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1.
日粮添加硫、磷提高水牛瘤胃纤维素消化率的研究   总被引：19，自引：0，他引：19  
应用装有永久性瘤胃瘘管的４头水牛研究了以稻草加精料和羟甲基尿素（ＦｏｒｍａｌｄｅｈｙｄｅｔｒｅａｔｅｄｕｒｅａＦＤＵ）（Ｉ）为基础日粮,分别添加硫（Ⅱ）及硫、磷（Ⅲ）后瘤胃内纤维素消化率的变化。添加硫（Ⅱ）后瘤胃液内硫化物、总硫水平均显著提高（Ｐ＜０．０１）;瘤胃内ｐＨ下降（Ｐ＜０．０１）;总挥发性脂肪酸（ＴＶＦＡ）含量增加（Ｐ＜０．０１）,发酵类型发生改变;瘤胃尼龙袋法纤维素消失率提高９．１９％（Ｐ＜０．０１）。在Ⅱ期的基础上添加磷,瘤胃ＴＶＦＡ含量、纤维素消失率分别提高了１６．１７％、１４．４８％（Ｐ＜０．０１）。而瘤胃容积、稀释率却未见显著变化。结果表明添加硫可促进瘤胃纤维素消化,而添加复合硫、磷效果更好。  相似文献   

2.
采用瘘管手术方法对３头生长牦牛在饲喂代谢能ＭＥ均为９．６ＭＪ／ｋｇＤＭ，粗蛋白（ＣＰ）为８％和１２％的日粮时的复胃氮代谢与瘤胃、肠道消化代谢进行研究。试验结果表明，日粮ＣＰ水平升高后，生长牦牛瘤胃氨氮浓度由３．３升至５．９ｍｇ／１００ｍｌ（Ｐ＜０．０１），瘤胃内氮的消失率由１．９％升到２１．１％（Ｐ＜０．０１）。瘤胃微生物蛋白质合成效率基本不变（平均６９．１ｇＣｐ／ｋｇＤＯＭ）；一昼夜进入十二指肠的食糜量及食糜干物质量基本不变；食糜总氮、氨氮及非氨氮量均显著增加（Ｐ＜０．０１），其中非氨氮增加２０％：非氨氮中微生物氮的比例由４５％降至３９％（Ｐ＜０，０５）；日粮ＤＭ，ＯＭ，ＣＰ和ＡＤＦ整体消化率分别提高１２．９％、１３．４％、３４％和２２．３％（Ｐ＜０．０１）。日粮ＣＰ由８％升至１２％后，生长牦牛瘤胃ＴＶＦＡ中乙酸比例由５４％降至４３．５％（Ｐ＜０．０１）．丙酸比例由２４．８％升至２８．４％（Ｐ＜０．０５），丁酸比例也由２１．１％增至２８．５％（Ｐ＜０．０１）。同时Ｃ２／Ｃ３比由２．１９降至１．５４（Ｐ＜０．０１）。  相似文献   

3.
生长期牦牛蛋白质需要量的研究   总被引：2，自引：0，他引：2  
将１８头１．５岁生长牦牛分为Ⅰ、Ⅱ、Ⅲ三组，分别饲喂含ＣＰ６．７１％，１０．１４％，１３．４３％的日粮，用比较屠宰试验、消化代谢试验和饲养试验相结合的方法研究其氮代谢。结果表明：Ⅰ、Ⅱ、Ⅲ组日增重分别为５４．０６ｇ，１９３．６７ｇ，２４７．４７ｇ，其中Ⅱ组与Ⅰ组差异显著（Ｐ＜０．０５），Ⅲ组与Ⅰ组差异极显著（Ｐ＜０．０１），而Ⅲ组与Ⅱ组差异不显著（Ｐ＞０．０５）；相应的尿氮（ＵＮ）排出（ｇ／ｄ·Ｗ￣（０．０５２））分别为０．５６２，１．２９１，１．７６２，其中Ⅱ、Ⅲ与Ⅰ差异极显著（Ｐ＜０．０１），Ⅱ与Ⅲ差异显著（Ｐ＜０．０５）；在氮沉积（ＮＲ）、采食氮利用效率方面，三组均无显著差异（Ｐ＞０．０５）。生长牦牛的维持需要量ＲＤＣＰｍ＝６．０９３Ｗ￣（０．５２），增重需要量ＲＤＣＰｇ＝（１．１５４８／△Ｗ＋０．０５０９／Ｗ￣（０．５２））￣（－１）。得出的三个回归方程均呈强直线相关（Ｐ＜０．０１）：１．ＵＮ与进食氮（ＮＩ）的回归方程ＵＮ（ｇ／ｄ）＝－０．１１Ｗ￣（０．５２）＋０．４７３２ＮＩ（ｎ＝９，ｒ＝０．９２８）２．粪氮（ＦＮ）与干物质进食量（ＤＭＩ）及ＮＩ的回归方程ＦＮ（ｇ／ｄ）＝－０．７５１０（１＋０．８  相似文献   

