应用肉牛小肠蛋白质新体系验证肉牛日粮的瘤胃能氮平衡

结合瘤胃尼龙袋法测定的饲料蛋白质瘤胃降解率和有机物发酵率,计算日粮的瘤胃能氮平衡,使日粮配合更合理,同时满足瘤胃微生物蛋白质合成对可发酵有机物和降解蛋白质的需要。     

不同来源可发酵碳水化合物和可降解氮合成瘤胃微生物蛋白质效率…

本论文研究了不同来源可发酵碳水化合物和可降解氮合成瘤微生胃微生物蛋白质的效率，结果表明，６种不同饲料和精粗比日粮的可发酵碳水化合物合成微生物氮的效率相似（Ｐ〉０．０５），平均值为２５．９１ｇＭＮ／ｋｇＦＣＨ２Ｏ。７种不同可降解氮源合成微生物氮的效率差异显著（Ｐ〈０．０５），豆饼日粮最高为０．９１。尿素日粮最低，为０．６６，缓释技术能使尿素可降解氮的利用效率提高到０．８４６９（Ｐ〈０．０５），瘤胃内     

甲醛保护豆饼的动态降解及其对日粮体外发酵影响的研究

研究了不同浓度甲醛保护豆饼蛋白质后对蛋白质动态降解以及日粮体外发酵的影响。结果表明,当甲醛水平为0.6g/100gCP时,蛋白质的快速降解部分减少,慢速降解部分增加,降解速度变慢。根据降解模型p=a+b(1-e~(-ct))判断,0.6％的甲醛即能增加过瘤胃蛋白30％,又不会对蛋白质过保护。用甲醛保护豆饼配合日粮时,对有机物的降解率和有机物合成微生物的效率没有显著影响(P>0.05),但是甲醛保护能使可降解氮的利用效率从0.7928提高到0.8482(P<0.05)。     

日粮精粗比对瘤胃微生物合成效率的影响

本文用瘤胃持续模拟装置研究了精粗比为７：３、１：１和３：７时对日粮有机物、中洗纤维和酸洗纤维的降解、蛋白质的转化和微生物合成效率的影响。结果表明，精粗比不影响瘤胃微生物对可发酵能的利用效率（Ｐ〉０．０５），但是显著影响瘤胃微生物对可降解氮的利用效率（Ｐ〈０．０５）；最后探讨了瘤胃内可降解氮和可发酵能与微生物氮合成量之间的定量模型。     

饲料蛋白质保护对肉牛饲料氮的降解,消化和利用的影响

本研究用甲醛和新型保护剂保护豆饼日粮及未保护豆饼日粮在 3头装有瘤胃和真胃瘘管的阉牛中进行 3× 3拉丁方试验 ,研究保护及未保护豆饼蛋白质在瘤胃降解、真胃后消化吸收及吸收蛋白质的利用率的差异。结果表明 ,新型保护剂保护豆饼明显降低豆饼蛋白质在瘤胃的降解率 (p<0 .0 1 ) ,增加日粮过瘤胃蛋白质量 ,而不影响蛋白质在小肠的消化率及氮的沉积效率 ,但甲醛保护豆饼会导致吸收蛋白质的沉积效率明显下降 (p<0 .0 1 )     

