日粮硝酸盐水平对湖羊瘤胃硝态氮动态消失率、发酵参数及血液高铁血红蛋白含量的影响

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陈志远, 马婷婷, 方伟, 左晓昕, 林淼, 赵国琦. .日粮硝酸盐水平对湖羊瘤胃硝态氮动态消失率、发酵参数及血液高铁血红蛋白含量的影响. 草业学报, 2016,25(2): 95-104
CHEN Zhi-Yuan, MA Ting-Ting, FANG Wei, ZUO Xiao-Xin, LIN Miao, ZHAO Guo-Qi. .Effects of dietary nitrate dosage on ruminal nitrate disappearance rate, fermentation parameters and concentration of blood methemoglobin of Hu Sheep . Acta Prataculturae Sinica,2016,25(2): 95-104 复制到剪切板

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日粮硝酸盐水平对湖羊瘤胃硝态氮动态消失率、发酵参数及血液高铁血红蛋白含量的影响

陈志远^**, 马婷婷^**, 方伟, 左晓昕, 林淼^*, 赵国琦^*

扬州大学动物科学与技术学院,江苏扬州 225009

*通信作者Corresponding author. E-mail:linmiao@yzu.edu.cn, gqzhao@yzu.edu.cn

作者简介:陈志远(1988-),男,山东德州人,在读硕士。E-mail:czy0323@163.com。马婷婷(1989-),女,山东潍坊人,在读硕士。E-mail:285086492@qq.com。**共同第一作者 These authors contributed equally to this work.

收稿日期: 2015-08-30

基金项目:基金项目:江苏省博士后科研资助计划(1402114C)和江苏高校优势学科建设工程资助项目资助

摘要

本试验研究日粮硝酸盐的添加量对湖羊瘤胃还原硝态氮程度和对发酵参数及血液高铁血红蛋白的影响。试验选取6头湖羊,采用随机区组试验设计,每期分别饲喂含0%,1%,2%,3%,4%,5%硝酸钾的日粮。测定喂后0,0.5,1.0,1.5,2.0,4.0,6.0,8.0 h瘤胃液硝酸盐和亚硝酸盐含量及瘤胃发酵参数。晨饲后2.0 h通过颈静脉采血,测定高铁血红蛋白含量。结果表明,湖羊在采食1.0 h后硝酸盐含量达到最高(0.952.14 g/L),之后快速消失,亚硝酸盐含量在喂后1.5 h达到最高(0.936.22 μmol/L),之后降低。高铁血红蛋白的含量随硝酸盐添加量的增加而显著升高( P<0.01),最高达0.32%。添加硝酸盐显著提高瘤胃液pH值( P<0.01)和2.0 h的氨态氮含量( P<0.01)以及乙酸/丙酸,添加量高于3%会降低微生物蛋白和总挥发性脂肪酸的浓度,2%的硝酸盐添加量微生物蛋白和总挥发性脂肪酸的合成量最高,最有利于微生物发酵。

关键词: 微生物蛋白; 硝酸盐还原; 瘤胃发酵; 添加量

Effects of dietary nitrate dosage on ruminal nitrate disappearance rate, fermentation parameters and concentration of blood methemoglobin of Hu Sheep

CHEN Zhi-Yuan^**, MA Ting-Ting^**, FANG Wei, ZUO Xiao-Xin, LIN Miao^*, ZHAO Guo-Qi^*

College of Animal Sciences and Technology, Yangzhou University, Yangzhou 225009, China

Abstract

This study investigated the effects of dietary nitrate dosage on ruminal nitrate disappearance rate, fermentation parameters and blood methemoglobin of Hu sheep. The experiment used a randomized block design. Six selected Hu sheep were fed different levels of dietary potassium nitrate (0%, 1%, 2%, 3%, 4%, 5% of DM intake). The concentration of nitrate, nitrite and fermentation parameters in rumen fluid were obtained 0, 0.5, 1.0, 1.5, 2.0, 4.0, 6.0 and 8.0 h after feeding. In addition, the concentration of blood methemoglobin was determined 2.0 h after feeding through blood collection from the jugular vein. The nitrate concentration increased to a maximum value (0.95-2.14 g/L) at 1.0 h after feeding, then reduced rapidly. The nitrite concentration increased to maximum value (0.93-6.22 μmol/L) 1.5 h after feeding. The content of methemoglobin significantly increased with the nitrate addition ( P<0.01), to a peak of 0.32% at 5% dietary potassium nitrate. Nitrate addition also significantly increased rumen fluid pH value, ammonia nitrogen concentration and acetic acid/propionic acid 2.0 h after feeding ( P<0.01). In conclusion, potassium nitrate addition at over 3% of DM intake was found to reduce the concentration of microbial protein and total volatile fatty acids. Microbial protein synthesis and total volatile fatty acids were highest with 2% potassium nitrate addition, and the dosage of 2% potassium nitrate was beneficial to rumen fermentation.

Keyword: microbial protein; reducing nitrate; rumen fermentation; dosage

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中国是畜产品生产大国, 也是消费大国, 尤其是近年来, 人们对反刍动物产品的需求越来越大^[1]。但目前, 我国蛋白质饲料自给自足率非常低, 蛋白质饲料的匮乏严重制约我国畜牧业的发展。非蛋白氮饲料原料作为一种良好的蛋白质饲料替代品, 能够为瘤胃微生物蛋白的合成提供氮源。硝酸盐作为一种非蛋白氮, 制作工艺简单, 成本低廉, 尤其是在低蛋白日粮情况下, 其在瘤胃内的利用效率甚至高于尿素^[2]。硝酸盐在厌氧条件下主要有3条代谢途径:同化还原作用、异化还原作用和反硝化作用。反硝化作用产生N₂的过程较为困难, 在瘤胃内极少存在^{[3, 4]}。同化还原和异化还原过程均为N $\begin{matrix} {O_{3}}^{-} \end{matrix}$ → N $\begin{matrix} {O_{2}}^{-} \end{matrix}$ → N $\begin{matrix} {H_{4}}^{+} \end{matrix}$ , 但异化还原作用是硝酸盐在瘤胃内的主要代谢途径^[5]。硝酸盐在被还原过程中, 能够抢夺供氢体的电子, 抑制甲烷的产生, 降低温室气体的排放, 减少饲料能量的浪费^[6]。但硝酸盐还原为亚硝酸盐的速度要大于亚硝酸盐还原为氨的速度, 所以, 若一次性大量饲喂硝酸盐, 极易造成亚硝酸盐的积累, 而亚硝酸盐具有强烈的氧化性, 通过瘤胃上皮进入血液, 将血液里的Fe²⁺氧化成Fe³⁺, 使血红蛋白失去携带氧的能力, 从而引起高铁血红蛋白症。研究表明, 如果经过一段适应期后, 反刍动物对于硝酸盐的耐受性能够提高35倍^[7]。Mamvura等^[8]使用芝麻油将21 mmol/L硝酸盐包被后进行体外试验发现, 包被后的硝酸盐能大大降低亚硝酸盐的积累, 并且氨态氮的水平提高了44%, 但总挥发性脂肪酸浓度显著下降, 另外, 其包被工艺较为复杂, 在实际生产中推广较为困难。如何合理利用硝态氮, 降低中毒风险仍是急需解决的问题。

目前对于硝酸盐的研究多集中在其毒性及体外产气方面, 并且研究结果并不一致, 代俊芳等^[9]采用双外流连续培养系统的体外研究结果表明, 硝态氮的添加水平对瘤胃pH值和总挥发性脂肪酸没有显著影响, 但能提高氨态氮的水平, 乙酸/丙酸随硝态氮的提高而呈二次曲线规律变化。Lin等^[10]的体外试验表明, 硝态氮并不影响总挥发性脂肪酸的浓度, 但会提高乙酸的浓度, 降低丙酸和丁酸的浓度。Patra和Yu等^[11]在培养底物中分别加入5和10 mmol/L的硝酸盐, 甲烷产量分别降低23%和43%, 提高了总挥发性脂肪酸和乙酸浓度, 而对氨态氮的产量无显著影响。由于动物瘤胃复杂的内环境及体外培养的条件限制, 因此体外模型并不能真实反映瘤胃硝态氮的变化规律和发酵的影响。本研究以湖羊为试验动物, 通过活体试验研究日粮硝酸钾添加量不同对瘤胃硝酸盐消失率和发酵参数的影响, 为调控硝酸盐的还原及优化硝酸盐在反刍动物日粮中的应用提供参考资料。

1 材料与方法

1.1 试验动物及试验设计

选取6头9月龄, 体况良好, 体重相近(30± 5) kg且装有永久性瘘管的湖羊, 采用随机区组设计, 试验分为6期, 以不添加硝酸钾为对照期, 每期逐量增加硝酸钾的添加量至占日粮干物质的1%, 2%, 3%, 4%, 5%, 每个添加梯度设置14 d预试期, 2 d采样期, 试验时间为2014年4-7月。

1.2 试验日粮及饲养管理

参照饲养标准(NRC 2007)绵羊营养需要配制日粮, 并制粒, 日粮由豆皮、燕麦草、混合精料等组成, 精粗比6∶ 4, 具体营养成分见表1。试验羊每天饲喂2次(9:00和16:00), 每次饲喂日粮600 g, 自由饮水, 保持羊舍适宜的光照和通风, 定期消毒。

表1 试验日粮组成及营养水平(干物质基础) Table 1 Composition and nutrient levels of experimental diets (DM basis)

