山羊胚胎分割及同卵双生试验

选择山羊晚期桑椹胚、囊胚、孵出囊胚和孵出增大胚泡,用简化分割法二分。将19对裸半胚移植于18只受体羊,结果有12只妊娠,其中两只胚胎消失,两只流产,其余8只足月分娩,共产半胚羔11只。晚期桑椹胚、囊胚、孵出囊胚和孵出增大胚泡各组的半胚发育为羔羊的发育率分别为12.5％(1/8)、20％(2/10)、25％(3/12)和62.5％(5/8)。前三组均未获得同卵双生羔羊。在第四组,将4对裸半胚移植于4只受体,有3只妊娠,足月分娩半胚羔5只,其中两对为同卵双生。本研究证明,对称分割山羊孵出增大胚泡,不仅其半胚在体内仍可继续发育形成正常胎儿,而且不装透明带移植其裸半胚,仍能获得较高的同卵双生率。山羊孵出增大胚泡更适宜用简化分割法分割。     

酵母菌生长最适条件和最佳菌种的探讨

利用食品工业生产过程中排出的大量废水,培养酵母菌可提高原料的利用率,缓解蛋白质饲料资源的不足,经利用后的废水大大净化,减少了环境污染。酵母菌作为单细胞生物,其蛋白质含量很高,含有８～１２种氨基酸,必需氨基酸含量也很高,富含脂肪和维生素,特别是Ｂ族维生素多达９种。利用食品工业废水培养酵母菌制成饲料,对发展我国畜牧业、饲料工业有重大的社会经济意义。基于此,我们通过大量试验,尽可能准确地得出了酵母菌生长的最适条件和最佳菌种,为推广工业化大规模生产提供依据。１材料与方法１．１材料１．１．１菌种　白地霉Ａ…     

祁连山黑河上游不同退化草地有机碳和酶活性分布特征

为揭示草地退化过程中土壤有机碳和酶活性的分布特征及相关性,在祁连山黑河上游俄博岭区域的高山灌丛草甸土上,根据草地退化程度,划分了未退化草地、轻度退化草地、中度退化草地、重度退化草地,采用野外采样室内分析方法,研究了不同退化草地土壤有机碳和酶活性的分布特征。结果表明：4种退化草地0～60 cm土层有机碳的含量、密度、储量,以及土壤酶活性变化顺序为：未退化草地>轻度退化草地>中度退化草地>重度退化草地;4种退化草地（从轻到重）0～10 cm土层有机碳密度是50～60 cm土层有机碳密度的1.78倍、1.98倍、1.87倍和2.00倍,说明土壤有机碳密度在表层具有很强的表聚性;4种退化草地不同土层有机碳的含量、密度和储量,以及土壤酶活性均随着土壤剖面垂直深度的增加而递减;4种退化草地土壤有机碳含量与有机碳密度、土壤酶活性成显著正相关关系。     

基于VG-PENG收缩特征曲线与收缩各向异性的裂隙率估算模型

为量化农田裂隙发育程度,考虑脱湿过程中土壤孔隙在基质域、沉降域和裂隙域间转化,该研究提出基于土壤收缩特征和收缩各向异性的裂隙体积比率(裂隙率)关于含水率的预测模型.该模型包括3个子模型:改进VG型式的基质域收缩特征VG-PENG模型,描述收缩各向异性的几何因子Logistic模型,基于上述VG-PENG收缩特征模型和几...     

昆虫嗅觉在监测物质开发上的应用

本文对昆虫嗅觉传导信息化合物的机理在监测物质开发方面的应用前景进行了综述。首先介绍了参与昆虫嗅觉传导的多种蛋白组分、关键组分OBPs和Ors缺失后对昆虫行为的影响;其次对昆虫嗅觉及其关键组分在害虫监测仪器的开发和高效诱集物质研发上的应用进行了阐述,以期提高害虫监测水平。     

“中国春”小麦不同缺体的RAPD分析

利用ＰＣＲ－９０Ａ型ＤＮＡ扩增仪，对７个中国春小麦缺体核ＤＮＡ进行了扩增。结果显示，中国春小麦缺体核ＤＮＡ的ＲＡＰＤ产物可分为二种类型：（１）所有供试材料均能扩增出的片段，代表了核ＤＮＡ在进化上的保守性。有一个引物检测到这类片段。（２）全部供试材料间存在的差异片段，这类片段是用来基因定位的主要依据。另外，建立中国春小麦缺体系统的ＲＡＰＤ指纹图谱对研究小麦的系统进化也将有重要意义     