4.
饲粮结构与非结构碳水化合物比例对绵羊消化代谢的影响   总被引：4，自引：0，他引：4  
旨在探讨绵羊饲粮的结构碳水化合物（Structural carbohydrate,SC）与非结构碳水化合物（Nonstructural carbohydrate,NSC）的适宜比例。选用6只1．5岁左右,装有十二指肠近端套管和瘤胃瘘管的甘肃高山细毛羊羯羊,按3×3有重复拉丁方设计（3个饲养循环,每个循环为预试期10d,收集期9d）,研究3种饲粮（Ⅰ、Ⅱ、Ⅲ）的SC／NSC比（1．57、1．95、2．29）对绵羊胃内、肠内、全消化道内养分表观消化率及氮代谢的影响。结果表明：饲粮Ⅰ的DM和OM全消化道消化率极显著高于Ⅲ（P〈0.01）;饲粮间NDF和ADF的全消化道消化率的差异均不显著（P〉0．05）;3种饲粮的DM、NDF胃内、肠内消化率也无显著差异（P〉0．05）。饲粮Ⅰ全消化道氮消化量极显著高于Ⅱ、Ⅲ（P〈0．01）,Ⅱ也极显著高于Ⅲ（P〈0．01）;呈现出饲粮Ⅱ胃内氮消化率高于Ⅰ、Ⅲ（P＝0．278）和饲粮Ⅰ、Ⅱ全消化道氮消化率（P＝0．244）及氮存留量（P＝0．091）较高的趋势。结果提示,SC／NSC为1．57时,绵羊消化代谢的各项指标最优。  相似文献   

5.
不同组合饲粮对绵羊消化代谢的影响   总被引：5，自引：2，他引：3  
选用3只安装永久瘤胃瘘管的甘肃高山细毛羯羊(1.5岁,平均体重22.5kg),采用3×3拉丁方设计,研究3种组合饲粮,即对照饲粮(Ⅰ)、含甜菜渣饲粮(Ⅱ)、含苹果渣饲粮(Ⅲ)对绵羊消化代谢的影响。试验分3期,每期预试期10d,正试期9d。结果表明,饲粮Ⅰ、Ⅱ的干物质(DM)和有机物质(OM)消化量与消化率均显著高于Ⅲ(P＜0.05);饲粮Ⅱ的中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)消化量及消化率呈现出高于Ⅰ、Ⅲ的趋势(P＞0.05),饲粮Ⅲ的NDF和ADF消化率也呈现出低于Ⅰ的趋势;饲粮Ⅱ的氮消化量显著高于Ⅰ(P＜0.05),其消化率显著高于饲粮Ⅰ、Ⅲ(P＜0.05),呈现出其氮存留量高于Ⅰ及氮存留率高于Ⅰ、Ⅲ的趋势;饲粮Ⅱ钙的表观消化率显著高于Ⅰ(P＜0.01)、Ⅲ(P＜0.05),Ⅲ也显著高于Ⅰ(P＜0.05);饲粮Ⅲ的磷表观消化量显著高于Ⅰ、Ⅱ(P＜0.05),且呈现饲粮Ⅲ磷消化率高于Ⅱ,Ⅱ也高于Ⅰ的趋势。  相似文献   