全混合日粮对羔羊瘤胃代谢产物浓度变化的影响

选用４只４月龄装置永久性瘤胃瘘管的羔羊,按４×４拉丁方试验设计,研究了４种不同处理的全混合日粮（ＴＭＲ）对羔羊瘤胃消化代谢的影响。试验期采集瘤胃液,研究其ｐＨ值、氨氮、尿素氮、总氮及蛋白质浓度的动态变化规律。试验结果表明,在含玉米秸的ＴＭＲ中,以尿素蛋白精料等氮代替豆饼,对试羊瘤胃液ｐＨ值及蛋白质含量均无明显影响（Ｐ＞０．０５）,虽显著提高了试羊瘤胃液氨氮浓度（Ｐ＜０．０１）,但仍未超出瘤胃微生物利用氨的限量范围;在含尿素蛋白精料的ＴＭＲ中,玉米秸的碱化处理,可明显提高试羊瘤胃液ｐＨ值（Ｐ＜０．０５）,而其氨氮浓度及蛋白质含量均无显著变化（Ｐ＞０．０５）;对含尿素蛋白精料及碱化玉米秸的ＴＭＲ进行颗粒化加工,并未明显影响试羊瘤胃液ｐＨ值、氨氮及蛋白质浓度（Ｐ＞０．０５）;各处理组试羊瘤胃液ｐＨ值及氨氮浓度均处于正常生理范围内。从而证明在全混合日粮中以尿素蛋白精料取代豆饼、玉米秸的碱化处理及ＴＭＲ的颗粒化加工均具有理论可行性。     

不同粗饲料日粮发酵规律及合成瘤胃微生物蛋白质效率研究

对玉米秸和稻草用30％水、3％尿素和4％石灰进行处理，用尼龙袋法测定了处理前后32种粗饲料的降解法;用持续人工瘤胃法研究了处理玉米秸、处理稻草和羊草为粗饲料配合日粮的降解规律．结果表明，化学处理使玉米秸的降解率从40．05％（P＜0．05）．3种粗饲料日粮合成微生物蛋白质的效率相似（P＞0．05）．     

奶牛高蛋白浓缩料的应用效果与推广意义

“９３１”奶牛高蛋白浓缩料，即糊化淀粉氨缓释剂尿素，含粗蛋白７５－８０％，能量１２５５千焦／１００克以上。本品在瘤胃内的氨释放速度比普通素降低１／３；其尿素氨转化为微生物氨的效率与豆饼降解氮的转化效率接近。     

绵羊日粮中瘤胃可降解氮与尿素氮转化为微生物氮的效率及其影响因素的研究

对12只安装有永久瘤胃及十二指肠瘘管的周岁细毛羯羊饲以不同代谢能水平和尿素添加量日粮的一系列试验得出绵羊瘤胃中每日生成微生物氮的数量在2.09～8.33 g之间;当日粮中瘤胃降解氮供给充足条件下,微生物产量与代谢能进食量密切相关;而瘤胃中可降解氮转化为微生物氮的效率在32.94%～82.64%之间,它和日粮中每兆焦代谢能所对应的瘤胃降解氮克数呈负相关;日粮中添加的尿素氮转化为微生物氮的效率范围为-1.03%～88.80%,它们既与日粮中总降解氮和总代谢能的比值相关,又与尿素氮占总降解氮的比例相关.     

绵羊日粮中瘤胃可降解氮与尿素氮转化为微生物氮的效率及其影响因素的研究

对12只安装有永久瘤胃及十二指肠瘘管的周岁细毛羯羊饲以不同代谢能水平和尿素添加量日粮的一系列试验得出：绵羊瘤胃中每日生成微生物氮的数量在2.09-8.33g之间；当日粮中瘤胃降解氮供给充足条件下，微生物产量与代谢能进食量密切相关；而瘤胃中可降解氮转化为微生物氮的效率在32.94%-82.64%之间，它和日粮中每兆焦代谢能所对应的瘤胃降解氮克数呈负相关；日粮中添加的尿素氮转化为微生物氮的效率范围为-1.03%～88.80%，它们既与日粮中总降解氮和总代谢能的比值相关，又与尿素氮占总降解氮的比例相关。     

