Comparison of feed intake,body weight gain,enteric methane emission and relative abundance of rumen microbes in steers fed sainfoin and lucerne silages under western Canadian conditions

Beef cattle are major contributors of enteric methane (CH₄) emissions in Canada. Feeding forages containing condensed tannins (CT) has been suggested as a means of reducing enteric CH₄ emissions and improving production efficiency. Sainfoin (Onobrychis viciifolia) is one of the CT‐containing legumes, which has also been recognized to have several additional beneficial properties. This study compared sainfoin silage (SS) and lucerne (Medicago sativa) silage (LS) with respect to animal performance, enteric CH₄ production, abundance of selected rumen microbes and selected serum parameters in yearling steers during a Canadian winter. Sainfoin silage in our study contained approximately 12 g CT kg^?1 dry matter (DM), a level which did not adversely affect silage palatability as steers fed SS experienced higher DM intake. However, animals fed LS and SS had similar body weight gain over the course of the trial. Feeding SS resulted in lower blood urea nitrogen concentrations and relative abundance of methanogenic archaea in rumen fluid. Yet, microbial population shifts fell short of exerting significant influence on enteric CH₄ emissions. This study suggests that under western Canadian growing and animal‐rearing conditions, sainfoin is not yet competitive with lucerne forage with respect to enteric CH₄ emissions or animal productivity warranting further research and development.     

Optimal harvest timing vs. harvesting for animal forage supply: Impacts on production and quality of lucerne on the Loess Plateau,China

The current promotion of larger areas of lucerne (Medicago sativa) production on the Loess Plateau in China prompted this study, which investigated lucerne harvesting practices by farmers and the scope for improved harvest yield and quality by optimizing harvest date, interval and height above ground. On-farm surveys were conducted to document the dominant harvesting practices used by farmers and their perceptions of barriers to adoption of alternative harvesting practices. In districts with less emphasis on livestock, less labour and inadequate facilities to store conserved lucerne, smaller areas of lucerne are grown and it is often harvested daily to meet demand from penned livestock. The consequence is that much of the lucerne is harvested either before or after flowering, resulting in suboptimal yield of biomass and crude protein. Field experiments conducted at low and high rainfall locations on the Loess Plateau over three seasons showed that delaying the start to harvest until after mid-June (the date of first flowering), while not affecting total biomass harvested for the season, does reduce leaf biomass harvested and hence crude protein concentration and yield. Lower crude protein is a consequence of a decline in both leaf percentage in harvested biomass and stem nitrogen concentration. Commencing harvests well before flowering with short (3 week) harvest intervals also penalized total and leaf biomass harvested. Raising cutting height from ground level (current farmer practice) to 50 mm (likely with the advent of mechanized harvesting) did not penalize harvested total or leaf biomass.     

杀菌剂拌种对紫花苜蓿,苏丹草不同活力种批出苗的影响

在４０％土壤饱和持水量和最适萌发温度下，研究了甲基托布津、甲霜灵、杀毒矾和福美双等杀菌剂拌种对紫花苜蓿和苏丹草出苗的影响；进而探讨了不同活力的供试种种批对杀毒矾拌种的反应。４种参试杀菌剂以杀毒矾效果最好，与对照比，其可使紫花苜蓿和苏丹草的存苗率分别提高１４１．９％和３７．７％（Ｐ＜０．０５），使紫花苜蓿死苗率降低８０．８％（Ｐ＜０．０５）。其他３种杀菌剂亦可显著（Ｐ＜０．０５）提高紫花苜蓿种子的存苗率和降低死苗率，提高存苗率的效果依次为甲霜灵（１０９．７％）、甲基托布津（８３．９％）和福美双（４８．４％），但对苏丹草种子作用不显著。杀毒矾处理对中活力和高活力紫花苜蓿种子较低活力种子更为明显、有效，与对照比，中活力和高活力种批的存苗率分别提高了１１１．５％和１００．０％，而低活力种批仅提高了３１．０％。但杀毒矾对苏丹草不同活力种批的作用效果不显著。     