6.
半胱胺对绵羊消化代谢的影响   总被引：28，自引：3，他引：25  
十二指肠灌注半胱胺后，４头湖羊平均日采食量（以ＤＭ计）虽无显著性变化，而由复胃进入十二指肠的食糜流量则增加１５．８１％（Ｐ〈０．０５）；食糜ＴＮ流量由１８．３４±０．４２ｇ／ｄ提高到２１．３４±０．５８ｇ／ｄ（Ｐ〈０．０１），其中ＭＣＰ－Ｎ及表观过瘤胃蛋白氮（ＢＰＮ）分别提高２８．５７％（Ｐ〈０．０５）和１４．４４％（Ｐ〈０．０５）。瘤胃液总脱氢酶活力平均提高２１．１５％（Ｐ〈０．０２５），ＮＨ３  相似文献   

7.
以装有瘤胃瘘管的肉牛（３９０±３０ｋｇ）饲喂全羊草的基础日粮，瘤胃灌注４种不同摩尔比例的混合ＶＦＡ（乙酸：丙酸：丁酸为７５∶１５∶１０，６５∶２５∶１０，５５∶３５∶１０和４５∶４５∶１０），按４×４拉丁方试验设计测定了灌注后代谢产热率（ＨＰ／ＭＥ），ＶＦＡ转化为体脂肪的效率（Ｋｆ）和可消化氮转化为沉积氮的效率。结果表明，随着灌注混合ＶＦＡ中丙酸比例超过２５％，ＨＰ／ＭＥ明显降低（Ｐ＜００５），Ｋｆ值极显著地增加（Ｐ＜００１）；可消化氮转化为沉积氮的效率显著增加（Ｐ＜００５）；ＨＰ／ＭＥ与瘤胃中乙酸比例、Ｋｆ值与瘤胃液中丙酸比例均呈线性正相关。  相似文献   

8.
不同蛋白质水平的日粮对内蒙古白绒山羊消化代谢的影响   总被引：8，自引：1，他引：7  
选用 9只 2周岁左右的装有永久性瘤胃瘘管和十二指肠近端瘘管的内蒙古白绒山羊羯羊 ,研究同一硫源(硫酸钠 )、同一氮硫比 (7 6 0 :1)条件下 ,3种不同蛋白水平的日粮对内蒙古白绒山羊营养物质消化代谢的影响。试验结果表明 :(1)Ⅱ组 (CP为 9 41% )干物质进食量、沉积氮显著高于Ⅰ组 (CP为 7 14% )和Ⅲ组 (CP为 10 77% )(P <0 0 5 )。Ⅱ组和Ⅲ组氮的表观消化率显著高于Ⅰ组 (P <0 0 5 )。研究发现当日粮粗蛋白为 8 87% ,硫水平为0 186 %时 ,沉积氮可获最佳值 4 17(g/d)。 (2 )硫的沉积量以Ⅱ组最高 ,显著高于其它两组 (P <0 0 5 )。各组间硫的表观消化率无显著差异 (P >0 0 5 )。研究发现当日粮粗蛋白水平为 8 78%时 ,硫的沉积量可以获得最佳值0 337g/d。 (3)Ⅱ组和Ⅲ组的瘤胃总氮流量以及十二指肠总氮流量均显著高于Ⅰ组 (P <0 0 5 )。Ⅱ组瘤胃微生物氮显著高于Ⅰ组和Ⅲ组 (P <0 0 5 )。Ⅱ组和Ⅲ组十二指肠微生物氮显著高于Ⅰ组 (P <0 0 5 )。Ⅱ组瘤胃总硫流量显著高于Ⅰ组和Ⅲ组 (P <0 0 5 )。十二指肠总硫流量各组间没有显著差异 (P >0 0 5 )。  相似文献   