不同蛋白质和碳水化合物饲料来源对牛瘤胃洗涤纤维降解和瘤胃液产物的定量研究

试验采用3×3拉丁方设计,3头安装永久性大口径瘤胃瘘管的青年母牛饲喂3种不同精饲料的日粮,3种精饲料分别为豆粕+玉米(日粮1),猪血粉+玉米(日粮2)和豆粕+小麦(日粮3)。精料日喂量按活牛体重的1%喂给,干玉米秸等量组成的日粮配给。试验为3个试验周期,每一周期为37d,其中适应期26d,在早晨采食后2、4、8、16和24h,分别5次实施瘤胃掏空,全量测定瘤胃物存留量。结果表明:日粮1在采食后2～8h瘤胃干物质、液体和NDF的存留量最低,与其他两种日粮相比差异显著(P<0.05);日粮1和日粮3瘤胃液氨氮存留量在采食后2～8h始终高于日粮2(P<0.05),但日粮3在采食4h后瘤胃液氨氮开始下降,而日粮1至采食后16h开始下降,日粮1瘤胃液氨氮数量采食后2～8h处于高峰状态,说明瘤胃微生物在瘤胃环境长时间一直保持稳定的降解能力;日粮1和日粮3在采食2～4h后处于较高的总挥发性脂肪酸(VFA)瘤胃存留量,日粮1在采食后8～16h瘤胃存留量降低,与日粮2和日粮3相比差异显著(P<0.05),日粮1对瘤胃VFA的快速移除,意味着瘤胃液的快速流出以及可能解释瘤胃固体物的快速移除。因此,日粮1和日粮3在牛瘤胃洗涤纤维降解和瘤胃液产物代谢模式发挥不同作用。     

Ruminal peptide concentration required to optimize microbial growth and efficiency

Experimentation, with a single-phase continuous culture system operated at fractional dilution rates of 0.03 and 0.09 per hour and four cannulated crossbred steers (260 +/- 20 kg) used in a 4 x 4 Latin square design, was conducted to determine the level of ruminally degradable protein (RDP) that maximized microbial efficiency (MOEFF), microbial nitrogen flow, and nutrient digestibility in the rumen. Treatments consisted of increasing diet RDP levels (from 3.5 to 17.5% RDP on a DM basis). The basal diet was corn with casein or soybean meal used as the source of RDP in the continuous culture experiment and animal study, respectively. Dietary nonstructural carbohydrate (NSC) ranged from 52 to 75% on a dry matter basis. Urea was added to ensure an adequate ammonia nitrogen source for microbial growth. The RDP levels did not affect true digestibility of dry matter and organic matter, ruminal pH, particulate passage rate, or liquid passage rate in the animal study. As RDP increased, bacterial nitrogen production increased linearly (P < 0.05) only for the 0.09/h dilution rate. Microbial efficiency was not influenced by RDP level. Ruminal peptide and NH3 N concentration increased linearly (P < 0.05) as RDP increased. Based on this experimentation, 1.8 mM peptide maximized MOEFF when ammonia nitrogen was not limiting (> 2 mg/dL). We concluded from this research that the RDP requirement of NSC-fermenting bacteria was lower than that currently fed in many diets.     

Ruminal protein metabolism and intestinal amino acid utilization as affected by dietary protein and carbohydrate sources in sheep.

Eight wether lambs fitted with ruminal, duodenal, and ileal cannulas were used in a replicated 4 x 4 Latin square design to study the effects of carbohydrate and protein sources on ruminal protein metabolism and carbohydrate fermentation and intestinal amino acid (AA) absorption. Treatments were arranged as a 2 x 2 factorial. Carbohydrate sources were corn and barley; protein sources were soybean meal (SBM) and fish meal (FM). Diets contained 15.5% CP, of which 40% was supplied by SBM or FM. Corn or barley provided 39% of dietary DM that contained equal amounts of grass hay and wheat straw. Fish meal diets produced a lower (P less than .05) ruminal NH3 concentration and resulted in less CP degradation and bacterial protein flow to the duodenum than did SBM diets. Replacing SBM with FM increased (P less than .05) ruminal digestion of all fiber fractions. In addition, cellulose and hemicellulose digestibilities in the rumen tended to increase (P greater than .05) when barley replaced corn in the FM diets. Carbohydrate x protein interactions (P less than .05) were observed for OM digestion in the rumen and AA absorption in the small intestine (percentage of AA entering); these interactions were highest for the barley-FM diet. These results suggest that feeding FM with barley, which is high in both degradable carbohydrate and protein, might benefit ruminants more than feeding FM with corn, which is high in degradable carbohydrate but relatively low in degradable protein.     

