淮北地区氮肥群体最高生产力水稻钾素吸收利用特征

以淮北地区有代表性的34个中熟中粳品种为试材,设置7个氮肥水平(0、150.0、187.5、225.0、262.5、300.0、337.5 kg hm~(–2)),得出各品种的最高产量,将该最高产量定义为氮肥群体最高生产力。在此基础上,明确处于顶层水平(≥10.50 t hm~(–2))、高层水平(9.75~10.50 t hm~(–2))、中层水平(9.00~9.75 t hm~(–2))和底层水平(≤9.00 t hm~(–2))水稻品种的钾素积累、分配及转运特征。结果表明,4个生产力等级水稻品种地上部植株、茎鞘和叶片的含钾率在拔节期最高;抽穗期顶层水平品种的这3个参数高于其他3个等级的品种;穗部含钾率差异不显著。随着氮肥群体生产力等级的提高,钾素总积累量增多;拔节前底层水平钾素积累量最多,两年平均为120.56 kg hm~(–2),比例占50.56%,顶层水平为最少,两年平均为108.02 kg hm~(–2),比例占35.99%;拔节至抽穗期和抽穗至成熟期顶层水平钾素阶段积累量及比例显著高于其他3个等级。移栽至拔节期,钾素积累速率为中层底层高层顶层水平,拔节后则为顶层高层中层底层水平。叶片的钾素转运量及转运率明显高于茎鞘;顶层水平叶片的钾素转运量高于其他3个等级,高层水平叶片的转运率最高;穗部增加量随生产力等级的递增而变大;抽穗到成熟期,茎鞘、叶片对穗的钾素转运贡献率表现为底层最高,中层次之,顶层最低。4个等级水稻品种籽粒生产率和百千克籽粒吸钾量差异不显著;钾素偏生产力和钾收获指数均表现为顶层高层中层底层水平。总之,氮肥群体最高生产力越高,水稻中后期植株钾素积累量及器官对钾素的吸收利用效率越显著。抽穗后保持较高的钾素吸收利用及转运效率是高产水稻品种的重要特征。     

保定地区几个早熟苹果品种(系)生长观察

为筛选适宜保定地区栽植的早熟苹果品种,以嫁接在SH40中间砧上的不同早熟苹果品种(系)为试材,测定了不同品种(系)早熟苹果树体生长发育指标和果实品质。结果表明:除嘎啦早熟变异外,其他供试品种(系)树体生长较好,3年生时Xu2-7、Xu3-2树高330.0~352.5 cm,4年生时为394.0~417.5 cm,Xu3-2、藤牧1号、信浓红4年生为336.5~381.0 cm。4年生时,干径以Xu2-5最大;短枝、中枝、叶丛枝均以Xu2-5最多,长枝以Xu2-7最多,总枝量以Xu2-5最多;藤牧1号短枝所占比例最高(57.4%)。应用模糊综合评判法得出Xu2-5、Xu2-7、信浓红、藤牧1号果实品质较高。     

玉米青贮与花生秧配比对奶牛瘤胃中花生秧降解特性的影响

本试验旨在研究玉米青贮与花生秧配比对奶牛瘤胃中花生秧降解特性的影响。选择4头体重、生理状态、生产性能相近,装有永久瘤胃瘘管的中国荷斯坦奶牛,分别饲喂含有玉米青贮与花生秧不同配比的全混合日粮(TMR),3种TMR中玉米青贮与花生秧的干物质(DM)配比分别为3.9∶1.0(A组)、1.2∶1.0(B组)、0.4∶1.0(C组)。试验分3期进行,依次进行A、B、C组试验。每期预试15 d,采样期4 d;共57 d。采用尼龙袋瘤胃降解技术测定花生秧在奶牛瘤胃中DM、粗蛋白质(CP)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的72 h瘤胃降解率,并求得目标养分的动态降解参数及有效降解率。结果表明:1)花生秧的DM在瘤胃中有效降解率为56.49%~59.62%,CP为40.45%~47.36%,NDF为33.26%~35.20%,ADF为36.31%~37.45%。2)B组DM的有效降解率显著高于C组(P0.05),极显著高于A组(P0.01);B、C组的CP有效降解率显著高于A组(P0.05)。3)B、C组的NDF快速降解部分含量显著高于A组(P0.05);3种TMR对花生秧粗NDF和ADF有效降解率无显著影响(P0.05)。由此可见,花生秧具有较高的饲用价值。本试验条件下,玉米青贮与花生秧DM配比为1.2∶1.0时,可有效提高花生秧DM和CP的瘤胃降解率。     