9.
为探讨不同产地羊草营养成分、奶牛瘤胃降解特性及瘤胃非降解蛋白小肠消化率,选用生理阶段相同的3头装有永久性瘤胃瘘管和十二指肠瘘管的荷斯坦奶牛,采用尼龙袋法评定安达地区(Ⅰ)、大庆地区(Ⅱ)、肇东地区(Ⅲ)和齐齐哈尔地区(Ⅳ)4个产地羊草干物质(DM)、粗蛋白(CP)和总氨基酸(TAA)72 h瘤胃降解特性及小肠消化率。结果发现：不同产地羊草营养成分不同,地区Ⅰ的CP显著高于其他3个地区(P<0.05),地区Ⅱ的中性洗涤纤维(NDF)显著低于其他3个地区(P<0.05);地区Ⅲ的DM有效降解率显著高于其他3个地区(P<0.05),地区Ⅰ最低;地区Ⅰ和Ⅱ的CP有效降解率显著高于地区Ⅲ和Ⅳ(P<0.05),地区Ⅱ的TAA有效降解率显著高于地区Ⅳ(P<0.05);地区Ⅱ和Ⅳ的DM小肠消化率显著高于地区Ⅲ和Ⅰ(P<0.05),地区Ⅰ和Ⅲ的CP小肠消化率显著高于Ⅱ和Ⅳ(P<0.05),TAA、必需氨基酸(EAA)、非必需氨基酸(NEAA)小肠消化率在地区Ⅲ最高,不同氨基酸小肠消化率各地区也不相同。综上,不同产地羊草营养成分不同,地区Ⅰ的羊草CP含量较高;不同...  相似文献   

10.
本文旨在研究饲粮蛋白质水平对冬毛期水貂胃肠道消化酶活性以及空肠形态结构的影响。选择 ９０日龄的健康公貂 ６０只,随机分成 ６组（每组 １０个重复,每个重复 １只）,分别饲喂蛋白质水平为 ２８％（Ⅰ组）、３０％（Ⅱ组）、３２％（Ⅲ组）、３４％（Ⅳ组）、３６％（Ⅴ组）和 ３８％（Ⅵ组）的试验饲粮。预试期 ７ｄ,正试期 １１５ｄ。饲养试验结束后进行屠宰,制备胃肠道内容物上清液,用于测定消化酶活性;制备空肠组织切片,用于观察空肠的形态结构。结果表明：Ⅴ组水貂的胃蛋白酶活性极显著高于Ⅰ、Ⅱ和Ⅲ组（Ｐ＜０．０１）,与Ⅳ和Ⅵ组差异不显著（Ｐ＞０．０５）。Ⅳ组水貂的十二指肠和空肠胰淀粉酶活性极显著高于Ⅰ、Ⅱ、Ⅲ、Ⅴ和Ⅵ组（Ｐ＜０．０１）。Ⅳ和Ⅴ组水貂的回肠胰淀粉酶活性显著或极显著高于Ⅰ和Ⅱ组（Ｐ＜０．０５或 Ｐ＜０．０１）。Ⅳ组水貂的十二指肠胰蛋白酶活性极显著高于Ⅰ、Ⅱ、Ⅴ和Ⅵ组（Ｐ＜０．０１）,空肠胰蛋白酶活性极显著高于Ⅰ、Ⅱ、Ⅲ、Ⅴ和Ⅵ组（Ｐ＜０．０１）。Ⅲ组水貂的回肠胰蛋白酶活性显著高于Ⅵ组（Ｐ＜０．０５）,与其他各组差异不显著（Ｐ＞０．０５）。Ⅵ组水貂的十二指肠胰脂肪酶活性显著或极显著高于Ⅱ、Ⅳ和Ⅴ组（Ｐ＜０．０５或 Ｐ＜０．０１）,空肠胰脂肪酶活性显著或极显著高于Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅴ组（Ｐ＜０．０５或 Ｐ＜０．０１）。Ⅰ、Ⅲ和Ⅴ组水貂的回肠胰脂肪酶活性极显著高于Ⅱ和Ⅵ组（Ｐ＜０．０１）,与Ⅳ组差异不显著（Ｐ＞０．０５）。饲粮蛋白质水平为 ３６％时,水貂空肠绒毛高度、隐窝深度、绒毛高度与隐窝深度比值、黏膜厚度以及肠壁厚度均处在较高水平。由此得出,饲粮蛋白质水平可影响冬毛期水貂胃肠道消化酶活性,并可调节其空肠形态结构。  相似文献   