Effects of supplemental energy and/or degradable intake protein on performance,grazing behavior,intake, digestibility,and fecal and blood indices by beef steers grazed on dormant native tallgrass prairie

To evaluate the effects of balancing total diet degradable intake protein with dietary total digestible nutrients (TDN), we conducted two studies during 2 yr with 100 (302 +/- 8 kg initial BW) mixed-breed yearling steers and 12 ruminally cannulated steers (526 +/- 28 kg). Steers individually received one of four supplements 5 d/wk while grazing dormant native tallgrass prairie. Supplements included: 1) corn and soybean meal, balanced for total diet degradable intake protein in relation to total diet TDN (CRSBM), 2) corn and soybean hulls, equal in supplemental TDN to CRSBM (CORN), 3) soybean meal, equal in supplemental degradable intake protein to CRSBM (SBM), or 4) a cottonseed hull-based control supplement (CONT). At each feeding (5 d/wk), steers consumed 13.6, 13.6, or 4.2 g of dry matter/kg of body weight, or 178 g of DM, respectively, of supplement. Steers fed CRSBM had greater (P < 0.01) average daily gain than cattle fed CORN or SBM. Feeding soybean meal (CRSBM, SBM) resulted in improved (P < 0.01) efficiency of supplement. Grazing time, intensity, and harvesting efficiency were reduced (P < 0.05) by corn supplementation (CRSBM and CORN), whereas the number of grazing bouts per day was increased (P < 0.08). Intake and digestibility of forage organic matter were reduced (P < 0.01) for steers supplemented with corn (CORN and CRSBM) vs cattle not fed corn (SBM and CONT). Total diet digestibility (P < 0.12) and digestible organic matter intake (P < 0.01) were greater for CRSBM-fed steers than for cattle fed either CORN or SBM. Steers fed CRSBM had greater (P < 0.01) fecal nitrogen and serum insulin than cattle fed CORN or SBM. Corn-fed cattle had lesser (P < 0.01) fecal pH and ADF concentrations than steers not consuming grain. Cattle fed supplements with soybean meal (CRSBM and SBM) had greater (P < 0.01) serum urea nitrogen than steers fed supplements without soybean meal (CORN, CONT). Supplemented steers grazing dormant tallgrass prairie had a greater rate of gain, with the greatest response in animal performance occurring when grain supplements were balanced for total diet degradable intake protein in relation to total diet TDN. These results lead us to suggest that grain-supplemented cattle grazing dormant tallgrass prairie require a balance of total diet degradable intake protein in relation to total diet TDN to optimize animal performance.     

