Xu Junzhao, Wang Xiaoni, Niu Huaxin
College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, Inner Mongolia 028000, China.
Anim Biosci. 2025 Feb;38(2):293-302. doi: 10.5713/ab.24.0246. Epub 2024 Aug 26.
This study aimed to assess the impact of corn straw-based unfermented and fermented total mixed rations (TMR) supplemented with exogenous cellulase on the in vitro fermentation characteristics, growth performance, feeding behavior, apparent digestibility, rumen fermentation and digestive enzyme activities of Chinese Simmental bulls.
Unfermented (direct spraying of exogenous cellulase onto TMR, TMR) and fermented (exogenous cellulase fermentation for more than 7 d, fermented total mixed rations [FTMR]) TMR were collected, dried, powdered and used as fermentation substrates. The fermentation liquid was ruminal fluid collected from Chinese Simmental bulls. The artificial rumen culture fluid were continuously cultured in vitro for 48 h. Based on the diets they were fed, 24 healthy Chinese Simmental bulls (average weight of 495.93±10.89 kg) were randomly divided into two groups, with 12 bulls in each group, which were fed TMR or FTMR. The study lasted 56 d.
In in vitro experiments, the neutral detergent fiber (NDF) degradability and total volatile fatty acid, propionate, iso-butyrate, iso-valerate and valerate concentrations were greater in the FTMR group (p<0.05) than in the TMR group. However, the methane production, pH and acetate/propionate (A/P) of the FTMR group tended to be lower (p<0.05) than those of the TMR group. In the in vivo experiments, the average daily gain, eating rate, and feed efficiency of the FTMR groups were greater (p<0.05) than those of the TMR group. Similarly, the NDF degradability of the FTMR group was greater (p<0.05) than that of the TMR group. Compared to those in the TMR group, the concentrations of total volatile fatty acids, iso-butyrate, propionate and butyrate were greater in the FTMR group (p<0.05), and the A/P ratio was lower (p<0.05). Similarly, cellulase, xylanase, and β-glucosidase activities were greater (p<0.05) in the FTMR group than in the TMR group.
Corn straw-based FTMR supplemented with exogenous cellulase play a vital role in decreasing the structural carbohydrate content of TMR and ruminal methane production in vitro, improving nutrient digestion and absorption, optimizing rumen fermentation, and improving the growth performance of beef cattle.
本研究旨在评估添加外源纤维素酶的玉米秸秆基未发酵和发酵全混合日粮（TMR）对中国西门塔尔牛体外发酵特性、生长性能、采食行为、表观消化率、瘤胃发酵和消化酶活性的影响。
收集未发酵（将外源纤维素酶直接喷洒到TMR上，即TMR）和发酵（外源纤维素酶发酵7天以上，即发酵全混合日粮[FTMR]）的TMR，干燥、粉碎后用作发酵底物。发酵液为采集自中国西门塔尔牛的瘤胃液。人工瘤胃培养液在体外连续培养48小时。根据所饲喂的日粮，将24头健康的中国西门塔尔牛（平均体重495.93±10.89千克）随机分为两组，每组12头，分别饲喂TMR或FTMR。研究持续56天。
在体外实验中，FTMR组的中性洗涤纤维（NDF）降解率以及总挥发性脂肪酸、丙酸、异丁酸、异戊酸和戊酸浓度均高于TMR组（p<0.05）。然而，FTMR组的甲烷产量、pH值和乙酸/丙酸（A/P）比值均低于TMR组（p<0.05）。在体内实验中，FTMR组的平均日增重、采食率和饲料效率均高于TMR组（p<0.05）。同样，FTMR组的NDF降解率高于TMR组（p<0.05）。与TMR组相比，FTMR组的总挥发性脂肪酸、异丁酸、丙酸和丁酸浓度更高（p<0.05），A/P比值更低（p<0.05）。同样，FTMR组的纤维素酶、木聚糖酶和β-葡萄糖苷酶活性高于TMR组（p<0.05）。
添加外源纤维素酶的玉米秸秆基FTMR在降低TMR的结构性碳水化合物含量和体外瘤胃甲烷产量、改善养分消化吸收、优化瘤胃发酵以及提高肉牛生长性能方面发挥着至关重要的作用。
