青贮饲料发酵过程及其影响因素

青贮是保存青绿饲料营养物质的有效方法之一,青贮饲料以适口性好、家畜消化率高、经济安全等原因而被广泛应用在大规模养殖场和中小型养殖企业中。同时,青贮饲料还因能扩大饲料来源并不受季节影响全年提供优质饲料等原因,成为草地畜牧业可持续发展的重要保障。我国发展青贮饲料时间较晚,随着国家政策的导向和市场的实际需要,目前在青贮发酵原理、青贮发酵过程、青贮饲料营养物质损失、青贮添加剂等方面的研究都非常多,有很多研究成果进行了转化。其中,青贮饲料发酵过程的控制尤为重要,受到许多因素的影响。本文就这些因素进行阐述,以期为制作优质的青贮饲料提供参考。     

纤维素酶制剂在青贮饲料中的应用

青贮过程中添加纤维素酶制剂 ,通过纤维素酶对植物细胞壁的分解 ,不仅为青贮发酵提供充足的糖源 ,促进乳酸发酵 ;而且可降低青贮饲料中性洗涤纤维和酸性洗涤纤维含量 ,提高青贮饲料的消化率。近年来 ,纤维素酶制剂作为青贮添加剂受到国内外的广泛关注。虽然纤维素酶的应用研究结果尚有分歧 ,但随着酶工程和酶技术的发展 ,纤维素酶制剂在青贮中的应用前景将十分光明     

优质青贮饲料发酵的调控

优质青贮饲料发酵的调控安徽农业大学畜牧水产学院李槿年青贮饲料是新鲜作物经厌氧微生物发酵而使其营养物质得到保存的一种优质多汁饲料。已在畜牧业生产，尤其是养牛业中广泛应用。青贮饲料品质的好坏，直接影响其使用效果，成功地调制优质青贮饲料的关键在于促进有益微...     

乳酸菌对青贮饲料发酵品质影响的研究进展

青贮是常用的饲料储存方法之一,添加乳酸菌可以提高青贮饲料环境酸性,抑制病原微生物生长,提高有氧稳定性,提高动物生产性能。使用乳酸菌对饲料进行厌氧发酵能够保持饲料的新鲜度,提高饲料的营养价值,改善适口性。用于青贮的乳酸菌数量和种类会对饲料品质产生不同影响。青贮饲料发酵过程包括有氧阶段、厌氧阶段和稳定阶段等。不同乳酸菌在饲料发酵过程中的不同阶段发挥作用。文章主要介绍了用于饲料青贮的乳酸菌的常见种类及其对青贮饲料发酵品质的影响,为研发优质的青贮微生物添加剂、提高青贮饲料发酵品质提供参考。     

青贮饲料发酵的控制

一、青贮饲料与微生物青贮饲料是通过发酵制成的饲料。在调制过程中与植物和微生物的发酵作用密切相关,尤以微生物的作用重要。因此可通过控制微生物的繁殖调制优质青贮饲料。青贮饲料中的微生物有好氧菌(好氧细菌、酵母菌、霉菌等)和厌氧菌(乳酸菌、     

青贮发酵过程与青贮饲料的特点

青贮发酵是一个复杂的微生物活动和生物化学变化过程。青贮过程是为青贮原料上的乳酸菌生长繁殖创造有利条件,使乳酸菌大量繁殖,将青贮原料中可溶性糖类变成乳酸,当达到一定浓度时,抑制了有害微生物的生长,从而达到保存饲料的目的。因此,青贮的成败,主要决定于乳酸发酵的程度。     

青贮饲料发酵品质评定体系及其新进展

牧草青贮发酵品质评定体系的建立是对青贮饲料质量好坏更好的监督与评价,是提高青贮饲料质量、减少资源浪费的重要途径与方法,同时对提高家畜饲草料营养价值以及生产性能有着重要的意义.牧草青贮发酵品质评定体系中常规的实验室评定指标一般以有机酸(乳酸、乙酸和丁酸)和氨态氮含量为基准,但目前的研究结果表明,青贮料中乳酸含量增多就容易发生二次发酵,而且牧草青贮的pH值和氨态氮含量与牧草本身化学成份不同有关,因此在青贮饲料发酵品质评定体系中不宜将这些指标用作青贮料发酵品质评定的统一标准.     