茶渣单宁含量对绵羊养分消化利用与氮代谢参数的影响

旨在研究茶渣单宁含量对绵羊养分消化利用与氮代谢参数的影响.本研究分析了茶渣(RTL)的营养成分和单宁含量;用体外法测定6种配比茶渣/大豆粕混合料(0∶10、1∶9、2∶8、3∶7、4∶6、10∶0,其中茶渣缩合单宁(RTL-CT)含量依次为0.00、0.16、0.31、0.47、0.63和1.57 g·kg -1DM)的瘤胃液与瘤胃液+HCl-胃蛋白酶干物质(DM)与粗蛋白质(CP)降解率( rdDM、tdDM、rdCP、tdCP);用4只安装永久性瘤胃瘘管的甘肃高山细毛羊羯羊(1岁半,体质量(29士2.55)kg),按4×4拉丁方方案进行试验,研究了饲粮RTL-CT水平(A、B、C、D分别为0.00、0.77、1.53、2.30 g·kg-1DM)对绵羊养分消化利用与氮代谢参数的影响,共4个15d的饲粮循环(预试期9d,收集期6 d).试验结果:(1)3个茶渣样的粗蛋白质(CP)、粗纤维(CF)、单宁(单宁酸等价,TAE)与CT含量范围分别为23.23％～28.11％、16.68％～17.84％、1.98％～2.10％和1.47％～1.57％.(2)茶渣/大豆粕混合料的rdDM、tdDM、rdCP、tdCP均随茶渣比例提高而线性下降,变化范围相应为61.39％～25.67％、79.61％～26.47％、60.76％～16.68％和84.85％～17.69％.(3)体内试验中,高比例茶渣影响采食量,饲粮D(P＜0.01)、C(P＞0.05)的DM与有机物质(OM)采食量低于A、B; RTL-CT对DM、OM、中性洗涤纤维、酸性洗涤纤维、氮、钙和磷的消化率无显著影响(P＞0.05);但随RTL-CT水平提高尿氮排出量线性下降,导致氮存留率上升,C的氮存留率较A提高23.61％ (P＜0.05),B、D分别提高12.57％和15.88％ (P＞0.05);随RTL-CT提高,瘤胃液pH、总氮浓度无显著变化(P＞0.05),而NH3-N与血浆尿素氮(BUN)含量线性下降,C、D的NH3-N分别是A的50.36％( P＞0.05)和46.55％ (P＜0.05),BUN相应为A的68.04％与59.99％(P＜0.05).可见,茶渣是高蛋白质、低纤维物质,单宁含量为中等的物质;本试验中,RTbCT降低了饲粮的体外瘤胃CP降解率,但未影响体内全消化道消化率,且通过减少尿N排出而提高了氮存留率;但高比例RTL-CT降低了绵羊采食量.显然,RTL-CT l.53 g·kg-1DM对饲粮蛋白质的保护效果较好,且对采食量无显著影响.     

碳水化合物与蛋白质同步降解对瘤胃发酵特性及微生物蛋白质合成的影响

本研究通过一系列的体外研究来确定酶和甲醛处理对碳水化合物和蛋白质的降解特性及同步降解碳水化合物和蛋白质对瘤胃体外发酵和微生物蛋白合成的影响.未处理玉米和酶处理玉米与豆粕或酶处理或甲醛处理豆粕相结合,制备6种不同同步指数的试验饲料.结果:使用未经酶处理的玉米时,高同步指数日粮的干物质消化率最高(P<0.05).但酶处理玉...     

Milk yield and composition of lactating Comisana ewes fed total mixed rations containing nitrogen sources with different ruminal degradability

The objective of this study was to examine the effects of pelleted total mixed rations (PTMR) containing two crude protein (CP) levels and N sources with different ruminal degradability on milk yield and composition of lactating ewes. The experiment, which lasted 14 weeks, was conducted during the spring and summer of 2007 and used 80 multiparous Comisana ewes in mid-lactation, reared in permanent stabling. A 2 × 2 factorial design was used, with ewes receiving two levels of CP (low 15.5% CP and high 17.5% CP) and two type of N sources with different rumen degradable protein (low and high) for each dietary treatment: (1) high-degradable protein diet (17.5% CP) composed by soybean meal, sunflower meal and urea (HPHD), (2) low-degradable protein diet (17.5% CP) included only corn gluten meal (HPLD), (3) high-degradable protein diet (15.5% CP) composed by soybean meal, sunflower meal and urea (LPHD), and (4) low-degradable protein diet (15.5% CP) included only corn gluten meal (LPLD). In order to evaluate in vivo digestibility of PTMRs, four adult rams were placed in metabolic cages and their individual faeces and urine were collected. In the performance trial, ewe milk yield was recorded daily and Individual milk samples were analysed weekly for milk composition and to determine milk renneting parameters. The 17.5% CP diets led to better nutrient apparent digestibility coefficients and had positive effects on milk production than the 15.5% CP diets. Similar results were obtained for corn gluten meal diets, compared to diets containing soybean meal, sunflower meal and urea. Data showed that corn gluten meal diets have had a positive effects on milk fat (P < 0.05), but not on milk protein, lactose and renneting parameters. All ewes gained weight during the experimental period, but the body weight change was not significant among treatments. Our findings indicate that an increase in rumen undegradable protein (RUP) content does not negatively affect nutrient digestibility of sheep rations and milk yield and composition.     

