蒸汽爆破技术在玉米秸秆饲料化利用中的研究进展

玉米秸秆是作物残余物中最丰富的木质纤维素生物质之一,主要由纤维素、半纤维素和木质素通过氢键及其他化学键、分子键结合而成,是具有复杂聚合结构的高分子化合物,作为动物饲料的可利用率较低。蒸汽爆破即汽爆,是应用蒸汽弹射原理实现爆炸过程中对生物质预处理的技术。将蒸汽爆破技术应用于玉米秸秆处理,可高效分离纤维素,对玉米秸秆具有明显的解聚作用,有利于提高玉米秸秆的饲料化利用程度。作者介绍了蒸汽爆破工艺原理与参数,综述了蒸汽爆破处理对玉米秸秆纤维结构、化学成分和酶解产糖的影响,以及对玉米秸秆的营养成分消化率和瘤胃微生物附着的影响。已有研究表明,蒸汽爆破可使蒸汽分子渗入植物组织,经过瞬时释放将内能转化为机械能,作用于生物质组织细胞层间,达到原料分解的目的;蒸汽爆破可改变玉米秸秆的纤维结构,降低半纤维素和木质素含量,提高纤维素含量(随着蒸汽爆破的压强和维压时间的增加,半纤维素含量显著降低,而物料含水率的增加会导致纤维素含量升高);蒸汽爆破可提高玉米秸秆体外发酵酶解产糖率,随着蒸汽爆破压强和维压时间的增加,玉米秸秆体外培养酶解还原糖产量增加;蒸汽爆破可使玉米秸秆的体外发酵产气量、产气速率、干物质和酸性洗涤纤维含量显著提高,可提高反刍动物对玉米秸秆的消化利用率,充分利用玉米秸秆的纤维素,提高玉米秸秆的营养价值;蒸汽爆破通过破坏玉米秸秆的表面结构,可促进瘤胃微生物在玉米秸秆上的附着,从而促进玉米秸秆的降解。综上,蒸汽爆破技术处理玉米秸秆可提高其作为饲料的利用率。     

响应面法优化蒸汽爆破小麦秸秆工艺

试验旨在利用Box-Behnken响应面法优化蒸汽爆破预处理小麦秸秆最佳条件，从而解决小麦秸秆营养成分利用率较低的问题。选取蒸汽压强（1.5~2.5 MPa）、水分含量（10%~50%）和维压时间（90~210 s）为自变量，瘤胃体外发酵产气速率为响应值，利用响应面建立回归模型并进行回归方程拟合，预测最佳工艺参数。结果显示：维压时间对瘤胃体外发酵产气速率的影响极显著（P<0.01），蒸汽压强和水分含量对瘤胃体外发酵产气速率无显著影响（P>0.05）。由F值可知：3个自变量对瘤胃体外发酵产气速率的影响大小依次为维压时间、蒸汽压强和水分含量。Box-Behnken响应面法优化蒸汽爆破预处理小麦秸秆的最优工艺参数为蒸汽压强1.77 MPa、水分含量49.91%和维压时间209.98 s。此条件下瘤胃体外发酵产气速率可达0.0794 mL/h。3次平行试验验证的体外发酵产气速率为0.0786 mL/h，与理论预测值误差仅为1.02%。将小麦秸秆在最佳爆破条件下重新爆破并进行体外发酵试验，与未蒸汽爆破的小麦秸秆相比，蒸汽爆破极显著降低了小麦秸秆中中性洗涤纤维（NDF）、酸性洗涤纤维（ADF）和半纤维素的含量（P<0.01），同时极显著提高了体外发酵液中挥发性脂肪酸（VFA）和NH₃-N的含量（P<0.01）。综上，采用响应面法优化蒸汽爆破小麦秸秆的条件合理可行，优化的蒸汽爆破参数可用于提高小麦秸秆营养价值的蒸汽爆破工艺中。     

Application of Straw Steam Explosion Technology in Livestock Production

Steam explosion technology is a comprehensive fiber processing craft of physical and chemical,which through vapor phase heating and exploding effect to achieve the purpose of changing fiber chemical composition and structure.It can improve the potential of animal feed intake and digestibility of straw,and contribute to the straw resources utilization in China.The author introduced the principle and processing technology of steam explosion,summarized the difference of steam explosion making on straw nutritional value and the problems of this techndogy in straw feed development,and its application prospects in livestock production,hoping to provide the reference for its application in livestock.     