产前和产后香味剂印迹训练对仔猪断奶后采食偏好的影响及其机理

仔猪断奶后受到心理、营养、环境等多方面的刺激,导致应激反应,影响仔猪的采食量。固体饲粮代替母乳是最大的应激源,通过在母猪饲粮中添加香味剂对仔猪产前和产后进行香味剂印迹训练,使仔猪逐渐喜欢这种气味,降低其对添加相同香味剂饲粮的应激反应,并对有相同气味的饲粮有采食偏好,从而提高仔猪的采食量。本文对产前和产后香味剂印迹训练对仔猪断奶后采食偏好的影响及其机理进行综述,为养猪业相关试验研究提供理论依据。     

Time-course comparison of pulmonary inflammation induced by intratracheal instillation of four different nickel oxide nanoparticles in male Fischer rats

Occupational exposure to nickel oxide (NiO) is an important cause of respiratory tract cancer. Toxicity is known to be associated with the dissociated component, i.e. nickel (II) ions. To address the relationship between physicochemical properties, including solubility in artificial lysosomal fluid, of NiO and time-course changes in the pulmonary response, we conducted an intratracheal instillation study in male Fischer rats using four different well-characterized NiO products, US3352 (NiO A), NovaWireNi01 (NiO B), I small particle (NiO C), and 637130 (NiO D). The NiOs were suspended in purified water and instilled once intratracheally into male F344 rats (12 weeks old) at 0 (vehicle control), 0.67, 2, and 6 mg/kg body weight. The animals were euthanized on days 3, 28, or 91 after instillation, and blood analysis, bronchoalveolar lavage fluid (BALF) testing, and histopathological examination were performed. The most soluble product, NiO B, caused the most severe systemic toxicity, leading to a high mortality rate, but the response was transient and surviving animals recovered. The second-most-soluble material, NiO D, and the third, NiO A, caused evident pulmonary inflammation, and the responses persisted for at least 91 days with collagen proliferation. In contrast, NiO C induced barely detectable inflammation in the BALF examination, and no marked changes were noted on histopathology. These results indicate that the early phase toxic potential of NiO products, but not the persistence of pulmonary inflammation, is associated with their solubility.     

Growth and morphologic response of rumen methanogenic archaea and bacteria to cashew nut shell liquid and its alkylphenol components

The growth and morphology of rumen methanogenic archaea (15 strains of 10 species in 5 genera, including 7 strains newly isolated in the present study) and bacteria (14 species in 12 genera) were investigated using unsupplemented in vitro pure cultures and cultures supplemented with cashew nut shell liquid (CNSL) and its phenolic compound components, anti-methanogenic agents for ruminant animals. Growth of most of the methanogens tested was inhibited by CNSL and alkylphenols at different concentrations ranging from 1.56 to 12.5 μg/ml. Of the alkylphenols tested, anacardic acid exhibited the most potent growth inhibition. Three gram-negative bacterial species involved in propionate production were resistant to CNSL and alkylphenols (>50 μg/ml). All the methanogens and bacteria that were sensitive to CNSL and alkylphenols exhibited altered morphology; disruption of the cell surface was notable, possibly due to surfactant activity of the tested materials. Cells division was inhibited in some organisms, with cell elongation and unclear septum formation observed. These results indicate that CNSL and alkylphenols, particularly anacardic acid, inhibit both rumen bacteria and methanogens in a selective manner, which could help mitigate rumen methane generation.     

