) and founder genomes (Ng) were calculated for seven five-year periods. The inbreeding coefficient was calculated per year of birth, from 1984 to 2018, whereas the gene contribution of the most influential ancestors was calculated for the latter period.
Results
Average complete generation equivalent consistently increased across periods, from 4.76, for the first period (1984-1988), to 7.86, for the last period (2014-2018). The inbreeding coefficient showed a relative steadiness across the last seventeen years, oscillating from 0.0110 to 0.0145. During the last period, the average generation interval for the father-offspring pathways was nearly 1 yr. longer than that of the mother-offspring pathways. The effective population size increased steadily since 1984 (105.0) and until 2013 (237.1), but showed a minor decline from 2013 to 2018 (233.2). The population displayed an increase in the fa since 1984 and until 2008; however, showed a small decrease during the last decade. The effective number of founder genomes increased from 1984 to 2003, but revealed loss of genetic variability during the last fifteen years (from 136.4 to 127.7). The fa:fe ratio suggests that the genetic diversity loss was partially caused by formation of genetic bottlenecks in the pedigree; in addition, the Ng:fa ratio indicates loss of founder alleles due to genetic drift. The most influential ancestor explained 1.8% of the total genetic variability in the progeny born from 2014 to 2018.
Conclusion
Inbreeding, Ne, fa and Ng are rather beyond critical levels; therefore, the current genetic status of the population is not at risk.
Keywords: Cattle; Effective Number of Ancestors; Effective Number of Founder Genomes; Effective Population Size; Average Complete Generation Equivalent; Generation Interval


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