苜蓿+玉米间作系统产量表现及其种间竞争力的评定

本试验目的在于探讨不同苜蓿+玉米间作模式下种间竞争力变化,及其对间作系统产量建成的影响。试验设苜蓿、玉米行数比分别为2∶2,3∶2,4∶2,5∶2四个间作处理,每处理3个重复,其所占间作面积比分别为33％∶67％,43％∶57％,50%∶50%,55%∶45%,玉米、苜蓿单作为对照组。测定各处理干物质产量,采用土地当量比(LER)、侵占力(Aam)、相对拥挤系数(RCC)等指标来评定不同间作处理系统内的作物竞争力。结果表明,在苜蓿+玉米间作系统第1年生产中,苜蓿竞争力大于玉米,所有间作处理总产量和经济产出均低于单作玉米,高于单作苜蓿,各间作处理相比以5∶2间作模式生产性能最佳。在第2年生产中,苜蓿进入高产期,始终占据间作系统的优势生态位,所有间作处理生物总产量都不低于单作玉米和单作苜蓿,经济产出均大于单作苜蓿和单作玉米,5∶2间作模式表现出最佳的生产优势。     

瘤胃微生物体外降解玉米秸秆与苜蓿干草混合粉的研究

试验利用瘤胃微生物体外降解不同比例组合(8∶2、7∶3、6∶4、5∶5、4∶6、3∶7、2∶8)的玉米秸秆与苜蓿干草混合粉,通过测定不同发酵时间段气体产量与干物质降解率,初步探索瘤胃微生物对玉米秸秆与苜蓿干草混合粉的降解规律。结果表明:玉米秸秆粉和苜蓿干草粉配比为3∶7的组合有利于瘤胃微生物生长繁殖,其次是4∶6组合。     

带幅设计对玉米/苜蓿间作群体光环境特征及光能利用效率的影响北大核心CSCD

探究间作带幅设计对玉米/苜蓿间作群体光环境特征、产量及光能利用效率(LUE)的影响,提出黄土高原旱作条件下玉米/苜蓿间作群体最佳带幅比例。研究设置了玉米单作(SM)、紫花苜蓿单作(SA)以及玉米/紫花苜蓿1∶2(I_(12))、2∶2(I_(22))和2∶4(I_(24))间作5种种植模式,并采用田间试验和数学模拟相结合的方法,分别测定了玉米和苜蓿的干物质产量及作物冠层光合有效辐射(PAR)等指标;建立了考虑光线入射角度和群体冠层结构几何关系的玉米/苜蓿间作群体辐射传输模型,并用实测值对其进行了验证。试验结果表明,在2018年,单作处理的苜蓿干物质产量显著高于间作处理(P<0.05),而在2019年各间作处理苜蓿的干物质分别比单作高197.8、180.3和197.0 g·m^(-2);处理I_(12)、I_(22)和I_(24)两年总的玉米生物量比SM处理高12.1%、0.9%和23.9%。所有间作处理的土地当量比在2019年均大于1.0,表现出间作优势。辐射传输模型可准确模拟玉米/苜蓿间作群体冠层底部的光合有效辐射,间作群体光合有效辐射模拟值与实测值的平均绝对误差和均方根误差分别为59.0和66.6μmol·m^(-2)·s^(-1)。除玉米和苜蓿生育前期及玉米收获后,不同间作处理苜蓿群体冠层上方的PAR均低于单作苜蓿。2018和2019年I_(12)、I_(22)和I_(24)间作处理玉米的光能利用效率分别比单作处理高52.5%、9.3%、51.7%和28.5%、9.6%、21.0%,而间作苜蓿的LUE仅在2019年显著高于单作19.2%、32.4%和20.9%(P<0.05)。因此,合理的玉米/苜蓿间作带幅搭配可改善苜蓿的光照环境,提高其光能利用效率,尤其是玉米/紫花苜蓿2∶4间作群体光能利用效率和产量优势显著,建议在具有类似气候的地区推广种植。     

