相对湿度对家禽水蒸发散热和健康的影响

相对湿度(RH)作为温热环境的重要因素之一,与温度和风速等共同影响家禽的热平衡状态。当RH适宜时,蒸发散热(EHL)达到最大;高温环境下,高湿会阻碍家禽的EHL,从而造成体温上升、呼吸加快、食欲下降,严重时导致酸碱平衡紊乱、热虚脱和呼吸性碱中毒。本文主要综述水蒸发散热(EWL)在家禽热平衡调节中的重要作用,及RH对家禽EWL的影响,并结合由此而引发的对家禽健康的影响,探讨RH在家禽实际生产中的重要作用。     

环境温度、湿度等因素对家禽体温调节的影响及评估模型

温热环境是影响家禽福利、健康以及生产性能的重要因素。家禽属恒温动物,当环境温度、湿度等因素改变时,可通过调节自身产热和散热维持体温恒定,因此家禽体温调节的变化是反映温热环境舒适程度的重要指标。本文针对环境温度、湿度、风速对家禽产热量、采食量、蒸发散热量、呼吸频率、皮肤温度、深层体温等体温调节指标的影响进行了总结和分析,为今后研究、建立家禽舒适环境模型,科学调控家禽舍内温热环境提供参考。     

暖棚养猪可提高效益

在温度、湿度、太阳辐射和气流等诸多环境因素中,温度是对猪生长、繁殖影响最重要的因素之一。气温是变化最大的气候因素,在不同的季节,甚至同一天的不同时间里,气温都有差异。猪为了维持产热和散热的平衡,保持体温的恒定,随着外界环境和肌体内环境的不断变化,猪肌体要不停地对散热进行调控。猪体热调节通过化学调节(产热)和物理调节(散热)来进行。当气温下降,散热增加时,必须提高代谢率,增加产热量,以维持体温的恒定,开始提高代谢率的温度,称之为临界温度。如果气温升高,肌体散热受阻,物理调节方法不能维持体温的恒定,     

热带奶牛饲养专家研讨会资料

1.环境因素对奶牛产奶量的影响环境温度升高后,动物产热超过散热,体内的贮热引起体温升高。体温显著升高后便引起一系列的热平衡反应,包括通过呼吸和皮肤增加热的挥发、增加排尿散热等。但当机体散热仍不能保证高温和阳光辐射热有效地散失后,那么机体就通过减少采食量、降低代谢、减少体重和奶产量来缓轻这种热不平衡。生长或泌乳奶牛受环境影响后,还通过神经——内分泌系统来改变能量、体温和矿物质代谢平衡。一般来讲,每增加1单位温湿指数或直肠温度     

热应激降低鸡生产性能的探讨

鸡与哺乳动物一样属于恒温动物，但鸡没有哺乳动物那样发达的汗腺，体表又被厚厚的羽毛覆盖，处于高温环境申时只能依靠呼吸蒸发散热，而环境湿度过高时，蒸发散热的效率大大降低，致使热量在体内异常蓄积导致鸡群生产性能降低、对疫病的易感性增加、甚至是大量死亡。我国家禽养殖集中的地区如广东、山东、河北     

猪舍内风速对猪只散热及有效环境温度的影响研究

猪舍的温度环境是影响猪只健康生长的基本要素,其中猪舍的通风速度对猪只的散热及猪只的有效环境温度具有十分重要的影响。本文对猪只的散热方式进行简单介绍,对猪只由于风速影响的对流传热方式及猪只有效环境温度进行了相应的计算。结果表明,通常情况下,随着猪舍内风速的增大,猪只的散热量增加,猪只所处位置的有效环境温度降低。本文所研究内容对猪舍的通风设计及养殖过程中猪舍环境控制有非常重要的指导意义。     

热应激对猪的影响及控制措施

热应激是指当环境温度超过最适温度范围时,猪的产热大于散热,就要通过增加呼吸蒸发和辅射散热,或通过减少采食量进而减少体热产生来调节体温平衡,通过增加散热和减少产热仍不能维持机体的体温平衡时,就会引起猪体温升高,从而导致猪的神经内分泌系统发生变化,这种引起猪的不良反应叫做热应激。     

养鸡生产中抗热应激的措施

极高的温度对快速生长的肉鸡和高产蛋鸡生产性能有很大的影响,当外界环境温度很高时,我们有必要在禽舍内创造一个舒适的环境以便降低鸡的体热。在这种极端环境下,我们必需采取一些重要措施来维持家禽的生产性能。提高脂肪的消化吸收率就是其中的措施之一。鸡不像其它动物具有汗腺散热以维持体温恒定。鸡散热主要通过四种方式:体热可通过体表辐射到空     

环境因素对奶牛的影响

1温度 奶牛是通过自身的体温调节而适应外界环境的,体温调节就是奶牛借助于产热过程与散热过程进行的热平衡。当外界气温降低到适宜的环境温度范围以下时,牛体就尽量减少体热的散发,提高新陈代谢作用,以增强体热。反之,当外界气温上升到接近于奶牛的皮温或高于皮温时,牛体就增加体热的散发,降低新陈代谢作用,以减少体热。     

