Factors associated with time to neonatal diarrhoea in French beef calves

A prospective study was carried out on 92 randomly selected beef herds in the Midi-Pyrénées region in France. The objective was to determine factors associated with time to neonatal gastroenteritis. By taking into account the “intra-herd” correlation in failure time (in the semiparametric Cox model), we identified 12 management risk factors associated with hazard of diarrhoea. Some previously have been identified, but “new” risk factors were feeding of corn silage and the incidence of diarrhoea in the last season. We used the two main approaches which are often reviewed: marginal and frailty Cox models. Our results show that these two models give different parameter estimates, so the choice of the model remains crucial.     

乳牛体型性状线性评定数学模型的指导和应用

本文说明了乳牛体型性状线性评定的常规方法,在此基础上推导出了该评定方法的数学模型。该模型的提出,极大地简化了常规评定方法的繁琐计算,值得在乳牛业生产实践中推广使用。     

生长猪大米蛋白消化能、代谢能的评定及预测模型研究

本试验通过采集我国多个地区大米蛋白样品,分析大米蛋白常规成分,测定生长猪消化能(DE)、代谢能(ME),建立大米蛋白常规成分与生长猪DE、ME之间的关系。试验选用体重(33.0±1.3)kg的"杜×长×大"三元杂交健康去势公猪12头,采用2个6×6拉丁方试验设计,包括1种基础饲粮和11种大米蛋白替代15%基础饲粮的试验饲粮。采用全收粪法和套算法结合测定大米蛋白猪DE、ME,并将大米蛋白的常规成分与猪DE、ME进行相关和回归分析,建立大米蛋白猪DE、ME预测模型。结果表明,11种大米蛋白风干基础下猪DE为(18.13±1.12)M J/kg,M E为(16.44±1.59)M J/kg。由此得出,大米蛋白猪DE最佳预测模型(绝干基础)为DE=22.17-0.51NDF(R2=0.50,RSD=0.93),DE=18.58-0.49 CF+0.31 EE(R2=0.70,RSD=0.77);M E最佳预测模型(绝干基础)为ME=21.42-0.74 NDF(R2=0.52,RSD=1.30)。NDF为大米蛋白猪DE、M E最佳预测因子。     

Assessment of stiffness and strength of 4 different implants available for equine fracture treatment: a study on a 20 degrees oblique long-bone fracture model using a bone substitute

OBJECTIVE: To compare the mechanical properties of 4 stabilization methods for equine long-bone fractures: dynamic compression plate (DCP), limited contact-DCPlate (LC-DCP), locking compression plate (LCP), and the clamp-rod internal fixator (CRIF--formerly VetFix). STUDY DESIGN: In vitro mechanical study. SAMPLE POPULATION: Bone substitute material (24 tubes) was cut at 20 degrees to the long axis of the tube to simulate an oblique mid-shaft fracture. METHODS: Tubes were divided into 4 groups (n=6) and double plated in an orthogonal configuration, with 1 screw of 1 implant being inserted in lag fashion through the "fracture". Thus, the groups were: (1) 2 DCP implants (4.5, broad, 10 holes); (2) 2 LC-DCP implants (5.5, broad, 10 holes); (3) 2 LCP implants (4.5/5.0, broad, 10 holes) and 4 head locking screws/plate; and (4) 2 CRIF (4.5/5.0) and 10 clamps in alternating position left and right of the rod. All constructs were tested in 4-point bending with a quasi-static load until failure. The implant with the interfragmentary screw was always positioned on the tension side of the construct. Force, displacement, and angular displacement at the "fracture" line were determined. Construct stiffness under low and high loads, yield strength, ultimate strength, and maximum angular displacement were determined. RESULTS: None of the implants failed; the strength of the bone substitute was the limiting factor. At low loads, no differences in stiffness were found among groups, but LCP constructs were stiffer than other constructs under high loads (P=.004). Ultimate strength was lowest in the LCP group (P=.01), whereas yield strength was highest for LCP constructs (409 N m, P=.004). CRIF had the lowest yield strength (117 N m, P=.004); no differences in yield strength (250 N m) were found between DCP and LC-DCP constructs. Differences were found for maximum angular displacement at the "fracture" line, between groups: LPC相似文献   

Bright artificial light at night is associated with increased body mass,poor reproductive success and compromised disease tolerance in Australian budgerigars (Melopsittacus undulatus)