不同处理玉米秸秆与精粗比饲粮对滩湖F_2代育成公羊瘤胃干物质降解率的影响

为研究不同处理玉米秸秆与精粗比饲粮对滩湖F_2代育成公羊瘤胃干物质降解率的影响,试验采用瘤胃尼龙袋法,选用4只体质量相近、体况健康且装有永久瘤胃瘘管的滩湖F_2代育成公羊,分别测定不同复合氨化处理玉米秸秆和全株玉米青贮饲料及不同精粗比全混合饲粮尼龙袋样品,在其瘤胃培养4、8、16、24、48和72 h时的干物质降解率。结果表明:以复合氨化玉米秸秆为基础即粗饲料60%(氨化玉秸50%+苜蓿干草10%)+精补料40%全混合饲粮和以全株玉米青贮饲料为基础即粗饲料70%(全株玉米青贮30%+苜蓿干草20%+玉米秸秆20%)+精补料30%全混合饲粮在瘤胃内的干物质降解率较高,可以作为宁夏引黄灌区肉羊生产全混合饲粮的推荐配方。     

体外产气法与尼龙袋法评定粗饲料干物质降解率的相关性分析

为寻求可在实验室条件下简单地评定饲料降解性能的方法,试验以玉米秸秆及不同尿素、石灰比例复合处理的玉米秸秆为发酵底物,对饲料体外产气量和尼龙袋瘤胃干物质降解率作了相关性分析。统计分析表明,体外产气量与体内干物质降解率呈高度正相关,相关系数分别为:对照组0.967、料A0.964、料B0.999和料C0.994。结果证明,在对饲料降解性能及潜在可降解能力作快速、定性判断时,体外产气法可以代替尼龙袋法。     

奶牛常用饲料瘤胃干物质和淀粉降解规律的研究

以3头安装有永久性瘤胃瘘管的泌乳前期荷斯坦奶牛为试验动物,在精粗比为55∶45的日粮条件下,采用In sacco法测定了奶牛常用饲料瘤胃内干物质和淀粉的降解规律。试验结果表明,不同饲料的干物质和淀粉在奶牛瘤胃中的降解率不同。能量饲料中,麸皮的干物质和淀粉的瘤胃降解率均高于玉米;蛋白质饲料中,干物质和淀粉的降解率顺序是豆粕>胡麻饼>棉粕;常用粗料中,玉米青贮的干物质和淀粉的降解率均高于青干草。     

玉米－紫花苜蓿间作模式与效应研究

以玉米和紫花苜蓿间作系统为研究对象,研究了不同间作模式和不同减氮水平下的光照强度、透光率、土壤养分含量、玉米产量、苜蓿产量和单位面积纯收益变化规律。结果表明,随着玉米大行距的加大,玉米行间和苜蓿带与玉米带间隔中部、底部的光照强度和透光率均表现增大趋势,除T4处理外,其他处理的玉米行间中部、底部的光照强度和透光率均高于对照CK。间作处理的有机质、有机氮、速效氮较对照均成增加趋势,而且这种趋势随着间作时间的延长越发明显,土壤有机质、有机氮、速效氮含量随玉米大行距的加大均成增加趋势。在保持单位面积株数相同的情况下,3个试验年份玉米籽粒产量均以T2处理最高,除T4处理玉米籽粒产量低于对照外,其他处理产量均高于对照,苜蓿产量随玉米大行距的加大均成增加趋势;3个试验年份单位面积纯收益均以T3处理最高,所有间作处理单位面积纯收益均高于对照。减氮均不同程度地造成了玉米减产,但随着间作时间的延长减氮所造成的减产幅度逐渐降低,到试验第3年,R1和R2处理的玉米产量与CK相比没有显著性差异(P>0.05);试验第3年R1和R2处理的单位面积纯收益均高于CK,但差异不显著(P>0.05)。     

