两种饲喂方式对哺乳母猪生产性能的影响研究

选取年龄、胎次、品种基本一致的哺乳母猪20头,随机分成对照组和试验组,试验分两批进行,每批10头.在相同的环境条件下,母猪自由饮水,饲喂同一哺乳母猪料.母猪分娩后4 d内,采用原场饲养制度,逐步增加哺乳母猪采食量,第5天开始,对照组采用不限量饲喂,试验组采用限量和添加哺乳母猪补充料的饲喂方式,仔猪21日龄断奶.结果显示两组仔猪21日龄的断奶窝重、母猪断奶后再发情时间和母猪哺乳失重等差异均不显著(P>0.05).     

Estimating nocturnal ecosystem respiration from the vertical turbulent flux and change in storage of CO2

Micrometeorological measurements of nighttime ecosystem respiration can be systematically biased when stable atmospheric conditions lead to drainage flows associated with decoupling of air flow above and within plant canopies. The associated horizontal and vertical advective fluxes cannot be measured using instrumentation on the single towers typically used at micrometeorological sites. A common approach to minimize bias is to use a threshold in friction velocity, u_*, to exclude periods when advection is assumed to be important, but this is problematic in situations when in-canopy flows are decoupled from the flow above. Using data from 25 flux stations in a wide variety of forest ecosystems globally, we examine the generality of a novel approach to estimating nocturnal respiration developed by van Gorsel et al. (van Gorsel, E., Leuning, R., Cleugh, H.A., Keith, H., Suni, T., 2007. Nocturnal carbon efflux: reconciliation of eddy covariance and chamber measurements using an alternative to the u_*-threshold filtering technique. Tellus 59B, 397–403, Tellus, 59B, 307-403). The approach is based on the assumption that advection is small relative to the vertical turbulent flux (F_C) and change in storage (F_S) of CO₂ in the few hours after sundown. The sum of F_C and F_S reach a maximum during this period which is used to derive a temperature response function for ecosystem respiration. Measured hourly soil temperatures are then used with this function to estimate respiration R_Rmax. The new approach yielded excellent agreement with (1) independent measurements using respiration chambers, (2) with estimates using ecosystem light-response curves of F_c + F_s extrapolated to zero light, R_LRC, and (3) with a detailed process-based forest ecosystem model, R_cast. At most sites respiration rates estimated using the u_*-filter, R_ust, were smaller than R_Rmax and R_LRC. Agreement of our approach with independent measurements indicates that R_Rmax provides an excellent estimate of nighttime ecosystem respiration.     

Impact of Bacillus thuringiensis strains on survival,reproduction and foraging behaviour in bumblebees (Bombus terrestris)

BACKGROUND: Bacillus thuringiensis (Bt) and its protein crystals are used worldwide, either as a spray or when expressed in transgenic crops, for the control of pest insects. However, owing to their intensive use, there exists a debate regarding the involvement of this microbial insecticide in bee colony losses. In this study, in a tiered approach using laboratory microcolonies, an evaluation was made of the potential lethal and sublethal hazards on colony reproduction and foraging behaviour of workers of the bumblebee Bombus terrestris (L.) of two commercial Bt strains: kurstaki (Dipel^®) and aizawai (Xentari^®). Bumblebees, like honey bees, are intensively used in modern agriculture for pollination and fulfil a crucial role in the natural ecosystem. RESULTS: Exposure of bumblebees dermally or via treated pollen to either of the two Bt formulations at their field recommended rates (0.1%) caused no reduction in survival. However, when applied in the feeding sugar water, aizawai killed all workers at a concentration of 0.1%, but this lethal effect was lost at 0.01%. With respect to reproductive effects, kurstaki was harmless, while aizawai at 0.1% delivered in the feeding sugar water and pollen reduced reproduction by 100 and 31% respectively. Lower doses of 0.01% aizawai in the sugar water showed no more effect. In addition, kurstaki at 0.1% and aizawai at 0.01% in the feeding sugar water did not impair the foraging behaviour, resulting in normal nest colony performance. CONCLUSION: The results with kurstaki and aizawai demonstrated that, in general, the Bt strains are safe to B. terrestris bumblebees, although in some cases there were detrimental effects that depended on strain and route of exposure. In addition, the authors believe that to draw firm conclusions regarding the hazards of Bt to bumblebees would require more information on relevant concentrations of Bt products in the environment. Hence, routine testing for lethal and sublethal effects is recommended to ascertain combined use of Bt products and bumblebees in modern agriculture. Copyright © 2009 Society of Chemical Industry     

Epidemiologic survey of thrombocytopenia in dogs: a report on 987 cases

Thrombocytopenia was documented in 987 of 18,910 (5.2%) dogs admitted to North Carolina State University, College of Veterinary Medicine, Veterinary Teaching Hospital, between 1983 and 1989. Classifying thrombocytopenic dogs by etiologic groups revealed the following proportionate ratios: 5% (48/987) immune-mediated thrombocytopenia; 13% (130/987) neoplasia-associated thrombocytopenia; 23% (224/987) inflammatory/infectious thrombocytopenia; and 59% (585/987) miscellaneous thrombocytopenia. Dogs with immune-mediated thrombocytopenia had significantly (P < 0.05) lower platelet counts (mean 36,760 +/- 50,288 microliter) than dogs in the other three groups, and Doberman Pinschers were overrepresented in all groups except the immune-mediated thrombocytopenic group. We conclude that thrombocytopenia is a prevalent and potentially important diagnostic finding in a variety of disease states.     

