Select nutrients and their effects on conceptus development in mammals

The dialogue between the mammalian conceptus(embryo/fetus and associated membranes) involves signaling for pregnancy recognition and maintenance of pregnancy during the critical peri-implantation period of pregnancy when the stage is set for implantation and placentation that precedes fetal development. Uterine epithelial cells secrete and/or transport a wide range of molecules, including nutrients,collectively referred to as histotroph that are transported into the fetal-placental vascular system to support growth and development of the conceptus. The availability of uterine-derived histotroph has long-term consequences for the health and well-being of the fetus and the prevention of adult onset of metabolic diseases. Histotroph includes numerous amino acids, but arginine plays a particularly important role as a source of nitric oxide and polyamines required for fetal-placental development in rodents, swine and humans through mechanisms that remain to be fully elucidated. Mechanisms whereby arginine regulates expression of genes via the mechanistic target of rapamycin cell signaling pathways critical to conceptus development, implantation and placentation are discussed in detail in this review.     

Pharmacological and toxicological study of turimycin]

Turimycin is characterised by low acute toxicity. Mean lethal doses for mouse and rat are 750 mg/kg body weight for intraperitoneal application of something in excess of 3,000 mg/kg for oral administration. The blood pressure of anaesthetised cats may be reduced by amounts depending on intravenous Turimycin doses (between 10 and 50 mg/kg). The hypotensive effect of Turimycin is attributable to its negative inotropic effect on the heart and its spasmolytic action on the unstriated muscles. Reversible reduction of urine and ion excretion of rat following intraperitoneal application of 50 mg/kg body weight of Turimycin is interpreted as a consequence of such action upon blood pressure. A preliminary study was conducted into dogs which had orally received daily Turimycin doses of 50 or 125 mg/kg body weight over twelve months. No substance-depending functional or morphological damage was recorded.     

营养对猪肉质性状的影响

<正>影响猪肉品质的因素很多,主要包括遗传、营养、环境、屠宰与加工等,因此,对肉质的改良也应从这些方面着手采取综合措施。本文主要从营养的角度总结     

Clinical forms of enzootic pneumonia in calves and their effects on respiration]

Enzootic pneumonia was diagnosed in 160 of 225 bullocks in a livestock fattening unit. Within the first 10 weeks, 51 of those affected contracted the disease a second time after the symptoms had vanished. Acute catarrhal bronchopneumonia were most common (49.3%) during the first outbreak, whereas acute catarrhal purulent bronchopneumonia (39.2%) and chronic pneumonia (29.4%) were most common during the second. Arterial blood gas analysis was undertaken for 33 clinically healthy bullocks and 100 bullocks with clinically diagnosed acute bronchitis, acute catarrhal bronchopneumonia, acute catarrhal purulent bronchopneumonia and chronic pneumonia. The pO2, SATO2 and A-aDO2 levels found in blood from the abdominal aorta of all diseased animals differed significantly from those of healthy animals. The values for animals with distinct catarrhal bronchopneumonia and catarrhal purulent bronchopneumonia showed the greatest differences.     

几种处理对柠条养分的影响及其在瘤胃内的降解

用3头瘘管羊,以尼龙袋法(in situ)测定黄贮柠条Caragana microphylla、氨化柠条、生化处理柠条等在瘤胃发酵6,12,24,36,48和72 h后粗蛋白(CP)、酸性洗涤纤维(ADF)、中性洗涤纤维(NDF)、酸性洗涤木质素(ADL)的降解率。结果表明,与对照组相比,处理柠条CP含量都上升(P<0.05),其中氨化柠条粗蛋白上升最高,NDF、ADF和ADL含量却都有所下降;柠条以尼龙袋法在瘤胃内降解48 h后,氨化处理柠条各营养物质降解效果都表现出最好,CP降解率为56.62%,NDF降解率为47.03%,ADF降解率为37.08%,NDL降解率为35.58%,与其它各组相比,差异显著(P<0.05)。     

Damages to feed proteins and their nutritional consequences: a review

The consequences of heat processing of feeds for sterilization and to destroy antinutritive substances can be beneficial as well as detrimental. Damages to feed proteins may be primarily explained by complex reactions between proteins and carbohydrates, by interactions between protein molecules and by oxidation. The chemical mechanisms and nutritional consequences of these reactions are reviewed.     

种植密度对光敏型高丹草营养成分及动态变化的影响

在黄土高原雨养农业区,以光敏型高丹草品种“大卡BMR”和“海牛”为材料,采用8.33、12.50和16.67万穴·hm^-2 3个低、中、高密度全膜平铺穴播种植,在植株不同生长阶段,测定了粗蛋白(CP)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、总可消化养分(TDN)和糖锤度(BX)含量,以研究光敏型高丹草在当地的最佳种植密度和收获时期。结果表明:生长发育进程在植株营养形成过程中占主导地位。在品种间,两品种生长前期CP含量差异较大(P<0.05);“大卡BMR”的NDF、ADF和BX整体低于“海牛”,TDN含量高于“海牛”。密度对营养成分有影响,CP含量随密度的增大有所降低;密度对BX含量前期影响较大(P<0.05),中后期影响不明显(P>0.05);在全生长期内NDF和ADF含量整体上高密度处理明显低于(P<0.05)低密度处理;密度对TDN含量影响明显(P<0.05),生长后期(出苗后126~140 d)依次均为高密度>中密度>低密度。营养成分和产量的动态变化表现为,两品种随生长发育进程的延长,CP含量均呈逐渐下降的变化趋势,BX均呈逐渐上升的变化趋势,NDF和ADF含量均呈“升—降—升”的变化趋势,TDN含量均呈“降—升—降”的变化趋势;在出苗后126~140 d,干物质产量仍在上升,CP和TDN产量平稳,TDN的含量处于下降趋势。这种动态变化为北方不抽穗或能抽穗不能成熟的光敏型高丹草最佳刈割期的决策提供了重要依据。从饲草生产角度考虑,在春播一茬青贮收割模式下,当地以“大卡BMR”品种较好,种植密度以每公顷12.50万穴较好,两品种均在出苗后126~140 d(9月上中旬,大卡BMR处于抽穗期、海牛处于开花期)刈割最佳。     