苜蓿草粉干物质、有机物及粗蛋白质在农户育肥模式下哈萨克羊瘤胃有效降解率评定

为了使优质苜蓿草粉饲料能够在新疆育肥羊饲养上得到科学利用,试验采用瘤胃尼龙袋法对农户养殖模式下苜蓿草粉干物质、有机物、粗蛋白质在育肥羊瘤胃内的降解动力学参数进行了评定,计算有效降解率、瘤胃停留时间及瘤胃能氮平衡。结果表明:在瘤胃固相食糜的平均外流速度为1.84%/h的条件下,干物质、有机物及粗蛋白质的有效降解率分别为63.08%、60.75%、86.95%。苜蓿在瘤胃内停留时间为20 h,瘤胃能氮平衡为负平衡。     

大豆秸秆作为粗饲料的营养价值评定

试验旨在测定大豆秸秆作为饲料的营养价值,以及氨化和微生物处理对豆秸营养价值的影响。试验采用化学分析和动物试验方法,测定豆秸与氨化、微生物处理豆秸的养分含量、动物采食量、干物质瘤胃降解率和日粮养分消化率。结果表明:豆秸饲料质地坚硬,酸性洗涤木质素(ADL)含量比玉米秸秆高66.74%,绵羊对豆秸的采食量比玉米秸秆低20.06%(P0.05),豆秸干物质(DM)绵羊瘤胃有效降解率比玉米秸秆低43.26%(P0.05)。豆秸经过微生物处理后,仅采食量得到一定程度提高(P0.05)。豆秸经过氨化后,中性洗涤纤维(NDF)和ADL含量分别降低6.75%和21.48%,采食量和干物质瘤胃有效降解率分别提高22.7%和32.09%(P0.05),但仍显著低于玉米秸秆(P0.05)。豆秸直接作为饲料,营养价值较低,经过氨化处理后其营养价值得到一定程度提高。     

玉米不同处理方式对泌乳奶牛瘤胃降解规律的影响

为了研究不同加工处理方法对玉米在奶牛瘤胃内降解率的影响,本试验选用5头荷斯坦泌乳牛利用尼龙袋法测定玉米渣、膨化玉米、玉米片和蒸汽压片玉米的干物质和淀粉在泌乳奶牛瘤胃中的降解率．．结果表明,48h的瘤胃降解率规律为：玉米片〉膨化玉米〉蒸汽压片玉米〉玉米渣。瘤胃内可降解干物质为：膨化玉米和玉米片〉蒸汽压片玉米和玉米渣;而可降解淀粉则为：膨化玉米〉玉米片〉蒸汽压片玉米〉玉米渣,以上结果表明,加工过程中温度湿度和压力的作用下,玉米籽实的结构发生变化,改变了瘤胃微生物接触淀粉的机会,从而影响玉米在瘤胃内的降解率。     

Amino acid profiles of rumen undegradable protein: a comparison between forages including cereal straws and alfalfa and their respective total mixed rations

Optimizing the amino acid (AA) profile of rumen undegradable protein (RUP) can positively affect the amount of milk protein. This study was conducted to improve knowledge regarding the AA profile of rumen undegradable protein from corn stover, rice straw and alfalfa hay as well as the total mixed ratio diets (TMR) based on one of them as forage source [forage‐to‐concentrate ratio of 45:55 (30% of corn stover (CS), 30% of rice straw (RS), 23% of alfalfa hay (AH) and dry matter basis)]. The other ingredients in the three TMR diets were similar. The RUP of all the forages and diets was estimated by incubation for 16 hr in the rumen of three ruminally cannulated lactating cows. All residues were corrected for microbial colonization, which was necessary in determining the AA composition of RUP from feed samples using in situ method. Compared with their original AA composition, the AA pattern of forages and forage‐based diets changed drastically after rumen exposure. In addition, the extent of ruminal degradation of analysed AA was not constant among the forages. The greatest individual AA degradability of alfalfa hay and corn stover was Pro, but was His of rice straw. A remarkable difference was observed between microbial attachment corrected and uncorrected AA profiles of RUP, except for alfalfa hay and His in the three forages and TMR diets. The ruminal AA degradability of cereal straws was altered compared with alfalfa hay but not for the TMR diets. In summary, the AA composition of forages and TMR‐based diets changed significantly after ruminal exposure, indicating that the original AA profiles of the feed cannot represent its AA composition of RUP. The AA profile of RUP and ruminal AA degradability for corn stover and rice straw contributed to missing information in the field.     

