Genetic diversity evolution in the Mexican Charolais cattle population

Abstract

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 (N e), and effective numbers of founders (f e), ancestors (f a) and founder genomes (N g) 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 f a 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 f a :f e ratio suggests that the genetic diversity loss was partially caused by formation of genetic bottlenecks in the pedigree; in addition, the N g :f a ratio A c c e p t e d A r t i c l e 4 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, N e , f a and N g are rather beyond critical levels; therefore, the current genetic status of the population is not at risk.

Process of Introduction of Australian Braford Cattle to South America: Configuration of Population Structure and Genetic Diversity Evolution

“…Núñez-Domínguez et al [55] reported a value of 183 to 827 founders in the Romosinuano breed. The number of founders in the present study exceeds even those reported in other highly selected breeds, such as the Mexican Charolais with a value ranging between 5000 and 13,000 founders [67]. The effective number of nonfounders (N ef ) in this work was 490,067, about seven times higher than the value reported for the Simmental breed (68,400) [64].…”

“…The number of founders was higher than fe, which was indicative of a reduction in genetic diversity, which may be ascribed to an imbalanced use in the number of founders. The effective number of ancestors (fa) was 162 and higher than the values reported for the Romosinuano breed [55], which ranged between 24 and 31, while in the aforementioned six breeds in Mexico, these values ranged between 33 and 254 [61], which were similar to those in the Charolais, which ranged between 207 and 247 [67].…”

Analysis of Endangered Andalusian Black Cattle (Negra Andaluza) Reveals Genetic Reservoir for Bovine Black Trunk

“…While these values fall below the threshold of 0.6 for reliability in estimates, they have steadily improved since 2000, when the breed was included in the official catalog of Spanish bovine breeds, alongside enhanced management of genealogical records and genetic improvement plans by the association [2]. These values align with other bovine breeds undergoing conservation processes, such as the Curraleiro Pé Duro in Brazil, Italian Pontremolese, Sardo Modicana, and German Angler and Red and White dual-purpose breeds [36][37][38], but are lower than those in commercial-industrial dairy and beef cattle breeds with extensive record-keeping and genetic evaluation histories [39][40][41][42][43][44][45].…”

Logros, retos y perspectivas de la investigación en mejoramiento genético de bovinos productores de carne en el INIFAP

“…La proporción del número efectivo de ancestros en relación con el número efectivo de fundadores sugiere que la pérdida de diversidad genética en el período de 1999 a 2018 se debió, en parte, a la formación de cuellos de botella en el pedigrí. Además, la proporción del número efectivo de genomas fundadores en relación con el número efectivo de ancestros sugiere pérdida de alelos fundadores por deriva génica (39) .…”