体外产气法和尼龙袋法测定饲料营养成分的比较

以玉米、豆粕、啤酒糟和玉米秸青贮为对象,分别测定了每种饲料的体外产气参数和瘤胃尼龙袋发酵参数,比较2种方法测定饲料营养成分发酵的异同及相互关系.结果表明,2种方法在评价玉米干物质(Dry matter,DM)和有机物(Organic matter,OM),豆粕DM,啤酒糟OM 48 h消失率方面存在显著差异(P＜0.05),在玉米、豆粕、啤酒糟的其余成分和玉米秸青贮各成分方面差异不显著;玉米和豆粕DM和OM的快速降解部分比例(a)较高,因而2种方法的体外产气速率(C)也快;玉米DM和OM有较高的可发酵成分(a+b),因而其48 h产气量(Y)最高;豆粕较高的粗蛋白(Crude protein,CP)导致其体外产气量最低;对低纤维饲料来说,DM和OM c值高者具有较高的产气速率和较小的延滞期,而对高纤维饲料来说,造成较高的产气速率和较小延滞期的主要原因可能来自于高的OM c值而非高的DM c值;影响理论最大产气量(B)的最主要因素是中性洗涤纤维,其次是酸性洗涤纤维.     

狍常用饲料瘤胃外流速度和降解率测定

利用尼龙袋法对狍常用饲料的营养价值进行了初步评定,测定了2个细度、4种有代表性饲料的瘤胃外流速度(kp)和8种饲料在狍瘤胃中的干物质有效降解率(DMD)、蛋白质有效降解率(CPD)、有机物有效降解率(OMD)。试验结果表明:不同种类饲料通过狍瘤胃的速度不同,但性状、粒度相近的饲料外流速度相近,饲料颗粒加大时,瘤胃外流速度减慢。豆粕、玉米面、柞树叶、玉米青贮瘤胃外流速度分别为3.40,2.68,2.25,2.18%/h。精饲料和优质牧草在狍瘤胃的降解率高于粗饲料,表明狍对这些粗饲料的利用率较低,生产实践中应限量饲喂。玉米面、豆粕、紫花苜蓿、玉米青贮、菊芋叶、高粱、青柞叶、草木樨的DMD分别为62.15%,58.21%,57.22%,26.29%,54.23%,61.98%,40.75%,55.89%;CPD分别为67.28%,68.24%,66.15%,34.23%,65.23%,40.09%,37.13%,54.47%;OMD分别为70.01%,70.14%,66.49%,34.47%,67.57%,58.53%,40.41%,57.55%。     

Nutritive evaluation of legume seeds for ruminant feeding

Chemical composition, rumen degradability and the effect of particle losses, and intestinal digestibility of protein by using in situ‐in vitro and in vitro techniques were stated for beans (Vicia faba), lupin (Lupinus albus), vetch (Vicia sativa) and bitter vetch (Vicia ervilia) and four diets including those legume seeds. In addition, the apparent digestibility of experimental diets was determined in goats. The legume seeds showed high protein content (206–319 g/kg dry matter). Effective degradability of protein for legumes and diets varied from 0.80 to 0.87 and 0.76 to 0.82, respectively, decreasing to 0.53–0.76 and 0.61–0.67, respectively, when particle loss was taken into account. Different intestinal digestibility values were obtained with both methodologies without significant relationship between them (y = 1.058–0.463x; R² = 0.068; RSD = 0.140; p = 0.53). There were no differences in the apparent nutrients and energy digestibility among diets (p > 0.05). These legumes can supply rapidly degradable protein for microbial protein synthesis and contribute to the pool of amino acids available for the synthesis of milk protein and for retention in the body.     