苎麻营养成分分析及瘤胃降解特性研究

为系统的研究苎麻的营养价值及其在山羊瘤胃中的降解特性,利用化学分析等方法检测了7个茬次苎麻的粗蛋白(CP)、氨基酸(AA)组成、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)等营养成分、单宁等抗营养成分的含量,并采用3只装有永久瘤胃瘘管的波尔山羊为试验动物,对苎麻的部分营养成分的降解率和降解参数进行测定。结果表明,7个茬次苎麻的CP含量均较高且品质较好,CP平均值达到了19.57%,而且呈现出随着茬次的增加,CP含量有所下降的趋势,但是第7茬和第6茬相比CP含量略有升高。AA总和平均值达到了16.40%,占CP平均值含量的83.80%,赖氨酸(Lys)的平均含量达到了0.84%,苏氨酸(Thr)的平均含量达到了0.82%。抗营养因子方面,单宁可能是苎麻最主要的抗营养因子,平均值达到了0.67%。苎麻的干物质(DM)、CP、有机物(OM)、NDF和ADF的降解率均随着瘤胃消化时间的延长而不断提高,有效降解率分别达到了47.00%,35.53%,44.29%,57.68%和38.59%。由此得出,苎麻的营养价值较高,主要体现在CP含量高且品质较好,主要营养成分的瘤胃降解率均较高,可以作为反刍动物优良的粗饲料资源加以开发利用。     

Evaluation of alfalfa-corn cob associative action. III. The effect of mechanically separated alfalfa fractions on intake, digestibility and ruminal characteristics of ammonia-treated corn cob diets fed to sheep

The influence of mechanically separated alfalfa fractions on intake, digestibility and rate of ruminal passage was investigated using 48 lambs (32 kg) in a digestion trial. Whole plant pre-bloom alfalfa (25% crude protein) or fractions (presscake, dehydrated presscake, protein coagulum, dehydrated protein coagulum, whole juice or deproteinized juice) were added to a 3% ammonia (NH3)-treated corn cob negative control diet at levels equal to 20% wholeplant alfalfa dry matter (DM); eight treatments, six lambs/treatment. Ad libitum intake was greater (P less than .05) for alfalfa fiber (presscake) or juice supplemented diets compared with 20% direct cut alfalfa. Dry matter intake, digestibility of DM and cell walls, and rate of passage were highly correlated when diets were fed ad libitum. At equal DM intakes, dehydrated vs wet presscake increased (P less than .05) DM and cell wall digestibility. Heating of the protein may have reduced degradation rate and consequently a slower release of nutrients for microorganisms in the rumen. Whole vs deproteinized juice increased digestibility of cob DM (P = .11) and cell walls (P = .13), suggesting a response to level of degradable alpha-amino N. Whole and deproteinized juice increased cell wall digestibility compared with the negative control by 23.0 and 18.5 percentage units, respectively, suggesting that degradable alpha amino-N and cell solubles or other nutrients interacted to maximize microbial fiber digestion. Total and branch-chain volatile fatty acids measured at 6, 12 and 18 h post-feeding were highly correlated with nutrient digestibility. Ruminal NH3-N measured at 18 h was negatively correlated with dry matter (r = -.74) and cell wall (r = -.72) digestibility, showing that alfalfa supplies nutrients required by ruminal microorganisms for NH3 assimilation and fiber digestion. The mode of alfalfa associative action in high fiber diets is in supplying ruminal microorganisms with degradable protein and (or) other nutrients, rather than altering ruminal retention time.     

