青海扁茎早熟禾混播草地生产性能与种间关系的研究

为了探究早熟禾混播草地种间关系与生产特征,使用‘青海’中华羊茅（Festuca sinensis ‘Qinghai’）、'青牧1号’老芒麦（Elymus sibiricus ‘Qingmu No.1’）、‘同德’小花碱茅（Puccinellia tenuiflora ‘Tongde’）分别与‘青海’扁茎早熟禾（Poa pratensis var. anceps Gaund.‘Qinghai’）混播,在海北州西海镇开展了植株形态特征、生物量积累和分配、混播草地养分特征等研究。结果表明：使用老芒麦与早熟禾混播具有较高的生产性能。该处理相较于老芒麦单播草地的粗蛋白与总磷含量,分别提高7.51%与14.50%。相对饲用价值较早熟禾单播草地提高34.12%。因此,为解决青海扁茎早熟禾单播草地生产力不足的问题可以选用老芒麦与早熟禾进行混播。使用碱茅与早熟禾混播具有较高的种间相容性,因此碱茅与早熟禾混播具有较高的群落稳定性与产量稳定性。选用碱茅与早熟禾进行混播可以用于建植以生态治理为目的的混播草地。     

浅析发酵乳霉菌零星污染来源及控制方法

霉菌在自然环境中普遍存在,而且以孢子形态随空气、水等媒介进行扩散。对食品原辅料及生产环境均可造成污染,是造成发酵乳变质的主要原因。发酵乳作为保质期较短且需冷链储运、销售的产品,零星的霉菌污染不会引起食品安全问题,但由于部分销售终端及三四线市场冷链运输缺失,造成霉菌生长,发酵乳呈现明显霉斑,导致消费者体验差,给企业品牌造成极坏影响,也影响了食品安全。本文概述了发酵乳中来自原辅料、环境、水中霉菌零星污染来源、验证方法以及相应控制措施,以期为发酵乳中霉菌控制提供参考。     

Betaine Alleviates Heat Stress-Induced Hepatic and Mitochondrial Oxidative Damage in Broilers

The aim of this study was to evaluate the effects of dietary betaine (BET) on growth performance, redox state, and related gene expression in broilers under heat stress (HS). A total of 144 21-day-old male broiler chickens with similar body weights were assigned randomly to three treatments with six replicates (eight chickens per replicate cage). Broilers in the control (CON) group were kept at thermoneutral (TN, 22±1°C) conditions and fed a basal diet until they were 42 days of age. Broilers in the other two groups (defined as HS and HS + BET) were exposed to HS (34±1°C, 8 h/day) and fed the basal diet without or with 1000 mg/kg BET, respectively. Rectal and cockscomb temperature of broilers was increased (P<0.05) in HS and HS + BET groups compared with the CON group, whereas there was no difference between HS and HS + BET groups. Dietary BET supplementation restored (P<0.05) average daily gain (ADG) and average daily feed intake (ADFI) of broilers and reversed (P<0.05) the increase in serum alanine transaminase (ALT) activity and malondialdehyde (MDA) content in the liver tissue of broilers under HS. The HS + BET group had higher (P<0.05) activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) in the liver tissue and mitochondria than the HS group, and the same pattern was observed for glutathione (GSH) and GSH/glutathione disulphide (GSSG) in the liver tissue. The decreased mRNA levels of GPX1 and uncoupling protein (UCP) in the liver induced by HS were restored by BET supplementation. In conclusion, dietary BET supplementation can alleviate HS-induced hepatic and mitochondrial oxidative damage of broilers by regulating mRNA expressions of GPX1 and UCP.     