苏氨酸在家禽营养中的研究进展

苏氨酸是家禽体内4种主要的必需氨基酸之一,对维持家禽正常的生长、发育及免疫具有十分重要的作用。尽管过去十多年来有关苏氨酸对肉鸡、蛋鸡的影响机理研究较为全面,但在肉鸭上的研究相对较少。作者总结了近年来苏氨酸在肉鸡、蛋鸡和肉鸭生物学和营养生理功能上的研究成果,主要包括苏氨酸在平衡日粮氨基酸、促进蛋白质合成、提高生产性能、提升胴体品质、增强免疫机能及维护肠道健康等方面的作用效果;同时也简要分析了家禽苏氨酸需要量的影响因素,包括家禽的生长阶段、日粮粗蛋白质水平、日粮能量浓度、日粮其他氨基酸含量及饲养环境等,以期为家禽的生产实践提供一定的指导。     

Technological,environmental and biological factors: referent variance values for infrared imaging of the bovine

Background

Despite its variety of potential applications, the wide implementation of infrared technology in cattle production faces technical, environmental and biological challenges similar to other indicators of metabolic state. Nine trials, divided into three classes (technological, environmental and biological factors) were conducted to illustrate the influence of these factors on body surface temperature assessed through infrared imaging.

Results

Evaluation of technological factors indicated the following: measurements of body temperatures were strongly repeatable when taken within 10 s; appropriateness of differing infrared camera technologies was influenced by distance to the target; and results were consistent when analysis of thermographs was compared between judges. Evaluation of environmental factors illustrated that wind and debris caused decreases in body surface temperatures without affecting metabolic rate; additionally, body surface temperature increased due to sunlight but returned to baseline values within minutes of shade exposure. Examination/investigation/exploration of animal factors demonstrated that exercise caused an increase in body surface temperature and metabolic rate. Administration of sedative and anti-sedative caused changes on body surface temperature and metabolic rate, and during late pregnancy a foetal thermal imprint was visible through abdominal infrared imaging.

Conclusion

The above factors should be considered in order to standardize operational procedures for taking thermographs, thereby optimizing the use of such technology in cattle operations.     

Thermoregulatory capacity of the Thoroughbred racehorse and its relationship to the pathogenesis of exertional heat illness

When racehorses fail to thermoregulate effectively, whether due to intrinsic or extrinsic factors, a condition called exertional heat illness (EHI) may occur, which can be life-threatening and represents a significant welfare issue. Horses usually become affected in the recovery phase soon after racing, so that a knowledge of the ‘normal’ thermoregulatory processes which operate at this time and their variations is essential to enable early detection of EHI. Racing in hot or warm and humid weather conditions represents the upper extreme of thermoregulatory variations, and observations on how horses normally recover at the racetrack may provide a clearer perspective on the physiology of that process for all sports horses. This review focuses on the post-exercise thermoregulatory capacity of the Thoroughbred racehorse, with a view to understanding the physiological mechanisms that should efficiently dissipate excess heat. The clinical manifestations of exertional heat illness are due to inadequate or harmful physiological responses, and if recognised and treated early can be effectively curtailed.     

应激蛋白研究进展

应激蛋白（HSP）可在多种应激原刺激下产生，并具有伴随性、自卫性、协同性、模拟性、双重性等特性。近年研究表明：HSP可提高机体耐热性，保护、修复细胞蛋白质，参与机体免疫反应，介导肿瘤增殖并参与肿瘤免疫，参与胚胎分化发育等诸多作用。因此，HSP的研究在生命科学的诸多领域受到重视。     

动物机体热休克应答相关信号途径的研究进展

动物处于不良饲养、运输、屠宰等环境下产生热应激,机体对热应激的反应称为热休克应答,多条信号途径调控热休克应答,引发热休克蛋白的产生。本文综述了MAPK、PI3K/Akt、PKC等信号途径对热休克蛋白的调控作用,从分子机制上阐明了热应激的调控机理。     

Estimation of endogenous protein and amino acid ileal losses in weaned piglets by regression analysis using diets with graded levels of casein

Background： Many studies have investigated endogenous loss of proteins and amino acids （AAs） at the ileal level in growing pigs. However, only a few studies have researched this subject in piglets. Knowledge regarding AA ileal digestibility in piglets would be helpful during the formulation of diets for weaning piglets, rather than just using coefficients obtained in growing pigs. Therefore, in this study, we sought to estimate endogenous protein and AA ileal losses in piglets. Furthermore, apparent and true ileal digestibility （AID and TID） of protein and AAs from casein were measured. Results： The average flow of protein was 20.8 g/kg of dry matter intake （DMI）. Basal protein loss, as estimated by regression, was 16.9 g/kg DMI. Glutamic acid, arginine, and aspartic acid （2.2, 1.4, and 1.2 g/kg DMI, respectively） were the AAs for which greater losses were seen. The AID of protein and AAs increased as the protein level in the diet increased. A higher increment in AID was observed between diets with 80 and160 g CP/kg of feed; this finding was mainly attributable to increases in glycine and arginine （46.1% and 18%, respectively）. The TID of protein was 97.8, and the TID of AAs varied from 93.9 for histidine to 100.2 for phenylalanine. Conclusions： The basal endogenous protein loss in piglets was 16.9 g/kg DMI. Endogenous protein was rich in glutamic acid, aspartic acid, and arginine, which represented 32.7% of endogenous protein loss in weaning piglets. The TID of casein was high and varied from 93.0 for histidine to 100.2 for phenylalanine.     