磷、锌、硼、钴对苜蓿肥效与施用技术研究

经二年在庆阳黄土高原试验进行磷、锌、硼、钴作苜蓿基肥和苜蓿种子丸衣化田间试验。结果证明锌、硼用于苜蓿种子丸衣对苜蓿有显著增产效果,但锌与硼配合会互抑制降低肥效,其它处理对苜蓿投有显著增产效果。     

新疆阿勒泰新垦区苜蓿病害调查与分析

对新疆阿勒泰地区三县一市新垦殖的２８１７项目区苜蓿病害进行了调查研究，共发现１１种病害，其中田野菟丝子、丛枝病、炭疽病等发生普遍，且为害严重，我区常见和主要的苜蓿病害大多均已在新垦殖区发生，且程度已与老的苜蓿生产区相差无几。据此提出了对我区苜蓿病害防治的几点意见和建议     

Nodulation and root growth of forage legumes sown into tall fescue swards

Establishing forage legumes into endophyte‐infected tall fescue (Festuca arundinacae Schreb.) pastures is problematic, especially in well‐established stands. A oversowing field experiment determined if this problem was because of poor nodulation. Four renovation techniques, clipped sward (treatment A), herbicided + rye seeding in the previous autumn (treatment B), herbicided in the autumn and spring (treatment C) and herbicided to suppress the sward (treatment D), were investigated to determine their effect on nodulation and root growth of lucerne (Medicago sativa L.), red clover (Trifolium pratense L.) and white clover (T. repens L.) at 16, 22 and 29 d after sowing the legumes. A pot experiment was also conducted under optimal growth conditions and using the same soil to determine the nodulation and root growth potentials of these legume species. At adequate rhizobial populations (>6 × 10⁴ cfu g^?1 soil), substantial nodulation of all species occurred by 29 d after sowing in treatments C and D, whereas nodulation of clovers was usually reduced in treatment A. Total root lengths for all sampling dates, species and treatments were severely restricted, especially under treatment A. A general correspondence of nodulation with root growth was observed for all species, with high correlations (r ≥ 0·85) between these variables for all legume species and treatments, suggesting that soil moisture, and possibly competition for light, were the limiting factors. These results demonstrate that weak stands of forage legumes, typically found when sown into tall fescue swards, are probably not because of inadequate nodulation. Rather, inhibition of root growth by detrimental physical/chemical conditions or allocation of limited photosynthate to shoots instead of roots is suggested.     

Production, survival and nutritive value of the perennial legumes Dorycnium hirsutum and D. rectum subjected to different cutting heights

Dorycnium hirsutum and D. rectum are perennial legumes which may have potential for use as pastures for the control of groundwater recharge in southern Australia. Little is known about the quality of the forage of Dorycnium species for grazing livestock or how these species respond to cutting. The effect of cutting height on plant survival, production of dry matter (DM), the proportion of leaf, edible stem (approximately <5 mm diameter) and woody stem in the DM and the nutritive value of the edible components was investigated. Biomass above five cutting‐height treatments (uncut, ground level, 5–8 cm, 10–15 cm and 15–30 cm above ground level) was removed at 8‐week intervals from plots of D. hirsutum and D. rectum from September 2002 to July 2003. In both species, plants subjected to lower cutting height treatments produced less DM above the height of the cut than those cut at higher heights. DM production declined over time in all treatments. Plants cut to ground level failed to regrow after the second harvest in D. hirsutum and the fourth harvest in D. rectum. Thus, these Dorycnium species were susceptible to high severity defoliations at 8‐week intervals. Negligible inedible woody stem was present in regrowth of both species after 8 weeks but D. hirsutum regrowth had a higher proportion of leaf (0·72) than D. rectum (0·56). Plants left uncut accumulated a large proportion of inedible woody stem in the DM (0·69 in both species) by July 2003, particularly at the base of the plant. Edible DM from regrowth of D. hirsutum and D. rectum had crude protein (CP) concentrations of 120 and 150 g kg^?1 DM; dry matter digestibility (DMD) values of 0·45 and 0·58; organic matter digestibility (OMD) values of 0·50 and 0·64; neutral‐detergent fibre (NDF) concentrations of 370 and 290 g kg^?1 DM; and acid‐detergent fibre (ADF) concentrations of 260 and 210 g kg^?1 DM, respectively. Medicago sativa, grown under similar conditions, had higher digestibility values (0·63 DMD and 0·66 OMD) and similar CP concentrations to D. rectum (140 g kg^?1 DM), but higher concentrations of NDF and ADF (410 and 290 g kg^?1 DM). Leaf material from both Dorycnium species had a higher nutritive value than edible stems, with DMD and OMD values of leaf of D. rectum being 0·68 and 0·74 respectively. Uncut plants had a much lower nutritive value of edible DM than the regrowth from cut treatments; older material was also of a lower nutritive value. The relatively low nutritive value of even the young regrowth of Dorycnium species suggests that forage quality is a major limitation to its use. Forage of Dorycnium species could be used during periods when other sources of forage are in short supply but infrequent grazing it is likely to produce forage of a low nutritive value.     

