Animal Molecular Breeding 2024, Vol.14, No.4, 271-279 http://animalscipublisher.com/index.php/amb 275 5.2 Impact of housing conditions on development Housing conditions, particularly those affecting oxygen levels, can significantly impact embryonic development in goats. Research indicates that hypoxic environments are more suitable for the in vitro development of mammalian embryos, including goats. Under hypoxic conditions, differentially expressed genes (DEGs) related to biological processes and function regulation are observed, suggesting that housing conditions that mimic these environments could enhance embryonic development by modulating gene expression. The expression levels of zygotic genes and transcription factors are notably affected by oxidative stress, which is influenced by housing conditions, further highlighting the importance of environmental control in goat breeding (Wan et al., 2021; Yang et al., 2022). 5.3 Role of seasonal variations in fertility Seasonal variations can influence fertility in goats by affecting gene expression related to reproductive processes. The hypothalamus, which coordinates the neuroendocrine system, plays a pivotal role in regulating reproductive hormones and processes. Seasonal changes can alter the expression of lncRNAs and mRNAs in the hypothalamus, impacting pathways such as the estrogen and oxytocin signaling pathways, which are crucial for ovarian development and hormone synthesis. These seasonal effects on gene expression can lead to variations in fertility rates, emphasizing the need to consider seasonal factors in goat breeding programs (Fernandes et al., 2018; Hou et al., 2023). In summary, environmental factors such as nutrition, housing conditions, and seasonal variations significantly influence gene expression related to embryonic development and fertility in goats. Understanding these influences can help optimize breeding strategies and improve reproductive outcomes in high fertility goat breeds. 6 Case Study: Analysis of a Specific High Fertility Goat Breed 6.1 Selection criteria and overview of the breed The Dazu black goat (DBG) was selected for this study due to its high fertility and adaptability, making it an ideal model for examining reproductive performance in goats. This breed is popular in southwest China and is known for its robust reproductive traits, which are crucial for understanding the genetic basis of fertility in goats (Zhao et al., 2023). 6.2 Detailed analysis of relevant genes In the study of the Dazu black goat, transcriptome analysis identified several differentially expressed genes (DEGs) during embryo implantation. Key genes such as CSF1, C1S, CST6, SLC24A4, HOXA10, HOXA11, MMP9, and ITGA11 were highlighted for their roles in processes like oxidative phosphorylation and immune response, which are critical during early pregnancy (Zhao et al., 2023). Additionally, the study of the Jintang black goat (JTG) revealed significant DEGs like SRD5A2, MSMB, STAR, and 3BHSD, which are associated with high fecundity and ovulation rate (Zi et al., 2018). The DNMT3B gene, with its 11-bp indel mutation, was also found to be significantly associated with litter size, indicating its potential as a marker for breeding high-fertility goats (Hui et al., 2020). 6.3 Implications for breeding strategies and genetic improvement The identification of these genes provides valuable insights for breeding strategies aimed at enhancing fertility in goats. The DEGs and pathways identified, such as the Hippo signaling pathway and ECM-receptor interaction, offer targets for genetic improvement programs (Guo et al., 2024). Marker-assisted selection (MAS) using genes like DNMT3B could be employed to select for goats with higher litter sizes, thereby improving breeding efficiency and economic returns (Hui et al., 2020). Furthermore, understanding the role of miRNAs, such as miR-21-5p, in follicular development can aid in developing strategies to enhance ovulation rates in prolific breeds like the Jintang black goat (Zi et al., 2017). In summary, the analysis of high fertility goat breeds like the Dazu black goat provides critical insights into the genetic mechanisms underlying reproductive performance. These findings can inform breeding strategies and genetic improvement efforts to enhance fertility traits in goats.
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