Estimation of endogenous protein and amino acid ileal losses in weaned piglets by regression analysis using diets with graded levels of casein

Background

Many studies have investigated endogenous loss of proteins and amino acids (AAs) at the ileal level in growing pigs. However, only a few studies have researched this subject in piglets. Knowledge regarding AA ileal digestibility in piglets would be helpful during the formulation of diets for weaning piglets, rather than just using coefficients obtained in growing pigs. Therefore, in this study, we sought to estimate endogenous protein and AA ileal losses in piglets. Furthermore, apparent and true ileal digestibility (AID and TID) of protein and AAs from casein were measured.

Results

The average flow of protein was 20.8 g/kg of dry matter intake (DMI). Basal protein loss, as estimated by regression, was 16.9 g/kg DMI. Glutamic acid, arginine, and aspartic acid (2.2, 1.4, and 1.2 g/kg DMI, respectively) were the AAs for which greater losses were seen. The AID of protein and AAs increased as the protein level in the diet increased. A higher increment in AID was observed between diets with 80 and160 g CP/kg of feed; this finding was mainly attributable to increases in glycine and arginine (46.1% and 18%, respectively). The TID of protein was 97.8, and the TID of AAs varied from 93.9 for histidine to 100.2 for phenylalanine.

Conclusions

The basal endogenous protein loss in piglets was 16.9 g/kg DMI. Endogenous protein was rich in glutamic acid, aspartic acid, and arginine, which represented 32.7% of endogenous protein loss in weaning piglets. The TID of casein was high and varied from 93.0 for histidine to 100.2 for phenylalanine.     

Effect of Cooking on Residues of the Quinolones Oxolinic Acid and Flumequine in Fish

Steffenak, I., V. Hormazabal and M. Yndestad: Effect of cooking on residues of the quinolones oxolinic acid and flumequine in fish. Acta vet. scand. 1994,35,299-301.– The effect of cooking on residues of the quinolones oxolinic acid and flumequine in fish was investigated. Salmon containing residues of oxolinic acid and flumequine was boiled or baked in the oven. Samples of raw and cooked muscle, skin, and bone, as well as of the water in which the fish was boiled and juice from the baked fish, were analysed. Oxolinic acid and flumequine did not degrade at the temperatures reached when cooking the fish. However, fish muscle free from drug residues may be contaminated during boiling and baking due to leakage of the drug from reservoirs in the fish.     

An exploratory study to investigate animal health and reproductive wastage among Australian meat goat producers

The Australian goat meat industry has grown significantly in the last decade, with the value of exports nearly tripling. However, because carcase weight has remained constant over this time, the drivers of industry growth are price and supply. Animal health and reproduction are key factors contributing to supply and productivity, yet limitations to production management are poorly understood, hampering advice for effective intervention. This exploratory study aims to provide insights into the animal health and reproductive management practices and perceptions among meat goat producers in Australia. To achieve this aim, 20 producers, located in New South Wales, Queensland, Western Australia and Victoria, operating under different production systems were interviewed. The results of this study suggest that animal health management could be improved and that producers perceive a lack of relevant and species-specific information available to help them make informed decisions. Reproductive management and records varied greatly across producers interviewed. Kid loss was identified as an issue, with a 28% estimated average (6%–47% range) of losses from kidding until weaning. Producers identified predation, doe nutrition and mismothering as the biggest contributors to kid loss, with the majority of losses occurring within a week of birth. All producers believed management could minimise kid loss. This study highlights the importance of improving reproductive rates among goat enterprises and provides new information on the current practices within the Australian meat goat industry. This may assist the development of appropriate strategies for improving health and reproductive management and delivery of advice to producers.     

牧草和草坪草耐热性研究进展

对近年来牧草和草坪草耐热性方面的研究进行了综述,包括高温对牧草和草坪草生理生化指标及形态结构的影响;高温胁迫下牧草和草坪草对高温的响应,包括细胞膜热稳定性、水分状况、碳氮素代谢、光合及呼吸作用、热激蛋白诱导、内源激素等基本耐热影响因素的变化情况,旨在为耐热品种筛选奠定基础。对抗热基因的差异表达、分离克隆,热胁迫下信号转导、热激蛋白及蛋白差异表达情况方面的研究进展做了综述。并对今后此领域的研究方向和应用前景进行了讨论。