养殖模式对霍尔巴羊生长发育影响的研究

本研究旨在探讨不同养殖模式对霍尔巴羊生长发育的影响。试验选取体重（11.00±3.00）kg的3月龄霍尔巴羊60只,随机分为放牧组和舍饲组（每组3个重复,每个重复10只）,放牧组采取放牧养殖模式,舍饲组采取舍饲养殖模式。结果表明,试验的21周内,舍饲组试验羊体重、体尺（体长、体高、胸围、管围）增量均显著高于放牧组（P＜0.05）。生长发育指标阶段性增量数据显示,放牧组3个阶段体重增量差异显著（P＜0.05,Ⅰ阶段＞Ⅱ阶段＞Ⅲ阶段）。放牧组Ⅰ阶段体高、体长增量显著大于Ⅱ阶段（P＜0.05）,胸围增量显著小于Ⅱ阶段（P＜0.05）,管围增量显著小于Ⅲ阶段（P＜0.05）。Ⅱ阶段胸围增量显著大于Ⅲ阶段（P＜0.05）,其他体尺增量显著小于Ⅲ阶段（P＜0.05）。舍饲组Ⅰ阶段体高、体长和管围增量显著大于Ⅱ阶段、Ⅲ阶段（P＜0.05）,胸围增量显著大于Ⅱ阶段（P＜0.05）,显著小于Ⅲ阶段（P＜0.05）,Ⅱ阶段体高、胸围增量显著大于Ⅲ阶段（P＜0.05）。由此可见,舍饲养殖显著提高霍尔巴羊生长性能|舍饲养殖霍尔巴羊Ⅲ阶段增重较快|霍尔巴羊生长发育有一定规律,出现不对称“V”字型曲线,即Ⅰ阶段＞Ⅲ阶段＞Ⅱ阶段。 [关键词]养殖模式|霍尔巴羊|生长发育     

Growth and nutrient accumulation of Brazil nut trees (Bertholletia excelsa) in agroforestry at different fertilizer levels

The Brazil nut tree(Bertholletia excelsa) is a frequent component of agroforestry systems in the Amazon because of its adaptation to nutrient-poor upland soils and multiple uses.We investigated the aboveground biomass production(kg dry weight),nutrient uptake and requirements(N,P,Ca,Mg,K) of Brazil nut trees of different sizes grown under agroforestry conditions and fertilized at different levels.Eight of 70 experimental trees with different size were harvested and stem,branches and leaves were separated.Nutrient contents were determined for three trees of varying size.Average tree growth was fast,but variability was high,suggesting considerable potential for the improvement of this economically important species.The trees responded to increased levels of fertilizer and lime with significantly increased foliar nutrient contents and growth,probably because of the improved availability of Mg and Ca for which the species seems to have a relatively high demand.In contrast to Brazil nut trees grown in forest or dense plantations,the agroforestry trees invested a substantial part of their biomass and nutrients in large branches and developed spreading crowns.To improve stem form,reduce competition with associated crops for light and recycle nutrients,regular pruning of lower branches or planting arrangements that favor self-pruning are recommended.These measures would also increase the recycling of Ca and Mg,large quantities of which are contained in the branches.     

Why cuckoos should parasitize parrotbills by laying eggs randomly rather than laying eggs matching the egg appearance of parrotbill hosts?

The coevolutionary interaction between cuckoos and their hosts has been studied for a long time, but to date some puzzles still remain unsolved. Whether cuckoos parasitize their hosts by laying eggs randomly or matching the egg morphs of their hosts is one of the mysteries of the cuckoo problem. Scientists tend to believe that cuckoos lay eggs matching the appearance of host eggs due to selection caused by the ability of the hosts to recognize their own eggs.In this paper, we first review previous empirical studies to test this mystery and found no studies have provided direct evidence of cuckoos choosing to parasitize host nests where egg color and pattern match. We then present examples of unmatched cuckoo eggs in host nests and key life history traits of cuckoos, e.g. secretive behavior and rapid egg-laying and link them to cuckoo egg laying behavior. Finally we develop a conceptual model to demonstrate the egg laying behaviour of cuckoos and propose an empirical test that can provide direct evidence of the egg-laying properties of female cuckoos. We speculate that the degree of egg matching between cuckoo eggs and those of the host as detected by humans is caused by the ability of the hosts to recognize their own eggs, rather than the selection of matching host eggs by cuckoos. The case of Common Cuckoos(Cuculus canorus) and their parrotbill hosts(Paradoxornis alphonsianus), where it has been shown that both have evolved polymorphic eggs(mainly blue and white), was used to develop a conceptual model to demonstrate why cuckoos should utilize parrotbill hosts by laying eggs randomly rather than laying eggs matching the appearance of host eggs.In conclusion, we found no evidence for the hypothesis that cuckoos lay eggs based on own egg color matching that of the parrotbill-cuckoo system. We argue theoretically that laying eggs matching those of the hosts in this system violates a key trait of the life history of cuckoos and therefore should be maladaptive.     

