牦牛肉中稳定同位素指纹特征及影响因素

【目的】分析牦牛肉中稳定碳、氮、氢同位素组成,以及它们受地域、牧草和饮水的影响,为其产地溯源及真伪鉴别提供技术支撑。【方法】从青海省海北、海南、玉树3个不同地域采集牦牛肉、牧草及水样品,利用GPS定位采样地的经度、纬度及海拔高度,利用元素-稳定同位素比率质谱仪（EA-IRMS）分析样品中稳定碳、氮、氢同位素比率。【结果】牦牛脱脂肌肉、粗脂肪中的δ¹³C平均值分别为（-23.99±0.25）‰和（-28.77±0.50）‰;脱脂肌肉中的δ¹⁵N和δ²H平均值分别为（4.04±0.91）‰和（-107.99±11.08）‰。牦牛肉中δ¹³C、δ¹⁵N值主要受其食用的牧草影响,地域对牦牛肉中的δ¹³C值也有一定的影响,即牦牛肉中δ¹³C值有随海拔的增加而增加的趋势。青海省海北、海南、玉树3个地区牧草和水中的δ²H值均有极显著差异,牧草中δ2H值由高到低的顺序依次为海南＞海北＞玉树,水中δ²H值由高到低的顺序依次为海北＞海南＞玉树。牦牛肌肉中δ²H值由高到低的顺序依次为海南＞海北＞玉树,与牧草中δ2H值的地域变化顺序一致。说明牦牛肉中的δ²H值与牧草、饮水密切相关,均有随海拔升高而降低的趋势,且牧草对牦牛组织中氢同位素组成的影响可能大于水的影响,但这还需要进一步研究证实。【结论】牦牛肉中稳定同位素指纹与高海拔地区的牧草、饮水、地形密切相关,具有独特的指纹特征。     

中国和新西兰绵羊群体FABP4基因遗传特性比较分析

脂肪型脂肪酸结合蛋白（adipocyte fatty-acid binding protein,A-FABP）在家畜脂肪沉积中发挥重要作用,但在藏绵羊群体中的遗传特性和特异的作用机制尚不明确,研究不同生产方向绵羊品种的FABP4基因变异及分布有助于揭示藏绵羊独特的种质特性。应用PCR-SSCP（polymerase chain reaction-single strand conformation polymerase）和测序技术检测了中国和新西兰共10个绵羊群体（575只个体）FABP4基因编码区（外显子2和外显子3）的变异,并分析其连锁不平衡状态。结果表明,两多态区域共鉴定8处单核苷酸突变,两多态区域SNPs间呈弱连锁不平衡状态（D′=0.548,r2=0.119）,鉴定14种潜在的单体型。外显子2-内含子2区域A1为优势等位基因（38.4%）,A1B1为优势基因型;外显子3-内含子3区域B2为优势等位基因（48.3%）,A2B2为优势基因型。新西兰绵羊群体在两多态区域偏离Hardy-Weinberg平衡状态（P<0.01）,而藏绵羊处于Hardy-Weinberg平衡状态（P>0.05）。罗姆尼与派仑代群体基因型分布无显著差异（P>0.05）,美利奴与考力代群体基因型分布差异显著（P<0.05）。新西兰绵羊群体两多态区域均为高杂合度及高度多态,藏绵羊群体均为高纯合度及中度多态。聚类分析表明欧拉和甘伽羊、考力代和美利奴羊、罗姆尼和派仑代羊分别聚在一起。c.246+37A>G和c.348+298T>C位点多态性在藏绵羊和新西兰绵羊群体中分布差异较大,该两处SNPs可作为潜在的分子标记应用于藏绵羊肌内脂肪含量性状选育。     

Using balance of seasonal herbage supply and demand to inform sustainable grassland management on the Qinghai–Tibetan Plateau

To mitigate the impacts of grassland degradation on the Qinghai–Tibetan Plateau (QTP), in recent decades China has been implementing large-scale conservation programs and has invested about 42 billion CNY (7 billion USD). However, these programs are faced with major challenges involving trade-offs between ecological function, livestock production and income of pastoralists. Scientific assessments, as well as technical and policy issues, have not fully captured the complex ecological, social and economic dynamics of the challenges facing grassland management on the QTP. Pastoral livestock production on the QTP is characterized by imbalance in both quality and quantity between livestock seasonal nutrient requirements and herbage production, which forces pastoralists to keep larger numbers of livestock for longer periods, leading to overgrazing. To solve these problems, an integrated crop-livestock system is promoted to improve the efficiency of livestock production and conserve natural grassland as well for a sustainable system for the QTP.     

