全方位入手实现无抗、替抗养猪

抗生素是由微生物(包括细菌、真菌、放线菌属)或高等动植物在生命过程中所产生的,具有抗病原体或其他活性的,一类次级代谢产物,能对抗在人或动物体内的致病菌等病原体,可治疗大多数细菌、立克次体、支原体、衣原体、螺旋体等微生物感染导致的疾病。现临床常用的抗生素有微生物培养液中提取物以及用化学方法合成或半合成的化合物,目前已知天然抗生素不下万种。     

乡村振兴背景下乡村生态旅游规划研究——以重庆市石柱县瓦屋村为例

在乡村振兴战略的引领下,乡村的发展日新月异,平衡乡村旅游发展与乡土环境保护是乡村发展的首要前提.在分析乡村旅游发展现状的基础上,总结出乡村生态旅游的规划原则,并以重庆市石柱县瓦屋村为实践案例,以生态为切入点,针对不同生态敏感度区域提出不同规划建设意见,最终实现生态旅游目标.     

遵义烟区不同海拔下植烟土壤细菌群落及影响因素分析

为探究不同海拔下植烟土壤细菌群落结构特征及影响细菌群落结构的主要因素,在贵州省遵义地区选择海拔800（ZL）、1000（ZS）和1200m（ZH）的3块植烟土壤,采用16S rRNA高通量测序法对植烟土壤微生物多样性进行分析。结果表明,ZL和ZH处理植烟土壤细菌α多样性均低于ZS处理;3个海拔下植烟土壤优势门为放线菌门（Actinobacteriota）、变形菌门（Proteobacteria）、绿弯菌门（Chloroflexi）和酸杆菌门（Acidobacteriota）,放线菌门的相对丰度以ZL处理最高,较ZH处理提高了34.22%;变形菌门表现则相反,ZH处理变形菌门丰度较ZL处理显著提高。绿弯菌门与酸杆菌门丰度在3个海拔处理中表现较为一致,均为ZS>ZL>ZH。聚类热图分析结果显示,土壤含水率和pH与Armatimonadota和蓝细菌门（Gyanobacteria）存在显著正相关关系,与变形菌门存在显著负相关关系;变形菌门、厚壁菌门（Firmicutes）和髌骨菌门（Patescibacteria）与土壤微生物量氮存在显著正相关关系,而与速效钾存在极显著负相关关系。     

何刚德《抚郡农产考略》农业经济思想初探

《抚郡农产考略》是清末江西有代表性的农学著作,不仅保存有抚州地区大量农产种类、栽培与加工技术等资料,还包含了大量的商品经济信息。作者何刚德已经认识到自给自足的自然经济会对生产有束缚作用,他在记载各类农产品时,提出“价值”的概念且用货币价格对其衡量,并深入揭示了农产品上市时间、供求、地理、交通条件等因素对价格的影响,进而寻求增值之道。何氏提倡多种经营,大力种植棉花、烟叶等经济作物,发挥柑橘、甘蔗等名优特产优势,促进农业的商品化生产。他还建议通过深加工的方式获取更高利润,并对未能引进西方的先进加工技术而感到惋惜。《抚郡农产考略》体现了中国近代官僚知识分子对农业经济转型的探索,具有重要的历史价值与现实意义。     

基于网络药理学分析黄芪防控猪繁殖与呼吸综合征的物质基础及靶点信息

为揭示黄芪防控猪繁殖与呼吸综合征(PRRS)的物质基础及靶点信息,采用网络药理学方法,从中药系统药理学数据库与分析平台(TCMSP)筛选黄芪的潜在活性成分、作用靶点,同时从比较毒理基因组学数据库(CTD)收集PRRS相关宿主基因,最后构建"活性成分-关键靶点"网络、蛋白互作网络,并进行GO功能和KEGG通路富集分析。结果显示,从黄芪筛选出的17个潜在活性成分中,有14个潜在活性成分共计65个基因靶点与PRRS相关宿主基因交叉,其中槲皮素、山奈酚、刺芒柄花素、异鼠李素等潜在活性成分可能对治疗PRRS有重要作用,TNF、IL8、TP53、IL6、IL10、IL1B、JUN等45个蛋白靶点间存在相互作用。此外,黄芪治疗PRRS的作用机制可能涉及细胞外间隙和胞浆等组分,并可能与炎症反应、细胞凋亡、T细胞受体信号通路等生物过程相关。本研究为临床应用黄芪及其提取物治疗PRRS奠定了理论基础。     