Effects of extracerebral dopamine on salsolinol‐ or thyrotropin‐releasing hormone‐induced prolactin (PRL) secretion in goats

The aim of the present study was to clarify the effect of extracerebral dopamine (DA) on salsolinol (SAL)‐induced prolactin (PRL) secretion in goats. An intravenous injection of SAL or thyrotropin‐releasing hormone (TRH) was given to female goats before and after treatment with an extracerebral DA receptor antagonist, domperidone (DOM), and the PRL‐releasing response to SAL was compared with that to TRH. DOM alone increased plasma PRL concentrations and the PRL‐releasing response to DOM alone was greater than that to either SAL alone or TRH alone. The PRL‐releasing response to DOM plus SAL was similar to that to DOM alone, and no additive effect of DOM and SAL on the secretion of PRL was observed. In contrast, the PRL‐releasing response to DOM plus TRH was greater than that to either TRH alone or DOM alone and DOM synergistically increased TRH‐induced PRL secretion. The present results demonstrate that the mechanism involved in PRL secretion by SAL differs from that by TRH, and suggest that the extracerebral DA might be associated in part with the modulation of SAL‐induced PRL secretion in goats.     

Changes in the myocardial performance index during dobutamine administration in anesthetized cats

OBJECTIVE: To investigate the relationship between myocardial performance index (MPI; also known as the Tei index) and cardiac function in anesthetized cats administered dobutamine. ANIMALS: 6 adult cats. PROCEDURES: Cats were anesthetized by administration of propofol (6 mg/kg, IV), and anesthesia was maintained by administration of isoflurane. Heart rate and systolic arterial pressure (SAP) were monitored. Stroke volume, cardiac output, and aortic blood flow (ABF) were measured by use of transesophageal ultrasonography. Left ventricular fractional shortening (LVFS), mitral E-wave velocity-to-A-wave velocity (E:A) ratio, and ejection time were measured by use of transthoracic echocardiography. Dobutamine was administrated via a cephalic vein at rates of 2.5, 5.0, and 10 microg/kg/min. RESULTS: Heart rate, SAP, cardiac output, and ABF increased with dobutamine administration, whereas stroke volume significantly decreased. The LVFS significantly increased, and the E:A ratio significantly decreased. Total isovolumic time and the MPI significantly decreased. The MPI was negatively correlated (r=-0.63) with LVFS. Conversely, the MPI was positively correlated with the E:A ratio (r=0.47), stroke volume (r=0.66), and total isovolumic time (r=0.95). However, the MPI was not significantly correlated with heart rate, SAP, cardiac output, or ABF. CONCLUSION AND CLINICAL RELEVANCE: Analysis suggested that the MPI provides a sensitive clinical assessment of cardiac response to medication in cats, which may be similar to the usefulness of the MPI reported in humans.     

Purification and characterization of feline ghrelin and its possible role

Ghrelin, a novel 28-amino acid peptide with an n-octanoyl modification at Ser3, has been isolated from rat and human stomach as an endogenous ligand for the growth hormone secretagogue receptor. Here, we purified feline ghrelin and examined its possible physiological role in cats. The major active form of feline ghrelin is a 28-amino acid peptide octanoylated (C8:0) at Ser3; except for one amino acid residue replacement, this structure is identical to those of rat and human ghrelins. However, much structural divergence in peptide length and fatty acid modification was observed in feline ghrelin: peptides consisting of 27 or 26 amino acids lacking Gln14 and/or Arg28 were found, and the third serine residue was modified by octanoic acid (C8:0), decanoic acid (10:0), or unsaturated fatty acids (C8:1, C10:1 and C10:2). In agreement with the structural divergence, two kinds of cDNA with different lengths were isolated. Administration of synthetic rat ghrelin increased plasma growth hormone levels in cats, with a potency similar to that in rat or human. Plasma levels of ghrelin in cats increased approximately 2.5-fold after fasting. The present study indicates the existence of structural divergence in feline ghrelin and suggests that, as in other animals, ghrelin may play important roles in GH release and feeding in cats.     

Comparison of antibody titers in rabbits following immunization with inactivated influenza virus via subarachnoidal or subcutaneous route

Rabbits were immunized with inactivated influenza virus via the subarachnoidal (SA) or subcutaneous (SC) route, and the antibody titers in cerebrospinal fluid (CSF) and serum were assayed. There were no nervous signs or morphological lesions related to SA immunization. In the SC group, the antibody titer was elevated in serum, but not elevated in CSF. In the SA group, the antibody titer was significantly elevated in serum and even in CSF, and their antibody titers were much greater than in the SC group. The present results suggest that intrathecal immunization is more effective than SC immunization at inducing a protective immune response against the transneural spread of viruses.