Influence of rumen protein degradability and supplementation frequency on steers consuming low-quality forage: I. Site of digestion and microbial efficiency

Seven cannulated (rumen and duodenal) Angus x Hereford steers (264 +/- 8 kg BW) consuming low-quality forage (5% CP; 61% NDF; 31% ADF) were used to determine the influence of CP degradability and supplementation frequency (SF) on DMI and nutrient digestion. Treatments included an unsupplemented control and degradable intake protein (DIP) or undegradable intake protein (UIP) provided daily, every 3 d, or every 6 d. The DIP treatments (18% UIP) were calculated to provide 100% of the DIP requirement, while the UIP treatments (60% UIP) were provided on an isonitrogenous basis compared with DIP. Forage DMI was not affected by treatment. Total DM and N intake, duodenal N flow, and intestinal N disappearance increased (P < 0.01) with supplementation. Dry matter intake and duodenal N flow responded quadratically (P < 0.04; greatest values on the every-third-day treatments) as SF decreased. However, no differences in N intake or intestinal N disappearance were observed because of CP degradability or SF. Duodenal bacterial N flow and true bacterial N synthesis (g bacterial N/kg of OM truly digested in the rumen) were increased (P < 0.05) with supplementation. Also, duodenal bacterial N flow was greater (P < 0.05) for DIP compared with UIP. Duodenal nonbacterial N flow was increased (P = 0.02) with CP supplementation and for UIP compared with DIP (P < 0.01). Supplemental CP increased (P < 0.01) total tract DM and N digestibility with no difference due to CP degradability or SF. Results suggest CP supplements consisting of 20 to 60% UIP can be effectively used by steers consuming low-quality forage without adversely affecting DMI, nutrient digestibility, or bacterial CP synthesis, even when provided as infrequently as once every 6 d.     

羊常用粗饲料干物质和粗蛋白的瘤胃降解特性研究

试验通过尼龙袋法研究了羊草、苜蓿干草、玉米秸秆、尿素-秸秆和NaOH-秸秆5种粗饲料在绵羊瘤胃内干物质和粗蛋白的降解特性。结果表明:5种粗饲料的有效降解率均在20%以上,其中以苜蓿干草最高。粗饲料干物质的有效降解率与干物质的快速降解部分呈显著强的正相关,与慢速降解部分和不可降解部分都呈弱的负相关,与慢速降解部分的降解速率呈较强的正相关。粗饲料粗蛋白的有效降解率与快速降解部分呈极显著强的正相关,与不可降解部分呈强的负相关。5种粗饲料的干物质和粗蛋白的瘤胃降解率均表现出较强的正相关,其中苜蓿干草的相关系数高达0.9435(P0.0001)。5种粗饲料的干物质和粗蛋白的瘤胃降解率相关性,由高到低依次为苜蓿干草羊草NaOH-秸秆尿素-秸秆玉米秸秆(P0.005)。     

苜蓿鲜草和青饲玉米对奶牛生产性能和乳品质的影响

探讨日粮中添加苜蓿鲜草和青饲玉米对奶牛生产性能及其乳成分的影响,本试验选用荷斯坦泌乳奶牛20头,随机分为2组,对照组饲喂秸秆和精料补充料;试验组饲喂苜蓿鲜草、青饲玉米和精料补充料日粮。试验结果表明,日粮中添加苜蓿鲜草和青饲玉米,可极显著提高奶牛的生产性能和乳脂率(P<0.01),显著提高干物质采食量和乳蛋白含量(P<0.05)。     