秸秆蒸汽爆破技术在畜牧生产中的应用研究进展

蒸汽爆破技术是一种物理化学相结合的纤维处理工艺,通过蒸汽蒸煮和爆破作用达到改变纤维化学组成和结构的目的。采用蒸汽爆破技术处理农作物秸秆,具有能够提高动物采食量和秸秆消化率的作用,有利于中国秸秆资源开发。作者介绍了蒸汽爆破技术的原理及加工工艺,综述了蒸汽爆破技术对秸秆营养价值的影响及其在秸秆饲料开发领域存在的问题,并对其在畜牧生产中的应用前景作出展望,旨在对秸秆蒸汽爆破技术在畜牧业中应用奠定理论基础。     

Improving the quality of rice straw by urea and calcium hydroxide on rumen ecology,microbial protein synthesis in beef cattle

Four rumen‐fistulated beef cattle were randomly assigned to four treatments according to a 4 × 4 Latin square design to study the influence of urea and calcium hydroxide [Ca(OH)₂] treatment of rice straw to improve the nutritive value of rice straw. Four dietary treatments were as follows: untreated rice straw, 50 g/kg urea‐treated rice straw, 20 g/kg urea + 20 g/kg calcium hydroxide‐treated rice straw and 30 g/kg urea + 20 g/kg calcium hydroxide‐treated rice straw. All animals were kept in individual pens and fed with concentrate at 0.5 g/kg of BW (DM), rice straw was fed ad libitum. The experiment was conducted for four periods, and each period lasted for 21 days. During the first 14 days, DM feed intake measurements were made while during the last 7 days, all cattle were moved to metabolism crates for total faeces and urine collections. The results revealed that 20 g/kg urea + 20 g/kg calcium hydroxide‐treated rice straw improved the nutritive value of rice straw, in terms of dry matter intake, digestibility, ruminal volatile fatty acids, population of bacteria and fungi, nitrogen retention and microbial protein synthesis. Based on this study, it could be concluded that using urea plus calcium hydroxide was one alternative method to improve the nutritive value of rice straw, rumen ecology and fermentation and thus a reduction of treatment cost.     

不同汽爆处理下玉米秸秆品质综合评价

为缓解农牧交错地因天然草原破坏引起的饲草短缺、草畜平衡等问题，保证牛羊粗饲料的充足供给及畜牧业健康发展，本试验以玉米秸秆为原料，采用蒸汽爆破技术，通过调控汽爆腔压力和原料水分，对玉米秸秆进行汽爆处理。结果表明：蒸汽爆破处理后玉米秸秆粗蛋白质（Crude protein，CP）、粗脂肪（Crude fat，EE）和单糖（Monosaccharide）等养分相对含量与未汽爆秸秆相比均明显增加；中性洗涤纤维（Neutral detergent fiber，NDF）、酸性洗涤纤维（Acid detergent fiber，ADF）和酸性洗涤木质素（Acid detergent lignin，ADL）相对含量显著下降（P<0.05），康奈尔净碳水化合物-蛋白质体系（Cornell Net Carbohydrate and Protein System，CNCPS）评价结果表明，蒸汽爆破处理能将玉米秸秆中慢速降解成分转化为快速降解成分；聚类分析结果表明，汽爆处理秸秆与原样营养相对含量之间差异显著，汽爆腔压力1.25 MPa，原料水分50%~60%最优；且与CNCPS体系评价基本一致。在汽爆腔压力1.25 MPa和原料水分50%~60%条件下，营养成分相对含量增加最为显著，为汽爆玉米秸秆预处理最佳条件。     

