Shahid Bahonar University of Kerman and Iranian Society of Animal Science Journal of Livestock Science and Technologies 2322-3553 14 2 2026 02 01 The effect of fennel (Foeniculum vulgare) on MYOD1 gene expression in the muscle tissues of the thigh, shoulder, and loin in Kermani lambs 49 56 5048 10.22103/jlst.2025.25689.1658 EN Narjis Alhasoon Department of Animal Science, Faculty of Agriculture, Yasouj University, Yasouj, Iran Mohammad Reza Bahreini Behzadi Department of Animal Science, Faculty of Agriculture, Yasouj University, Yasouj, Iran Mohammadreza Mohammadabadi Department of Animal Science, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran Journal Article 2025 08 12 Medicinal plants have gained attention as natural alternatives to antibiotic growth promoters in livestock nutrition due to their bioactive compounds. Among these, fennel (<em>Foeniculum vulgare</em>) shows promise, though its role in muscle development remains underexplored. The MYOD1 gene, a key member of the myogenic regulatory factors (MRFs) family, regulates muscle cell differentiation and growth. Increased expression of this gene is associated with enhanced muscle performance. This study examined the impact of fennel supplementation on MYOD1 gene expression in selected muscle tissues. A total of 48 muscle samples were collected from 16 lambs, with 8 animals assigned to each of two experimental groups. From each lamb, three muscle types (shoulder, thigh, and loin) were sampled, resulting in 24 samples per group. Fennel supplementation significantly increased MYOD1 expression in all muscle types (P<0.05), with the highest expression in thigh and the lowest one in shoulder tissue. The results suggested that fennel may positively influence muscle development at the molecular level by upregulating the MYOD1 gene expression although its potential as a natural feed additive to support muscle growth and meat quality in livestock warrants further investigation. Given the MYOD1’s central role in muscle growth regulation, exploring how medicinal plants affect its expression could advance functional livestock nutrition and genetic improvement strategies. Future studies should examine the underlying molecular mechanisms and interactions with other growth-related genes.<br /><strong>Keywords:</strong> functional nutrition, fennel, muscle development, MYOD1 gene, medicinal plants https://lst.uk.ac.ir/article_5048_e43e90231fa97fa6a75e200e28dd6eae.pdf