日粮添加过瘤胃保护胆碱对喀斯特山区奶牛泌乳性能的影响及其延续效应研究

研究日粮添加过瘤胃胆碱(RPC)对喀斯特山区奶牛泌乳性能及其延续效应的影响。以10头喀斯特山区泌乳盛期奶牛为试验动物,进行自身对照试验设计。试验按照对照期、正试期(试验Ⅰ期、试验Ⅱ期)、延续效应期(试验Ⅲ期)连续进行,每期12 d。其中,正试期RPC每头奶牛的添加水平为40 g/d;试验Ⅲ期停喂RPC以观察其是否可对奶产量产生延续效应。结果表明,对照期、试验Ⅰ期、试验Ⅱ期、试验Ⅲ期奶牛干物质采食量差异不显著(P>0.05)。试验Ⅰ期奶产量显著高于其他3期(25.5∶27.7∶26.5∶24.8 kg/d,P<0.05);正试期(试验Ⅰ期、试验Ⅱ期)奶产量显著高于对照期、延续效应期(25.5∶27.2∶24.8 kg/d,P<0.05);当停喂RPC后,延续效应期奶产量即下降至对照期水平(25.5∶24.8 kg/d,P>0.05)。奶成分不受日粮添加RPC的影响(P>0.05),乳脂、乳固型物含量数值上较对照期有所增加。由此可见,日粮添加RPC有利于提高喀斯特山区奶牛泌乳性能,但未对奶产量表现出延续效应,生产实践中需持续添加。     

基于APSIM模型的旱地小麦和豌豆水肥协同效应分析

为探索水肥协同作用对作物产量影响的机制和规律,在田间试验的基础上调试APSIM模型参数,并对模型进行检验,然后用该模型模拟近30多年来研究区的小麦/豌豆产量,并采用多元回归方法分析了施N量(X1)、生育期降水量(X2)和休闲期降水量(X3)对小麦/豌豆模拟产量的协同效应.结果表明,APSIM模型可以准确用来模拟小麦和豌...     

益生菌对奶牛亚急性瘤胃酸中毒的保护作用

亚急性瘤胃酸中毒对奶牛的生产性能有很大影响,使用益生菌来稳定奶牛分娩后-产奶过渡期瘤胃pH可以减轻这种代谢紊乱的症状。因此,本试验选择了体重(741±55)kg,产奶期在(212±19.5)d的奶牛4头,试验采用4×4拉丁方设计,共4种日粮:对照组饲喂基础日粮,处理1组为日粮添加0.5 g/d米曲菌,处理2组为日粮添加2.5 g/d米曲菌,处理3组为日粮添加2 g/d粪肠球菌和酿酒酵母菌的混合物。每组经过3 w的适应期、4 d酸中毒期以及3 d恢复期。结果显示:瘤胃最大pH范围在5.6～6.0,占比最高,与适应期和中毒期的结果相似。中毒期间,其他pH范围表现为显著差异(P <0.05)。中毒期,处理3组较对照组显著提高了瘤胃pH(P <0.05),同时处理3组瘤胃pH在5.6～6.0的占比也显著高于对照组(P <0.05)。日粮添加2.5 g/d米曲菌显著降低了产奶量(P <0.05)。奶牛遭受瘤胃酸中毒后,随着时间的推移,丙酸、丁酸和戊酸含量显著升高(P <0.05),而乙酸、异丁酸和异戊酸含量显著降低(P <0.05)。除了处理3组外,其他组瘤胃乳酸含量随时间的增加而升高(P <0.05)。饲喂12 d后,处理3组较对照组显著提高了乳酸含量(P <0.05)。瘤胃白球菌和大肠杆菌含量在饲喂2 h后显著升高(P <0.05),之后在6 h达到稳定。结论 :粪肠球菌和酿酒酵母菌复合物可以缓解奶牛亚急性瘤胃酸中毒的症状,米曲菌可以调控瘤胃pH,但高剂量米曲菌添加水平对瘤胃pH无显著影响。     

Effects of insect infestation on rodent‐mediated dispersal of Quercus aliena: results from field and enclosure experiments

Rodents influence plant establishment and regeneration by functioning as both seed predators and dispersers. However, these rodent–plant interactions can vary significantly due to various environmental conditions and the activity of other insect seed predators. Here, we use a combination of both field and enclosure (i.e. individual cage and semi‐natural enclosure) experiments, to determine whether rodents can distinguish sound seeds from those infested with insects. We also demonstrate how such responses to insects are influenced by food abundance and other environmental factors. We presented rodents with 2 kinds of Quercus aliena seeds (sound and insect‐infested seeds) in a subtropical forest in the Qinling Mountains, central China, from September to November of 2011 to 2013. The results showed that rodents preferred to hoard and eat sound seeds than infested seeds in the field and semi‐natural enclosure, while they preferred to eat infested seeds over sound seeds in the individual cages. In addition, both hoarding and eating decisions were influenced by food abundance. Rodents hoarded more sound seeds in years of high food abundance while they consumed more acorns in years of food shortage. Compared with field results, rodents reduced scatter‐hoarding behavior in semi‐natural enclosures and ate more insect‐infested seeds in smaller individual cages. These results further confirm that rodents distinguish infested seeds from non‐infested seeds but demonstrate that this behavior varies with conditions (i.e. environment and food abundance). We suggest that such interactions will influence the dispersal and natural regeneration of seeds as well as predation rates on insect larvae.     

