Effects of transportation during the hot season and low voltage electrical stimulation on histochemical and meat quality characteristics of sheep longissimus muscle

The effect of transportation during the hot season (42 °C) and low voltage electrical stimulation on physiological, histochemical and meat quality characteristics of Omani sheep was studied. Forty intact male sheep were divided into two equal groups: 3 h transported or non-transported. The non-transported group remained in holding pens for 48 h prior to slaughter, while the transported group was transported 300 km (approximately 3 h) in an open truck under solar radiation on the day of slaughter. Blood samples were collected from the animals before loading and prior to slaughter. Fifty percent of the carcasses from each group were randomly assigned to low voltage (90 V) at 20 min postmortem. Temperature and pH decline of the left longissimus thoracis muscle were monitored. Ultimate pH, WB-shear force, sarcomere length, myofibrillar fragmentation index (MFI), expressed juice, cooking loss and color L, a, b were measured on samples from both sides muscles collected at 24 h postmortem at 3–4 °C. The transported sheep had significantly higher plasma cortisol (P < 0.01), adrenaline, nor-adrenaline and dopamine concentrations (P < 0.05) than non-stimulated animals. Electrical stimulation resulted in a significantly (P < 0.05) more rapid pH fall in muscle during the first 12 h after slaughter. Muscles from electrically-stimulated carcasses had significantly (P < 0.05) lower pH values, longer sarcomere length, lower shear force value, higher expressed juice, MFI and lighter L than those from non-stimulated ones. The muscle samples from the transported sheep had significantly (P < 0.05) smaller and lower proportion of Types I and IIA fibers than those from the non-transported group. This study indicated that pre-slaughter transport at high ambient temperatures can cause noticeable changes in physiological and muscle metabolism responses in sheep. Electrical stimulation improved meat quality characteristics, which indicate that meat quality of transported sheep can be improved by electrical stimulation.     

钦南、钦北区冬种辣椒生产存在问题与发展对策

钦南、钦北区发展冬种辣椒生产,进行南菜北运,已有十多年历史,种植面积不断增加,也取得了一定的经济效益。一般亩产值1000元~1500元,比种植水稻的效益高。本文针对目前生产中出现的主要问题,提出相应的发展对策,供椒农们参考。     

运输温度与时间对猪孤雌胚胎发育的影响

[目的]比较不同运输温度与时间对猪孤雌胚胎发育的影响,确立猪克隆胚胎的最佳运输温度与时间。[方法]研究不同温度（37、38、39℃）对孤雌胚胎卵裂率、囊胚率的影响;不同时间（2、3、4h）对孤雌胚胎卵裂率、囊胚率的影响。[结果]培养3h后,在39℃运输时,孤雌胚胎的卵裂率和囊胚率与37℃、38℃的卵裂率和囊胚率相比,差异显著（P〈0．05）;培养3h后,孤雌胚胎的卵裂率和囊胚率与培养2h、4h的卵裂率和囊胚率相比,差异显著（P〈0．05）。[结论]在39℃,3h内进行孤雌胚胎的运输,能获得较高的卵裂率、囊胚率。     

稳定振动条件下梨的振动损伤研究

通过梨的振动试验，研究了稳定振动条件下，振动加速度、振动频率对梨的损伤影响，分析了梨振动至失去商品性时的振动次数N与损伤能量的关系，探讨了在相同振动加速度、不同频率下梨振动至失去商品性时的振动次数N1、N2与振动圆频率ω1、ω2的关系。试验结果表明，振动加速度越大，梨越容易产生损伤；在相同加速度条件下，振动频率越小，梨越容易产生损伤。     

柑橘生产机械化研究

从灌溉、施肥、施药、修剪、采摘和运输等主要田间作业环节,对国外柑橘生产机械化技术进行了分析。针对中国柑橘生产机械化水平较低和柑橘生产机械化发展中存在的问题,借鉴国外发展经验和先进技术,提出了中国柑橘生产机械化的发展方向、主要机械化技术与装备发展要点。     