11.
In order to confirm earlier fragmentary results, the effect of defaunation and refaunation of the rumen on the fermentation pattern and flow of N-components in the proximal duodenum of two sheep was investigated. Defaunation had no effect on acetic acid as a proportion of the total volatile fatty acids in the rumen, while the proportions of propionic acid increased with a concomitant decrease in butyrate. Refaunation resulted in lower acetic acid and higher butyric acid proportions. The concentration of ammonia N in the rumen was clearly decreased after defaunation, already indicating an effect of the elimination of protozoa on nitrogen metabolism in the rumen. Defaunation also increased significantly the flow of total N, non ammonia N and individual and total amino acids in the proximal duodenum. Defaunation resulted in higher bacterial growth efficiency, significantly in one sheep, but the decrease after refaunation was statistically significant for both sheep. Determination of rumen digestibility of organic matter and acid detergent fibre (ADF) revealed lower values in the absence of the protozoa, while total digestibility was only influenced to a much lower extent. This indicated a shift of digestion from rumen to the lower digestive tract. Finally, earlier work is discussed in the light of the present findings.  相似文献   

12.
The effect of supplementation with different levels of cracked corn on the sites of OM, total dietary fiber (TDF), ADF, and starch digestion in steers fed fresh alfalfa indoors was determined. Six Angus steers (338 +/- 19 kg) fitted with cannulas in the rumen, duodenum, and ileum consumed 1) alfalfa (20.4% CP, 41.6% NDF) ad libitum (AALF); 2), 3), and 4) AALF supplemented (S) with .4, .8, or 1.2%, respectively, of BW of corn; or 5) alfalfa restricted at the average level of forage intake of S steers (RALF), in a 5 x 5 Latin square design. Total OM intake was lower (P < .01) in steers fed RALF than in those fed AALF but level of forage intake did not affect sites of OM, TDF, or starch digestion (P > .05). Forage OM intake decreased (P < .01) linearly (8,496 to 5,840 g/d) but total OM intake increased (P = .03) linearly (8,496 to 9,344 g/d) as corn increased from .4 to 1.2% BW. Ruminal apparent and true OM disappearance was not affected, but OM disappearing in the small intestine increased (P < .01) linearly with increasing levels of corn. Total tract OM digestibility (71.2 to 76.2%) and the proportion of OM intake that was digested in the small intestine (15.4 to 24.5%) increased (P < .01) linearly as corn increased. The TDF and ADF intakes decreased (P < .01) linearly as level of corn increased. Total tract TDF and ADF digestibilities were not different among treatments (average 62.9 and 57.8%, respectively). Starch intake and starch digested in the rumen and small and large intestine increased (P < .01) linearly with increasing corn level. Ruminal pH and VFA concentrations decreased and increased (P < .01), respectively, with increasing corn. Supplementation with corn increased OM intake, decreased forage OM intake, and increased the proportion of OM that was digested in the small intestine, but fiber digestion was not affected.  相似文献   

13.
Five sheep (average BW 48 kg) with ruminal, duodenal, and ileal cannulas were fed 63% roughage: 37% concentrate diets (CP = 14.5%) in a 5 x 5 Latin square design to study effects of urea and sodium bicarbonate supplementation on nutrient digestion and ruminal characteristics of defaunated sheep. Diets were fed twice daily (DMI = 1,076 g/d). Defaunation was accomplished with 25-ml doses of alkanate 3SL3/sheep daily for 3 d. Control sheep were faunated (Treatment 1) and fed soybean meal as the major N supplement. Remaining sheep were maintained defaunated and fed either the same diet as Treatment 1 (Treatment 2), Treatment 1 with urea replacing 30% of the soybean meal N (Treatment 3), or Treatment 1 with 2% sodium bicarbonate in the diet (Treatment 4). Treatment 5 was a combination of Treatments 3 and 4. Compared with the faunated control, defaunation decreased (P less than .05) total tract DM, OM, NDF, ADF, and CP digestibilities (71.5 vs 69.4, 73.8 vs 71.7, 64.6 vs 61.4, 58.7 vs 55.8, and 74.2 vs 70.6%, respectively) and average (2 to 12 h postfeeding) ruminal fluid ammonia (23.5 vs 13.7 mg/dl) and isobutyrate (.9 vs .7 mM) concentrations. However, defaunation increased (P less than .05) linoleic and linolenic acid flows (.58 vs .45 g C18:2/d; .17 vs .14 g C18:3/d) to and disappearance (.50 vs .39 g C18:2/d; .14 vs .11 g C18:3/d) from the small intestine. Urea supplementation increased (P less than .05) total tract DM (70.2 vs 68.6%) and OM (72.3 vs 71.0%) digestibilities of defaunated sheep but lowered (P less than .05) ruminal fluid isobutyrate concentration (.6 vs .8 mM). Sodium bicarbonate supplementation increased (P less than .05) ruminal fluid pH (6.4 vs 6.2), isobutyrate concentration (.75 vs .60 mM), total tract ADF digestibility (57.6 vs 54.2%), and ruminal NDF (41.6 vs 28.5%), ADF (36.6 vs 22.8%), and CP (-5.5 vs -26.8%) digestibilities in defaunated sheep. Dietary supplementation of urea or sodium bicarbonate increased nutrient digestion by defaunated sheep.  相似文献   