Effects of three methionine sources in diets on temporal B0AT1 and ASCT2 mRNA expression in different intestinal segments of cobia,Rachycentron canadum

A 4‐week feeding trial was conducted using five groups of hybrid grouper (61.15 ± 0.15 g) to explore the potential effects of three methionine (Met) sources. Five isonitrogenous and isolipidic diets were formulated that included a fishmeal (FM) diet; nonsupplemented (NS) diet; or NS diets with the addition of the L‐methionine (L‐Met), DL‐methionine (DL‐Met), or coated Met (Co‐Met) to obtain the same Met level as the FM diet. Fish were randomly distributed into sea cages (30 fish per cage). Weight gain and specific growth rate in the DL‐Met group and FM group were significantly higher than those in all other groups (p < .05). In the proximal and distal intestines, of the 20 gene and time combinations (10 per gene), there were 14 combinations (70%) in which there were no significant differences in gene expression levels between the FM and DL‐Met groups (p > .05). The main reason for the same growth effect between the DL‐Met and FM groups may be attributed to the synchronized absorption at most time points after feeding, which had similar expression patterns of B⁰AT1 and ASCT2 of the proximal and distal intestines between two groups.     

Effects of Altitude Change on Nutritional Quality and Elymus nutans Regularity in Qinghai-Tibet Plateau

In order to reveal the effects of different altitudes on the nutritional quality of wild forage in Qinghai-Tibet Plateau,this study used Elymus nutans as the tested plants to evaluate the changes of nutrient contents and the correlation between the nutrient contents and altitudes.Four sampling sites were set up at altitudes of 2 562,2 660,2 775 and 2 905 m with the vertical distance among each sampling point was about 100 m.The results showed that the crude protein,ash and phosphorus contents of Elymus nutans decreased significantly with an increase in altitudes.The crude protein contents decreased by 1.87 % with each 100 m increase in altitudes.The variation rule of crude protein contents with altitudes in the simulated curve was "y=–0.0187x+63.244 (R~2=0.9557)".The crude ash contents decreased by 1.77% with each 100 m increase in altitudes.The variation rule of crude ash contents with altitudes in the simulated curve was "y=–0.0177x+56.144 (R~2=0.978)".Neutral detergent fiber (NDF) and acid detergent fiber (ADF) showed an overall increasing trend with the increase of altitudes,but the most obvious increase was at 2 775 m.The contents of crude fat and Ca did not change regularly with altitudes.     

基于表型多样性构建向日葵核心种质

为鉴定评价我国向日葵（Helianthus annuus L.）种质资源在南方地区的表现，筛选构建向日葵核心种质，以422份向日葵种质为材料，在进行2年鉴定观察的基础上，采用描述性统计、相关性分析、主成分分析等方法对11个表型农艺性状进行分析评价。结果表明，原始群体的这些农艺性状具有较大的变异幅度，其变异系数（CV）为3.60%~83.32%，平均变异系数为20.93%，其中分枝株率（0%~62.5%）、单株粒重（9.70~232.35 g）、百粒重（4.60~14.92 g）、叶片数（14.40~48.38个）和株高（103.75~260.00 cm）变异幅度较大；性状间表现出显著的相关性，主成分分析表明，影响性状的4个主要成分解释了总方差的71.72%。采用QGAstation 2.0软件构建了72组核心种质候选群体，并根据均值差异百分数（MD）、方差差异百分率（VD），极差符合率（CR）和变异系数百分率（VR），获得组获得1组包含84份材料的最佳核心种质群体。聚类分析将84份核心资源分为5大类，与原群体相比，所选核心种质均值无显著差异，方差显著提高，能最大限度代表原始油葵种质资源保存和利用。