Dietary fiber in a low-protein diet during gestation affects nitrogen excretion in primiparous gilts,with possible influences from the gut microbiota

We investigated the effects of dietary fiber (DF) supplementation in normal or low crude protein (CP) diets on reproductive performance and nitrogen (N) utilization in primiparous gilts. In total, 77 Landrace × Yorkshire pregnant gilts were randomly allocated to four dietary treatments in a 2 × 2 factorial design. The groups comprised 1) equal intake of normal CP (12.82% and 0.61% total lysine), 2) low CP (LP) (10.53% and 0.61% total lysine), and 3) with or 4) without DF supplementation (cellulose, inulin, and pectin in a 34:10:1 ratio). A low-protein diet during gestation significantly reduced daily weight gain from days 91 to 110 of pregnancy (−162.5 g/d, P = 0.004). From N balance trials conducted at days 35 to 38, 65 to 68, and 95 to 98 of pregnancy, DF addition increased fecal N excretion at days 65 to 68 (+24.1%) and 95 to 98 (+13.8%) of pregnancy (P < 0.05) but reduced urinary N excretion (P < 0.05), resulting in greater N retention at each gestational stage. DF increased fecal microbial protein levels and excretion during gestation. An LP diet also reduced urinary N excretion at different gestational stages. An in vitro fermentation trial on culture media with nonprotein N urea and ammonium bicarbonate (NH₄HCO₃) as the only N sources revealed that microbiota derived from feces of gestating gilts fed the high DF diet exhibited a greater capacity to convert nonprotein N to microbial protein. Microbial fecal diversity, as measured by 16S rRNA sequencing, revealed significant changes from DF but not CP diets. Gilts fed an LP diet had a higher number of stillbirths (+0.83 per litter, P = 0.046) and a lower piglet birth weight (1.52 vs. 1.37 kg, P = 0.006), regardless of DF levels. Collectively, DF supplementation to gestation diets shifted N excretion from urine to feces in the form of microbial protein, suggesting that the microbiota had a putative role in controlling N utilization from DF. Additionally, a low-protein diet during gestation negatively affected the litter performance of gilts.     

Sulfadiazine pharmacokinetics in grass carp (Ctenopharyngodon idellus) receiving oral and intravenous administrations

This study aimed to examine the bioavailability (BA) and pharmacokinetic (PK) characteristics of sulfadiazine (SDZ) in grass carp (Ctenopharyngodon idellus) after oral and intravenous administrations. Blood samples were collected at predetermined time points of 0.083, 0.17, 0.5, 1, 2, 4, 8, 16, 24, 48, 72, and 96 hr (n = 6). The samples were extracted and purified by organic reagents and determined by the ultra‐performance liquid chromatography. The software named 3P97 was used to calculate relevant PK parameters. The results demonstrated that the concentration–time profile of SDZ was best described by a one‐compartmental open model with first‐order absorption after a single oral dose. The main PK parameters of the absorption rate constant (K_α), the absorption half‐life (t_{1/2 Kα}), the elimination rate constant (K_e), the elimination half‐life (t_1/2Ke), and the area under concentration–time profile (AUC_0‐∞) were 0.3 1/h, 2.29 hr, 0.039 1/h, 17.64 hr, and 855.78 mg.h/L, respectively. Following intravenous administration, the concentration–time curve fitted to a two‐compartmental open model without absorption. The primary PK parameters of the distribution rate constant (α), the elimination rate constant (β), the distribution half‐life (t_1/2α), the elimination half‐life (t_1/2β), the apparent distribution volume (V_SS), the total clearance (CL), and AUC_0‐∞ were 9.62 1/hr, 0.039 1/hr, 0.072 hr, 17.71 hr, 0.33 L/kg, 0.013 L h^?1 kg^?1, and 386.23 mg.h/L, respectively. Finally, the BA was calculated to be 22.16%. Overall, this study will provide some fundamental information on PK properties in the development of a new formulation SDZ in the future and is partially beneficial for the appropriate usage of SDZ in aquaculture.     

基于UHPLC-QTOF-MS代谢组学方法筛选奶牛不同妊娠状态时的候选生物标志物

旨在筛选人工授精后第17天奶牛在不同妊娠状态时的候选生物标志物。本研究以宁夏某奶牛场体重为（550±50） kg,体况评分相近的经产（2~3胎次）健康荷斯坦奶牛为试验对象。同期发情后,在人工授精后第17天晨饲前对奶牛进行尾静脉采血,后期采用计步器和B超仪诊断出奶牛的妊娠状态。根据诊断结果将奶牛分为妊娠组（A组,n=12）和未妊娠返情组（B组,n=24）,将这两组血样进行代谢轮廓及代谢物变化分析。主成分分析（PCA）和正交偏最小二乘法-判别分析（OPLS-DA）结果显示,A、B两组血浆代谢轮廓均发生了明显变化,A、B两组之间共检测出8种ROC （Receiver operating characteristic curve）曲线下面积（area under the ROC curve,AUC）＞0.8的差异代谢物。丙氨酸-亮氨酸、甘氨酸、脯氨酸、L-正亮氨酸、DL-苯丙氨酸、肌氨酸、吡咯-2-羧酸和缬氨酸-蛋氨酸有望成为识别妊娠组（A组）和未妊娠返情组（B组）的差异代谢物。综上表明,血浆中的这8种代谢物有望成为奶牛妊娠识别阶段潜在的生物标志物,为配种早期妊娠识别提供新思路。     