膨化玉米秸秆发酵饲料对肉羊育肥效果的影响

为研究膨化玉米秸秆发酵饲料对肉羊育肥的效果,选取杂交绵羊(南非美利奴羊×东北细毛羊)16只,随机分为2组,每组8只,每只为一个重复。对照组以干玉米秸秆为粗饲料来源,试验组以膨化玉米秸秆发酵饲料为粗饲料来源,两组精料相同,每天每只1 000 g。日粮均以先精后粗的方式饲喂。试验共计90 d。试验结束后每组随机选择3只羊进行屠宰。结果表明:(1)试验组干物质采食量比对照组提高20%(P<0.05),净增重比对照组提高14.16%(P>0.05);(2)试验组羊血液中总蛋白含量显著高于对照组(P<0.05),而尿素氮含量显著低于对照组(P<0.05),其他血液指标两组间未见显著性差异(P>0.05);(3)试验组瘤胃食靡中的滤纸酶活性和果胶酶活性均显著高于对照组(P<0.05),木聚糖酶活性两组间未见显著性差异(P>0.05)。     

应用白腐真菌发酵曲种发酵玉米秸秆的研究

本试验研究了4种配方生产的白腐真菌曲种对奶牛常用粗饲料玉米秸秆的发酵效果,旨在筛选出以玉米秸秆为主料生产白腐真菌曲种的最佳配方,从而为奶牛等反刍动物提供优质的粗饲料。试验菌种培养基分成4个处理组,主料为74%的粉碎玉米秸秆与1%石灰,加入不同配比的玉米粉和麦麸(比例分别为处理Ⅰ20%、5%,处理Ⅱ15%、10%,处理Ⅲ10%、15%和处理Ⅳ5%、20%),用生产好的白腐真菌曲种进行发酵玉米秸秆试验。试验结果表明:处理30d,各处理组曲种均能发酵玉米秸秆,提高粗蛋白(CP)含量,降低中性洗涤纤维(NDF)含量。白腐真菌曲种对发酵玉米秸秆CP含量有极显著影响(P0.01),对NDF含量影响显著(P0.05)。74%的粉碎玉米秸秆和1%的石灰添加5%的玉米粉、20%的麦麸配合生产的白腐真菌曲种对玉米秸秆的发酵效果最好,更适宜作为生产白腐真菌菌种的配方。     

Effect of different fibre sources on performance,carcass characteristics and gastrointestinal tract development of growing Greylag geese

1. The effects of different fibre sources on the growth performance, carcass characteristics and gastrointestinal tract development were studied in growing Greylag geese (Anser anser).

2. Four experimental diets were formulated with corn (maize) straw silage (CSS), steam-exploded corn (maize) straw, steam-exploded wheat straw, and steam-exploded rice straw as fibre sources. A total of 224 male Greylag geese at 28 d of age were randomly assigned to one of the 4 experimental diets.

3. The birds fed on the CSS diets had higher average daily feed intakes than those fed on the steam-exploded straws. However, the 4 treatments had similar average daily gain, which contributed to significant differences in feed conversion ratios. The different fibre sources had no significant effects on the carcass characteristics.

4. The CSS-fed birds had larger gizzards and lower relative length of the caeca than the other three groups. However, the relative weights and lengths of the other gut segments, the relative weights of major organs and the pH values of the gastrointestinal contents were similar between the 4 treatments.

5. It was concluded that straw fibres with different physico-chemical properties exerted an effect on daily feed intake and gastrointestinal development, especially for the gizzard. The pretreatment of straw had a large effect on utilisation efficiency and animal performance. Steam explosion is a promising straw pretreatment for inclusion in diets for geese.

     