Interacting effects of yak dung deposition and litter quality on litter mass loss and nitrogen dynamics in Tibetan alpine grassland

The effects of grazing‐induced dung deposition on plant growth and soil attributes are well established, but little is known about dung effects on litter decomposition. Here, we tested effects of yak dung on litter decomposition and nutrient content in a Tibetan alpine meadow. We incubated litter of four common alpine meadow species using litter bags in the field. Two low‐quality species (Kobresia capillifolia and Elymus nutans) with low nitrogen (N), high C/N and Lignin/N, and two high‐quality species, (Saussurea nigrescens and Thermopsis lanceolata) were incubated in monoculture with and without dung addition. Mass loss of leaf litter, fibre fraction (cellulose, hemi‐cellulose and lignin), N and phosphorus (P) were measured after 6, 12 and 18 months of incubation in the field. Dung addition significantly increased decomposition constants for low‐quality litter species, but not for high‐quality litter species. Dung addition promoted cellulose and hemi‐cellulose loss, but lignin loss was not affected by dung addition, except after 12 months for high‐quality litter species. Dung reduced N immobilization after 6 months and did not affect subsequent release in low‐quality litter species, and promoted N release after 6 and 12 months in high‐quality litter species. Regardless of litter quality, dung increased P release after 6 and 12 months. Our results suggest grazing‐induced dung deposition may accelerate C and nutrient turnover, primarily through increasing the mass loss of low‐quality litter, P release from litter and N release from high‐quality litter. The mechanisms underlying the effects of dung deposition need to be clarified in future studies.     

青藏高原高寒湿地不同季节土壤理化性质对放牧模式的响应

本文分析了青藏高原东缘高寒湿地在全年放牧、冬季放牧和全年禁牧3种放牧模式下土壤理化性质的变化,探讨其在不同土层深度的变化及季节性动态。结果如下:1)沿着全年禁牧—冬季放牧—全年放牧3种放牧模式,土壤表层(0~15 cm)及下层(15~30 cm)的土壤含水量和有机碳含量显著减小。2)土壤含水量、有机碳、全氮、全磷和速效氮含量均随土层深度的增加而降低,而速效磷表现为无规律。3)3种放牧模式下表层土壤有机碳含量均为:9月>5月>7月;全氮和全磷含量一般都在9月份较高,而速效氮和速效磷含量9月份最低,每种放牧模式下它们之间的具体差异也不完全相同。4)除5月份,两个土层土壤全氮含量均与有机碳含量呈极显著正相关。综上,全年放牧模式加快了土壤中C、N、P的周转,使土壤养分输出量增加,进而导致土壤肥力下降,草地退化。     

放养过程中补饲对青海高原牦牛产肉能力及肉品质的影响

为研究补饲对放养牦牛产肉能力及肉品质的影响,试验选取12头在海北州天然放养的牦牛,随机分为2组,即无补饲处理组(对照组)和补饲处理组(补饲组),屠宰后测定2组牦牛8个分割部位的肉重量以及辣椒条、眼肉、外脊3个部位的肉品质指标.结果发现,补饲处理显著增加了牦牛优质部位里脊和眼肉的产肉量(P< 0.05),增产幅度分别达到了80%和100%.辣椒条、眼肉和外脊的加工性能会受到补饲处理的影响,持水能力有所下降,而嫩度却显著改善(P< 0.05).肉色不会受到补饲处理的显著影响(P >0.05).补饲处理不会显著影响辣椒条、眼肉、外脊的蛋白质含量(P >0.05),但却可显著提高辣椒条的脂肪含量(P< 0.05),并显著降低其水分含量(P< 0.05).结果表明,补饲可增加牦牛优质部位肉产量,并改善牦牛肉嫩度.     

日粮组成对成年牦牛消化和能量代谢的影响

在海拔3980m的果洛州大武乡对3头成年牦牛饲喂3种不同的日粮,按3×3拉丁方设计安排消化代谢试验,结果表明：（1）随日粮中精料比例的增加,粗蛋白的消化率逐渐升高,而其它各营养成分的消化率则逐渐降低,且日粮粗蛋白、粗灰分和能量消化率之间的差异显著（P〈0.05）,干物质和有机物质消化率之间的差异不显著（P〉0.05）;（2）能量代谢率和消化能转化为代谢能的效率之间的差异显著（P〈0.05）,且其平均转化效率为0.77;（3）钙、磷食入量之间的差异不显著（P〈0.05）,磷存留量随日粮中精料比例的增加而增加;钙存留量在B日粮下最大,B日粮显著高于A和C日粮。     

长角血蜱侵袭致藏獒"蜱麻痹"和巴贝斯虫感染的诊治

对卫辉市某2.5月龄的以后肢麻痹为特征的藏獒进行临床检查、血液涂片染色镜检、血液常规检测、蜱形态学观察和蜱种鉴定.结果表明:藏獒红细胞内有大量犬巴贝斯虫寄生,血液常规检查白细胞数升高,血红蛋白含量正常,感染蜱为长角血蜱.最终确诊为长角血蜱侵袭致藏獒"蜱麻痹"和巴贝斯虫感染.应用伊维茵素、血虫净等药物进行治疗,3 d后该...     

祁连县白藏羊选育技术研究

[目的]研究青海省祁连县白藏羊的品种特征。[方法]选取100只白藏羊为研究对象,对其产毛量、毛长、体重及体尺指数进行测定,并用SPSS软件进行相关性和回归性分析。[结果]除体重和毛长相关系数不显著外,其他指标间相关性均达到显著（P〈0.05）或极显著水平（P〈0.01）;多元回归分析表明,白藏羊体重和毛长呈消长关系。[结论]该研究为祁连县白藏羊选育方案的确定和完善提供了有益参考。