Artificial light at night (ALAN) can cause circadian disruption and result in adverse behavioral and ecological effects in free‐living birds, but studies on captive pet birds as companion animals have been infrequent. We studied the effects of exposure to bright ALAN on body mass, melatonin sulfate levels, reproduction and disease severity in Australian budgerigars (Melopsittacus undulatus) kept in captivity. During the experiment, birds were kept under outdoor temperature, humidity and natural photoperiod from September to December. A total of 48 birds were equally split into 4 groups (6 mating pairs each) and concurrently exposed to ALAN of 200 lux with different duration (0, 30, 60 and 90 min). Monthly observations were recorded for all dependent parameters. ALAN exposure increased mass gain and suppressed melatonin levels in a dose‐dependent manner, especially during December. In addition, ALAN exposure in all duration groups decreased egg production and reduced hatchability from 61% ± 14% in the ALAN‐unexposed control group to 0% in the ALAN‐exposed birds. Disease severity was also found to increase in line with the duration of ALAN exposure. In captive M. undulatus, ALAN exposure was demonstrated to affect photoperiodic regulation with subsequent excess mass gain and reproduction impairment, and increased susceptibility to infections plausibly through duration dose‐dependent suppression of melatonin. To the best of our knowledge, this is the first study to demonstrate a possible association between acute bright ALAN of increasing duration and both natural development of infections as well as reproductive cessation in captive birds. Our findings could be used to improve breeding conditions of captive birds.     

西北干旱灌区紫花苜蓿高产田施肥效应及推荐施肥量研究

为揭示紫花苜蓿氮、磷、钾肥效应,采用“3414”不完全正交回归设计,对紫花苜蓿氮、磷、钾肥合理配比施肥效应进行研究,同时对紫花苜蓿产量及蛋白总量进行肥效模型拟合。结果表明,氮、磷、钾对建植2年苜蓿产量的贡献为钾>磷>氮,对建植3年苜蓿产量的贡献为磷>钾>氮,建植2与3年苜蓿交互效应均表现为氮磷>氮钾>磷钾。氮、磷、钾对建植2年苜蓿蛋白总量的贡献为氮>钾>磷,对建植3年苜蓿蛋白总量的贡献为氮>磷>钾。建植2年苜蓿氮磷肥互作效应明显优于氮钾、磷钾互作;建植3年苜蓿氮磷、氮钾交互对苜蓿蛋白总量的增产效果明显大于磷钾交互。采用频度分析法,通过模拟寻优,得出建植2年紫花苜蓿目标产量大于平均产量17522kg·hm^-2时,优化施肥量为氮56.27~67.51kg·hm^-2、磷77.69~90.48kg·hm^-2、钾76.43~87.18kg·hm^-2;建植3年紫花苜蓿目标产量大于平均产量19234.1kg·hm^-2时,优化施肥量为氮46.75~57.66kg·hm^-2、磷80.15~92.28kg·hm^-2、钾57.79~69.74kg·hm^-2;建植2年紫花苜蓿目标蛋白总量大于平均2115kg·hm^-2时,优化施肥量为氮66.35~77.48kg·hm^-2、磷79.34~92.87kg·hm^-2、钾73.68~85.38kg·hm^-2;建植3年紫花苜蓿目标蛋白总量大于平均2656kg·hm^-2时,优化施肥量为氮68.44~79.50kg·hm^-2、磷72.74~85.96kg·hm^-2、钾50.68~61.61kg·hm^-2。     

Usefulness of the murine model to study the immune response against Histoplasma capsulatum infection

The present paper is an overview of the primary events that are associated with the histoplasmosis immune response in the murine model. Valuable data that have been recorded in the scientific literature have contributed to an improved understanding of the clinical course of this systemic mycosis, which is caused by the dimorphic fungus Histoplasma capsulatum. Data must be analyzed carefully, given that misinterpretation could be generated because most of the available information is based on experimental host–parasite interactions that used inappropriate proceedings, i.e., the non-natural route of infection with the parasitic and virulent fungal yeast-phase, which is not the usual infective phase of the etiological agent of this mycosis.     

生物地球化学模型DNDC的研究进展与碳动态模拟应用

脱氮脱碳模型(denitrification-decomposition,DNDC)是通过计算反硝化和有机质分解来模拟氮和碳从土壤丢失而转移入大气时的主要生物地球化学过程模型。作为目前国际上最成功的模拟陆地生物地球化学循环的模型之一,本文主要阐述了DNDC模型的发展过程及其结构,整理了DNDC模型在碳动态模拟过程中的主要研究进展,总结了当前DNDC模型在碳动态模拟领域的应用热点和优势。     

Pigs as an experimental model for systemic Mycobacterium avium infectious disease

Mycobacterium avium complex (MAC) is an opportunistic pathogen in AIDS patients and pigs, and causes dissemination through primary intestinal lesions. However, its pathogenesis is not well understood. In this article, we hypothesize that pigs can provide a suitable experimental model of disseminated MAC disease. We compared the initial route of infection, the characteristics of the pathogenic strains, the immunological status of the hosts, and the histological characteristics. The route of infection and infective strains are similar in AIDS patients and pigs. Pigs can respond to infection by the formation of systemic epithelioid granuloma with sufficient cell-mediated immunity. However, there are differences in immunological status and histological features between AIDS patients and pigs. Therefore, pigs might be used as an appropriate animal model because of their good cell mediated immunity triggered by systemic mycobacterial infection. In conclusion, MAC infections in AIDS patients and pigs show similarities in terms of the initial route of infection and the genetic characteristics of the pathogenic strains.