不同添加剂发酵处理对汽爆玉米秸秆发酵品质及微生物数量的影响

为研究不同添加剂对汽爆玉米秸秆发酵品质与微生物数量的影响,本研究以干黄玉米秸秆为原料,经蒸汽爆破处理后,添加Sila-Max、Sila-Mix、纤维活性菌(活性菌)进行密封发酵,以不添加任何添加剂为对照(CK),发酵60 d后取样分析不同处理秸秆营养成分、发酵品质以及微生物数量变化.结果表明:1)不同添加剂处理下汽爆玉米秸秆粗蛋白(crude protein,CP)、中性洗涤纤维(neutral detergent fiber,NDF)、酸性洗涤纤维(acid detergent fiber,ADF)和粗灰分(crude ash,Ash)含量无显著差异(P>0.05),但与汽爆前干黄玉米秸秆相比,青贮后的汽爆玉米秸秆CP含量提高了2.01～2.05倍,NDF和ADF含量则分别降低了18.16％～20.17％和2.38％～3.94％,淀粉含量活性菌组最高,与Sila-Max、Sila-Mix组无显著差异(P>0.05).2)发酵过程中,活性菌组、CK组出现霉变情况,霉变量分别达5.07％和7.75％,而其余处理组未出现霉变现象.3)活性菌组乳酸含量显著高于其他处理(P<0.05);Sila-Max组汽爆玉米秸秆的乙酸、丙酸、丁酸含量显著高于其他处理(P<0.05).4)不同添加剂处理下,发酵后汽爆玉米秸秆中微生物数量出现不同变化,乳酸菌数量Sila-Max组显著高于其他处理组(P<0.05);好氧细菌和梭菌数CK组显著高于其他处理(P<0.05),但与Sila-Max组无显著差异(P>0.05);霉菌在Sila-Max、Sila-Mix组均未检测到,在CK组和活性菌组中分别达3.17和3.47 lg cfu·g-1.5)主成分与隶属函数综合分析得出,Sila-Max(0.55)>Sila-Mix(0.42)>活性菌(0.41)>CK(0.20).综上,不同添加剂发酵处理对汽爆玉米秸秆发酵品质及微生物数量有一定影响,活性菌虽能增加乳酸含量,但在抑制有害微生物,防止霉变方面有所欠缺;Sila-Max可以提高乳酸菌、乙酸、丙酸含量,抑制有害微生物活动,防止霉变,并具有抑制二次发酵的潜力;Sila-Mix能够提高汽爆玉米秸秆乳酸菌数量,抑制有害微生物的活动,防止霉变.综合主成分与隶属函数得分,汽爆玉米秸秆青贮时添加Sila-Max综合表现最优,可以推广使用.     

不同添加剂发酵处理对汽爆玉米秸秆发酵品质及微生物数量的影响

为研究不同添加剂对汽爆玉米秸秆发酵品质与微生物数量的影响,本研究以干黄玉米秸秆为原料,经蒸汽爆破处理后,添加Sila-Max、Sila-Mix、纤维活性菌(活性菌)进行密封发酵,以不添加任何添加剂为对照(CK),发酵60 d后取样分析不同处理秸秆营养成分、发酵品质以及微生物数量变化.结果表明:1)不同添加剂处理下汽爆玉...     

Silage fermentation and ruminal degradation of stylo prepared with lactic acid bacteria and cellulase

In order to improve the silage fermentation of stylo (Stylosanthes guianensis ) in tropical areas, stylo silages were prepared with commercial additives Lactobacillus plantarum Chikuso‐1 (CH 1), L. rhamnasus Snow Lact L (SN ), Acremonium cellulase (CE ) and their combination as SN +CE or CH 1 + CE , and the fermentation quality, chemical composition and ruminal degradation of these silages were studied. Stylo silages treated with lactic acid bacteria (LAB ) or cellulase, the pH value and NH ₃‐N ? total‐N were significantly (P  <  0.05) decreased while the ruminal degradability of dry matter (DM ), crude protein (CP ), neutral detergent fiber (aNDF om) and acid detergent fiber (ADF om) were significantly (P  <  0.05) increased compared to control. Compared to LAB or cellulase‐treated silages, the DM , CP contents and relative feed value (RFV ), and the ruminal degradability in LAB plus cellulase‐treated silages were significantly (P  <  0.05) higher, but the aNDF om content was significantly (P  <  0.05) lower. CH 1 + CE treatment was more effective in silage fermentation and ruminal degradation than SN +CE treatment. The results confirmed that LAB or LAB plus cellulase treatment could improve the fermentation quality, chemical composition and ruminal degradation of stylo silage. Moreover, the combined treatment with LAB and cellulase may have beneficial synergistic effects on ruminal degradation.     