1.3 样品的采集及测定指标

采样期分别于晨饲后0, 0.5, 1.0, 1.5, 2.0, 4.0, 6.0, 8.0 h通过真空负压装置, 从瘤胃上下左右不同点采集瘤胃液, 用4层无菌纱布过滤, 采用便携式pH计立即测定pH值, 然后将过滤瘤胃液分装于6支5 mL离心管中, 存放于-20℃的冰箱中, 待测氨态氮、硝酸盐含量、亚硝酸盐含量、微生物蛋白和挥发性脂肪酸。正试期每日晨饲后2.0 h通过颈静脉采集5 mL血液, 存入含有肝素钠的抗凝管中, 立即测定血液中高铁血红蛋白的含量。

1.4 指标测定方法

硝酸盐含量:参照蔡顺香^[12]的方法, 并调整如下:吸取5 mL瘤胃液, 加入5 mL饱和硼砂溶液, 沸水浴10 min, 并不时搅拌, 冷却, 转入250 mL容量瓶中, 加2 g活性炭脱色, 定容。震荡混匀, 过滤, 取适量滤液, 用石英比色皿在220和260 nm处比色, 计算差值, 同时做空白, 通过标准曲线计算出硝酸盐的含量。

亚硝酸盐浓度:采用南京建成生物工程研究所试剂盒所述方法(比色法)进行测定。

氨态氮浓度:采用酚-次氯酸钠比色法^[13]。

挥发性脂肪酸含量:采用日本岛津GC-14B气相色谱仪测定乙酸、丙酸、丁酸、戊酸含量^[14]。瘤胃液经12000 r/min离心20 min, 取上清液1 mL, 加0.2 mL 25%的偏磷酸(含60 mmol/L巴豆酸)冷冻过夜, 之后再次12000 r/min离心20 min, 用0.45 μ m滤膜过滤上清液, 以巴豆酸为内标, 上样量5 μ L。测定条件:毛细管柱CP-WAX(柱长30 m, 内径0.53 mm, 膜厚1 μ m)载气为高纯N₂(压力0.7 MPa, 流量30 mL/min), 燃气H₂(流量 30 mL/min), 气化室温度200℃, FID检测器温度200℃, 柱温采用程序升温法, 初温100℃, 末温130℃, 升温速率3℃/min, 灵敏度为101, 衰减为25。

高铁血红蛋白的测定:采用南京建成生物工程研究所高铁血红蛋白测定试剂盒测定。

微生物蛋白:考马斯亮蓝法测定微生物蛋白浓度^[15]。

1.5 统计分析

采用Excel 2013软件整理试验数据, 采用SAS 9.2软件的PROC MIXED模型进行方差分析, 并用Tukey’ s法进行差异显著性比较。

2 结果与分析

2.1 不同硝酸盐剂量对血液高铁血红蛋白含量的影响

由表2可知, 湖羊采食2 h后, 血液高铁血红蛋白的含量随着硝酸盐添加量的增加而逐渐升高, 且添加量为4%和5%时, 其含量极显著高于对照组和1%处理组(P< 0.01)。

表2 添加不同剂量硝酸钾对湖羊血液高铁血红蛋白含量的影响 Table 2 Effects of nitrate dosages on blood methemoglobin of Hu sheep %

2.2 不同硝酸盐剂量对瘤胃液pH值的影响

由表3可知, 各处理组瘤胃液pH值变化趋势基本一致, 呈先下降后上升趋势。在采食24 h后达到最低点, 之后逐渐回升。5%处理组的pH值均最高(6.666.87), 且除0 h外, 5%组均极显著高于对照组、1%和2%组(P< 0.01); 0.5和2.0 h, 对照组和1%4%处理组之间无显著差异; 在1.0和1.5 h, 4%处理组pH值极显著高于对照组(P< 0.01); 对照组与1%3%处理组之间在各个时间点差异不显著。

表3 添加不同剂量硝酸盐对湖羊瘤胃液pH值动态变化的影响 Table 3 Effects of nitrate dosages on dynamic change of pH value in rumen fluid

2.3 瘤胃液硝酸盐浓度的动态变化

经检测, 对照组硝酸盐含量保持较低水平(≤ 0.79 g/L), 并且无动态变化。各处理组硝酸盐含量在采食后01 h逐渐上升, 之后下降; 采食0.5 h后, 5%处理组硝酸盐含量极显著高于其他组(P< 0.01), 其他处理组之间无显著差异。其他时间点, 各组之间无显著差异(表4)。

表4 湖羊瘤胃液硝酸盐含量的动态变化 Table 4 Dynamic changes of nitrate concentration in rumen fluid of Hu sheep g/L

2.4 瘤胃液亚硝酸盐浓度的动态变化

经检测, 对照组亚硝酸盐含量保持较低水平(≤ 0.35 μ mol/L), 并且无动态变化。由表5可知, 动物在采食后1.01.5 h亚硝酸盐含量达到最高, 之后迅速下降。0.5, 1.0和1.5 h时, 5%处理组极显著高于其他处理组(P< 0.01), 其他处理组之间无显著差异。2 h时, 5%处理组极显著高于其他处理组, 4%处理组极显著高于1%处理组(P< 0.01)。其他时间点各组之间无显著差异。

表5 湖羊瘤胃液亚硝酸盐含量的动态变化 Table 5 Dynamic changes of nitrite concentration in rumen fluid of Hu sheep μ mol/L

2.5 不同硝酸盐添加水平对氨态氮含量的影响

由表6可知, 各组之间氨态氮的浓度变化基本一致, 在采食后逐渐上升, 1 h后达到最大值, 之后逐渐下降。采食2 h后, 5%处理组氨态氮浓度显著高于1%处理组(P< 0.05), 其他时间点各组之间无显著差异。

表6 不同硝酸盐添加剂量对湖羊瘤胃液氨态氮浓度的影响 Table 6 Effects of nitrate dosages on NH₃-N concentration in rumen fluid of Hu sheep mg/dL

2.6 不同硝酸盐添加水平对微生物蛋白浓度的影响

由表7可知, 0 h时, 4%处理组微生物蛋白极显著高于对照组(P< 0.01)。0.5, 1.0, 1.5, 4.0, 6.0, 8.0 h均以2%处理组微生物蛋白浓度最高, 且极显著高于对照组(P< 0.01)。2 h的各组之间微生物蛋白浓度差异不显著。综合起来看, 2%处理组微生物蛋白浓度最高。

表7 不同硝酸盐添加剂量对湖羊瘤胃液微生物蛋白浓度的影响 Table 7 Effects of nitrate dosages on microbial protein concentration in rumen fluid of Hu sheep g/L

2.7 不同硝酸盐添加水平对挥发性脂肪酸含量的影响

由表8可知, 各组的乙酸、丙酸、丁酸、戊酸、总挥发性脂肪酸的变化趋势基本一致, 在采食后02 h逐渐上升, 之后下降。乙酸浓度在1.5, 2.0, 6.0 h以2%处理组浓度最高, 且极显著高于对照组和5%处理组(P< 0.01)。1.5 h时, 5%处理组乙酸浓度极显著低于对照组(P< 0.01)。丙酸浓度在0.5, 1.0, 1.5, 6.0 h时, 2%处理组极显著高于对照组(P< 0.01), 在0.58.0 h之间, 5%处理组丙酸浓度最低, 且极显著低于对照组(P< 0.01)。丁酸浓度在1 h时, 2%, 3%, 4%处理组极显著高于其他处理组(P< 0.01), 2 h的5%处理组丁酸浓度极显著低于其他处理组(P< 0.01)。6 h时, 2%处理组丁酸浓度极显著高于0%, 1%, 3%, 5%处理组(P< 0.01)。0 h时的戊酸浓度2%处理组最高, 且极显著高于对照组(P< 0.01)。2 h时, 1%和4%处理组戊酸浓度极显著高于5%处理组(P< 0.01)。总挥发性脂肪酸在0.58.0 h均以2%处理组最高, 并且在0.5, 1.0, 1.5, 2.0, 6.0 h极显著高于对照组(P< 0.01)。5%处理组的总挥发性脂肪酸浓度最低。乙酸/丙酸在0.58.0 h均以5%处理组最高, 且极显著高于0%处理组(P< 0.01)。综合起来看, 总挥发性脂肪酸浓度2%处理组最高, 乙酸/丙酸5%处理组最高。

表8 不同硝酸盐添加量对瘤胃液挥发性脂肪酸含量的影响 Table 8 Effects of nitrate dosages on the concentration of volatile fatty acids in rumen fluid of Hu sheep

