调环酸钙-青鲜素复配剂对甜高粱株高和倒伏的影响

选用甜高粱品种原甜1号,在拔节后第20天叶面喷施一次调环酸钙-青鲜素复配剂,设2.6、5.2和10.4mg/m23个处理,研究了不同用量调环酸钙-青鲜素复配剂对甜高粱株高和倒伏的影响.试验结果表明,处理后14 d内复配剂处理植株高度和日生长量显著下降;甜高梁在开花前倒伏率显著降低,10.4 mg/m2处理倒伏率比对照降低了70.9%.各复配剂处理使植株后期生长出现反弹,灌浆期植株倒伏率增加,达到52%～65%,与对照无显著差异.根倒伏是对照区植株主要倒伏类型,茎倒伏是复配剂处理植株主要倒伏类型.     

施肥对柚木目标树土壤理化性质及其胸径生长的影响

采用L₈（4×2⁴）正交设计开展复合肥、尿素、P₂O₅、生石灰和施肥方式的组合试验;分别于0～20（上层）和20～40（下层）cm取样测定土壤理化性质,分析施肥对49 a生柚木目标树胸径生长和土壤理化性质的影响。结果表明：处理组合0～20 cm土层的pH值、土壤的含水率、容重、有机质、全氮、全磷、全钾、有效氮、有效磷和有效钾分别为5.01～5.59、21.5%～26.9%、1.59～1.71 g/m³、23.08～32.89 g/kg、0.123%～0.164%、0.078%～0.173%、1.00%～1.33%、113.5～140.6、10.63～97.09、163～453 mg/kg,0～40 cm的则是4.91～5.41、22.5%～29.5%、1.67～1.79 g/m³、18.57～23.52 g/kg、0.097%～0.122%、0.066%～0.136%、1.02%～1.59%、79.8～154.6、5.9～65.7、121～657 mg/kg;其胸径增长率为4.22%～5.39%,对照仅3.09%。0～20 cm的有机质、全氮、有效氮和有效钾显著或极显著地高于20～40 cm的;土壤的理化性质间呈现复杂的相关性。影响胸径生长的主导因子为复合肥;柚木胸径增长率与土壤全钾和20～40 cm的全氮含量呈极显著和显著的正相关,土壤施肥促进柚木生长,其人工林抚育经营必须关注土壤养分管理。     

The effect of hindclaw height differential and subsequent trimming on lameness in large dairy cattle herds in Canterbury,New Zealand

Abstract

AIMS: To determine if inequality in height between claws within each hindlimb of dairy cattle is a risk factor for the development of lameness and to determine the effect of preventive trimming of these claws on the subsequent risk of lameness.

METHODS: Cows (n=2,695) on three dairy farms in Canterbury, New Zealand, were examined and the height differential between their hind claws on each limb was measured. Cows were blocked by age, then breed and grouped by height differential, before being randomly assigned to either treatment or control groups. Cows in the control group were not trimmed, whilst cows in the treatment group were all trimmed according to the ‘Dutch Trimming’ method by an experienced foot trimmer. All subsequent clinical incidences of lameness were identified, recorded and classified according to five categories. The overall incidence of lameness, the effect of claw height differential on the incidence of lameness and the effect of trimming on the incidence of lameness were assessed using both GEE modelling and survival analysis.

RESULTS: The incidence of lameness identified in any untrimmed hindlimb irrespective of diagnosis, measured at a limb level and assessing the first incidence of lameness only, was 10.0% for a 6-month period from November to drying off. The predominant lesion identified was white line disease (WLD; 7.9% incidence and 78.6% of all lameness). The overall incidence of hindlimb lameness measured at cow level for the same period was 14.5%. The risk of lameness was influenced by breed (p=0.016), age (p=0.002) and claw height differential (p=0.026). There were no significant interactions. The risk of lameness was lowest where the claw height differential was 0–2 mm. The incidence of lameness in the first 70 days following trimming was higher in older cows than in younger cows (p<0.001). Trimming did not affect lameness incidence (p=0.185). The Cox proportional hazard model demonstrated that farm (p<0.001), trimming group (p=0.021); and age (p=0.021) significantly affected the median days to lameness in the first 70 days following trimming.

CONCLUSIONS AND CLINICAL RELEVANCE: Hind feet with lower height differentials between claws had a lower incidence of lameness. Trimming of these feet to remove the height differential did not reduce their overall incidence of lameness, but did increase days to first lameness.     

基于光束法空中三角测量理论的树高测量方法研究

在总结了传统树高测量方法的基础上,提出了根据光束法空中三角测量理论对树高进行测量的方法,并对影响树高测量精度的外方位元素误差进行了检验,结果表明,外方位元素在一定的误差范围内,利用光束法空中三角测量理论测量树高,精度较高。     

燕麦与毛苕子混播试验初报

通过对比试验的方法，进行了燕麦与毛苕子混播试验，结果表明：B处理鲜草产量明显高于其它处理，其抗倒伏性能随毛苕子播量的增加而降低。B处理的燕麦与毛苕子植株增高幅度也最大。     

中小型圆柱形钢油罐直径和高度的计算方法

从实际计算出发，将等壁厚油罐和变壁厚油罐统一考虑，得到了最省材料的中小型油罐的高度确定方法。计算表明，油罐的最优高度不但与钢材种类，焊接水平，顶底厚度之和有关，而且还与所设计油罐的圈板数（或圈板高度），最小壁厚、液面蒸气压等有关。用原有方法确定油罐高度有些偏大。地公称容积同但计算容积不同的油罐，其设计高度应有所区别。     

半干法石膏纤维板工艺研究：Ⅱ.搅拌和铺装均匀性因素分析

石膏和纤维的搅拌和铺装的均匀性对石膏纤维板质量影响很大。试验表明，所采用的搅拌机和铺装机性能良好，搅拌和铺装质量较好，铺装机料仓中料高影响板坯密度的均匀性，料高与板坯密度呈很强的一元线性关系；板密度与ＭＯＲ、ＭＯＥ有较好的一元线性关系，但与ＩＢ线性关系相对较差，板密度增加，ＭＯＲ、ＭＯＥ和ＩＢ也增加。     

威提特东非狼尾草种子生产技术的研究

比较了4种土壤类型和3种留茬高度对威提特东非狼尾草(Pennisetum clandestinum cv. Whittet)种子产量和质量的影响。结果表明:以单因素而言,生土处理和0.05 m留茬高度处理所获得的平均种子产量最高;两因素处理的结果表明,以生土和0.05 m留茬高度互作后所获得的种子产量最高,其种子产量达447kg/hm2;各土壤类型和不同留茬高度的处理对种子的质量影响差异不显著。     

不同断奶日龄对奶公犊生长性能和体尺指标的影响

30头新生荷斯坦奶公犊出生日期和体重相近,随机分成6组,对照组按常规饲喂鲜牛奶,60日龄断奶;各试验组分别于10、20、30、40和50日龄断奶,试验期为60d。结果表明:试验结束时,20日龄断奶组、30日龄断奶组的体重、平均日增重均显著高于对照组,40日龄断奶组、50日龄断奶组与对照组间无明显差异;各试验组犊牛与对照组在体长和体斜长上无显著差异。