Zhou Shuaibin, Zhu Zhenxin, Chen Xiaoping, Pu Qiuju, Liu Shuai, Luo Yuheng, Shao Yongbin, Sun Yaoqiang, Sun Xinwen, Shang Cuiling, Shen Wen, Hua Dengke, Wang Xinfeng
Laboratory of Forage Comprehensive Utilization, College of Animal Science and Technology, Shihezi University, Shihezi, China.
Tumushuke Tuxing Animal Husbandry Co., Ltd., Tumushuke, China.
Front Microbiol. 2025 Jun 23;16:1610850. doi: 10.3389/fmicb.2025.1610850. eCollection 2025.
Cotton straw is a widely available agricultural by-product in Xinjiang, China, but its utilization as livestock feed is hindered by challenges such as high fiber content and the presence of toxic free gossypol, which can negatively impact animal health and feed digestibility. Urea addition in feed fermentation has shown potential in improving feed quality by providing a nitrogen source for microorganisms, promoting fiber degradation, and increasing the content of crude protein. However, the optimal urea addition level for cotton straw fermentation remains unclear. The objective of this study was to explore the effects of urea addition on the fermentation quality, nitrogen fractions, bacterial community, and metabolic characteristics of cotton strawlage. The experiment included a control group with 0 % urea added (U0), a 0.1% urea group (U1, 1 g/kg fresh matter), a 0.2% urea group (U2, 2 g/kg fresh matter), and a 0.4% urea group (U3 4 g/kg fresh matter). After 45 days of fermentation, samples of the strawlage were collected and analyzed for their chemical composition, fermentation quality, nitrogen fractions, bacterial community, and metabolic characteristics.
Compared to the U0 group, the U3 group significantly increased total nitrogen (TN), non-protein nitrogen (NPN), acetic acid, and propionic acid contents by 17.93%, 0.08%, 13.26%, and 0.01%, respectively, while significantly reducing free gossypol and non-structural nitrogen (NSN) levels by 48.50% and 14.22%, respectively, thereby optimizing the protein composition of cotton straw. Furthermore, the U1 and U2 groups exhibited significant downregulation of metabolites associated with amino acid and energy metabolism pathways, such as L-arginine, L-proline, L-ornithine, and 2-Oxoglutaric acid, compared to the U0 group.
The addition of urea significantly altered the fermentation quality, nitrogen fraction composition, microbial community composition, and metabolic profiles of cotton straw.
棉秆是中国新疆广泛存在的一种农业副产品，但其作为牲畜饲料的利用受到诸如纤维含量高和存在有毒游离棉酚等挑战的阻碍，这些因素会对动物健康和饲料消化率产生负面影响。在饲料发酵中添加尿素已显示出通过为微生物提供氮源、促进纤维降解和增加粗蛋白含量来提高饲料质量的潜力。然而，棉秆发酵的最佳尿素添加水平仍不明确。本研究的目的是探讨添加尿素对棉秆青贮发酵质量、氮组分、细菌群落和代谢特征的影响。实验包括一个添加0%尿素的对照组（U0）、一个0.1%尿素组（U1，1克/千克鲜物质）、一个0.2%尿素组（U2，2克/千克鲜物质）和一个0.4%尿素组（U3，4克/千克鲜物质）。发酵45天后，收集青贮秸秆样品并分析其化学成分、发酵质量、氮组分、细菌群落和代谢特征。
与U0组相比，U3组的总氮（TN）、非蛋白氮（NPN）、乙酸和丙酸含量分别显著增加了17.93%、0.08%、13.26%和0.01%，同时游离棉酚和非结构氮（NSN）水平分别显著降低了48.50%和14.22%，从而优化了棉秆的蛋白质组成。此外，与U0组相比，U1组和U2组与氨基酸和能量代谢途径相关的代谢物，如L-精氨酸、L-脯氨酸、L-鸟氨酸和2-氧代戊二酸，表现出显著下调。
添加尿素显著改变了棉秆的发酵质量、氮组分组成、微生物群落组成和代谢谱。
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