项目 Items	时间 Time (h)		添加量 Dosage levels												SEM		P
项目 Items	时间 Time (h)		对照CK						1%		2%		3%		4%		5%
乙酸Acetate	0		30.72		41.42		38.19		24.78		42.51		29.93		3.97		0.05
(mmol/L)	0.5		33.43		37.86		52.84		39.59		49.33		23.17		7.23		0.12
	1.0		41.23		46.56		53.45		53.29		61.84		36.45		4.51		0.08
	1.5		50.09b		55.90b		76.78a		35.74bc		45.10bc		27.41c		4.23		< 0.01
	2.0		47.97b		62.30ab		88.88a		52.66b		63.18ab		39.38b		3.97		< 0.01
	4.0		41.14		47.12		44.56		47.23		43.08		27.98		4.03		0.05
	6.0		37.38bc		42.51bc		64.40a		28.24c		47.26b		28.60c		3.03		< 0.01
	8.0		32.02		33.91		45.32		29.22		36.56		30.17		2.92		0.08
丙酸Propionate	0		16.38		17.90		16.57		10.80		12.23		8.71		1.55		0.05
(mmol/L)	0.5		18.31b		21.53b		31.92a		12.40c		20.81b		7.13c		1.01		< 0.01
	1.0		22.10bc		28.63b		44.06a		20.57bc		17.08cd		9.41d		1.50		< 0.01
	1.5		28.59b		31.00b		54.34a		17.28c		16.27c		7.89d		1.62		< 0.01
	2.0		33.07ab		34.35ab		42.11a		24.83abc		19.81bc		9.72c		3.79		< 0.01
	4.0		28.71ab		31.21a		27.10ab		24.48ab		21.58b		9.44c		1.77		< 0.01
	6.0		27.54b		29.19b		44.56a		13.76c		24.45b		7.27c		1.48		< 0.01
	8.0		24.88a		25.09a		26.76a		9.90b		11.88b		10.58b		1.61		< 0.01
丁酸Butyrate	0		4.32		5.16		7.14		2.92		7.00		4.95		1.01		0.20
(mmol/L)	0.5		4.22		4.48		6.06		5.29		6.52		2.90		0.68		0.05
	1.0		4.85b		4.98b		9.82a		9.05a		9.93a		3.15b		0.41		< 0.01
	1.5		7.69a		9.13a		11.41a		9.07a		8.48a		2.50b		0.87		< 0.01
	2.0		9.67a		10.37a		10.06a		10.10a		11.13a		3.16b		1.23		< 0.01
	4.0		7.35		8.54		9.72		10.07		7.89		3.16		1.67		0.12
	6.0		7.07b		7.63b		15.20a		5.59b		8.65ab		3.68b		1.46		< 0.01
	8.0		5.51		6.60		7.33		4.41		4.58		3.90		0.98		0.23
戊酸Pentanoic acid	0		0.55b		0.93ab		1.52a		0.48b		1.01ab		0.61b		0.12		< 0.01
(mmol/L)	0.5		0.66		1.15		1.16		0.49		0.99		0.53		0.17		0.07
	1.0		0.81		1.02		1.55		0.83		0.97		0.70		0.17		0.06
	1.5		0.94		1.44		1.43		0.85		0.95		0.59		0.19		0.06
	2.0		0.96ab		1.57a		1.26ab		1.16ab		1.40a		0.56b		0.15		< 0.01
	4.0		0.75		0.80		0.65		0.76		0.58		0.47		0.07		0.06
	6.0		0.73b		0.75b		1.37a		0.66b		1.02ab		0.53b		0.11		< 0.01
	8.0		0.63		0.68		0.77		0.55		0.65		0.49		0.11		0.68
总挥发性脂肪酸Total volatile fatty acid (TVFA) (mmol/L)	0		54.14ab		72.57a		66.50ab		39.19b		70.01ab		53.24ab		6.68		0.04
	0.5		58.65b		67.18ab		103.93a		62.02b		59.28b		35.37b		7.07		< 0.01
	1.0		71.02bc		83.36b		119.37a		84.08b		80.94bc		46.59c		6.68		< 0.01
	1.5		88.93b		98.70b		142.37a		74.62bc		78.10bc		40.16c		7.44		< 0.01
	2.0		108.79b		110.18b		149.80a		87.65b		86.98b		48.86c		5.13		< 0.01
	4.0		79.90ab		97.48a		108.21a		84.15a		74.75ab		42.47b		8.48		< 0.01
	6.0		74.51b		81.79ab		99.47a		49.46c		82.95ab		46.27c		4.59		< 0.01
	8.0		64.81ab		67.57ab		81.76a		42.54b		57.86ab		46.75b		5.55		< 0.01
项目 Items		时间 Time (h)		添加量 Dosage levels												SEM		P
项目 Items		时间 Time (h)		对照CK						1%		2%		3%		4%		5%
乙酸/丙酸Acetate/propionate		0		1.90		1.99		2.20		2.92		3.54		2.97		0.33		0.07
		0.5		1.82c		1.76c		2.14bc		2.46bc		3.70a		3.27ab		0.19		< 0.01
		1.0		1.88bc		1.63c		1.59c		2.06bc		2.80ab		3.18a		0.20		< 0.01
		1.5		1.76b		1.80b		1.68b		2.38b		2.49b		3.55a		0.16		< 0.01
		2.0		1.32c		1.85bc		1.86bc		2.14bc		2.57ab		3.60a		0.23		< 0.01
		4.0		1.44b		1.76b		1.68b		1.99ab		2.22ab		3.24a		0.27		< 0.01
		6.0		1.36b		1.46b		1.42b		1.65b		2.43a		2.92a		0.08		< 0.01
		8.0		1.29c		1.37c		1.76bc		2.91ab		3.07ab		3.36a		0.24		< 0.01

表8 不同硝酸盐添加量对瘤胃液挥发性脂肪酸含量的影响 Table 8 Effects of nitrate dosages on the concentration of volatile fatty acids in rumen fluid of Hu sheep

3 讨论

硝酸盐在瘤胃内可被还原为亚硝酸盐, 亚硝酸盐被吸收进入血液, 将亚铁血红蛋白氧化成高铁血红蛋白, 从而使血红蛋白失去携氧能力, 引起组织缺氧, 甚至动物死亡; 此外, 亚硝酸盐中毒能显著抑制小鼠神经干细胞的增殖, 降低新生细胞的存活率^[16]。目前对于各种动物的中毒剂量并没有统一报道。王春林等^[17]研究发现, 日粮中亚硝酸盐含量达到900 mg/kg时, 对肉鸭的健康有明显的不良影响。Carrigan和Gardner^[18]研究发现, 当苏丹草含硝酸盐达3.1%时, 牛出现中毒现象, 并继发流产。Setchell和Williams^[19]发现, 山羊的中毒剂量为345 mg/(kg BW· d)。单胃动物对硝酸盐的耐受性较差, 而反刍动物瘤胃内微生物能将硝酸盐转化成亚硝酸盐, 进一步转化成氨态氮从而被机体利用。因此, 经过“ 适应” 能提高反刍动物对硝酸盐的耐受性^[7]。当动物血液中高铁含量达到30%50%时, 就会导致组织缺氧, 出现呼吸困难, 神经机能紊乱等症状^[20]。本试验中, 湖羊日粮含硝酸盐最高剂量为日粮5%, 高铁血红蛋白含量最高达0.32%, 并未出现明显的中毒现象。由于绵羊血液内高铁血红蛋白还原酶的活性较高, 还原Fe³⁺的能力较强, 所以绵羊对硝酸盐有较高的耐受性^[21]。湖羊在采食硝酸盐日粮0.5 h后, 硝酸盐浓度即以达到最大值, 而亚硝酸盐浓度1.5 h内达到最大值, 可见硝酸盐还原为亚硝酸盐的速度是很快的, 而亚硝酸盐的积累相对滞后。林淼^[22]的研究发现, 阉肉牛在适应2%DM的硝酸钾后, 硝态氮在1.0 h达到最高值, 4.0 h后硝态氮浓度趋近于0, 且不产生亚硝酸盐的积累。Lewis^[23]直接将25 g NaNO₃和10 g NaNO₂投入未经适应的绵羊瘤胃, 发现在投放1.0 h后, N $\begin{matrix} {O_{3}}^{-} \end{matrix}$ 的浓度达到最大, 而N $\begin{matrix} {O_{2}}^{-} \end{matrix}$ 的浓度则在投放4.0 h后达到最大值。Lee等^[24]的研究表明, 限制硝酸盐的快速还原是降低硝酸盐中毒风险的重要手段。硝酸盐的降解速率受多种因素影响。Allison和Reddy^[25]发现动物在采食硝酸盐36 d后, N $\begin{matrix} {O_{3}}^{-} \end{matrix}$ 和N $\begin{matrix} {O_{2}}^{-} \end{matrix}$ 的还原速率提高了35倍。日粮中碳水化合物在发酵过程中的某些中间产物可作为还原硝酸盐的供氢体, 从而影响硝酸盐的还原。Patra和Yu^[11]的研究表明, 日粮中添加皂苷和硝酸盐能够显著降低甲烷气体的产量, 且对瘤胃发酵有积极的影响。Yoshida等^[26]通过体外试验证明, 高精料水平下, 不利于硝酸盐的还原。Yoshii等^[27]将反刍月形单胞菌(Selenomonas ruminatium)与淀粉、淀粉分解菌共培养, 导致亚硝酸盐的积累, 而将S. ruminatium与纤维素、纤维分解菌共培养时, 亚硝酸盐的浓度显著降低。林淼等^[28]则指出, 饲粮中快速发酵的碳水化合物应维持在适当的水平, 过高或过低均不利于硝酸盐的还原。

正常瘤胃pH值为5.57.5, 本试验中pH值最低5.5, 最高6.87, 均属于正常范围。娄丽平^[29]研究发现, 绵羊日粮中添加尿素、小肽、大豆蛋白作为氮源时, 瘤胃液pH值并无显著差异。代俊芳等^[9]在日粮中添加占总氮的百分比为0%, 6%, 12%, 18%, 24%和30%的硝酸钾进行双外流连续培养体外发酵发现, 日粮硝态氮水平并不影响瘤胃pH值。张建刚^[30]研究表明, 日粮中添加0%, 0.5%, 1.0%的硝酸钾时, 并未对pH值产生显著影响。然而Zhou等^[31]的体外实验表明, 在硝态氮添加量大于24 μ mol/mol时, pH值呈明显的上升趋势。与本试验一致。在本试验中, 5%硝酸盐处理组0.58.0 h瘤胃pH值极显著高于其他组(P< 0.01)。高剂量的硝酸盐能够提高瘤胃pH值可能与氨态氮浓度的升高和挥发性脂肪酸浓度的降低有关。