Chitosan nanoparticles enhance developmental competence of in vitro-matured porcine oocytes

Oxidative stress is inevitable as it is derived from the handling, culturing, inherent metabolic activities and medium supplementation of embryos. This study was performed to investigate the protective effect of chitosan nanoparticles (CNPs) on oxidative damage in porcine oocytes. For this purpose, cumulus–oocyte complexes (COCs) derived from porcine slaughterhouse ovaries were exposed to different concentrations of CNPs (0, 10, 25 and 50 µg/ml) during in vitro maturation (IVM). Oocytes treated with 25 µg/ml CNPs showed significantly higher levels of GSH, along with a significant reduction in ROS levels compared to control, CNPs10 and CNPs50 groups. In parthenogenetic embryo production, the maturation rate was significantly higher in the CNPs25 group than that in the control and all other treated groups. In addition, when compared to the CNPs50 and control groups, CNPs25-treated oocytes showed significantly higher cleavage and blastocyst development rates. The highest concentration of CNPs reduced the total cell number and ratio of ICM: TE cells in parthenogenetic embryos, suggesting that there is a threshold where benefits are lost if exceeded. In cloned embryos, the CNPs25 group, as compared to all other treated groups, showed significantly higher maturation and cleavage rates. Furthermore, the blastocyst development rate in the CNPs25-treated group was significantly higher than that in the CNPs50-treated group, as was the total cell number. Moreover, we found that cloned embryos derived from the CNPs25-treated group showed significantly higher expression levels of Pou5f1, Dppa2, and Ndp52il genes, compared with those of the control and other treated groups. Our results demonstrated that 25 µg/ml CNPs treatment during IVM improves the developmental competence of porcine oocytes by reducing oxidative stress.     

计算机视觉技术在智慧羊场中的研究进展

智慧羊场具有科学化、标准化管理的优点,是羊场转型发展的趋势。计算机视觉技术是人工智能的核心,可以实现非接触性、自动化、实时监测羊的个体信息。本文总结并分析了计算机视觉在羊场的个体识别方法、行为识别方法、体尺与体重估测、疾病监测的研究现状,并指出计算机视觉在智慧羊场的进一步发展趋势。 [关键词] 计算机视觉|智慧羊场|个体识别|行为识别|体尺与体重估测|疾病监测     

金融管理对中小饲料企业融资难的影响及解决

我国饲料行业已从发展的快速增长期步入成熟期。当前,饲料企业数量众多,分布广泛,但不少饲料企业规模较小,市场竞争力弱,急需进行转型升级。由于中小饲料企业信用评级低,经营风险大,且资产抵押物少,导致企业融资渠道较为狭窄,融资成本高。融资难的问题已经成为了制约饲料企业发展、扩大企业规模、提升企业技术水平的瓶颈。金融管理作为提升企业管理水平、优化金融管理的重要手段,对帮助或解决中小饲料企业融资难有一定的效果。因此,本文以中小饲料企业融资难问题为切入点,通过分析金融管理对融资难的影响,归纳总结出当前中小饲料企业金融管理的问题和解决对策,为饲料行业转型升级提供理论参考。     