复合乳酸菌对番茄皮渣与苜蓿混合青贮发酵品质及瘤胃降解率的影响

本研究旨在探究接种复合乳酸菌对番茄皮渣与苜蓿混合青贮品质的影响,通过分析营养品质、发酵品质及瘤胃降解率,明确最优发酵条件,为提高资源利用率,拓宽本地区饲草料资源提供理论基础。试验采用真空袋法调制混合青贮,设计10个处理,其中5个处理不接种复合乳酸菌,混合比例（质量比）为：番茄皮渣∶苜蓿=3∶7（T₁）,4∶6（T₂）,5∶5（T₃）,6∶4（T₄）,7∶3（T₅）;另外5个处理在各混合青贮比例基础上均匀加入复合乳酸菌（布氏乳杆菌+植物乳杆菌,比例为1∶1,1×10⁶ CFU·g^-1）,即分别为JT₁、JT₂、JT₃、JT₄、JT₅。发酵60 d后开袋进行感官评定,分析营养品质、发酵品质、瘤胃降解率,采用隶属函数分析法评价最优处理。结果表明：接种复合乳酸菌可改善番茄皮渣与苜蓿混合青贮的气味及质地,T₁、JT₁、T₂及JT₂处理的混合青贮感官评定为优等。接种复合乳酸菌显著提升了番茄皮渣与苜蓿混合青贮的干物质（DM）、粗蛋白（CP）、乳酸（LA）、乙酸（AA）（P<0.05）,显著降低了水溶性碳水化合物（WSC）、中性洗涤纤维（NDF）、酸性洗涤纤维（ADF）、pH、丙酸（PA）、丁酸（BA）、氨态氮/总氮（NH₃-N/TN）（P<0.05）。各混合青贮中,JT₂处理的DM、CP含量最高,T₂处理的WSC含量最高,JT₂处理的NDF、ADF含量最低,JT₁、JT₂处理的pH较低,JT₁、JT₂处理的LA含量较高,T₁、T₂处理的AA含量较低,JT₁、JT₂的PA、BA含量及NH₃-N/TN较低。瘤胃降解24 h时,接种复合乳酸菌显著提升了番茄皮渣与苜蓿混合青贮的干物质降解率（DMD）、中性洗涤纤维降解率（NDFD）、酸性洗涤纤维降解率（ADFD）（P<0.05）,JT₁和JT₂处理的DMD、NDFD较高,JT₂处理的ADFD最高。综上,接种复合乳酸菌对番茄皮渣与苜蓿混合青贮营养品质、发酵品质及瘤胃降解率均有显著改善;将各混合青贮的14项核心指标进行隶属函数分析得出,JT₂处理最优,即在番茄皮渣添加量为40%（番茄皮渣∶苜蓿=4∶6,干物质含量为30.64%）的混合青贮中接种复合乳酸菌最具推广意义。     

Effect of N fertilisation rate, energy supplementation and supplementation strategy on efficiency of N utilisation in the sheep rumen.

The effect of nitrogen (N) fertilisation (200 vs. 400 kg N ha-1 year-1) of pasture cut in the beginning (end of May) and the end (end of August) of the grazing season and of simultaneous or separated feeding of maize and grass (400 kg N ha-1 year-1) on efficiency of N utilisation in the rumen has been studied using four rumen cannulated wethers. Doubling N fertiliser rate increased grass CP production by about 60%, but induced extensive excess of rumen degradable N, reflected in high urinary urea excretion (rpearson = 0.747). The latter was lower (74% at the maximum) when feeding less fertilised or older grass or when supplementing with maize silage. Although simultaneous feeding of maize silage with grass changed patterns of rumen ammonia concentrations, no change in urinary excretion of purine derivatives was observed. Hence, faecal or urinary N excretion was unaffected by the supplementation strategy. Microbial growth efficiency was estimated from urinary excretion of purine derivatives and fermented OM. The latter was calculated from total rumen CH4 production, based on rumen fermentation stoichiometry and taking into account proportional concentrations of individual volatile fatty acids. Higher levels of intake tended to improve rumen microbial growth efficiency slightly (rpearson = 0.406), which, however, could not compensate for the reduced effective rumen DM degradability (rpearson = -0.442). The latter was apparently associated with a partial shift of the fermentation from the rumen to the hindgut, as suggested from the negative correlation (rpearson = -0.745) between faecal RNA concentrations and rumen effective degradability.