瘤胃液中氨氮浓度主要取决于日粮蛋白质水平及其降解程度、瘤胃上皮对氨氮的吸收以及日粮能量水平。本研究中, 各处理组氨氮浓度在采食后呈上升趋势, 在1.52.0 h时达到最大, 之后下降。表明日粮中的含氮物质快速降解, 超过了微生物利用氨氮的速度使氨态氮浓度升高。随着瘤胃上皮对氨氮的吸收以及瘤胃微生物蛋白的合成, 氨氮浓度逐渐下降。日粮中添加硝酸盐均能提高氨态氮的产量^{[24, 32]}。从2.0 h来看, 5%处理组氨氮浓度显著大于1%处理组(P< 0.05), 也是造成pH值升高的原因之一。反刍动物之所以能够利用氨态氮, 主要原因是瘤胃中的微生物能够利用氨氮合成菌体蛋白, 然后进一步被动物机体利用。本研究中, 微生物蛋白的浓度变化与氨态氮并不一致。各组均在采食后0.5 h达到最大值, 微生物蛋白浓度以2%处理组最高。前人研究表明, 氨态氮浓度小于5 mg/dL时, 微生物能够充分利用氨态氮合成菌体蛋白^[33]。本研究中, 各处理组以及各时间点均远远高于此值, 表明微生物在本试验条件下, 氨态氮不是影响微生物蛋白合成的限制因素。

日粮中的碳水化合物在瘤胃微生物的作用下降解为挥发性脂肪酸(VFA), 经瘤胃上皮吸收, 是反刍动物主要的能源物质。日粮精粗比是影响VFA的因素之一, Merchen等^[34]试验表明, 日粮精粗比并不影响总VFA的浓度, 但高精日粮组乙酸和丁酸浓度显著降低, 丙酸浓度显著升高。而日粮中添加淀粉能显著降低乙酸浓度, 提高丁酸浓度^[35]。本试验中, 在保持精粗比一致的前提下(6∶ 4)发现, 湖羊在采食硝酸盐1.52.0 h后, 2%剂量组乙酸和总VFA的浓度极显著高于对照组(P< 0.01)。代俊芳等^[9]的体外试验表明, 日粮硝态氮水平对总挥发性脂肪酸的浓度无显著影响, 但乙酸呈先降低后上升的二次曲线关系, 丙酸和丁酸则是先升高后下降, 乙酸/丙酸先下降后上升。Nolan等^[6]的体内试验表明, 日粮中添加4%的KNO₃对干物质采食量、消化率以及氨氮没有显著影响, 乙酸的摩尔比例有升高趋势, 乙酸/丙酸显著上升。Li等^[36]的研究表明, 3%硝酸盐处理组总挥发性脂肪酸低于尿素组, 但乙酸及乙酸/丙酸要显著高于尿素组。本研究中, 2%处理组的乙酸、丙酸和总挥发性脂肪酸在大多数时间里要高于其他组, 乙酸/丙酸在多数时间内也随硝酸盐剂量的增加而升高, 与前人研究结果一致。纤维素和半纤维素发酵过程中伴随着氢的产生, 硝酸盐与氢的亲和力较高, 当氢减少时, 细胞中的还原型辅酶Ⅰ (NADH)就会减少, 相应的辅酶Ⅰ (NAD⁺)就会升高, 这有利于瘤胃乙酸的产生^[37]。亚硝酸盐在快速还原过程中, 也促使了电子从丁酸转移到硝酸盐还原过程中, 促进了乙酸的形成^[6]。纤维在分解过程中产生的腺苷三磷酸(ATP)和挥发性脂肪酸可为微生物蛋白的合成提供能量和碳架。前人研究表明, 添加硝酸盐能够降低黄色瘤胃球菌和产琥珀酸丝状杆菌的丰度^[31]。这两种菌是瘤胃内主要的纤维分解菌^[38]。本研究中, 3%5%处理组总挥发性脂肪酸浓度降低, 可能是此浓度的硝酸盐对纤维分解菌产生了不利影响, 降低了纤维的降解率, 不利于微生物蛋白的合成, 同时也引起了pH值的升高。

4 结论

综上所述, 添加硝酸盐能提高瘤胃总挥发性脂肪酸和微生物蛋白的浓度, 但过高对瘤胃发酵有不利影响。本试验条件下, 添加硝酸盐能提高瘤胃pH值和乙酸/丙酸。采食后2.0 h能显著提高氨态氮的浓度。硝酸盐的浓度在采食后的1.0 h内上升, 之后下降; 亚硝酸盐的浓度在采食后1.5 h内上升之后开始下降。2%的添加量能显著提高微生物蛋白浓度和总挥发性脂肪酸的合成量。添加3%5%的硝酸盐并没有引起湖羊中毒, 但高铁血红蛋白含量升高, 总挥发性脂肪酸和微生物蛋白浓度降低, 不利于瘤胃发酵。

The authors have declared that no competing interests exist.

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[1]	张重丽, 于应文, 付强国, 等. 我国畜产品生产与贸易. 草业学报, 2015, (7): 163-171. [本文引用:1]
[4]	石彩霞, 侯先志, 孟庆翔, 等. 硝态氮在绵羊瘤胃中的代谢途径初探. 中国饲料, 2013, (7): 19-22. [本文引用:1]
[9]	代俊芳, 孟庆翔, 周振明, 等. 硝态氮添加水平对体外瘤胃发酵和微生物合成效率的影响. 中国农业科学, 2010, (16): 3418-3424. [本文引用:3]
[12]	蔡顺香. 紫外分光光度法快速测定蔬菜中的硝酸盐含量. 福建农业学报, 2005, (2): 125-127. [本文引用:1]
[13]	冯宗慈, 高民. 通过比色测定瘤胃液氨氮含量方法的改进. 畜牧与饲料科学, 2010, (Z1): 37. [本文引用:1]
[15]	宋范成. 日粮磷水平对奶牛瘤胃发酵、产奶性能及磷消化代谢的影响[D]. 呼和浩特: 内蒙古农业大学, 2010. [本文引用:1]
[16]	王久涛, 张伟, 安磊, 等. 亚硝酸盐中毒抑制小鼠成体神经发生. 中国兽医学报, 2014, (4): 641-646. [本文引用:1]
[17]	王春林, 于炎湖, 齐德生, 等. 肉鸭日粮亚硝酸盐中毒的血液学和组织病理学研究. 华中农业大学学报, 2003, (1): 49-54. [本文引用:1]
[22]	林淼. 硝态氮在瘤胃内的微生物还原特性及其对发酵的影响[D]. 北京: 中国农业大学, 2011. [本文引用:1]
[28]	林淼, 张建刚, 陈志远, 等. 饲粮中性洗涤纤维与非纤维性碳水化合物比例对湖羊瘤胃还原硝态氮的影响. 动物营养学报, 2014, (12): 3659-3665. [本文引用:1]
[29]	娄丽平. 不同氮源对绵羊氮代谢和瘤胃发酵的影响[D]. 哈尔滨: 东北农业大学, 2007. [本文引用:1]
[30]	张建刚. 不同日粮组成对湖羊瘤胃硝态氮还原特性的研究[D]. 扬州: 扬州大学, 2013. [本文引用:1]
[35]	王星凌, 朱承满. 运用 Rusitec 系统研究不同碳水化合物对麦秸消化率的影响机理. 山东农业科学, 2002, (1): 42-44. [本文引用:1]

2015

0.0

. 2015, (7):163-171 DOI:doi:10.11686/cyxb2012100

我国畜产品生产与贸易

张重丽, 于应文, 付强国

A systematic analysis on the production and international trade of the major animal products in China and the world and of the non-traditional animal products in China showed an increasing trend in the past 20 years as shown by the network database information of the Food and Agriculture Organization of the United Nations (UNFAO) from 1990 to 2009. During this time, world meat production and that from China increased from 17.99 ten million tons and 30 to 78 million tons and from 17.99 to 28.39 ten million tons respectively with the proportion from China increasing from 16.9% to 27.5%. World egg production increased by 3.52 ten million tons to 6.28 ten million tons, with the proportion from China increasing from 18.61% to 37.61%; In the past 20 years, China’s milk production increased by 8 times, the wool production of the world fell from 3.35 million tons to 2.04 million tons, and the wool production of China increased from 23.94 ten thousand tons to 36.40 ten thousand tons. The net trade deficit of beef increased from 478 tons to 1694 tons. The trade deficit quantity and the trade deficit value of sheep and goat meat in 2009 were 76.5 thousand tons worth 156.6 million dollars, compared to 1990 these are increases of 745.6% and 1102% respectively. In addition in the years 2000 and 2006-2008, the quantity and value of Chinese pork import and export were in surplus; Chinese poultry imports were far more than the exports; the trade value from 1990 to 2006 was in surplus, but from 2007 to 2009 it was in deficit. The egg export quantity from 2000 to 2009 continued to increase to 134.7 thousand tons, and the egg import quantity in 2009 was 268 tons; The milk trade of China from 1990 to 2009 was in surplus, its import quantity and value in 2009 increased to 14.6 thousand tons and 11.8 million dollars, increasing by 80.9% and 64.05% respectively compared with 2008. The wool trade of China from 1990 to 2009 was in deficit, with the deficit quantity and value increasing from 35.2 thousand tons and 127.4 million dollars to 269.2 thousand tons and to 136.8 million dollars. Animal production was closely related to that of forage. Due to animal diseases, drug residues, and animal welfare issues, the animal products trade of China is not dominant in the world. We need to improve production standards through feed production, aquaculture production, meat processing, circulation and other aspects, in order to promote animal products economic development.