Changes in various metabolic parameters in blood and milk during experimental Escherichia coli mastitis for primiparous Holstein dairy cows during early lactation

Background:The objective of this study was to characterize the changes in various metabolic parameters in blood and milk during IMI challenge with Escherichia coli(E.coli) for dairy cows during early lactation.Thirty,healthy primiparous Holstein cows were infused(h = 0) with-20-40 cfu of live ? coli into one front mammary quarter at ~4-6wk in lactation.Daily feed intake and milk yield were recorded.At-12,0,3,6,12,18,24,36,48,60,72,96,108,120,132,144,156,168,180 and 192 h relative to challenge rectal temperatures were recorded and quarter foremilk was collected for analysis of shedding of E.coli.Composite milk samples were collected at-180,-132,-84,-36,-12,12,24,36,48,60,72,84,96,132 and 180 h relative to challenge(h = 0) and analyzed for lactate dehydrogenase(LDH),somatic cell count,fat,protein,lactose,citrate,beta-hydroxybutyrate(BHBA),free glucose(fglu),and glucose-6-phosphate(G6P).Blood was collected at-12,0,3,6,12,18,24,36,60,72,84,132 and 180 h relative to challenge and analyzed for plasma non-esterified fatty acids(NEFA),BHBA and glucose concentration.A generalized linear mixed model was used to determine the effect of IMI challenge on metabolic responses of cows during early lactation.Results:By 12 h,E.coli was recovered from challenged quarters and shedding continued through 72 h.Rectal temperature peaked by 12 h post-challenge and returned to pre-challenge values by 36 h post-IMI challenge.Daily feed intake and milk yield decreased(P 0.05) by 1 and 2 d,respectively,after mastitis challenge.Plasma BHBA decreased(12 h;P 0.05) from 0.96 ± 1.1 at 0 h to 0.57 ±0.64 mmol/L by 18 h whereas concentration of plasma NEFA(18 h) and glucose(24 h) were significantly greater,11 and 27%,respectively,after challenge.In milk,fglu,lactose,citrate,fat and protein yield were lower whereas yield of BHBA and G6 P were higher after challenge when compared to pre-challenge values.Conclusions:Changes in metabolites in blood and milk were most likely associated with drops in feed intake and milk yield.However,the early rise in plasma NEFA may also signify enhanced adipose tissue lipolysis.Lower concentrations of plasma BHBA may be attributed to an increase transfer into milk after IMI.Decreases in both milk lactose yield and%after challenge may be partly attributed to reduced conversion of fglu to lactose.Rises in G6 P yield and concentration in milk after challenge(24 h) may signify increased conversion of fglu to G6 P.Results identify changes in various metabolic parameters in blood and milk after IMI challenge with E.coli in dairy cows that may partly explain the partitioning of nutrients and changes in milk components after IMI for cows during early lactation.     

Compressive failure of spruce wood rings reinforced with glass epoxy composite

We experimentally tested under radial compressive loads and statistically analyzed rings constructed from spruce wood and reinforced with glass fiber.We used the Weibull distribution in statistical analysis,and tested five types of rings including unreinforced and composite reinforced(CR) as wound around the ring,oriented as two layers at angles of 45°,60°,75° and 90° to the column axis.We calculated 95 % reliability of load carrying capacity of the rings by Weibull distribution.The highest load carrying capacity was obtained with CR rings at 60° to the axial axis of the ring.Load carrying capacities of rings at CR90,CR75,CR60 and CR45 were 137,192,215 and 126 %greater,respectively,than unreinforced rings.For unreinforced rings,failures resulted from catastrophic breaking of wood materials.None of the reinforced rings failed catastrophically because the outer surface of the rings was reinforced with glass–epoxy composite fiber.Cracks began at the core of the materials under the composite layer for all specimens and resulted in failure of the rings.     

青稞茎秆形态特性与抗倒伏性的关系

为筛选出优异的青稞抗倒伏亲本,以青稞茎秆基部第2节间抗折力大小作为抗倒伏指标,对367份青稞核心种质进行抗倒性评价。结果表明,农家品种和育成品种各个抗折力水平的品种占比一致,均为中等抗折力品种最多;所有材料中抗折力最强的品种是黑青稞（62.27 N）,最弱的是白青稞（5.13 N）,均为农家品种;育成品种抗折力最强的为昆仑14号（58.77 N,区外品种）;茎秆内部结构及田间表现研究发现,抗折力强的品种机械组织厚,田间表现为茎秆直立。农家和区外青稞品种可为西藏青稞品种的抗倒育种提供优异亲本。     

露地洋葱水肥一体化优质高产栽培技术

近年来,人们对洋葱需求量逐年增加,而实现洋葱规模化种植是满足市场需求和提高品质的最好方法.本文通过生产实践调查,从地块选择、种子处理、播种技术、田间管理、适时收获等方面总结洋葱水肥一体化优质高产栽培管理技术,供种植户参考.     

西藏山南亚麻引种试验

本试验引进双亚12号、坝选3号与当地品种进行比较试验,结果表明：双亚12号的原茎产量比对照当地品种高0.83%、种子产量比对照当地品种降低37.9%;坝选3号的原茎产量、种子产量分别比对照当地品种高19.1%、 10.8%,且生育期比当地品种短、抗寒性、抗旱性更强。为加速西藏干旱地区亚麻品种的更新换代,提高品质、产量提供了参考。     

柴胡注射液致犬过敏抢救的几点探讨

<正>柴胡作为解热镇痛药在兽医临床中应用较广,一般情况下肌内注射给药十分安全,无任何不良反应,过敏反应大多在静脉或肌内注射后的短时间内发生,也有的发生在静脉输液过程中。临床表现为用药后1² min之内患犬表现为呼吸困难,头面部及全身皮肤迅速产生皮疹,皮疹处被毛逆立剧痒,患犬烦躁不安,在口唇、舌尖、鼻梁、眼睑等处有轻度水肿。如能及时施用解救药,患犬的过敏症状消退较快,一般3 min左右症状即可消失并恢复正常。1抢救措施与原则     

碧护植物生长调节剂在玉米上施用肥效试验

<正>一、试验目的通过田间肥效对比试验,验证碧护植物生长调节剂在玉米上的施用效果,为其大面积推广应用提供依据。二、材料与方法1.供试材料碧护有效成分为天然赤霉素、吲哚乙酸等纯天然植物生长调节剂。试验作物为玉米,品种为鲜食玉米京科糯2000和新玉33号。2.试验地点及条件