Potential protective effects of thiamine supplementation on the ruminal epithelium damage during subacute ruminal acidosis

In ruminants, the ruminal epithelium not only has the function of absorbing nutrients but also is an important tissue to prevent harmful substances in the rumen from entering the blood circulation. Thus, the normal function of ruminal epithelium is critical for ruminants. However, subacute ruminal acidosis induced by high-concentrate diets often damages the barrier function of ruminal epithelium in ruminants. Recently, many studies have shown that dietary supplementation with thiamine is an effective method to alleviate subacute ruminal acidosis. In order to provide theoretical reference for the in-depth study of subacute ruminal acidosis and the application of thiamine in the future, this review introduces the effects of subacute ruminal acidosis on morphological structure, inflammatory response, and tight junction of ruminal epithelium. In addition, this paper summarizes the role of thiamine in maintaining ruminal epithelial function of ruminants during subacute ruminal acidosis challenge.     

新冠肺炎疫情与猪肉价格波动初探

基于2020年3月-2020年10月猪肉价格及新冠肺炎疫情指数,借助VAR模型,定量研究新冠肺炎疫情对于猪肉价格的影响。研究结果表明:新冠肺炎疫情对猪肉价格存在影响,促使猪肉价格上涨,在此基础上文章提出相应措施。     

Green tea polyphenols supplementation alters immunometabolism and oxidative stress in dairy cows with hyperketonemia

Peripartal cows often experience negative energy balance, and are therefore prone to suffering from metabolic diseases such as hyperketonemia, which causes financial losses in dairy farms. This study aimed to investigate the effect of green tea polyphenol (GTP) supplementation during the periparturient period on production performance, oxidative stress and immunometabolism in dairy cows with hyperketonemia. One hundred Holstein cows were assigned to GTP (0.2 g/kg DM; n = 50) or control (without GTP; n = 50) group based on body weight, previous milk yield, and parity on d 15 before expected parturition. Subsequently, 10 cows with hyperketonemia were selected from each group, according to blood β-hydroxybutyric acid (BHBA) concentration between 1.2 and 2.9 mmol/L from 2 to 3 d postpartum. All cows were fed a close-up diet and a lactation diet with or without GTP supply from 15 d prepartum until 30 d postpartum. Milk and blood samples were obtained from 20 cows selected with hyperketonemia on 10, 20, and 30 d postpartum. Compared with control cows, greater milk yield and lower somatic cell count were observed in GTP cows. The GTP group had lower concentrations of BHBA, free fatty acids, cholesterol, triglyceride, reactive oxygen species, malondialdehyde, and hydrogen peroxide, greater concentrations of glucose, lower activities of aspartate aminotransferase, alanine aminotransferase, and glutamyl transpeptidase, alongside greater activities of superoxide dismutase, glutathione peroxidase, and total antioxidant capacity. Additionally, GTP supplementation up-regulated concentrations of interleukin-6 and interleukin-10, but down-regulated concentrations of tumor necrosis factor-α, interleukin-1β, interleukin-2, interleukin-8, and interferon-γ in plasma. Greater concentrations of plasma immunoglobulin G were also detected in the GTP group. Overall, the data suggested that GTP supplementation from 15 d prepartum to 30 d postpartum improved the milk yield and health status in cows with hyperketonemia during early lactation.     

烟草田间起垄机作业适应性研究

对开沟式和盒式的1WG-6.3型自走式小型起垄机进行田间试验,并对其作业效益、作业效率及作业效果等指标进行测量及性能分析对比。结果表明:盒式起垄机每公顷平均油耗较低,作业效率较高,稳定性好,起垄效果较好,能满足烤烟种植起垄效果的农艺要求;开沟式起垄机能满足烤烟种植垄底宽、垄高的农艺要求,但不能满足烤烟种植垄基宽的农艺要求,且每公顷平均油耗较高,作业效率较低,稳定性较差,垄形一般。因此,盒式起垄机更能适应烟草田间起垄作业。