陇东旱塬区不同粮草轮作模式下土壤细菌群落组成特征

以陇东旱塬区冬麦-休闲-大豆(W-F-S)、冬麦-油菜-箭筈豌豆(W-R-V)和冬麦/休闲-苜蓿-苜蓿(W/F-L-L)粮草轮作系统为对象,基于16S rRNA基因序列扩增子测序,研究了3种轮作模式下耕层土壤(0~10 cm及10~20 cm)细菌群落组成特征。结果表明,3种轮作模式下,土壤细菌群落中占优势的菌门为变形菌门(Proteobacteria)和酸杆菌门(Acidobacteria);土壤细菌群落属组成中以红游动菌属(Rhodoplanes)、出芽菌属(Gemmata)、硝化螺旋菌属(Nitrospira)、慢生根瘤菌属(Bradyrhizobium)、Adhaeribacter菌属和Balneimonas菌属等与固氮相关的菌属为主。W-F-S轮作模式下土壤特异优势菌属为紫色杆菌属(Janthinobacterium)和溶杆菌属(Lysobacter),该类菌属与胞囊线虫的防治有关,间接揭示了该轮作模式可能抑制土传病害发生;W-R-V轮作模式下欧文氏菌属(Erwinia)丰度较高,主要与前茬油菜根系残留相关;W/F-L-L轮作模式下鞘脂单胞菌属(Sphingomonas)丰度较高,与苜蓿生长的少免耕措施有关。0~10 cm土层细菌多样性表现为W-F-S>W/F-L-L>W-R-V,10~20 cm土层表现则呈与之相反趋势。本研究从细菌群落组成和功能角度,阐释了包含豆科牧草的粮草轮作系统促进生物固氮、阻隔病害传播的微生物学机理,可为陇东旱塬区建立合理草田轮作制度和维持良好土壤生态环境提供理论依据。     

高产奶牛高效全混合饲料配方筛选试验

中国荷斯坦奶牛60头饲喂4种不同紫花苜蓿干草配比、不同精粗比的日粮,以研究日粮配方对奶牛产奶量、乳脂率、经济收益的影响.试验结果说明,大比例紫花苜蓿干草日粮（紫花苜蓿为24%DM）乳脂率显著（P＜0.05）或极显著提高（P＜0.01）;日粮营养水平提高,产奶量提高（P＜0.05 P＜0.01）;最佳经济效益日粮为含大比例紫花苜蓿,营养水平较低的日粮（P＜0.01）;在大的精粗比例下,紫花苜蓿干草不是日粮成本的限制因素,而青贮饲料配比为日粮成本的限制因素.合理安排精粗比例,适当使用紫花苜蓿干草,可提高奶牛饲养经济效益.