添加亚油酸条件下不同剂量硝酸钠对水牛瘤胃体外发酵脂肪酸组成及相关微生物数量的影响

为了探究添加亚油酸条件下不同剂量硝酸钠对水牛瘤胃体外发酵脂肪酸组成及相关微生物数量的影响,本试验选用3头装有永久性瘤胃瘘管的母水牛,以精粗比40∶60为底物进行瘤胃液体外发酵试验。试验组硝酸钠的浓度分别为1、2、3 mg·mL^-1,对照组不加硝酸钠,每组均添加0.25 mg·mL^-1的亚油酸,每组各5个重复。在体外培养3、6、9、12、24 h时测定产气量和甲烷产量,24 h结束培养,测定瘤胃体外发酵参数、脂肪酸含量及瘤胃微生物数量。结果表明：1）添加硝酸钠显著降低了总产气量和甲烷产量（P<0.05）;2）添加硝酸钠pH值和氨态氮（NH₃-N）含量显著升高（P<0.05）,异丁酸和异戊酸含量显著降低（P<0.05）,而对总挥发性脂肪酸（TVFA）含量无显著性影响（P>0.05）;3）添加1 mg·mL^-1硝酸钠,C18：2cis-9,trans-11、C18：2trans-10,cis-12含量和不饱和脂肪酸/饱和脂肪酸（UFA/SFA）显著高于其他组（P<0.05）,且C20：5n3 （EPA）含量显著高于添加3 mg·mL^-1硝酸钠组（P<0.05）,添加2 mg·mL^-1硝酸钠C22：6n3 （DHA）含量显著高于其他组（P<0.05）;4）添加硝酸钠组原虫数量显著低于对照组（P<0.05）,添加2、3 mg·mL^-1硝酸钠产甲烷菌数量显著低于添加1 mg·mL^-1硝酸钠组（P<0.05）,添加1 mg·mL^-1硝酸钠总细菌、真菌、溶纤维丁酸弧菌、蛋白分解丁酸弧菌、非典型丁酸弧菌、亨氏丁酸弧菌数量显著高于其他组（P<0.05）。由此可得,体外法添加1~3 mg·mL^-1硝酸钠和0.25 mg·mL^-1亚油酸在维持水牛TVFA含量不变的情况下显著降低了甲烷含量,且1 mg·mL^-1硝酸钠能促进亚油酸生成共轭亚油酸（CLA）,优化脂肪酸组成,并能增加大多数瘤胃微生物的数量。     

贵州锰矿废渣堆场重金属污染风险评价及草本植物重金属吸收特征

为明确锰矿废渣堆场重金属污染及优势草本植物重金属吸收特征,对贵州省典型锰矿废渣堆场的重金属污染风险进行了评价,并调查研究了锰矿废渣堆场草本植物的类群及重金属吸收特征。共采集优势草本植物18种,隶属11科18属,菊科和禾本科为优势科。对18种草本植物体地上部、地下部及其生长基质中Cr、Ni、Cu、Zn、Cd、Pb和Mn 7种重金属元素进行了测定,结果显示,锰矿废渣堆场重金属污染空间变异较大,Mn污染最严重,其次是Cd,属于Mn、Cd复合型污染。计算了草本植物对7种重金属元素的富集系数、转运系数,并对18种草本植物进行了聚类分析,综合分析了草本植物重金属吸收特征,结果显示,看麦娘对Cd富集系数达22.49,对Cd有较强的富集能力;五节芒、商陆对Cr、Ni具有较强的富集能力和转运能力;风毛菊和夏枯草对锰矿废渣区多种重金属均表现出较强的富集能力和转运能力。研究结果表明,锰矿废渣堆场主要为Mn和Cd污染,矿区本土自然生长的优势草本植物可作为生态修复的首选植物。     

松辽黑猪METTL23基因多态性及其与繁殖性状的关联分析

为探究松辽黑猪METTL23基因多态性及其与繁殖性状的关联性,试验选取178头松辽黑猪母猪为研究对象,利用Sanger直接测序法查找METTL23基因外显子1~5的单核苷酸多态性(SNP),使用SPSS 19.0软件分析METTL23基因SNP位点与松辽黑猪繁殖性状(总产仔数、产活仔数、断奶仔猪数、初生重、3周龄重、断奶重、乳头数)的关联性。结果显示,仅在松辽黑猪METTL23基因外显子4发现1个SNP位点,命名为A62G,在A62G位点上检测到3种基因型,分别是AA、AG和GG。GG和G分别为优势基因型和优势等位基因,且A62G位点处于Hardy-Weinberg平衡状态(P>0.05)。该位点的遗传纯合度(Ho)为0.6516,高于遗传杂合度(He,0.3484),说明其在松辽黑猪群体中的变异较小;多态信息含量(PIC)为0.2877,属于中度多态位点(0.25<PIC<0.5),说明该遗传标记能够提供一定量的遗传信息。关联分析结果表明,GG基因型个体总产仔数、产活仔数和断奶仔猪数均显著或极显著高于AA基因型个体(P<0.05;P<0.01),总产仔数还显著高于AG基因型个体(P<0.05);AG基因型个体断奶仔猪数显著高于AA基因型个体(P<0.05);初生重、3周龄重、断奶重、乳头数各基因型间差异均不显著(P>0.05)。综上所述,METTL23基因外显子4存在多态性位点A62G,该位点与松辽黑猪产仔数存在显著关联,可作为松辽黑猪产仔数的遗传标记,用于分子育种。     

我国农业机械化与城镇化关系的协整分析

在讨论我国农业机械化发展的内在机制以及与城镇化关系的基础上,运用协整分析方法建立时间序列数据模型,经过格兰杰因果关系检验,验证农业机械化与城镇化之间的长期稳定关系,进一步建立误差修正模型探讨这种稳定关系在长期内与短期内的动态变化特征,并预测我国2020年农业机械化发展水平。结果表明,在长期内,城镇化率增加一个单位农业机械化水平将提高1.09个单位。但是,农业机械化对当期城镇化的推进反应是滞后的,而是反映在长期趋势上。预测显示,2020年我国农业机械化水平将达到67.45%。