Effect of amount and degradability of dietary starch on animal performance and meat quality in beef bulls

Introduction   Even at a similar energy concentration of the diet, energy source may affect animal performance. O wens et al. (1997) reported that daily dry matter (DM) intake tended to be lowest for wheat-based diets and highest for milo and oat-based diets. O'M ara et al. (1997) found a lower pH and less ammonia in the rumen of lactating cows, when unmolassed beet pulp was replaced with ground wheat. Contrary to the results of O'M ara et al. (1997), M alestein et al. (1984) found a greater risk for lactic acidosis for citrus and beet pulp than for maize meal and tapioca. For years it has been known that rapidly degradable carbohydrates may provoke acidosis (H untington and B ritton 1979; F iems et al. 1993). Furthermore, low ruminal pH may inhibit cellulose digestion (M ould et al. 1983) and decrease efficiency of microbial protein synthesis (R ussell et al. 1979).
As energy concentration of the diet is important for finishing cattle (B oucqu & eacute ; et al. 1980), the amount of roughage is rather limited. This may result in sub-clinical acidosis with a negative impact on animal performance (O wens et al. 1998), especially when the diet is rich in rapidly fermentable carbohydrates. Therefore an experiment was conducted to investigate the impact of energy source in the finishing diet on voluntary daily feed intake, daily liveweight gain, feed efficiency, blood metabolites and carcass quality.
Energy source may also affect meat quality. C asteels et al. (1969) found differences in meat colour when concentrates were based on cereals or sugarbeet pulp. W ood (1984) reported that the concentrate : forage ratio in the diet affects the fatty acid composition of body fat through an increase in propionate production in the rumen. Therefore the effect on meat quality was also studied.     

蛋白质源对山羊瘤胃微生物蛋白AA组成的影响

以4只瘘管山羊作为试验动物,研究羽毛粉(A)、玉米蛋白粉(B)、豆粕(C)和鱼粉(D)等蛋白质源配合的混合日粮对瘤胃微生物蛋白AA组成模式的影响规律。采用4×4拉丁方设计进行试验。结果表明:部分种类AA的含量在原虫和细菌区系间和同一区系内不同蛋白质处理间差异显著。原虫的Val比例高于细菌的,而细菌的Lys则高于原虫。细菌的Arg,原虫的Met、Leu和His在蛋白质处理间差异显著。综上可见,瘤胃微生物AA组成是因蛋白质来源而变化的。     

The use of endogenous nitrogen for microbial crude protein synthesis in the rumen of growing bulls

The objective of this study was to quantify endogenous nitrogen (N) recycled for microbial protein synthesis in the rumen. Four growing bulls (Schwarzbuntes Milchrind; bodyweight: 240–310 kg) with duodenal T‐shaped cannulas were fed diets containing four levels of crude protein content (200, 156, 102 and 63 g/kg dry matter, respectively). The diets were based on wheat, barley, tapioca meal, soybean extracted meal, dried beet pulp, meadow hay and straw. The diets had an energy level of 11.1, 10.9, 10.2 and 9.6 MJ metabolizable energy/kg dry matter. Faeces and urine were collected in four 7‐day balance periods. Duodenal flow rate was estimated by TiO₂, pelleted with grain, as a marker. The relationship between urine N excretion, the amount of microbial N reaching the duodenum, ruminal N balance and N retention were examined and the amount of endogenous N available for microbial protein synthesis without negative effects on the N retention was determined. It can be concluded that up to 16% of the microbial N supply could be covered by recycled endogenous N, but N retention should not be decreased by more than 1.5 residual standard deviations of maximal N retention.