温度、光照和发芽床对假俭草种子萌发的影响

实验室内进行了假俭草种子净度检验样品最低限量和发芽检验方法的研究，探讨了光照（以黑暗为对照）、温度（分别包括２０℃恒温，１５／２５℃、２０／３０℃、２０／３５℃和２５／３５℃变温）和发芽床（分设纸上ＴＰ和砂中Ｓ）等因素对种子发芽的影响。结果表明：假俭草种子净度检验样品最低限量是３ｇ，送验样最低量以及计数其它植物种子检验样品最低量均为３０ｇ；最佳萌发条件为２０／３０℃或２０／３５℃变温（１６小时低温，８小时高温），高温时段设光照，和纸上（ＴＰ）发芽；发芽的初次和未次计数时间分别以第１０天和第２１天为宜；种子的幼苗发育可划分为单子叶植物子叶留土类型。     

Endozoochorous seed dispersal by golden snub-nosed monkeys in a temperate forest

Seed dispersal is essential for plant recruitment and the maintenance of biodiversity. Colobine monkeys are primarily folivorous, but they also consume fruits and are often assumed to be seed predators. Although they are known to be epizoochorous seed dispersers, their role as endozoochorous seed dispersers needs reassessment. We examined potential endozoochory in golden snub-nosed monkeys (Rhinopithecus roxellana) at Dalongtan in Shennongjia National Park, central China, by assessing potential germination of ingested seeds (n = 1806, 9 species) from fecal samples. Intact seeds were in almost all fecal samples (ranging from 5–130 seeds), and ingested seeds were from small seeded species (seed width <4.5 mm). The 2 most abundant species were Actinidia arguta (73%) and Rosa caudata (15%). The fruits of A. arguta were unripe when ingested (i.e. effective seed predation) and the ingested seeds did not germinate in the trials. Therefore, ingestion of unripe seeds does not lead to effective seed dispersal. However, germination rates of defecated R. caudata (9%) were greater than control seeds (6% and 0%), demonstrating potential endozoochorous seed dispersal. Thus, colobine monkeys do indeed disperse mainly small-seeded from multi-seeded fruits through potential endozoochory and this process enhances the recruitment of seedlings.     

盐分浓度对星星草种子萌发的影响

星星草（Ｐｕｃｃｉｎｅｌｌｉａｔｅｎｕｉｆｌｏｒａ）种子经不同浓度ＮａＣｌ溶液处理结果表明；与对照相比，低于０．６ｇ／１００ｍｌ的盐浓度对种子萌发有促进作用；介于０．７ｇ／１００ｍｌ—３．６ｇ／１００ｍｌ间，种子的萌发势和累积发芽率显著下降，但尚不影响其萌发潜势，解除盐分限制后，还可正常萌发；高于３．７ｇ／１００ｍｌ后，不仅抑制种子萌发，并对其萌发潜势有显著影响。     

湖南桔园土壤硫素含量及其影响因素研究

为掌握湖南柑桔园土壤硫素含量的丰缺程度、分布规律及影响土壤硫有效性的因素，采取野外调查与室内分析相结合的方法，于2000—2002年对湖南江永、洪江、桃源、石门、衡山等9个县(市)45个柑桔园土壤硫素含量进行了调查测定．结果表明：湖南省柑桔园0—20cm土层有效硫2．5—219．2mg／kg，低于临界值的桔园占15．6％，处于潜在缺硫的占13．3％．0—20，20—40，40—60cm土层有效硫平均含量分别为46．3，84．9，96．0mg/kg，全硫平均含量分别为0．236，0．193，0．181g/k8．有效硫的水平分布以衡山最高、江永最低、其他县(市)居中．柑桔叶片含全硫x^-2．45g/kg，约11％的柑桔园低于临界值．影响土壤有效硫含量主要有土壤全硫、土壤有机质、土壤类型及土壤质地等因素．在缺硫和潜在缺硫的桔园土壤中应重视硫肥的施用，以促进柑桔产量和品质的提高．     

Na+,K+,Mg2+,Ca2+浓度对嗜盐放线菌生长的影响

通过研究近30株嗜盐或耐盐放线菌在不同浓度的Na^＋，K^＋，M^2＋，Ca^2＋条件下的生长范围，发现耐盐放线菌对Na^＋，K^＋，M^2＋有广泛的适应性。只有少数耐盐放线菌能在较底浓度的CaCl2条件下生长；多数嗜盐放线菌生长所需的Na^＋可被K^＋，Mg^2＋所替代，而不能被Ca^2＋所替代，少数嗜盐放线菌的生长离不开Na^＋，对Na^＋有高度的专一性。因此，提出自然环境中是否也存在类似的专嗜K^＋或专嗜Mg^2＋的嗜盐放线菌的推测。