外源生物制剂对玉米秸秆和马铃薯渣混贮品质及瘤胃降解率的影响

【目的】 试验旨在研究外源生物制剂对玉米秸秆与马铃薯渣混贮饲料发酵品质、营养价值及72 h瘤胃降解率的影响, 筛选高效饲用生物制剂, 探索实用的玉米秸秆饲料转化技术。【方法】 以粮饲兼用型玉米品种原单32秸秆和克新1号马铃薯渣为试验材料, 以3∶1比例混合青贮。采用完全随机试验设计, 共15个处理, 分别采用酶制剂(CE₁、CE₂、CE₃和CE₄)、菌制剂(LAB)及酶菌复合处理(MCL₁、MCL₂、MCL₃、MCL₄、MCL₅、MCL₆、MCL₇、MCL₈和MCL₉), 并设置不添加任何酶菌制剂的对照组(CK)。青贮发酵60 d之后, 对混贮饲料青贮质量指标及瘤胃降解率进行测定。【结果】 混贮饲料各处理及对照感官评定均达到了优级; 酶处理组和酶菌处理组混贮饲料乳酸、乙酸含量均显著高于菌处理组及对照(P<0.05), 其中MCL₂和MCL₄处理组乳酸含量最高, 分别为2.82%和2.77%;与对照相比, 各处理组混贮饲料纤维素、中性洗涤纤维(NDF)及酸性洗涤纤维(ADF)含量均显著降低(P < 0.05), 其中MCL₂处理最低, 分别为22.86%、53.43%、33.99%;1 g/3 kg纤维素酶添加处理组(CE₁、MCL₂、MCL₆、MCL₇)纤维素72 h瘤胃降解率均显著高于其他处理组(P<0.05)。【结论】 酶、菌及菌酶协同作用不同程度促进玉米秸秆与马铃薯渣混贮饲料发酵, 改善混贮饲料营养价值, 提高反刍动物瘤胃对营养物质的降解效率, 综合玉米秸秆发酵品质、营养成分及养分瘤胃降解率: 酶菌复合处理>酶处理>菌处理, 其中MCL₂处理组(木聚糖酶1 g/3 kg、果胶酶1 g/3 kg、β-葡聚糖酶1 g/3 kg、乳杆菌3 g/3 kg、纤维素酶1 g/3 kg)效果最佳; 纤维素酶降低玉米秸秆混贮饲料纤维素、ADF、NDF含量, 最适纤维素酶添加量为1 g/3 kg。     

Adding sweet potato vines improve the quality of rice straw silage

Rice straw and sweet potato vines are the main by‐products of agricultural crops, and their disposal creates problems for the environment in the south of China. In order to establish an easy method for making rice straw silage successfully, experiments were conduct to evaluate fermentation quality and nutritive value of rice straw silages ensiled with or without sweet potato vine. Paddy rice straw (PR) and upland rice straw (UP) were ensiled alone or with sweet potato vines (SP) by a ratio of 1:1 (fresh matter basis), over 3 years. Compared with rice straw silages ensiled alone, the mixed‐material silages (PR + SP, UR + SP) showed higher fermentation quality with lower propionic acid content and NH₃‐N ratio of total N, and higher (P < 0.05) concentrations of lactic acid and acetic acid, resulting in decrease (P < 0.05) of dry matter loss and higher (P < 0.05) in vitro ruminal dry matter digestion. When the fermentation quality, chemical composition and in vitro rumen fermentation characteristics were considered, ensiling would be an effective way of utilization of rice straw and sweet potato vines in the regions where rice and sweet potato are harvested at same season, and the sweet potato vines have the potential to improve rice straw fermentation quality with low water soluble carbohydrate content in south of China.     

