Introduction
Selenium (Se) is an essential trace element for livestock and poultry and constitutes the active center of several selenoproteins, including glutathione peroxidase, thereby playing pivotal roles in antioxidant defense, thyroid hormone metabolism, and immune regulation. More than 70% of regions in China are classified as selenium-deficient areas, and owing to the unique ruminal fermentation characteristics of ruminants, the bioavailability of selenium is generally limited, predisposing animals to selenium deficiency-associated disorders such as white muscle disease and reproductive dysfunction. Consequently, dietary selenium supplementation has become an indispensable nutritional strategy in modern animal production systems [
1].
Currently, selenium sources commonly used in sheep production can be broadly categorized into inorganic selenium, organic selenium, and emerging nano-selenium preparations, each differing markedly in bioavailability and biological efficacy. Although selenium-enriched feeds have been extensively investigated in monogastric species such as swine and poultry, studies focusing on the precise application of selenium supplementation strategies in meat sheep remain comparatively limited. Therefore, the present study employed Dumeng sheep as the experimental model to evaluate the effects of three selenium sources—sodium selenite, selenomethionine, and nano-selenium—on growth performance, rumen microbial composition, meat quality, and selenium deposition. The findings are expected to provide a scientific basis for precision selenium supplementation strategies in meat sheep production.
Materials and Methods
Experimental animals consisted of forty-five 2-3-month-old female Dumeng lambs with comparable initial body weight (21.50±3.25) kg. Animals were randomly allocated into three treatment groups (n = 15 per group): a sodium selenite group (basal diet supplemented with sodium selenite), a selenomethionine group (basal diet supplemented with selenomethionine), and a nano-selenium group (basal diet supplemented with nano-selenium). The basal diet formulation and total selenium concentration were maintained consistently across all groups. The experiment included a 10-day adaptation period followed by a 60-day formal feeding trial, during which all lambs had free access to water.
At the end of the experiment, six lambs were randomly selected from each treatment group (18 animals in total) for slaughter and sample collection. Parameters evaluated included slaughter performance, meat quality traits, hematological and serum biochemical indices, ruminal fermentation characteristics, alterations in rumen microbial community composition, and tissue selenium deposition. Statistical analyses were conducted using SPSS 27.0 software. Data were analyzed by one-way analysis of variance (ANOVA), followed by LSD multiple comparison tests to determine differences among treatment groups.
Results
The results demonstrated that selenium source markedly influenced slaughter performance, antioxidant status, meat quality, selenium deposition, and rumen microbial composition in lambs. Among the treatments, the selenomethionine group exhibited the highest dressing percentage (50.68%) and loin eye area (20.11 cm²), both of which were significantly greater than those observed in the sodium selenite and nano-selenium groups (P < 0.05). In addition, lambs supplemented with selenomethionine showed significantly enhanced antioxidant capacity, elevated serum protein concentrations, and improved inflammatory cytokine profiles compared with the other two treatment groups (P < 0.05).
With respect to meat quality characteristics, the selenomethionine group presented a significantly lower shear force value in the longissimus dorsi muscle, indicating superior meat tenderness relative to the sodium selenite
and nano-selenium groups (P < 0.05). Regarding selenium deposition, selenomethionine supplementation resulted in the greatest selenium accumulation in both muscle tissue (0.87 μg/g) and visceral organs (1.26 μg/g). Furthermore, dietary supplementation with selenomethionine modulated the rumen microbial community by reducing the relative abundance of Bacteroidota while increasing the abundance of Firmicutes, thereby contributing to an improved ruminal microbial ecosystem in meat sheep.
Discussion
The present study demonstrated that different selenium sources exert distinct biological effects in meat sheep production systems. Among the evaluated selenium sources, selenomethionine exhibited superior efficacy in improving dressing percentage, enhancing meat tenderness, strengthening antioxidant capacity, and promoting selenium deposition in tissues. Previous studies conducted by Kang Yonggang and colleagues similarly reported that dietary supplementation with selenomethionine improved growth performance and antioxidant status in Xuhuai goats, which is consistent with the findings of the present study and aligns well with the production demands for high-quality lamb products.
Overall, as one of the most bioavailable organic selenium sources, selenomethionine exhibits considerable application potential in modern animal husbandry. Its use may provide an effective strategy for the precise selection of selenium additives in meat sheep production. Future studies should further investigate optimal supplementation dosages and synergistic additive combinations to establish a more efficient selenium utilization system for meat sheep production.
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