14.
An experiment examining nutritional effects of dietary corncob particle size was conducted using ruminal-, duodenal- and ileal-cannulated sheep in a 4 X 4 Latin square design. Site of nutrient digestion and digesta flow were the principal criteria evaluated. Analyses of dry matter (DM), N, starch and neutral detergent fiber (NDF) were performed on feed, feces and digesta samples. Chromic oxide-impregnated paper was used as an external marker to estimate digestibilities at different sites along the gastrointestinal tract. Ruminal pH and volatile fatty acid molar proportions were also determined. All diets (74.9% concentrates: 25.1% corncobs) were pelleted and were similar in ingredient composition but varied in corncob particle size (corncob mean particle sizes were 6.5, 5.4, 1.4 or .8 mm). Dietary crude protein levels differed little among treatments. Starch concentration was higher in diets containing the larger corncob particles while NDF, acid detergent fiber (ADF), cellulose and hemicellulose concentrations were lower in diets containing larger particles, suggesting a reaction between starch and fiber moieties during the pelleting process. Starch flow past the duodenum decreased (P less than .05) as dietary corncob particle size decreased. Apparent NDF digestion before the duodenum was highest for sheep fed diets containing 1.4-mm corncobs (P less than .05). Apparent starch digestion in the small intestine decreased (P less than .05) as dietary corncob particle size decreased. A considerable amount of NDF was apparently digested in the small intestine of sheep consuming diets containing 5.4- and .8-mm corncobs. Likewise, a substantial amount of NDF was apparently digested in the large intestine. Few differences in apparent total tract digestibilities were noted.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

15.
Crossbred steers (n = 7; 400 kg BW), fitted with T-type cannulas in the duodenum and ileum, were used to examine the effects of processing method, dry-rolled (DR) vs. steam-flaked (SF) sorghum grain, and degree of processing (flake density; FD) of SF corn (SFC) and SF sorghum (SFS) grain on site and extent of DM, starch, and N digestibilities and to measure extent of microbial N flow to the duodenum. In Exp. 1, diets contained 77% DRS or 77% SFS with FD of 437, 360, and 283 g/L (SF34, SF28, and SF22). In Exp. 2, diets contained 77% SFC with FD of SF34 or SF22. For sorghum and corn diets, respective average daily intakes were as follows: DM, 6.7 and 8.1 kg; starch, 3.8 and 4.7 kg; N, 136 and 149 g. Steers fed SFS vs. DRS increased (P = .01) starch digestibilities (percentage of intake) in the rumen (82 vs. 67%) and total tract (98.9 vs. 96.5%) and decreased digestibilities in the small intestine (16 vs. 28%; P = .01) and large intestine (.5 vs 1.2%; P = .05). As a percentage of starch entering the segment, digestibility was increased (P = .01) within the small intestine (91 vs. 85%) but was not altered within the large intestine by steers fed SFS vs. DRS. Decreasing FD of SFS and of SFC, respectively, linearly increased starch digestibilities (percentage of intake) in the rumen (P = .03, .02) and total tract (P = .03, .09) and linearly diminished starch digestibilities in the small intestine (P = .04, .09). Starch digestibilities (percentage of entry) within the small or large intestine were not changed by FD. The percentage of dietary corn or sorghum starch digested in the large intestine was very small, less than 2% of intake. Microbial N flow to the duodenum was not altered by SFS compared to DRS, or by decreasing FD of SFS and SFC. Reducing FD of SFS, but not of SFC, tended to decrease (P = .07) microbial efficiency linearly and tended to increase (P = .06) total tract N digestibilities linearly. Steam flaking compared to dry rolling of sorghum grain and decreasing FD of SFC and SFS grain consistently increased starch digestibility in the rumen and total tract of growing steers. The greatest total digestibility of dietary starch occurred when the proportion digested in the rumen was maximized and the fraction digested in the small intestine was minimized. These changes in sites of digestion account, in part, for the improved N conservation and greater hepatic output of glucose by steers fed lower FD of SFS reported in our companion papers.  相似文献   