紫色土区3种草本植物根系特征及改土培肥效应

为探讨紫色土区草本植物根系的改土培肥效应,选取已种植3年(2011-2013年)的水土保持常用草类紫花苜蓿、狗牙根和香根草为目标物种,分0~10 cm,10~20 cm,20~30 cm土层采集根系和土壤样品,WinRHIZO(Pro.2004c)根系分析系统测定根系指标,常规方法测定土壤理化性质。结果表明:所有土层,香根草的各项根系指标均较优,尤其是根长密度和根表面积密度(最大均值分别为13.46 cm/cm³和5.75 cm²/cm³),紫花苜蓿则总体上的根重密度最好(最小均值为18.10 mg/cm³);定植3年,这3种草本植物并未对试验区紫色土的机械组成产生显著影响,但在数值上草本区有粗颗粒减少、细颗粒增多的趋势;多数草本植物对多个土层的土壤有机质和速效钾产生显著影响(有机质增加,速效钾亏损),而对土壤全氮、碱解氮、总磷、有效磷和全钾的影响却很微弱;所有草本区的全钾含量较高3.93~4.83 g/kg,却在几乎所有土层出现速效钾的亏损,尤其是紫花苜蓿区最大亏损量达20.24 mg/kg;相关分析中,所有土壤养分与全部或部分根系指标呈现显著或极显著相关(最大相关系数为0.833)。     

Simulated economic consequences of foot-and-mouth disease epidemics and their public control in France

The efficient management of foot-and-mouth disease (FMD) epidemics in France was examined through a simulation model which combines epidemiological and economic modules. From the reactions of the importing countries in terms of the products subject to import bans and the regionalization commitments, the economic module assesses the financial consequences of FMD outbreaks borne not only by the breeding sector but also by the other economic sectors on regional and national levels. Among the control options for FMD, the strategy of stamping out infected herds and dangerous in-contact herds most often contributes to reducing the economic consequences of FMD epidemics. Implementing a campaign of emergency vaccination is socially optimal if the additional export losses associated with the delay of slaughtering the vaccinated animals are offset by the gains of reducing the duration of the FMD epidemic. The importance of reducing as much as possible the total duration of the import bans is stressed by the estimated cost of an extra week of import bans. The optimal control strategy was unaffected by the introduction of stochastic parameters.     

老芒麦衰老过程中叶片叶绿素和光合作用变化特征及对养分的响应

试验以青藏高原青海省高寒草地中广泛分布和退化草地补播改良中的常用牧草品种-青牧1号老芒麦为研究对象,分析老芒麦衰老过程中叶片叶绿素和光合作用变化特征及对养分的响应。在青藏高原东北部,青海湖湖东地区设置1~6龄老芒麦自然生长田,6龄老芒麦施肥田和老芒麦连续施肥田（6年）3个处理。从2015年开始,每年5月进行老芒麦种植,播量2.25 g·m^-2,行距30 cm,小区面积15 m² （3 m×5 m）。采用KONICA MINOLTA, INC公司的SPAD分析仪,每个处理随机选取10株健康植株,从旗叶开始从上往下依次测定3片叶子的叶绿素相对含量。采用LI-COR公司的LI-6400XT便携式光合作用测量系统,在老芒麦开花期（7月底-8月初）,选择天气晴朗早上10：30-11：30,随机选取5株健康植株对其旗叶进行测量。结果表明：3龄时老芒麦叶片叶绿素相对含量出现降低趋势,6龄时老芒麦叶片出现了逆向衰老现象;随着老芒麦年龄增加,旗叶净光合速率持续降低,而胞间二氧化碳浓度呈上升趋势,气孔导度和蒸腾速率从3龄开始显著降低,且3~6龄间无显著差异;青牧1号老芒麦6龄田,氮肥和磷肥施入普遍提高老芒麦叶片叶绿素相对含量,且不同部位叶片叶绿素相对含量（33.30%~48.23%）均显著高于对照组（27.05%~30.72%）,叶片逆向衰老现象在高氮处理下得到缓解,氮肥和磷肥施入普遍提高老芒麦叶片净光合速率,N（60 kg·hm^-2）处理下叶片净光合速率最高（10.77 μmol·m^-2·s^-1）;青牧1号老芒麦在连续施肥6年处理下,低氮（45 kg·hm^-2）施肥下叶片叶绿素相对含量较高,磷肥对保持老芒麦叶片叶绿素相对含量效果不显著;中度氮肥（60 kg·hm^-2）,同时配合磷肥添加长期施入,可有效维持高龄老芒麦叶片的光合效率。