林业发展所面临的形势及国民经济发展对林业的需求分析

文章着重分析了内蒙古当前林业发展形势及国民经济发展对林业的需求 ,并客观的论述了自治区林业发展的有利条件和制约因素 ,希望能够对今后的林业建设有所帮助 ,从而把握机遇 ,加快环境建设步伐 ,早日改善环境状况。     

Structural and Functional Events on the Porcine Zona Pellucida During Maturation, Fertilization and Embryonic Development: a Scanning Electron Microscopy Analysis

Porcine oocytes and pre-implantation embryos from the same, as well as from different animals, have an extremely heterogeneous morphology of the zona pellucida (ZP) surface, as shown by scanning electron microscopy. For years, it has been believed that this heterogeneous morphology plays an important role in the sperm-oocyte interaction. The aim of this study was to analyse the zona morphology and sperm-binding patterns on the porcine ZP. Oocytes were divided into four categories: immature, matured in vivo, or matured in vitro over a time period of 24 or 48 h. The zona morphology of early embryos grown in vivo or in vitro was also investigated. Four different types of zona morphology were detectable. They ranged from a porous, net-like structure to a nearly smooth and compact surface. No correlation could be established between the different kinds of maturation in terms of these zona types. All oocytes exhibited extremely heterogeneous zona morphologies, with no clear trend. During subsequent in vivo embryo development, the zona surface changes from a porous structure to one with a compact surface, while the morphology of in vitro embryos remained compact at all stages of development. The analysis of the number and distribution patterns of spermatozoa trapped in the ZP revealed extremely variable patterns, regardless of the zona morphology. Differences were only present if sorted or unsorted spermatozoa were used for insemination. Regardless of the number of inseminated spermatozoa after sorting, only a few (1-2) could be detected on the ZP. Whether oocytes were matured in vivo or in vitro was not a relevant factor. Unsorted spermatozoa bound in higher numbers than sorted ones. The number was directly dependent on the number of spermatozoa used for insemination.     

Twenty-four-hour patterns of hormones and metabolites in week 9 and 19 of lactation in high-yielding dairy cows fed triglycerides and free fatty acids

Effects of feeding crystalline triglycerides (TGA), free fatty acids (FFA), and a starch-rich ration (STA) on metabolite and hormone concentrations in blood plasma were studied in high-yielding dairy cows over a 24-h period in week 9 and 19 of lactating. Energy-corrected milk production in the three groups was similar, but was lower in week 19 than in week 9. Energy and protein intakes were greater in week 9 than in week 19, but energy and protein balances in the three groups and in weeks 9 and 19 were similar. Plasma glucose and triglyceride concentrations were lower in week 9 than in week 19. In cows fed FFA, glucose concentrations were highest in week 9. Plasma triglyceride, phospholipid and cholesterol concentrations were highest, whereas beta-hydroxybutyrate concentrations were lowest in FFA-fed cows in weeks 9 and 19. Concentrations of insulin-like growth factor-I in week 19 were lower in cows fed TGA and FFA than in those fed the starch-rich ration. Post-prandial responses were usually greater following morning than afternoon meals. Fructosamine, albumin, urea, growth hormone, thyroxine, and 3,5,3'-triiodothyronine concentrations were similar in weeks 9 and 19 and were not influenced by dietary treatment or feeding times. In conclusion, there were distinct metabolic and endocrine effects of feeding TGA and FFA compared with STA and the concentrations as well as the 24-h changes of various metabolic and endocrine traits in weeks 9 and 19 of lactation were also different.     

Probing cold dense nuclear matter

The protons and neutrons in a nucleus can form strongly correlated nucleon pairs. Scattering experiments, in which a proton is knocked out of the nucleus with high-momentum transfer and high missing momentum, show that in carbon-12 the neutron-proton pairs are nearly 20 times as prevalent as proton-proton pairs and, by inference, neutron-neutron pairs. This difference between the types of pairs is due to the nature of the strong force and has implications for understanding cold dense nuclear systems such as neutron stars.     

Thrombocytopenia Associated With Neoplasia in Dogs

Ten percent (214/2,059) of all dogs with cancer at North Carolina State University Veterinary Teaching Hospital had thrombocytopenia. The thrombocytopenia was associated with infectious/inflammatory etiologies in 4%, miscellaneous disorders (therapy, bone marrow failure, disseminated intravascular coagulation) in 35%, and neoplasia without identifiable secondary factors in 61% of cancer-bearing dogs. Classifying these dogs by tumor groups revealed the following proportionate ratios: lymphoid, 29%; carcinoma, 28%; sarcoma, 20%; hemic neoplasia, 7%; multiple, 5%; unclassified, 3%; benign, 3%; brain, 3%; and endocrine, 3%. Dogs with hemangiosarcoma, lymphoma, and melanoma were at increased risk of developing thrombocytopenia. Cytotoxic therapy was the major factor increasing the risk of thrombocytopenia in dogs with melanoma. Golden Retrievers were the only breed recognized with a predisposition to develop thrombocytopenia. If thrombocytopenia is identified in a dog with cancer, we recommend thorough evaluation of the coagulation system before surgery or therapy, and careful consideration of the risks and potential benefits of myelosuppressive or L-asparaginase therapy.