16.
Effects of advancing forage maturity and drought-induced summer dormancy on site and extent of digestion and microbial protein synthesis in beef steers grazing native blue grama rangeland were evaluated in four sampling periods. Five steers (avg initial wt 227 kg) fitted with ruminal, duodenal and ileal cannulae and three steers cannulated at the esophagus freely grazed a 12-ha study pasture. Sampling periods lasted 11 d and started June 2, which was during the early growing season (EGS); June 22, during early summer dormancy (ESD); July 21, during late summer dormancy (LSD); and August 25, 1985, during the late growing season (LGS). Dietary N content was lower (P less than .05) in ESD and LSD than in EGS and LGS. Neutral detergent fiber (NDF) content was lower (P less than .05) in EGS than in other sampling periods. Ruminal organic matter (OM) digestion was lower (P less than .05) in ESD than in EGS, probably because of increased dietary NDF and lower N content. Ruminal OM digestion was greater (P less than .05) in LSD and LGS than in ESD because of increased fiber digestion. Neutral detergent fiber and acid detergent fiber (ADF) digestion occurring in the rumen was greater (P less than .05) in LSD and LGS than in EGS and ESD. Organic matter digestion in the small intestine and OM, NDF and ADF digestion in the hindgut were similar for all sampling periods. Over 90% of the fiber digestion occurred ruminally.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

17.
本论文用1.5岁龄阿尔巴斯型白绒山羊,研究了瘤胃素及瘤胃素+沸石对妊娠母羊瘤胃发酵和营养物质消化代谢的影响。试验结果表明:与对照组相比,添加瘤胃素+沸石提高丙酸占总挥发性脂肪酸(VFA)的比例10个百分点,血液总蛋白含量提高20.94％。同时,补加瘤胃素或瘤胃素+沸石能促进绒山羊对日粮营养物质的利用,日粮干物质消化率分别比对照组提高19.50％、11.87％;日粮有机物质消化率分别提高19.91％、21.83％;日粮粗蛋白质消化率提高10.38％、0.11％;日粮酸性洗涤纤维消化率提高32.75％、17.35％:日粮总能量利用率提高14.93％、6.93％;每日氮沉积量也有显著提高。  相似文献   