Nutrient digestibility and ruminal fermentation characteristic in swamp buffaloes fed on chemically treated rice straw and urea

The experiment was conducted to determine effects of urea–lime-treated rice straw and urea levels in concentrate on rumen fermentation, apparent nutrient digestibility, and cellulolytic bacteria population of 4-year-old, rumen-fistulated swamp buffaloes. All animals were randomly assigned according to a 2 × 2 factorial arrangement in a 4 × 4 Latin square design to receive four dietary treatments: factor A, two sources of roughage (rice straw and 2%urea + 2%lime-treated rice straw); factor B, two levels of urea in concentrate mixture (0% and 4%). Roughages were given ad libitum together with 0.3% BW of concentrate. It was found that voluntary feed intake, the digestibility of DM, OM, CP, NDF, acetate, and propionate concentration were significantly increased (P < 0.05) by treated rice straw, while NH₃-N, BUN, and propionic acid concentration were increased by both factors of treated rice straw and 4% urea in concentrate. The real-time PCR quantification of Fibrobacter succinogenes and Ruminococcus albus population, and anaerobic fungi were greater (P < 0.05), but the population of Ruminococcus flavefaciens, protozoa, and methanogenic bacteria were reduced (P > 0.05) as influenced by treated rice straw and urea level. In conclusion, the combined use of urea–lime-treated rice straw and fed with concentrate (4% urea) could improve rumen ecology, rumen fermentation efficiency, and nutrient digestibility in swamp buffaloes.     

Effects of adding urea on fermentation quality of pruned persimmon branch silage and its digestibility,preference, nitrogen balance and rumen fermentation in beef cattle

Four cattle were used in a 4 × 4 Latin square design experiment to study digestibility, ruminal fermentation, nitrogen retention and preference of ensiling pruned persimmon branch (PPB) chips treated with urea. After 60 days of ensiling, urea‐treated PPB showed higher (P < 0.05) pH, acetic acid and ammonia‐N levels than no‐urea PPB. Both urea‐treated PPB and rice straw diets showed higher (P < 0.05) apparent digestibility and digestible nutrient content in cattle than no‐urea PPB diet. Neither mold nor yeast was detected in any urea‐treated PPB. Urinary and fecal excretion as well as nitrogen retention in cattle fed urea‐treated PPB were higher (P < 0.05) than in those fed no‐urea PPB and rice straw. With the exception that ruminal ammonia‐N levels in cattle fed urea‐treated PPB were higher (P < 0.05) than in those given no‐urea PPB and rice straw, ruminal pH, volatile fatty acid concentrations, and the acetic : propionic acid ratio of rumen content were unaffected by diets. The rank order of preference was rice straw > low‐urea > no‐urea > high‐urea. The results suggested that urea treatment of PPB inhibited growth of mold and yeast during silage storage, enhanced its digestibility and had nutritive value almost equivalent to that of rice straw.     

Pre‐soaking of the feed pellets: a trick for successful feed utilization in juvenile green turtles (Chelonia mydas Linnaeus, 1758)

Pre‐soaking of the feed pellets in water can improve feed utilization in juvenile green turtles (Chelonia mydas Linnaeus, 1758), but the pre‐soaking has not previously been optimized. This study aimed to optimize the water amount used for pre‐soaking the pellets. The experiments followed a completely randomized design with three replications of each dietary treatment group. Initially 10‐day‐old green turtles (20–22 g body weight) were treated in an indoor aquaculture system for 3 months. The dietary treatment pellets were pre‐soaked with 0.3, 0.5 or 0.7 (v/w) relative amounts of water that are here termed soaking ratios. At the end of experiment, there were no significant differences in survival (96% on average) and growth (average body weight 75.34 g and specific growth rate 2%/day, on average) of turtles in three dietary treatments (p > 0.05). Feed utilization was the best in turtles fed with 0.7 pre‐soaked ratio, as indicated by significant reductions (p < 0.05) in the feeding rate (7.44% body weight/day) and the feed conversion ratio (1.12 g feed/g gain). Digestion was also improved by the induction of faecal digestive enzymes as well as the faecal thermal properties. The rapid growth did not negatively affect the general haematological parameters of reared turtles. These findings indicate that the pre‐soaking of feed pellets at the optimal soaking ratio (1:0.7 w/v of pellet to water) can contribute through improved feed utilization of green turtles.     