对1990-2009年中国与世界主要畜产品生产和贸易进行分析,近20年世界和中国主要畜产品产量均呈增加趋势。1990-2009年,世界和中国肉类产量由17.99和3.0千万t增到28.39和7.8千万t,中国占世界比重由16.9%增到27.5%;世界鸡蛋产量由3.52千万t增到6.28千万t,中国占世界比重从18.61%增到37.61%;中国牛奶产量近20年增加8倍;世界羊毛产量从3.35百万t降至2.04百万t,中国羊毛产量由23.94万t上升到36.40万t。牛肉净贸易逆差量从478 t增到1694 t;2009年羊肉贸易逆差量和逆差额为7.65万t和1.566亿美元(美元),比1990年增加745.6%和1102%。中国猪肉进出口除2000年和2006-2008年外,其他年份贸易量和贸易额都处顺差;中国禽肉进口远超出口,1990-2006年贸易额处顺差,2007-2009年贸易额处逆差。2000-2009年,鸡蛋出口量持续增至13.47万t,2009年鸡蛋进口量268 t。过去20年,中国牛奶贸易处顺差,2009年其进口量和进口额增至1.46万t和1.18千万美元,比2008年增加80.9%和64.05%;中国羊毛贸易处逆差,逆差量和逆差额由3.52万t和1.274亿美元增至26.92万t和1.368亿美元。因动物疫病、药物残留、动物福利等问题,中国畜产品国际贸易受到限制,需从饲草生产、养殖、产品加工、流通等环节加以改善。

... 中国是畜产品生产大国,也是消费大国,尤其是近年来,人们对反刍动物产品的需求越来越大^[1] ...

2009

0.0

... 硝酸盐作为一种非蛋白氮,制作工艺简单,成本低廉,尤其是在低蛋白日粮情况下,其在瘤胃内的利用效率甚至高于尿素^[2] ...

1981

0.0

... 反硝化作用产生N₂的过程较为困难,在瘤胃内极少存在^[3,4] ...

2013

0.0

. 2013, (7):19-22 DOI:doi:10.3969/j.issn.1004-3314.2013.07.007

硝态氮在绵羊瘤胃中的代谢途径初探

石彩霞, 侯先志, 孟庆翔

本研究旨在通过产气量法研究绵羊适应硝酸盐前后硝态氮 (NO3--N)在瘤胃中的代谢途径.试验采用单因素完全随机设计,6只饲喂硝态氮日粮(试验组)和尿素氮日粮(对照组)的绵羊作为瘤胃液的供体.硝态氮在发酵底物中的含量为2％(干物质基础).结果表明,硝态氮经来自于尿素氮日粮的微生物发酵(24 h),NO3--N、亚硝态氮(NO2--N)、氨态氮(NH3-N)和微生物氮(MN)分别占发酵底物总氮的0.2％、0％、80％和15％；硝态氮经来自于硝态氮日粮的微生物发酵(24 h),NO3--N、NO2-N、NH3-N和MN分别占发酵底物总氮的0％、0％、32.8％和52.2％,对照组和试验组硝态氮的主要还原产物均为 NH3-N和MN,其中未检测到一氧化二氮(N2O),仅检测到有少量氮气(N2)产生,表明对照组和试验组的瘤胃微生物对硝态氮的代谢均以异化还原为主,并可能存在一定的反硝化作用.

... 反硝化作用产生N₂的过程较为困难,在瘤胃内极少存在^[3,4] ...

1985

0.0

. 1985, 50(4):812-815

Dissimilatory nitrate reduction to nitrate, nitrous oxide, and ammonium by Pseudomonas putrefaciens.

Samuelsson M.

The influence of redox potential on dissimilatory nitrate reduction to ammonium was investigated on a marine bacterium, Pseudomonas putrefaciens. Nitrate was consumed (3.1 mmol liter-1), and ammonium was produced in cultures with glucose and without sodium thioglycolate. When sodium thioglycolate was added, nitrate was consumed at a lower rate (1.1 mmol liter-1), and no significant amounts of nitrite or ammonium were produced. No growth was detected in glucose media either with or without sodium thioglycolate. When grown on tryptic soy broth, the production of nitrous oxide paralleled growth. In the same medium, but with sodium thioglycolate, nitrous oxide was first produced during growth and then consumed. Acetylene caused the nitrous oxide to accumulate. These results and the mass balance calculations for different nitrogen components indicate that P. putrefaciens has the capacity to dissimilate nitrate to ammonium as well as to dinitrogen gas and nitrous oxide (denitrification). The dissimilatory pathway to ammonium dominates except when sodium thioglycolate is added to the medium.

PMID: 4083881

... N H4+,但异化还原作用是硝酸盐在瘤胃内的主要代谢途径^[5] ...

2010

0.0

... 硝酸盐在被还原过程中,能够抢夺供氢体的电子,抑制甲烷的产生,降低温室气体的排放,减少饲料能量的浪费^[6] ...

... Nolan等^[6]的体内试验表明,日粮中添加4%的KNO₃对干物质采食量、消化率以及氨氮没有显著影响,乙酸的摩尔比例有升高趋势,乙酸/丙酸显著上升 ...

... 亚硝酸盐在快速还原过程中,也促使了电子从丁酸转移到硝酸盐还原过程中,促进了乙酸的形成^[6] ...

1988

0.0

. 1988, 59(2):301-313

Effect of nitrate and its reduction products on the growth and activity of the rumen microbial population.

Marais J P , Therion J J , Mackie R

Cedara Agricultural Research Institute, Pietermaritzburg, South Africa.

1. The nature of the digestion-inhibiting substance in Kikuyu grass (Pennisetum clandestinum, Hochst), containing high levels of nitrate, was investigated using in vitro digestibility techniques. 2. Nitrite, which accumulated during the reduction of nitrate to ammonia, seemed to be the primary factor reducing digestibility. Nitrate and ammonia did not affect digestion in vitro. 3. Nitrite caused a reduction in the cellulolytic, xylanolytic and total microbial population, with a concomitant reduction in cellulase and xylanase activity of the digesta. 4. The mode of action of nitrite on rumen microbial growth was investigated. 5. The possibility that the growth of cellulolytic rumen microbes was depressed by a reduction in concentration of essential branched-chain volatile fatty acids by nitrite was discounted. 6. Although nitrite caused a marked increase in the redox potential, due to its oxidizing properties, the more-positive redox potential did not reduce the digestibility of the grass. 7. The growth of three of the four major cellulolytic bacteria commonly found in the rumen was severely depressed by nitrite, while some rumen bacteria were relatively insensitive to nitrite. 8. Growth inhibition seemed to depend primarily on the extent to which these microbes derive their energy from electron-transport-mediated processes. 9. It was suggested that, due to the sensitivity of some rumen bacteria to nitrite, digestibility and therefore animal performance could be affected long before clinical symptoms of nitrite toxicity become apparent.

PMID: 3358930

... 研究表明,如果经过一段适应期后,反刍动物对于硝酸盐的耐受性能够提高35倍^[7] ...

... 能提高反刍动物对硝酸盐的耐受性^[7] ...

2014

0.0

... Mamvura等^[8]使用芝麻油将21 mmol/L硝酸盐包被后进行体外试验发现,包被后的硝酸盐能大大降低亚硝酸盐的积累,并且氨态氮的水平提高了44%,但总挥发性脂肪酸浓度显著下降,另外,其包被工艺较为复杂,在实际生产中推广较为困难 ...

2010

0.0

. 2010, (16):3418-3424 DOI:doi:10.3864/j.issn.0578-1752.2010.16.018

硝态氮添加水平对体外瘤胃发酵和微生物合成效率的影响

代俊芳, 孟庆翔, 周振明

[目的]本试验旨在探明日粮硝态氮含量对反刍动物瘤胃发酵参数以及微生物合成效率的影响.[方法]配合硝态氮添加水平分别为0,6%、12%、18%、24%和30%的处理日粮,进行双外流连续培养体外发酵,试验期 144h.[结果]日粮硝态氮添加水平不影响瘤胃pH值、总挥发酸浓度(P>0.05);随日粮硝态氮添加水平的提高,丙酸摩尔比例上升 (Q,P<0.01),乙酸摩尔比例(Q,P<0.01)和NH3-N浓度(L,P<0.01)下降,干物质、有机物和粗蛋白消化率提高(Q,P<0.01)和微生物合成效率(MOEEF)呈二次曲线规律变化(Q,P<0.01).[结论]硝态氮能被瘤胃微生物所利用.随日粮硝态氮添加水平的提高,瘤胃发酵参数,养分消化率和MOEEF均有不同程度的改变,其中在12%-18%添加水平范围内,MOEFF和瘤胃发酵程度最大,超过此水平有不利影响.

... 目前对于硝酸盐的研究多集中在其毒性及体外产气方面,并且研究结果并不一致,代俊芳等^[9]采用双外流连续培养系统的体外研究结果表明,硝态氮的添加水平对瘤胃pH值和总挥发性脂肪酸没有显著影响,但能提高氨态氮的水平,乙酸/丙酸随硝态氮的提高而呈二次曲线规律变化 ...

... 代俊芳等^[9]在日粮中添加占总氮的百分比为0%,6%,12%,18%,24%和30%的硝酸钾进行双外流连续培养体外发酵发现,日粮硝态氮水平并不影响瘤胃pH值 ...

... 代俊芳等^[9]的体外试验表明,日粮硝态氮水平对总挥发性脂肪酸的浓度无显著影响,但乙酸呈先降低后上升的二次曲线关系,丙酸和丁酸则是先升高后下降,乙酸/丙酸先下降后上升 ...

2013

0.0

. 2013, 7(7):1099-1105 DOI:10.1017/S1751731113000116

Effects of nitrate adaptation by rumen inocula donors and substrate fiber proportion on in vitro nitrate disappearance, methanogenesis, and rumen fermentation acid.

Lin M , Schaefer D , Zhao G Q

College of Animal Science and Technology, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing 100193, China.

