Estudos genômicos para a prolificidade em cabras: uma revisão sistemática.

Abstract

The reproductive traits are of importance for the goat production system. Among these characteristics, a prolific application to increase the number of multiple births per year, a selection pressure, reduction of production interval and annual genetic gain. The heritability for this characteristic in goats varies from 0.08 to 0.18. GWAS studies aim to detect variants in genomic loci that are associated with complex features. However, few genomic studies have been performed on goats. The objective of this research was to perform a systematic review to elucidate the advances of genomic studies in the field of goat proliferation. Three databases were selected for this review: SCOPUS (2007-2018), PubMed (20082018) and BIOMED CENTRAL (2008-2018). After the review work, 70 articles were identified according to the following search criteria: genomic or GWAS, reproduction, animal, prolificacy and goat. Among them, 4 repeated articles were excluded, 41 whose titles had content outside the proposed study area, 20 abstracts reporting divergent context of this research and 3 full-text articles outside the scope studied. Only two articles met all eligibility criteria, and were listed as objects of this study. The article entitled “Whole-Genome Scanning for the Litter Size Trait Associated Genes and SNPs Under Selection in Dairy Goat (Capra hircus)” using two groups of Laoshan goats (high fertility and low fertility), reported the existence of candidate genes related to reproduction. The genes CCNB2, AR, ADCY1, DNMT3B, SMAD2, AMHR2, ERBB2, FGFR1, MAP3K12 and THEM4 were specified for the group of high fertility goats. While KDM6A, TENM1, SWI5 and CYM, were recorded in the low fertility group. The SYCP2, SOX5 and POU3F4 genes were located in both groups. The second article accepted by the criteria described “Genetic Improvement of Litter Size in Four Goat Breeds in Egypt Using Polymorphism in Bone Morphogenetic Protein 15 Gene” aimed to investigate the polymorphism of the BMP15 gene using PCRRFLP and SNP techniques in four goat breeds in Egypt and its association with prolificity. The results showed the existence of seven SNPs, four SNPs for high prolificacy (760 G> C, 757 A> C, 762 G> A, and 769 G> C) and three SNPs for low prolificity. High prolificity coding nucleotides appeared in three breeds (Alpina, Zaraibe and Baladi). The nucleotide number 760 G> C showed presence in all goats of high prolificacy in all breeds. These SNPs can be used in MAS to improve this trait in herds.