玉米植株剪切力与其饲料特性变化规律和相互关系的研究

【目的】研究不同品种玉米生长后期植株剪切力和饲料营养特性的变化规律以及相互关系。【方法】选择3个玉米品种,从播种后第78天开始,每隔5 d,分7个时期（每期每个品种选24株）测定植株主要营养器官（茎秆、叶片、叶鞘）的剪切力、线性密度、营养成分含量;分乳熟期、蜡熟期和完熟期测定三大营养器官营养成分的48 h瘤胃降解率。【结果】随着玉米的生长,茎秆剪切力和线性密度线性增加,品种间差异显著（P＜0.05）;叶鞘剪切力线性增加（P＜0.05）,叶鞘和叶片线性密度线性降低（P＜0.01）,品种间无差异（P＞0.05）。叶鞘、茎秆的剪切力与线性密度相关显著（P＜0.05）。在鲜样基础上,茎秆、叶鞘中的干物质（DM）、有机物（OM）、中性洗涤纤维（NDF）、酸性洗涤纤维（ADF）含量和总能（GE）线性增加,茎秆中粗蛋白（CP）含量呈线性降低,不同品种间有差异（P＜0.05）;叶片中DM、OM、NDF和ADF含量逐渐增大（P＜0.05）,品种间无差异（P＜0.05）;叶鞘、茎秆的剪切力与营养成分相关显著（P＜0.05）。所测定营养物质的48 h瘤胃降解率,不同器官之间差异显著,结果为叶片＞叶鞘＞茎秆（P＜0.05）。叶鞘的剪切力与营养成分降解率相关显著（P＜0.05）。【结论】玉米生长后期（播种后78-108 d）剪切力、营养成分和养分降解率呈动态变化;植株剪切力与其饲料特性存在相关关系,选用剪切力预测植株营养成分含量和利用率,需根据植株的不同器官和具体品种应用。     

不同生长期白羊草的营养成分及绵羊瘤胃降解特性

为研究不同生长期白羊草(Bothriochloa ischaemum Keng)营养成分的变化规律及营养成分的瘤胃降解规律,试验选用15只安装永久性瘤胃瘘管的肉用绵羊,采用半体内法(in situ)对不同生长期白羊草营养成分的降解规律进行测定。结果表明,不同生长期白羊草的各营养成分均差异显著(P<0.05)。随生长期的推进,粗蛋白质(CP)、粗灰分(Ash)、粗脂肪(EE)、钙(Ca)和磷(P)含量不断降低,而有机物(OM)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)和酸性洗涤木质素(ADL)含量不断增加。白羊草干物质(DM)、OM、NDF和ADF的72 h降解率及有效降解率均随生长期的推进不断降低,而CP有效降解率以拔节期最高,其次是抽穗期。综合考虑白羊草各生长期的营养含量及产量,以及营养成分的瘤胃降解特性,建议白羊草的最佳利用时期为抽穗期。     

尿素对羊瘤胃饲料降解率影响的研究

为了探索尿素对饲料利用率的影响,以瘤胃瘘管羊为实验动物,采用尼龙袋法,研究了尿素浓度梯度对饲料在羊瘤胃内降解率和主要养分含量变化的影响。选择3只瘤胃瘘管羊为实验动物,实验设对照组和试验组,对照组未添加尿素,试验组尿素浓度分别设为1%、2%、3%、4%和5%,测定饲料在瘤胃内6、12和24h时的粗脂肪、粗纤维、灰分、粗蛋白、钙含量和总降解率。结果表明,尿素添加水平在2%和3%时,饲料的消化率显著高于对照组和5%尿素组,饲料蛋白质、纤维素和脂肪含量显著低于对照组和5%尿素组,说明适量添加尿素可促进饲料营养物质利用率;添加2%和3%尿素可促进饲料钙的前期利用率,添加3%和4%尿素可促进饲料灰分的前期利用率。     

生物改性聚乙烯醇可降解包膜材料的特征及其光谱特性

聚乙烯醇溶于水可作为肥料的包膜材料,通过物理或化学改性,可影响聚乙烯醇缓释膜层的吸水性和降解性,提高其缓释性能和环境安全。为了探究改性聚乙烯醇膜材料的改性效果和降解能力,以壳聚糖为改性剂、二氧化硅为添加剂对聚乙烯醇进行改性,分析了改性聚乙烯醇成膜物理特性、生物降解性、红外表征及表面微观结构。研究结果表明,聚乙烯醇浓度85 g/kg,壳聚糖浓度16 g/kg,混合温度80℃,混合时间2 h条件下制备的膜材料吸水率降低明显,添加二氧化硅使聚乙烯醇浓度70 g/kg,壳聚糖浓度8 g/kg,混合温度60℃,混合时间2h条件下制备的膜材料吸水率最低,且二氧化硅添加量为5 g/kg时成膜降解率最高。红外光谱和扫描电镜分析表明,膜降解后一些主要官能团O-H、C-O键数量发生了变化,透射率增强,同时2 300 cm-1处波峰消失,这说明膜材料发生了一定的降解,同时其表面微观结构变得极为粗糙,出现很多凸起物,整体结构也变得更加松散,也说明其具有良好的生物降解性。红外光谱和电镜扫描的结果与质量变化试验的结果相一致,能够更客观地表征膜材料的降解性。     