春季四季草莓体内氮素的运移研究

[目的]探讨四季草莓对氮素的吸收和利用规律,以提高草莓品质。[方法]试验通过施加15N尿素,于施肥后半个月、1个月和3个月后分别测定老叶、功能叶、幼叶、老茎（1年生）、新茎（当年生）、粗根（直径0.2 cm以上）、细根（直径0.2 cm以下）、花果蕾共8个部分中15N吸收量和全氮量。[结果]春季土壤15N施肥后,四季草莓各器官NDFF普遍不高,在4.47%～11.63%之间;幼叶与花果蕾等新生器官的NDFF要略高于其他器官。不同器官对15N的吸收量差异较大,同一器官在不同的时期对15N的吸收量也不同。四季草莓对15 N-尿素的15 N吸收很迅速,在施肥后的半个月内15 N吸收利用率达30.34%,1个月内的15 N吸收利用率变化不明显,3个月后15 N吸收利用率开始显著上升。[结论]植株各个器官的15N分配率在各个时期的差异较大,分配重点也不相同。     

苹果不同施肥方式对铁的吸收、运输与分配的影响

 红色邻二氮杂菲铁示踪结果表明: 二价铁肥根系输液以二价态由根被动吸收, 由靠近形成层的木质部, 运输到根、茎、叶及其主脉内, 运输速度每小时可达数十厘米。室内营养液培养的八棱海棠苗用⁵⁹Fe示踪, 结果表明, 断根中分配的⁵⁹Fe为19.3% , 叶中70.9% , 断1、2、3条根⁵⁹Fe在叶中分配的比例分别为57.9%、63.6%和68.0%。铁肥树干强力高压注射以二价铁沿中央木质部的导管运输, 大部分向下运往根系, 根中贮存大量的铁, 向上运输稍难。运输速度每小时达数百厘米, 矫正缺铁失绿症的速度比根系输液慢, 但由于根中贮存大量的铁, 持效期较长。铁可以通过枝条和叶片进入树体并且运输。     

杂种小麦花后干物质积累转运动态和分配

选用两个杂种及其亲本和对照7个材料, 进行了开花后干物质积累转运和分配规律的研究。 结果表明： 杂种小麦叶面积大, 生物量高, 灌浆强度大, 每日千粒重达1677～1812 mg, 超双亲平均值(MP)和对照(CK)8.6%～26.1%, 灌浆持续时间长1.4～3.1d, 是形成粒重优势的关键所在。 与亲本相比, 化杀杂种CH-1的干物质转运率(TR)     

A Study on the Mathematical Model of Postal Transportation Problem

The Postal Transportation Problem(PTP)is a very complex transportation problem. It has not any very effective solving method at present. This paper systemically analyze and define the problem according to its range, capability and time limit restrictions, random factors, dynamic factors, preferential factors, optimization objectives, cost composing, and so on. The multiobjective optimization mathematical modelof PTP is established and its relational problems are also analyzed. And the model is made up of 12 kinds of restraint conditions and three optimization objectives which are the whole transportation cost, average transportation time of mail and average use ratio of cars. This will be in favor of further study of PTP. The successful development of a logistics scheduling and dispatching optimization software based on the model and its corresponding algorithm proves the correctness of the model.[WT5HZ]     

肉用犊牛产生应激的原因及机理分析

肉用犊牛在转至育肥场会出现一系列的应激反应,对肉牛育肥产业带来极大损失,本文通过对犊牛运输应激及断奶应激全面剖析的基础上,对产生犊牛应激综合征提出了新的看法,并提出要从犊牛的心理、断奶、环境改变、饲草料变化和运输等方面所产生的一系列应激叠加角度上考虑,综合预防犊牛过渡应激的横发,降低犊牛应激综合征给肉牛生产造成的损失。