乳酸菌噬菌体的分离及生物学特性鉴定

为了解乳酸菌噬菌体的生物学特性,并为制定乳酸菌发酵生产过程中噬菌体污染的防控措施提供试验数据和参考,本研究通过斑点试验和双层琼脂平板法,以干酪乳杆菌（L. casei） ATCC 393、戊糖乳杆菌（L. pentosus） KLDS 1.0413、短小乳杆菌（L. brevis） ATCC 367为指示菌从乳制品、泡菜样品中分离乳酸菌噬菌体,通过透射电镜观察噬菌体形态,噬菌体基因组限制性内切酶作用分析其包装机制,并进行宿主范围和一步生长曲线的测定,SDS-PAGE分析噬菌体结构蛋白,对获得的噬菌体进行生物学特性鉴定。结果显示,分离获得3株烈性乳酸菌噬菌体,依次命名为Lc、Lpen和Lbre。电镜结果显示,噬菌体Lc、Lpen均由多面体头部和非收缩性尾部组成,而噬菌体Lbre由多面体头部和收缩性尾部组成。根据形态学分析,Lc和Lpen属于长尾噬菌体科（Siphoviridae）,B1类,Lbre属于肌尾噬菌体科（Myoviridae）,A1类。噬菌体基因组经限制性内切酶作用后,核酸电泳结果显示,噬菌体Lc、Lpen基因组均为异质平末端,其包装机制属满头包装,即pac-型,而Lbre含有黏性末端,其包装机制属于cos-型。宿主范围测定结果显示,噬菌体Lc、Lbre对宿主专一,而Lpen宿主谱较广。一步生长曲线显示,噬菌体Lc、Lpen和Lbre潜伏期分别为60、45和150 min,裂解期分别为45、90和105 min,裂解量分别为47、24和30 PFU/cell。SDS-PAGE分析显示,噬菌体Lc结构蛋白有7个,主要结构蛋白分子质量约为50 ku;噬菌体Lpen和Lbre结构蛋白均有5个,主要结构蛋白分子质量分别约为55和50 ku。综上,本研究分离获得3株乳酸菌烈性噬菌体,并对其主要生物学特性进行鉴定,对了解乳酸菌噬菌体及后续乳酸菌噬菌体污染的防治提供了试验数据和理论依据。     

人工养殖西伯利亚狍肠道微生物组成的雌雄差异

肠道微生物是一个复杂的生态系统,与宿主的健康、疾病以及其他因素有着密切的关系。目前,关于肠道菌群结构和功能的研究较多,但是对西伯利亚狍肠道菌群的研究还未见报道。西伯利亚狍(Capreolus pygargus)属于反刍动物,有独特的消化特性和微生物群来帮助它们适应高纤维的食物。本研究利用高通量测序技术在Illumina MiSeq平台上对14只狍肠道微生物进行16S rRNA基因分析。结果表明:个体样本中门类组成的差异,雌性个体JY3和雄性个体JY9除Firmicutes,Bacteroidetes,Proteobacteria这3类菌群外,其他门类菌群所占比例都很低。在科水平上,雌性个体中Ruminococcaceae在JY7和JY13肠道内含量相对较少,Bacteroidaceae在JY7,JY10和JY13中含量较高。雄性个体中Ruminococcaceae在JY11和JY14肠道内含量较少,Prevotellaceae在JY4中含量较少。在属水平上,雌性个体特有的菌属为Roseburia,Alloprevotella,Lachnospiraceae_incertae_sedis和Coprococcus;雄性个体特有的菌属为Fusobacterium,Succiniclasticum,Streptococcus和Clostridium sensu stricto。Alpha多样性分析表明,Ace指数范围2128.93—772.98,Chao1指数范围2128.89—785.27,Shannon指数范围5.44—3.78,Simpson指数范围0.07—0.01。在不同物种分类水平上,雌雄狍肠道内的优势菌群有些不同。PCoA(principal co-ordinates analysis)分析显示,狍样本几乎混在一起,没有明显差异。     

Effects of dietary supplementation of nucleotides from late gestation to lactation on the performance and oxidative stress status of sows and their offspring

Increased metabolic burdens in breeding sows, which are induced by elevated systemic oxidative stress, could increase the need for nucleotides to repair lymphocyte DNA damage; however, de novo synthesis of nucleotides may be insufficient to cover this increased need. This study investigated the effects of dietary nucleotides on milk composition, oxidative stress status, and the reproductive and lactational performance of sows. Forty multiparous sows were assigned to 2 dietary treatments (Control group, and 1 g/kg Nucleotides group) based on a randomized complete block design using their BW at 85 d of gestation as a block. Sows from 2 groups were fed a restricted diet during gestation and ad libitum during lactation. The experiment lasted from 85 d of gestation to 21 d of lactation. The reproductive performance of sows and the growth performance of suckling piglets were measured. Oxidative stress parameters and milk components were also analysed. Data were analyzed using contrasts in the MIXED procedure of SAS. Sows in the Nucleotides group consumed more feed during the first week (P < 0.01) and from 1 to 21 d (P < 0.05) of lactation than those in Control group. Correspondingly, the litter weight gain of piglets showed a tendency to increase from cross-fostering to 9 d (P = 0.09) and from cross-fostering to 20 d (P = 0.10) in the Nucleotides group relative to the Control group. Additionally, the Nucleotides group was higher (P < 0.01) than the Control group in the concentrations of uridine 5''monophosphate, guanosine 5''monophosphate, inosine 5''monophosphate, adenosine 5''monophosphate and total nucleotides in milk. Furthermore, the Nucleotides group was higher (P < 0.01) than the Control group in the serum levels of total antioxidant capacity (P < 0.01) for sows at 109 d of gestation and glutathione peroxidase for weaning piglets, but lower at the levels of thiobarbituric acid-reactive substances (P < 0.05) in serum of weaning piglets. This study indicated that maternal dietary nucleotides could promote piglet growth, probably due to the higher lactational feed intake and higher concentration of nucleotides in the milk of sows, and lower oxidative stress for both sows and piglets.     