水葫芦与甜玉米秸秆混合半干青贮的研究

本试验设3种比例的混合青贮，即水葫芦（Eichhornia crassipes）∶甜玉米（Zea mays）秸秆按鲜质量比为9∶1、8∶2和7∶3（W9M1、W8M2和W7M3）混合，并在每种混合比例中设无添加（CK）、添加2 mL/kg绿汁发酵液（FGJ）、添加3 mL/kg蚁酸（FA）和添加3 mL/kg四蚁酸铵（FOR）4个处理，探讨混合比例和添加剂对水葫芦与甜玉米秸秆混合半干青贮发酵品质的影响。每个处理3次重复，常温下贮存60 d，开封后评定其青贮品质。结果表明，3种添加剂均能显著（P<0.05）提高不同混合比例材料的青贮品质，另外W9M1的干物质回收率显著（P<0.05）高于W8M2和W7M3，CK和FGJ处理中，W7M3的可溶性碳水化合物极显著（P<0.01）高于W8M2和W9M1。3种混合比例中，W9M1的青贮效果最佳；3种添加剂对改善水葫芦与甜玉米秸秆混合青贮品质均有极显著效果，蚁酸的添加对营养物质的保留效果显著。     

绵羊全混日粮体外培养VFA的动态变化

为了探讨肉羊全混日粮配方最优配比,试验参照肉羊育肥饲料营养标准,以苜蓿、番茄皮渣等粗饲料及肉羊精料补充料为原料,按照不同配比组合设计八种全混日粮配方,利用体外发酵研究方法,对八种全混日粮羊瘤胃内总挥发性脂肪酸(TVFA)、乙酸、丙酸、丁酸的浓度及日粮组合效应进行了研究。结果表明:日粮中添加番茄皮渣可显著提高乙酸、丙酸、丁酸和TVFA的浓度,且乙酸/丙酸趋于平缓,有利于肉羊对营养的吸收;添加番茄皮渣的组合B2、D1的VFA浓度最大,未添加番茄皮渣的组合A1、C1的VFA浓度最大,为最佳配比。研究表明:小麦秸、玉米秸都不利于肉羊营养的吸收,相较于小麦秸,玉米秸易被肉羊消化吸收;番茄皮渣可提高肉羊对日粮的吸收利用率,利于肉羊育肥。     

Effects of treating rice straw with urea or urea and calcium hydroxide upon intake, digestibility, rumen fermentation and milk yield of dairy cows

Three, multiparous Holstein crossbred dairy cows with initial body weight of 385 ± 19 kg were randomly allocated to 3 treatments of rice straw (T1 = untreated rice straw; T2 = 5.5% urea-treated rice straw (5 g urea in 100 ml water to 100 g air-dry (91% DM) straw); T3 = 2.2% urea + 2.2% calcium hydroxide treated rice straw (2.0 g urea and 2.0 g Ca(OH)₂ in 100 ml to 100 g air-dry (91% DM) straw) according to a 3 × 3 Latin square design. Each period lasted for 21 days in which feed, feces and rumen fluid were collected during the last 7 days for chemical analyses. The findings revealed significant improvements in dry matter intake and digestibility by using 5.5% urea-treated rice straw and 2.2% urea + 2.2% calcium hydroxide treated rice straw. Ruminal pH and NH₃-N were found higher (P < 0.05) as compared with urea-treated rice straw fed group, while blood urea nitrogen and milk urea nitrogen were in normal ranges. Volatile fatty acid concentrations especially those of acetic acid were decreased (P < 0.05) and those of propionic acid were increased (P < 0.05), thus acetic acid:propionic acid was subsequently lowered (P < 0.05) in cows fed with 5.5% urea-treated rice straw and 2.2% urea + 2.2% calcium hydroxide treated rice straw, respectively. Moreover, ruminal viable and cellulolytic bacterial counts were enhanced by urea and calcium hydroxide treatments. Milk protein and fat concentrations were additionally increased by respective treatments while 3.5% fat-corrected milk was highest; ranking from 2.2% urea + 2.2% calcium hydroxide treated rice straw, 5.5% urea-treated rice straw and urea-treated rice straw fed groups. Based on this study, implications could be made that using 2.2% urea + 2.2% calcium hydroxide treated rice straw for straw treatment could be an alternative treatment to 5.5% urea treatment with regards to its effectiveness and treatment cost for lactating dairy cows.