A study was conducted to evaluate the main effects of dietary nitrate adaptation by cattle and alfalfa cell wall to starch ratio in in vitro substrates on nitrate disappearance and nitrite and volatile fatty acid (VFA) concentrations, as well as hydrogen (H2) and methane (CH4) accumulations. Rumen fluid from steers fed diets containing urea or nitrate was added into in vitro incubations containing sodium nitrate as the sole nitrogen source and 20 cell wall : 80 starch or 80 cell wall : 20 starch as the carbohydrate source. The results showed that during 24 h incubation, rumen fluid inoculums from steers adapted to dietary nitrate resulted in more rapid nitrate disappearance by 6 h of incubation (P < 0.01), no significant effect on nitrite concentration and diminished CH4 accumulation (P < 0.05). Cell wall to starch ratio did not affect nitrate disappearance, CH4 accumulation and total VFA concentration. The higher cell wall ratio had the lower total gas production and H2 concentration (P < 0.05). Ammonia-N (NH3-N) concentration increased because of adaptation of donors to nitrate feeding (P < 0.05). Nitrate adaptation did not alter total VFA concentration, but increased acetate, and decreased propionate and butyrate molar proportions (P < 0.01).

PMID: 23391259

... Lin等^[10]的体外试验表明,硝态氮并不影响总挥发性脂肪酸的浓度,但会提高乙酸的浓度,降低丙酸和丁酸的浓度 ...

2013

0.0

. 2013, 148:352-360 DOI:10.1016/j.biortech.2013.08.140

Effective reduction of enteric methane production by a combination of nitrate and saponin without adverse effect on feed degradability, fermentation, or bacterial and archaeal communities of the rumen.

Patra A K , Yu Z T.

Department of Animal Sciences, The Ohio State University, Columbus, OH 43210, USA; Department of Animal Nutrition, West Bengal University of Animal and Fishery Sciences, 37 K.B. Sarani, Belgachia, Kolkata 700037, India. Electronic address: patra_amlan@yahoo.com.

This study evaluated the effects of Quillaja saponin (0.6 and 1.2g/L), propynoate (4 and 8mM), and nitrate (5 and 10mM), alone or in combinations, on methanogenesis, fermentation, bacterial and archaeal communities, and abundances of select ruminal microbial populations. All treatment decreased methane production, but combination of all three inhibitors at high dose achieved the greatest inhibition (85%). Propynoate, alone or in combination with nitrate or saponin, decreased feed degradability and total volatile fatty acid (TVFA) concentrations. However, saponin and nitrate alone at high dose and in combination at low dose inhibited methanogenesis substantially while increasing feed degradability and TVFA concentrations. The abundances of methanogens were lowered by all inhibitors except saponin alone. Fibrobacter succinogenes and Ruminococcus flavefaciens were increased by saponin, both alone and in combination with nitrate, but inhibited by propynoate. Combination of saponin and nitrate may have practical application in mitigating methane emission from ruminants.

PMID: 24063817

... Patra和Yu等^[11]在培养底物中分别加入5和10 mmol/L的硝酸盐,甲烷产量分别降低23%和43%,提高了总挥发性脂肪酸和乙酸浓度,而对氨态氮的产量无显著影响 ...

... Patra和Yu^[11]的研究表明,日粮中添加皂苷和硝酸盐能够显著降低甲烷气体的产量,且对瘤胃发酵有积极的影响 ...

2005

0.0

. 2005, (2):125-127 DOI:doi:10.3969/j.issn.1008-0384.2005.02.016

紫外分光光度法快速测定蔬菜中的硝酸盐含量

蔡顺香

以市场上购买的5种蔬菜为材料,采用加入硼砂,沸水浴提取,提取液用活性炭过滤后直接利用双波长紫外分光光度法测定待测液中的硝酸盐含量.结果显示,5种蔬菜用该方法测定的结果与国标法测定结果无显著差异,RSD为0.46%～0.97%;其中春菜和菜心硝酸盐的回收率分别为105%和102%.该方法可适用于大批量蔬菜样品中硝酸盐含量的快速测定.

... 4 指标测定方法硝酸盐含量:参照蔡顺香^[12]的方法,并调整如下:吸取5 mL瘤胃液,加入5 mL饱和硼砂溶液,沸水浴10 min,并不时搅拌,冷却,转入250 mL容量瓶中,加2 g活性炭脱色,定容 ...

2010

0.0

. 2010, (Z1):37- DOI:doi:10.3969/j.issn.1672-5190.2010.06.015

通过比色测定瘤胃液氨氮含量方法的改进

冯宗慈, 高民

在本刊1990年第3期上介绍过一种测定瘤胃液氨氮含量的比色方法.该方法的最大优点是快速、简便、不用仪器.但同时该方法也有一些明显的缺点,即用肉眼比色,分辨力较低,误差较大,并且其中一种重要试剂(二氯异三聚氰酸)很难购到,而推荐的代用品次氯酸钙因往往含有氢氧化钙使溶液混浊,影响比色,而使该方法的应用受到限制.

... 氨态氮浓度:采用酚-次氯酸钠比色法^[13] ...

1991

0.0

... 挥发性脂肪酸含量:采用日本岛津GC-14B气相色谱仪测定乙酸、丙酸、丁酸、戊酸含量^[14] ...

2010

0.0

. 2010, :- DOI:doi:10.7666/d.d197992

日粮磷水平对奶牛瘤胃发酵、产奶性能及磷消化代谢的影响[D]

宋范成

本论文通过体内试验、饲养试验、消化代谢试验研究日粮磷水平对奶牛瘤胃发酵特性、产奶性能、血液生化指标以及磷的消化代谢的影响,旨在为合理地确定奶牛日粮中磷的适宜添加剂量,减少奶牛养殖业发展过程中的磷污染提供理论依据。论文共分5个试验内容。试验一选用3头体重相近(600kg)、健康且安装有永久性瘤胃瘘管的荷斯坦奶牛为试验动物。试验分两期进行,每期试验都由三种日粮组合构成,并采用3×3拉丁方试验设计进行试验,其中第一期日粮组合中磷的水平分别为0.27%、0.43%、0.59%,第二期分别为 0.35%,0.43%,0.51%。分别于每天饲喂奶牛后2h、4h、8h、12h、24h连续采集奶牛瘤胃液2d,以测定其胃液pH值、NH3-N、 BCP、VFA及磷的含量,研究不同磷水平的日粮对奶牛瘤胃发酵功能的影响。试验二、试验三及试验四采用单因子试验设计随机地将体重(600kg)、年龄、泌乳150d、产奶量(18kg/d)相近的40头荷斯坦奶牛分成5组(A 组、B组、C组、D组、E组),各组日粮中磷的添加水平分别为0.27%,0.35%,0.43%,0.51%和0.59%(DM),每组8头。试验期 75d,其中预饲期15d,正饲期60d,研究日粮磷水平对奶牛产奶性能、血液生化指标及日粮营养物质表观消化率的影响。试验五在饲养试验结束后,分别于A、B、C、D、E组中选择体重(600kg)、产奶量(18kg/d)及生理状态相近的15头荷斯坦奶牛作为试验动物, 每组3头。研究奶牛采食不同磷水平的日粮后,对体内磷的消化、代谢以及分配的影响。在本试验条件下初步得出以下结果: 1.日粮磷水平在0.27%～0.59%(DM)范围内,随着日粮中磷含量的增加,奶牛瘤胃液中磷的含量均有不同程度的增加,其波动范围在299.75 mg/L～469.86mg/L之间,瘤胃液BCP浓度也显著增加;日粮磷水平对瘤胃液中NH3-N、VFA含量和pH值的影响均不显著(P0.05)。 2.提高日粮磷水平对于提高奶牛的产奶量以及乳中成分含量的效果不明显,但低磷日粮(0.27%)组的产奶量略有降低。 3.提高日粮磷含量对于奶牛血清中磷含量的提高有促进作用,对血清钙和BUN的影响并不显著。本试验采用低剂量(0.27%)和高剂量(0.59%)的日粮磷,并未引起机体内与钙、磷代谢相关激素含量的显著变化。 4.日粮磷水平对于奶牛日粮中DM、NDF、ADF、CP、Ca表观消化率及DMI没有显著的影响(P0.05),但高水平日粮磷可显著降低日粮中磷和钙的表观消化率(P0.05),低水平磷的日粮有降低奶牛DMI的趋势。 5.日粮磷水平的增加可显著提高奶牛的进食磷、粪磷、排泄总磷和可消化磷,高磷水平组沉积磷显著降低(P0.05)。日粮磷水平的增加显著降低了磷的表观消化率(P0.05),但可消化磷与磷的进食量呈显著的一元二次相关关系(P0.05),R2=0.9176。 6.综合各项试验指标,根据回归结果初步认为奶牛日粮中磷的适宜添加剂量为0.46%(DM),此时达到奶牛体内最大可消化磷时的磷进食量为71.25 g/d,最大可消化磷为26.57 g/d,而排出的粪磷为44.67g/d。

... 微生物蛋白:考马斯亮蓝法测定微生物蛋白浓度^[15] ...

2014

0.0

. 2014, (4):641-646

亚硝酸盐中毒抑制小鼠成体神经发生

王久涛, 张伟, 安磊

雄性成年昆明小鼠分为亚硝酸盐染毒组和生理盐水对照组,通过灌胃进行亚硝酸盐染毒,用BrdU腹腔注射和免疫组织化学方法研究齿状回神经干细胞的增殖和新生细胞的存活状况,用多重免疫荧光标记研究神经干细胞的分化和迁移方向.结果显示,染毒组小鼠齿状回颗粒层中的BrdU阳性细胞数量、存活率均极显著低于对照组(P＜0.01),表明亚硝酸盐中毒对小鼠新生神经干细胞的增殖和存活产生了影响.染毒组BrdU/NeuN双阳性细胞的数量极显著低于对照组(P＜0.01).与对照组相比,染毒组中神经干细胞的迁移方向无显著性差异(P＞0.05).结果表明,亚硝酸盐中毒能显著抑制小鼠神经干细胞增殖,降低新生细胞的存活率.

