Bioscience Methods 2025, Vol.16, No.6, 299-307 http://bioscipublisher.com/index.php/bm 3 04 6 Case Studies: Comparative Analysis of Resistance Markers in Different Goat Breeds 6.1 Resistance differences between boer goats and indigenous breeds to Haemonchus contortus In fact, many studies have long mentioned whether there are differences among goats in terms of parasite resistance. Interestingly, some widely promoted breeds, such as the Boer goat and its hybrid offspring, do indeed perform more "tough" when facing the twisted blood spear nematode than local breeds like the Kachang goat. This is not based on impression but is supported by experimental data. For quantitative indicators like FEC (fecal Egg Count), under artificial infection conditions, the number of eggs in Boer goats is lower, anemia is not severe, and the development speed of the parasite body is significantly slower. A closer look reveals that the performance of male sheep is better than that of female sheep, which is quite interesting (Elieser et al., 2024). However, this difference is not limited to the comparison between Boer and Kachan. In a different geographical context, such as Africa, a similar situation can also be observed. Like Mubende goats and East African baby goats, under the same parasitic burden, the FEC values are usually also relatively low, indicating that they have a certain degree of resistance by nature (Onzima et al., 2017). Of course, it doesn't mean that all local varieties are weak; it's just that the resistance of certain specific groups is more prominent. This is also one of the reasons why in breeding projects, Boer goats are often crossed with local breeds, using their genetic characteristics to "enhance" the resistance of local populations. 6.2 QTL comparative studies between Indian Jamunapari and African red maasai goats Before discussing genetic resistance, it is necessary to mention the research progress of QTL. Some QTL loci found in African red Marseille sheep have also occurred in other resistant breeds, such as regions that control FEC and PCV. This overlap somewhat indicates one thing: regardless of the geographical background, certain genetic mechanisms are "universal" in the manifestation of resistance. In Indian goats, such as Jamunapari, the detection of microsatellite markers DYA and ODRB1.2 also found that they were associated with FEC and PCV indicators (Shrivastava et al., 2018). Combined with the expression differences of immune genes, such as IFNG and IL-10, the genetic basis behind resistance becomes clearer. Overall, this type of cross-variety QTL information not only reveals genetic patterns but also provides a reference path for marker-assisted selection. 6.3 SNP marker association validation based on FEC data Not every SNP is worth paying attention to, but those highly correlated with FEC are indeed worthy of repeated verification. SNPS in genes such as CIITA, ATP2A3, HSPA8, STAT5B, ESYT1 and SERPING1 have been shown to be significantly associated with FEC expression in various goat populations, especially in highly resistant individuals, where their expression levels are generally higher (Figure 2) (Alam et al., 2019). Interestingly, similar phenomena also occur in the genes NLRC3, NLRC5, HIP1 and LRP8, and some haplotypes at these loci are often associated with resistance (Omar et al., 2019). Importantly, these results are not only present in one experiment or one region, but can also be reproduced across regions and varieties, which endows these SNPS with higher application value in breeding. Incorporating them into the breeding strategy might be an effective entry point for enhancing population resistance in the future. 7 Conclusions and Future Perspectives Over the past few decades, research on goats' resistance to gastrointestinal parasites has gradually accumulated, but this path is far from over. As is known to all, this type of resistance is a rather complex trait that cannot be determined by just one or two genes, especially when it involves genes closely related to immunity such as MHC, IFN-γ, various interleukins, TLR, and T-cell receptors. However, to be on the other hand, although quite a few QTLS and SNPS have indeed been identified, each one, when viewed individually, does not have a significant impact. As for phenotypic indicators such as FEC, PCV and immunoglobulin, they remain the most commonly used selection tools. However, if these can be combined with genetic markers, the selection may be more accurate and faster. Recently, genomic approaches such as transcriptomics, RNA sequencing, and GWAS have continuously brought about new clues. For instance, TGF-β, the MAPK pathway, and cell adhesion molecules have all been drawn into the resistance network. Molecular means for resistance breeding do seem to be a reliable path now, and both MAS and genomic selection hold promise.
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