青贮饲料时如何抑制不良发酵

阿瓦提县自2002年申报《国家秸秆养畜(羊)示范项目》以来,推广秸秆青贮技术已有近10年了。抑制不良发酵类包括添加各种酸类、抑菌剂或半干青贮,可阻止腐败细菌和酪酸菌的生长,以达到保存青贮饲料的目的。     

Degradation of transgenic Cry1Ab DNA and protein in Bt-176 maize during the ensiling process

Maize silage is commonly used as feed for farm animals. The aim of this study was to monitor the time-dependent degradation of non-recombinant chloroplast DNA (exemplified by the rubisco gene) in comparison with the recombinant cry1Ab gene in the course of the ensiling process. In parallel, the Cry1Ab protein content and fragment sizes were determined. Fragments of the rubisco (173, 896, 1197, 1753 and 2521 bp) and of the cry1Ab gene (211, 420, 727 and 1,423 bp) were selected to investigate the DNA degradation process. The detection of the Cry1Ab protein was performed using an enzyme-linked immunosorbent assay (ELISA) and immunoblotting. Rubisco gene fragments of 173 bp were still detectable after 61 days, while fragments of 1,197 and 2,521 bp were detectable up to 30 days and on the first day only respectively. Polymerase chain reaction (PCR) analyses revealed that fragments of the cry1Ab gene with sizes of 211 and 420 bp were detectable up to 61 days, fragments with sizes of 727 and 1,423 bp, 30 and 6 days respectively. The ELISA showed a decrease of the Cry1Ab protein in maize silage during the ensiling process. No marked degradation was observed during the first 43 h. Thereafter, a sharp decrease was measured. After 61 days, 23.6 +/- 0.9% of the initial Cry1Ab protein was still detectable. Immunoblotting confirmed the results of the ELISA showing a positive signal of approximately 60 kDa size for 8 days of ensiling; no further immunoactive fragments were detectable by immunoblotting. In conclusion, the ensiling process markedly decreases the presence of long functional cry1Ab gene fragments and full size Cry1Ab protein.     

华北驼绒藜青贮贮藏过程中发酵品质的动态变化

本研究探讨了华北驼绒藜青贮过程中发酵品质动态变化及添加剂对其影响。试验处理设对照组、乳酸菌处理组、纤维素酶处理组和乳酸菌+纤维素酶混合处理组,分别在贮藏后的1,3,5,10,30和45 d后开封,测定其pH值、乳酸、乙酸、丁酸和氨态氮含量。结果表明,发酵最初3~5 d内pH值迅速下降;发酵最初10 d内乳酸和乙酸含量迅速增加;而随着贮藏时间延长氨态氮、丁酸含量逐渐增加。与对照组相比,添加乳酸菌制剂、纤维素酶和乳酸菌制剂+纤维素酶的3个处理组均可提高华北驼绒藜青贮料的乳酸含量,降低pH值、氨态氮、丁酸含量,改善华北驼绒藜青贮料的发酵品质;其中添加乳酸菌制剂+纤维素酶效果最明显。     

Changes of fumonisin production in rice grain during ensiling

We assessed fumonisin production during the ensiling of rice grain. Rice grain was harvested at the full‐ripe stage and prepared as rough rice, crushed rough rice, brown rice or crushed brown rice. Each material was ensiled under six conditions: (1) no fungus, anaerobic; (2) no fungus, aerobic; (3) water added, anaerobic; (4) water and fumonisin‐producing fungus added, anaerobic; (5) water and fumonisin‐producing fungus added, aerobic; or (6) fumonisin‐producing fungus added to autoclaved material, aerobic. After 40 days of ensilage, we analyzed the silage fermentative quality and fumonisin concentration. The fermentative quality of all materials was good in treatments (3) and (4) (pH < 4), reasonable in treatment (5) (pH = 5～6) and unacceptable in treatments (1) and (2) (pH > 6.5). The fumonisin concentration was low in all materials in treatments (1) to (4), slightly increased in the three materials other than rough rice in treatment (5), and enormously increased in all materials in treatment (6). The results indicate that the fumonisin‐producing fungus does not produce fumonisin in anaerobic conditions. It is important that an anaerobic condition be maintained during ensiling in order to reduce the fumonisin content in rice grain silage.     

Fermentation and microbial population dynamics during the ensiling of native grass and subsequent exposure to air

To study the microbial population and fermentation dynamics of large needlegrass (LN) and Chinese leymus (CL) during ensiling and subsequent exposure to air, silages were sampled and analyzed using culture‐based techniques and denaturing gradient gel electrophoresis (DGGE). A total of 112 lactic acid bacteria (LAB) strains were isolated and identified using the 16S rRNA sequencing method. Lactic acid was not detected in the first 20 days in LN silage and the pH decreased to 6.13 after 45 days of ensiling. The temperature of the LN silage increased after approximately 30 h of air exposure and the CL silage showed a slight temperature variation. Enterococcus spp. were mainly present in LN silage. The proportion of Lactobacillus brevis in CL silage increased after exposure to air. LN silage with a higher proportion of Enterococcus spp. and propionic acid concentration did not show higher fermentation quality or aerobic stability than CL silage, which had a higher concentration of acetic acid, butyric acid and increased proportion of L. brevis after exposure to air.     