... 此外,亚硝酸盐中毒能显著抑制小鼠神经干细胞的增殖,降低新生细胞的存活率^[16] ...

2003

0.0

. 2003, (1):49-54 DOI:doi:10.3321/j.issn:1000-2421.2003.01.012

肉鸭日粮亚硝酸盐中毒的血液学和组织病理学研究

王春林, 于炎湖, 齐德生

健康樱桃谷鸭156只,随机分为6个组,每组26只,试验设6个处理,即对照组(0组)和5个试验组(1、2、3、4、5组).6组饲喂的日粮中亚硝酸盐(以NaNO2计)含量依次为0、300、600、900、1200、1500 mg/kg.试验分两阶段饲养,试验结束时,每组随机抽5只宰杀,采抗凝血进行血液学分析.剖检观察病理变化,计算脏器系数.制作病理组织学切片.结果表明,日粮中亚硝酸盐含量超过900 mg/kg时,仅4、5组部分脏器表现异常,心/体、肾/体比值改变极为显著(P<0.01).血液中血红蛋白(Hb)和高铁血红蛋白(MHb)含量2、3、4、5组与对照组比有显著差异(P<0.05),但MHb的绝对浓度并不高.因此,日粮中亚硝酸盐含量达到900 mg/kg时,肉鸭健康状况明显受到不良影响,建议饲料中亚硝酸盐的无明显作用水平(NOEL)定为600 mg/kg.

... 王春林等^[17]研究发现,日粮中亚硝酸盐含量达到900 mg/kg时,对肉鸭的健康有明显的不良影响 ...

1982

0.0

. 1982, 59(5):155-157

Nitrate poisoning in cattle fed sudax (Sorghum sp. hybrid) hay.

Carrigan M , Gardner I.

PMID: 7165599

... Carrigan和Gardner^[18]研究发现,当苏丹草含硝酸盐达3 ...

1962

0.0

... Setchell和Williams^[19]发现,山羊的中毒剂量为345 mg/(kg BW#cod#x000b7 ...

1970

0.0

... 当动物血液中高铁含量达到30%50%时,就会导致组织缺氧,出现呼吸困难,神经机能紊乱等症状^[20] ...

2013

0.0

. 2013, 270(3):209-217 DOI:10.1016/j.taap.2010.11.008

Nitrite in feed: from animal health to human health.

Cockburn A , Brambilla G , Fern#cod#x000e1;ndez M-L

Institute for Research on Environment and Sustainability, Devonshire Building, University of Newcastle upon Tyne, Newcastle upon Tyne, NE17RU, UK.

Nitrite is widely consumed from the diet by animals and humans. However the largest contribution to exposure results from the in vivo conversion of exogenously derived nitrate to nitrite. Because of its potential to cause to methaemoglobin (MetHb) formation at excessive levels of intake, nitrite is regulated in feed and water as an undesirable substance. Forages and contaminated water have been shown to contain high levels of nitrate and represent the largest contributor to nitrite exposure for food-producing animals. Interspecies differences in sensitivity to nitrite intoxication principally result from physiological and anatomical differences in nitrite handling. In the case of livestock both pigs and cattle are relatively susceptible. With pigs this is due to a combination of low levels of bacterial nitrite reductase and hence potential to reduce nitrite to ammonia as well as reduced capacity to detoxify MetHb back to haemoglobin (Hb) due to intrinsically low levels of MetHb reductase. In cattle the sensitivity is due to the potential for high dietary intake and high levels of rumen conversion of nitrate to nitrite, and an adaptable gut flora which at normal loadings shunts nitrite to ammonia for biosynthesis. However when this escape mechanism gets overloaded, nitrite builds up and can enter the blood stream resulting in methemoglobinemia. Looking at livestock case histories reported in the literature no-observed-effect levels of 3.3mg/kg body weight (b.w.) per day for nitrite in pigs and cattle were estimated and related to the total daily nitrite intake that would result from complete feed at the EU maximum permissible level. This resulted in margins of safety of 9-fold and 5-fold for pigs and cattle, respectively. Recognising that the bulkiness of animal feed limits their consumption, these margins in conjunction with good agricultural practise were considered satisfactory for the protection of livestock health. A human health risk assessment was also carried out taking into account all direct and indirect sources of nitrite from the human diet, including carry-over of nitrite in animal-based products such as milk, eggs and meat products. Human exposure was then compared with the acceptable daily intake (ADI) for nitrite of 0-0.07 mg/kg b.w. per day. Overall, the low levels of nitrite in fresh animal products represented only 2.9% of the total daily dietary exposure and thus were not considered to raise concerns for human health. It is concluded that the potential health risk to animals from the consumption of feed or to man from eating fresh animal products containing nitrite, is very low.

PMID: 21095201

... 由于绵羊血液内高铁血红蛋白还原酶的活性较高,还原Fe³⁺的能力较强,所以绵羊对硝酸盐有较高的耐受性^[21] ...

2011

0.0

... 林淼^[22]的研究发现,阉肉牛在适应2%DM的硝酸钾后,硝态氮在1 ...

1951

0.0

. 1951, 48(2):175-

The metabolism of nitrate and nitrite in the sheep. 1. The reduction of nitrate in the rumen of the sheep.

Lewis D.

PMID: 14820824

... Lewis^[23]直接将25 g NaNO₃和10 g NaNO₂投入未经适应的绵羊瘤胃,发现在投放1 ...

2015

0.0

. 2015, 93(5):2405-2418 DOI:10.2527/jas.2014-8851

Effects of encapsulated nitrate on eating behavior, rumen fermentation, and blood profile of beef heifers fed restrictively or ad libitum.

Lee C , Araujo R , Koenig K

A slow-release form of nitrate (encapsulated nitrate [EN]) was investigated for effects on risk of toxicity, feed consumption rates, and feed sorting behavior in 2 experiments. In Exp. 1, 5 beef heifers (806 ± 72 kg BW) were fed once daily at 75% of ad libitum intake. Supplementary EN (85.6% DM; 71.4% NO3(-) on a DM basis) was increased by 1% every 4 d from 0 to 1.0, 2.0, 2.9, 3.9, 4.8, and 5.8% of dietary DM (from 10.3 to 15.6% CP and 0.11 to 4.8% total NO3(-)). During the study, a heifer was removed due to nitrate poisoning with 59% blood methemoglobin (MetHb; % of total hemoglobin) at 2.9% EN and another due to refusal to eat the 2% EN diet. When dietary EN increased from 0 to 5.8%, DMI (8.8 to 7.6 kg/d; P 3% EN may have caused lower feed intake, reduced feed consumption rates, and feed sorting. In addition, feed consumption rate, which was altered by restrictive or ad libitum feeding, was an important factor affecting the potential toxicity of nitrate (e.g., MetHb). Ad libitum feeding minimized risks of nitrate toxicity.

PMID: 26020336

... Lee等^[24]的研究表明,限制硝酸盐的快速还原是降低硝酸盐中毒风险的重要手段 ...

... 日粮中添加硝酸盐均能提高氨态氮的产量^[24,32] ...

1990

0.0

... Allison和Reddy^[25]发现动物在采食硝酸盐36 d后,N O3-和N O2-的还原速率提高了35倍 ...

1982

0.0

... Yoshida等^[26]通过体外试验证明,高精料水平下,不利于硝酸盐的还原 ...

2003

0.0

... Yoshii等^[27]将反刍月形单胞菌(Selenomonas ruminatium)与淀粉、淀粉分解菌共培养,导致亚硝酸盐的积累,而将S ...

2014

0.0

. 2014, (12):3659-3665 DOI:doi:10.3969/j.issn.1006-267x.2014.12.015

饲粮中性洗涤纤维与非纤维性碳水化合物比例对湖羊瘤胃还原硝态氮的影响

林淼, 张建刚, 陈志远

A 4 × 4 Latin square design in this study was used to investigate the effects of different dietary neutral detergent fiber to non-fiber carbohydrates ratios (NDF/NFC) (0.58, 0.71, 1.20 and 1.57) on dynamic changes of ruminal nitrate nitrogen content and fermentation characteristics of Hu sheep. The diet of each group contained 1.0% potassium nitrate, and rumen fluid was obtained at 0, 0.5, 1.0, 1.5, 2.0, 4.0, 6.0 and 8.0 h after feeding to determine the contents of nitrate and nitrite and ruminal fermentation parameters. Blood sample was collected at 2.0 h after feeding to determine the blood methemoglobin content. The results showed that the nitrite content of sheep fed diet with NDF/NFC=0.71 was lowest at 6.0 to 8.0 h after feeding. With the rising of NDF/NFC, NH 3 -N content had a trend of decrease at 0 to 1.5 h after feeding. Total microbial protein content of sheep fed diet with NDF/NFC=0.58 was highest at 0 and 8.0 h after feeding, and had no significant difference with sheep fed diet with NDF/NFC=0.71 ( P >0.05). In addition, the nitrite toxicity was not detected during experiment period. In conclusion, the optimum NDF/NFC in the diet of Hu sheep is 0.71 for nitrate nitrogen reduction and fermentation in the rumen under this experimental condition.