Feed degradability,rumen fermentation and blood metabolites in response to essential oil addition to fistulated non‐lactating dairy cow diets

The effects of essential oils (EOs) on ruminal nutrient disappearance, rumen fermentation and blood metabolites in fistulated non‐lactating dairy cows were studied. Four fistulated non‐lactaing dairy cows were used in a 4 × 4 Latin square design; the experiment consisted of four periods of 21 days in each period, with the first 14 days for adaptation followed by 7 days of measurement period. Animals were fed 3 kg/day of 21% crude protein (CP) concentrate and ad libitum corn silage. Treatments were: (i) control; (ii) 2 mL Allicin/cow/day; (iii) 2 mL zingiberene/cow/day; and (iv) 2 mL citral/cow/day. The results demonstrated that EOs increased dry matter and neutral detergent fiber degradabilities at 48 and 72 h, but had no effect on acid detergent fiber and CP degradabilities. EOs did not change ruminal pH, ammonia nitrogen, protozoa, volatile fatty acid concentrations and blood glucose but reduced blood urea nitrogen at 4 h.     

紫花苜蓿和黑麦草茎形态学、化学组成和养分瘤胃降解率与剪切力的相互关系

 【目的】研究盛花期紫花苜蓿与灌浆期冬牧70黑麦草茎形态学、化学组成及养分48 h瘤胃降解率与剪切力之间的相关性。【方法】采集2种牧草后,测定茎直径、长度、重量和线性密度,测定剪切力、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、木质素、纤维素及半纤维素含量,用尼龙袋法测定干物质(DM)、中性洗涤纤维(NDF)48 h瘤胃降解率,比较各项指标随茎直径变化的规律,探讨剪切力与各项指标之间的相关性。【结果】盛花期紫花苜蓿茎的线性密度、剪切力、木质素含量随直径增大而提高,直径、线性密度、木质素含量与剪切力均呈线性正相关(P＜0.01);含水量随直径增大而降低,两者之间存在线性负相关(P＜0.01);DM、NDF 48 h瘤胃降解率与剪切力存在线性负相关(P＜0.05)。灌浆期黑麦草茎的茎厚、线性密度、酸性洗涤纤维(ADF)、木质素、纤维素、含水量、剪切力均随着外直径的增大而提高,外径、茎厚、线性密度、ADF、木质素和含水量均与剪切力呈线性正相关(P＜0.05);DM、NDF 48 h瘤胃降解率与剪切力无相关性(P＞0.05)。【结论】对于盛花期紫花苜蓿及灌浆期冬牧70黑麦草,茎剪切力受形态学指标、化学组成的综合影响;紫花苜蓿茎剪切力与DM、NDF48 h瘤胃降解率之间存在显著负相关,因此可用剪切力估计紫花苜蓿茎养分降解率的大小。黑麦草茎剪切力与养分降解率之间无显著相关。     

Energy Supply to Livestock from Tropical Rangeland during the Dry Season

Nine key forage species (grasses and legumes), together with two types of crop residues, usually fed by farmers to their livestock, were collected from a rainfed area in western Sudan during the dry season (May–April). The grasses investigated were Leptadena pyrotechnia, Cenchrus setigrus, Arista pallida, Eragrotis tremula, Schoenefeldia gracilis, Chloris vergata and Cenchrus biflorus. The crop residues investigated were the grasses, sorghum straw (Sorghum bichlor) and millet straw (Pennisetum typhodium) and the legumes Stylosanthes flavicans and Cajanus cajana. Estimates of organic matter (OM) degradability were done using the nylon bag technique, which was fitted into the model Y = a + b (1 – e^–ct), in which the asymptote (a + b) represented the total potential degradability. Organic cell wall constituents and hence both metabolizable energy and total digestible energy or nutrients (TDN) were determined. S. flavicans showed the best organic matter degradability, and sorghum straw was better degraded than millet straw. The rest of the grasses showed poor OM degradability. Acid detergent insoluble nitrogen was inversely related to TDN, the latter falling within a narrow range for the different forages. Fermentable metabolizable energy differed only slightly, while the legume S. flavicans had the highest effective rumen digestible protein. Undegraded proteins were high for the straws and the grasses L. pyrotechnia and C. setigerus. Metabolizable protein and microbial protein were highest in the sorghum straw, C. setigerus and S. flavicans.