Polymorphism studies and candidate genes associated with litter size traits in Indonesian goats. a systematic review [version 2; peer review: 1 approved, 1 approved with reservations]

Background: Litter size (LS) is a significant, challenging, and economical aspect of the goat industry in Indonesia. It is influenced by several different factors and genes; consequently, identifying potential genes and loci associated with litter size has become a genetic problem. Several genetic indicators have been found to be associated with litter size in goats. This has prompted the need to discuss candidate genes associated with litter size in goats in Indonesia. Methods: A systematic review was conducted using critical databases including ResearchGate, Google Scholar, PubMed, Google search engine and Science direct. There were any exclusion criteria, they were as follows: articles published in languages other than English, Conference papers, short communication papers and papers not related to animals. After reviewing the abstracts of 42 publications, the remaining 17 investigations were chosen for full paper evaluation. A further eight studies were removed after a comprehensive evaluation of the publications because they did not match our inclusion criteria. Results: These markers include growth differentiation factor 9 ( GDF9), bone morphogenetic protein 15 ( BMP15), bone morphogenetic protein receptor type IB ( BMPR1B), and kisspeptin ( KISS1). Single nucleotide polymorphisms in these genes contribute to the development of novel genetic markers that helps in the selection of goats with the most favorable genotypes for litter size. This type of genetic selection is more successful than the traditional way of selecting animals for reproductive traits, particularly litter size. Conclusions: As a result, this study summarizes the genetic impacts of polymorphisms in candidate genes associated with litter size features in Indonesian goats.