添加剂对青贮水稻秸秆发酵品质的改善作用

水稻种植产生大量的作物残渣,其中只有20%用于工业和生活用途。在大多数发展中国家(特别是东南亚),水稻秸秆常常被用作反刍动物的饲料原料。但由于其蛋白质含量低,木质素和二氧化硅含量高,消化率和营养价值受到限制。青贮可以提高水稻秸秆的营养价值,促进其合理利用。影响青贮饲料质量的因素主要包括水溶性碳水化合物、微生物菌群和原料的收获条件。饲料添加剂可以控制发酵过程,提高青贮饲料的营养成分和稳定性。本文综述了青贮饲料加工的一些实际问题,以及利用添加剂提高水稻秸秆发酵质量。     

Changes in the bacterial community and composition of fermentation products during ensiling of wilted Italian ryegrass and wilted guinea grass silages

To gain further insights into temperate and tropical grass ensiling, fermentation products and bacterial communities were examined at both the initial and late stages of ensiling of wilted Italian ryegrass and wilted guinea grass silages. 2,3‐Butanediol and ethanol fermentation were observed in wilted Italian ryegrass silage. Enterobacteria such as Rahnella sp. and Enterobacter sp. may have been involved in fermentation; however, alcohol production was intensified after the silage enterobacterial community overwhelmed the pre‐ensiled enterobacterial community. Pediococcus spp. appeared in silage stored for 4 months, when a significant increase in lactic acid content was seen compared with that at 2 months. Prolonged storage enhanced acetic acid fermentation in wilted guinea grass silage. The disappearance of Enterococcus sulfureus and appearance of Lactobacillus plantarum may have been associated with the increased acetic acid content. Although many species of enterobacteria were found in common between the pre‐ensiled crop and silages of Italian ryegrass and guinea grass, marked differences were seen in the type of fermentation from the initial stages. These results indicate that the bacterial community of pre‐ensiled crops may be immediately replaced by one that is adapted to ensiling environments, although metabolic changes may continue over the course of ensiling.     

牛卵子发生过程中卵母细胞凋亡的调控机理

细胞凋亡是发育过程中的基本生命现象,除各种体细胞凋亡外,生殖细胞的发生过程中也发生细胞凋亡。就雌性生殖系而言,细胞凋亡是其发育过程中的一个重要组成部分。在母牛中,超过99.9%的雌性生殖细胞都会在卵子发生的不同阶段发生凋亡。本文主要综述了牛卵子发生过程中卵母细胞凋亡的现象、凋亡的分子机理等,同时还探讨了卵母细胞凋亡的途径。     

妊振内分泌调控

妊娠期间是动物内分泌最为活跃的阶段之一，体内的各种和生殖相关的激素和信号物质都随之发生变化，除了神经肽类和类固醇激素外，特别是母体和孕体分泌的一些生物活性因子。它们对妊娠都有着特殊重要的意义。深入了解它们在妊娠过程中调控机理，将有利于在生产和科研上进一步的应用。     

妊娠内分泌调控

妊娠是指一个受精卵从母体的输卵管下行到子宫 ,并在子宫内定植并维持胚胎发育完全直到分娩的全过程。在整个妊娠的过程中 ,内分泌的调控起着重要作用 ,它们包括妊娠识别、妊娠建立、胚胎的附植、妊娠的维持和胚胎的发育。通过各种激素和信号物质协同作用 ,使整个妊娠过程中母体对胎儿的免疫排斥受到抑制[1] 。深入研究其机理有利于人们在生产上对动物的繁殖活动进行更有效的控制。本文综合了近几年来在妊娠内分泌调控上的研究进展。1　妊娠识别和建立在妊娠的早期 ,孕体在子宫内必须产生某些信号物质 ,以抑制黄体的溶解和母体的免疫排斥[2 …     

Effect of ensiling process of total mixed ration on fermentation profile,nutrient loss and in situ ruminal degradation characteristics of diet

This experiment aimed to determine the changes in chemical composition, fermentation profile, in situ disappearance characteristics, and nutrient losses of ensiled total mixed ration (TMR) containing steam‐flaked corn or brown rice (BR) during storage. TMRs for dairy cows, containing either steam‐flaked corn or BR at 31.9% with 15.2% rye silage, 40.5% alfalfa silage, 5.0% beet pulp and 7.0% soybean meal, were prepared (dry matter (DM) basis). Each TMR was placed in a plastic drum silo, stored at 23°C in an air‐conditioned room and sampled 0, 7, 14, 30, 90 and 210 days after preparation. In both grain sources, the fermentation products increased, while DM and starch storage losses increased and starch content greatly decreased during storage. The rapidly degradable fraction and effective ruminal degradability of DM, crude protein and starch increased during storage. These changes of dietary characteristics were large during 30 days of storage, but small after 90 days of storage. Replacing corn with BR led to increased fermentation products, starch loss and effective ruminal degradability of the ensiled TMR. These results indicate that the ensiling process of TMR changes the dietary characteristics and replacing corn with BR in TMR had a large impact on these dietary characteristics.