湖南洋泉水库调度的最优气候决策方法探讨

充分利用气候资源作好水库水位（量）调度、提高水库在抗旱和发电中的经济效益,是当今水库调度决策亟待解决的一个重要课题.本文根据气象经济学原理,运用连续函数求极值方法,利用洋泉水库有关经济参数,建立水库气候最优调度决策,在水库的实际调度中应用,可取得明显的社会经济效益.     

畜牧工程技术的跃进与反思

近十年来,集约化畜牧生产在中国的一些城市郊区有了很大发展,同时推动了畜牧工程技术的进展。这些工作表明,中国的畜牧工程技术人员已经具备了设计、建造畜牧工程与设备的能力。中国人多地少,资金与能源紧缺,发展以高投入、高能耗、精饲料型为特点的全封闭、高密度饲养方式显然不符合中国国情,而只能走适合自己的道路。在企业中任何工程措施的采用,所花代价必须由其在生产中的经济效益所补偿。在任何情况下衡量畜牧生产效益只能根据动物的生产性能,不能根据生产单位的机械化水平。在城市郊区不顾环境的承受能力,过分追求城市肉、蛋、奶自给,由于大量家畜粪尿得不到妥善处理,将构成严重的威胁。总之,中国畜牧工程的发展必须从中国国情出发,走农牧结合的道路。     

台阶式溢洪道消能规律

为探讨台阶式溢洪道消能特性及水流的紊乱特性规律,将台阶式溢洪道与对应光滑溢洪道对比研究,通过试验数据计算出台阶式溢洪道消能率、阶顶断面弗劳德数,试算求出对应光滑溢洪道水力参数,用台阶式溢洪道消能率减去对应光滑溢洪道消能率得到相对消能率,光滑溢洪道断面弗劳德数减去对应台阶式溢洪道阶顶断面弗劳德数得到相对弗劳德数.两水力参数反映了台阶式溢洪道相对光滑溢洪道对消杀能量大小及水流紊乱剧烈程度.通过对26.57°,32.01°,33.69°,38.66°,51.3°这5组不同坡度,1.43~6.67 cm台阶高度的21组模型试验研究,探讨了相对消能率和相对弗劳德数之间关系,结果表明相对弗劳德数和相对消能率沿程呈线性关系,相关系数为0.993 7~0.999 5.且相同相对弗劳德数,单宽流量大对应相对消能率也大;台阶高度变化对直线关系影响很小;坡度对直线关系影响复杂,较小坡度同一单宽流量,坡度越大相对消能率越小,坡度较大时同一单宽流量,坡度大对应相对消能率大.相对消能率和相对弗劳德数的直线规律体现出台阶式溢洪道独特的水力特性,为探究其消能机理提供了重要依据.     

基于ZigBee的寒地水稻温室大棚智能控制系统设计

针对我国北方寒地水稻育秧大棚的结构特点,设计并开发了一套基于ZigBee的智能控制系统,并构建了该系统的星型网络,用以实现将传感器采集到的数据进行无线传输的功能。系统进行数据采集的模块分别采用AT89S52单片机、数字式空气温湿度传感器DB420、数字式土壤温度传感器DS18B20和数字式土壤水分传感器SM2802M,用这些模块来监测空气中的温湿度、土壤温度以及土壤水分等,将监测到的数据通过JM12864F显示出来。这些采集模块还可以监测到大棚内的空气温湿度、土壤温度、土壤水分含量等实时信息,并对这些信息进行分析处理,将分析处理的结果发送到用户手中,达到远程监控的目的。