18.
Protozoa are commensal eukaryotes in the rumen of herbivores. Protozoa are large producers of hydrogen, which is utilized by methanogenic archaea to produce methane, a greenhouse gas. The removal of protozoa from the rumen (defaunation) decreases methanogenesis, but also negatively affects fiber digestion, which is the main function of the rumen. The aim of this study was to examine the effect of long-term defaunation on the structure of the microbiota and particularly methanogenic archaea and fibrolytic bacteria to better understand the microbial mechanisms responsible for the decrease in methanogenesis and fibrolysis. The trial was conducted in 5 adult sheep subjected successively to long-term defaunation (2 yr), refaunation (12 wk), and short-term defaunation (10 wk). Methanogens were enumerated by quantitative PCR targeting the rrs (16S ribosomal RNA subunit) and mcrA (methyl coenzyme-M reductase) genes. The rrs gene was used to quantify the 3 major culturable rumen cellulolytic bacterial species (i.e., Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens) and total bacteria. Bacterial and methanogen diversity was also examined by PCR-DGGE (PCR-denaturing gradient gel electrophoresis) analysis targeting the rrs and mcrA genes, respectively. Total rumen bacterial density estimated as rrs copies per gram of DM of rumen content increased in response to long- and short-term defaunation (+1 log, P < 0.001), but without noticeable shifts in diversity. Defaunation increased the rrs copies per gram of DM of rumen content of R. albus and R. flavefaciens (+2 log, P < 0 0.001), but did not affect that of F. succinogenes. Despite a 20% reduction in methane emission in the 2 defaunated periods, the mcrA and rrs copies of methanogens per gram of DM of rumen content increased (+1 log, P < 0.001) in the absence of protozoa, whereas the diversity of the dominant methanogenic community was not modified. This study shows no major difference between long- and short-term defaunation in abundance and diversity of bacteria and archaea. It also provides evidence that monitoring the abundance and diversity of methanogens is not sufficient to comprehend the microbial mechanisms leading to a reduction in methane emissions by ruminants. This study also reports for the first time in sheep a selective effect of defaunation on the abundance of cellulolytic bacterial species.  相似文献   

19.
Effects of protozoa on bacterial nitrogen recycling in the rumen   总被引：7，自引：0，他引：7  
The effects of protozoa on ruminal NH3-N kinetics and bacterial N recycling were measured in five sheep (57.6+/-7.1 kg BW, x +/- SD) with ruminal and duodenal cannulas in naturally faunated, defaunated, and refaunated periods. The sheep were fed a diet of 239 g of alfalfa haylage and 814 g of barley concentrate per day (DM basis) divided into 12 equal portions and allocated at 2-h intervals. A pulse dose of 300 mg of 15N as [15N]NH4Cl was administered into the rumen (on d 1 and 15) and 300 mg of 15N as [15N]urea was administered intravenously to the blood (d 8). Enrichment of 15N was measured in ruminal NH3-N, bacterial N, and plasma urea N over a period of 35 h. Total collection of urine was made for 5 d and analyzed for purine derivatives to calculate the flow of microbial N. Ruminal parameters and nutrient digestibilities were also measured. Sheep were defaunated using a rumen washing procedure 50 d prior to measurements in the defaunated period. Sheep were refaunated with ruminal contents from a faunated sheep receiving the same diet. Measurements began 26 d following refaunation, at which time protozoal numbers had returned to those in the originally faunated sheep. Data reported in parentheses are for faunated, defaunated, and refaunated sheep, respectively. Total culturable and cellulolytic bacterial numbers were unaffected by defaunation, but there was an increase in flow of microbial N from the rumen (10.8, 17.3, and 11.1 g N/d; P < .05) in the defaunated period. Flux, irreversible loss, and intraruminal recycling of NH3-N and recycling of NH3-N from plasma urea N were not affected by defaunation. Defaunation had no effect on reducing the absolute amount (13.8, 10.0, and 11.3 g N/d; P > .20) of bacterial N recycling and the percentage of N flux through the bacterial N pool. Total-tract digestion was reduced in defaunated compared with faunated sheep by 8, 17, 15, and 32% for OM, N, NDF, and ADF, respectively. In conclusion, defaunation improved ruminal N metabolism through the enhancement of bacterial protein synthesis, and improvement in the flow of microbial protein to the host animal.  相似文献   

20.
用4只装有瘤胃瘘管、十二肠瘘管和回肠瘘管的去势(公母各半)萨福克羊体重平均为(45.5±5.2)kg,在不同粗精比日粮条件下 ,研究瘤胃细菌、纤毛虫体蛋白质在小肠内的利用率。结果表明 :到达十二指肠的瘤胃细菌和纤毛虫的量 ,随日粮中精饲料水平的提高而显著减少(P<0.05)。与此相反 ,过瘤胃饲料蛋白质的量则显著增加(P<0.05)。小肠内的细菌利用率显著受日粮变化的影响 ,而纤毛虫利用率则不易受日粮影响且显著地高于细菌的利用率(P<0.05)。小肠内被吸收的细菌和纤毛虫对微生物氮的贡献率在全试验组中平均为50 %。  相似文献   

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