This study investigated the degradability of corn silage (CS) and Leymus chinensis silage (LS) in vitro, and evaluated the effect of various ratios on growth performance, digestion and serum parameters in beef cattle. A 72‐hr bath culture trial was performed to evaluate degradability and rumen fermentation characteristics of CS, LS and their combinations [67:33, 33:67, dry matter (DM) basis]. Forty Simmental steers, averaging 441.46 ± 4.45 kg of body weight (BW), were randomly allocated into four dietary treatments for 120‐d period. Diets were given as total mixed rations with a forage‐to‐concentrate ratio of 60:40 and CS:LS ratios of 100:0, 67:33, 33:67 and 0:100 (DM basis). The in vitro trial showed that DM and neutral detergent fibre (NDF) degradability decreased linearly as LS proportion increased, whereas CP degradability increased linearly. Additionally, increased acid detergent fibre (ADF) degradability was detected at 48 hr of incubation. Increasing the proportion of LS increased rumen liquor pH and decreased volatile fatty acid linearly including acetate, propionate and butyrate, whereas the ammonia‐N increased linearly at 12 and 72 hr of incubation. With increasing LS ratio, final BW, average daily gain and feed conversion ratio of steers decreased linearly, whereas DMI was not affected. Additionally, apparent digestibility of DM, organic matter, NDF and ADF linearly and quadratically decreased while ether extract apparent digestibility decreased linearly, and CP apparent digestibility was not affected. Serum glucose and urea nitrogen linearly and quadratically decreased while glutamic‐pyruvic transaminase activity linearly decreased as the proportion of LS increased. Other serum parameters including total triglycerides, total cholesterol, total protein, albumin and glutamic‐oxalacetic transaminease were not affected. Overall, enhancing ratio of LS caused inferior DM and NDF degradability but improved CP degradability in the combinations of LS and CS. A CS:LS ratio of 67:33 resulted in the best growth performance and nutrient utilization in steers.

中文翻译：

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玉米青贮饲料和羊草青贮饲料的体外降解性及其混合比例对肉牛性能、消化和血清参数的评价。

本研究调查了玉米青贮饲料 (CS) 和羊草的降解性体外青贮饲料 (LS)，并评估了各种比例对肉牛生长性能、消化和血清参数的影响。进行了 72 小时的浴培养试验，以评估 CS、LS 及其组合的降解性和瘤胃发酵特性 [67:33、33:67，干物质 (DM) 基础]。40 头西门塔尔公牛，平均 441.46 ± 4.45 kg 体重 (BW)，被随机分配到 120 天期间的四种饮食处理中。日粮为总混合日粮，饲草与浓缩物的比例为 60:40，CS:LS 的比例为 100:0、67:33、33:67 和 0:100（以 DM 为基础）。体外试验表明，DM 和中性洗涤纤维 (NDF) 的降解性随着 LS 比例的增加而线性下降，而 CP 的降解性则线性增加。此外，在孵育 48 小时时检测到酸性洗涤纤维 (ADF) 降解性增加。增加 LS 的比例会增加瘤胃液的 pH 值并线性降低挥发性脂肪酸，包括乙酸盐、丙酸盐和丁酸盐，而氨氮在孵育 12 小时和 72 小时时线性增加。随着LS比的增加，肉牛的最终体重、平均日增重和饲料转化率线性下降，而DMI不受影响。此外，DM、有机质、NDF和ADF的表观消化率呈线性和二次下降，而乙醚提取物的表观消化率呈线性下降，CP表观消化率不受影响。随着 LS 比例的增加，血清葡萄糖和尿素氮呈线性和二次下降，而谷氨酸-丙酮酸转氨酶活性呈线性下降。其他血清参数包括总甘油三酯、总胆固醇、总蛋白、白蛋白和谷氨酸-草乙酸转氨酶不受影响。总体而言，在 LS 和 CS 的组合中，LS 的提高比例导致 DM 和 NDF 降解性较差，但提高了 CP 降解性。67:33 的 CS:LS 比率导致公牛的最佳生长性能和养分利用率。