本试验采用4×4拉丁方试验设计,研究4种中性洗涤纤维与非纤维性碳水化合物比例(NDF/NFC)的饲粮(0.58、0.71、1.20、1.57)对湖羊瘤胃硝态氮含量动态变化和发酵特性的影响.各组饲粮中均含有1.0%硝酸钾,在喂后0、0.5、1.0、1.5、2.0、4.0、6.0、8.0 h通过瘤胃瘘管采集瘤胃液,测定硝酸盐和亚硝酸盐含量以及瘤胃发酵参数;晨饲后2.0 h通过颈静脉采血,测定高铁血红蛋白含量.结果表明,6.0~8.0 h饲粮NDF/NFC=0.71时瘤胃亚硝酸盐含量最低;且0~1.5 h随着NDF/NFC的增大,氨态氮(NH 3 -N)含量有逐渐降低的趋势;0、8.0 h总微生物蛋白质含量以NDF/NFC=0.58时最高,且与NDF/NFC=0.71时差异不显著( P >0.05),整个试验期未出现亚硝酸盐中毒.因此,在本试验条件下,湖羊饲粮NDF/NFC=0.71时,最有利于瘤胃硝态氮还原及瘤胃发酵.

... 林淼等^[28]则指出,饲粮中快速发酵的碳水化合物应维持在适当的水平,过高或过低均不利于硝酸盐的还原 ...

2007

0.0

. 2007, :- DOI:doi:10.7666/d.y1165318

不同氮源对绵羊氮代谢和瘤胃发酵的影响[D]

娄丽平

本试验通过氮代谢试验、血浆尿素氮的测定和瘤胃微生物纤维素酶活性的测定，研究不同氮源对瘤胃内氮代谢和瘤胃微生物发酵的影响。本试验的目的是：一方面，探索瘤胃微生物利用不同氮源对粗饲料消化的作用；另一方面为反刍动物生产中合理开发和利用不同种类的蛋白饲料资源，提高反刍动物对氮素的利用效率提供基础理论依据。为研究日粮中添加不同结构氮源在绵羊体内氮的沉积以及绵羊瘤胃微生物对粗饲料消化利用的影响，本试验选用尿素、尿素+小肽、尿素+大豆蛋白三组等氮等能饲料配方作为日粮处理，选用三只体况良好，体重40 kg左右的瘤胃瘘管羊作为试...

... 娄丽平^[29]研究发现,绵羊日粮中添加尿素、小肽、大豆蛋白作为氮源时,瘤胃液pH值并无显著差异 ...

2013

0.0

. 2013, :-

不同日粮组成对湖羊瘤胃硝态氮还原特性的研究[D]

张建刚

本论文由三部分组成，研究硝酸盐对湖羊瘤胃发酵特性及血液指标的影响、对牧草瘤胃降解特性的影响及不同碳水化合物结构对硝态氮还原的影响。试验内容和结果如下: 　　试验一采用单因子试验设计，研究湖羊日粮中添加0％、0.5％和1.0％硝酸钾对硝态氮消失率、瘤胃发酵特性及血液指标的影响。喂后0、0.5、1、1.5、2、4、6和8h通过瘤胃瘘管采集瘤胃液，测定硝酸盐、亚硝酸盐浓度以及瘤胃发酵参数;同时，喂后2h颈静脉采血测定血清生化指标和血液高铁血红蛋白含量。结果表明:(1)瘤胃液硝酸盐和亚硝酸盐浓度分别在喂后1和2h达到最大值，之后迅速降低，至6～8 h基本完全消失...

... 张建刚^[30]研究表明,日粮中添加0%,0 ...

2012

0.0

. 2012, 103(1):173-179 DOI:10.1016/j.biortech.2011.10.013

Effects of nitrate on methane production, fermentation, and microbial populations in in vitro ruminal cultures.

Zhou Z M , Yu Z T , Meng Q X.

College of Animal Science and Technology and State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing 100193, China.

The objective of this study was to examine the effects of nitrate on methane production, important fermentation characteristics, Fibrobacter succinogenes, Ruminococcus albus, Ruminococcus flavefaciens, total bacteria, and methanogens using in vitro ruminal cultures. Potential adaptation of the above microbes and persistency of nitrate to mitigate CH4 production were also evaluated. Methane production was reduced by 70% at 12 μmol ml(-1) and nearly completely at ≥24 μmol ml(-1) nitrate. Production of volatile fatty acids (VFAs) was affected to different extents at different nitrate concentrations. Over a series of six consecutive cultures receiving 12 μmol ml(-1) nitrate, production of CH4 and VFA did not change significantly. R. albus and R. flavefaciens seemed to adapt to nitrate, while F. succinogenes and methanogens did not. Nitrate may be used in achieving persistent mitigation of CH4 production by ruminants.

PMID: 22047657

... 然而Zhou等^[31]的体外实验表明,在硝态氮添加量大于24 #cod#x003bc ...

... 前人研究表明,添加硝酸盐能够降低黄色瘤胃球菌和产琥珀酸丝状杆菌的丰度^[31] ...

2012

0.0

... 日粮中添加硝酸盐均能提高氨态氮的产量^[24,32] ...

1974

0.0

. 1974, 32(2):199-208

Effect of ammonia concentration on rumen microbial protein production in vitro.

Satter L , Slyter L.

PMID: 4472574

... 前人研究表明,氨态氮浓度小于5 mg/dL时,微生物能够充分利用氨态氮合成菌体蛋白^[33] ...

1986

0.0

. 1986, 62(1):216-225

Effect of intake and forage level on ruminal turnover rates, bacterial protein synthesis and duodenal amino acid flows in sheep.

Merchen N , Firkins J , Berger L.

PMID: 3957806

... 日粮精粗比是影响VFA的因素之一,Merchen等^[34]试验表明,日粮精粗比并不影响总VFA的浓度,但高精日粮组乙酸和丁酸浓度显著降低,丙酸浓度显著升高 ...

2002

0.0

. 2002, (1):42-44 DOI:doi:10.3969/j.issn.1001-4942.2002.01.016

Rusitec 系统研究不同碳水化合物对麦秸消化率的影响机理

王星凌, 朱承满, . 运用

试验运用Rusitec系统验证一种假设,即添加少量易溶解的碳水化合物能提高瘤胃微生物活性,瘤胃微生物细胞死亡和水解后可提供纤维分解细菌所需要的养分.试验采用4×4拉丁方设计.4个处理为基础日粮(麦秸+尿素)、基础+大豆壳、基础+淀粉和基础+果胶.4个处理的麦秸中性洗涤纤维(NDF)48 h尼龙袋降解率分别为:基础日粮54.7%、添加大豆壳和果胶的(57.3%和56.2%)显著高于基础日粮、添加淀粉的变化不大(55.4%).大豆壳、淀粉和果胶显著提高麦秸有机物(OM)总降解率和短链脂肪酸(SCFA)总产量.但是,果胶显著提高而淀粉显著降低乙酸浓度.通过电镜下观察,添加果胶导致麦秸上纤维分解菌数量增加,而大豆壳导致厌氧性真菌数量增加,真菌的活动提高氨氮浓度.通过最大概率记数法(MPN)测定发酵液的微生物总数和纤维分解菌数量,添加大豆壳和果胶显著提高发酵液的微生物总量,但不影响纤维分解菌数量,添加大豆壳和果胶导致麦秸N降解率低是由于麦秸纤维附着较多的纤维分解菌.因此,添加像大豆壳或果胶这样少量的碳水化合物对麦秸纤维降解具有益作用.

... 而日粮中添加淀粉能显著降低乙酸浓度,提高丁酸浓度^[35] ...

2012

0.0

... Li等^[36]的研究表明,3%硝酸盐处理组总挥发性脂肪酸低于尿素组,但乙酸及乙酸/丙酸要显著高于尿素组 ...

2006

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... (NAD⁺)就会升高,这有利于瘤胃乙酸的产生^[37] ...

1996

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. 1996, 79(8):1467-1475

How many ruminal bacteria are there?.

Krause D , Russell J.

Cornell University, Ithaca, NY 14853.

With the development of strictly anaerobic techniques and habitat-simulating media, a variety of bacteria were isolated from the rumen in the 1940s and 1950s. Based on standard morphological and physiological characteristics, the microbial ecosystem of the rumen contains a very complex population of bacteria. In recent years, ruminal bacteria have been re-evaluated with newer, more objective, and genetically valid methods of classification. Ribosomes are complicated structures, and their DNA-encoding sequences are relatively free from selective pressure. Because ribosomes have evolved slowly, they provide a long-term natural history of evolution. The invariable and hypervariable regions of rRNA genes can be used to group bacteria into kingdoms, genera, and species. The 16S rRNA sequences have provided a basis for renaming some ruminal species (Bacteroides amylophilus is now Ruminobacter amylophilus and Bacteroides succinogenes is now Fibrobacter succinogenes) and for classifying at least one recently isolated ruminal bacterium (e.g., Clostridium aminophilum). The DNA:DNA hybridization is a more sensitive method of assessing bacterial relatedness than is 16S rRNA. Bacterial strains within a species should have a high degree of DNA:DNA homology, but some species of ruminal bacteria (e.g., Prevotella ruminicola and Butyrivibrio fibrisolvens) had highly unrelated strains. Studies of 16S rRNA and DNA:DNA hybridization indicate that the diversity of ruminal bacteria has been greatly underestimated. Traditional studies of phylogeny of ruminal bacteria were stymied by the fastidious growth requirements of many ruminal bacteria, and enumeration was tedious and inaccurate. Modern methods of bacterial classification do not require in vitro culture and have the potential of detecting even a single cell.

PMID: 8880472

... 这两种菌是瘤胃内主要的纤维分解菌^[38] ...

2015

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. 2015, (7):163-171 DOI:doi:10.11686/cyxb2012100

我国畜产品生产与贸易

张重丽, 于应文, 付强国

... 中国是畜产品生产大国,也是消费大国,尤其是近年来,人们对反刍动物产品的需求越来越大^[1] ...

2013

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. 2013, (7):19-22 DOI:doi:10.3969/j.issn.1004-3314.2013.07.007

硝态氮在绵羊瘤胃中的代谢途径初探