热应激对动物生殖机能的影响及其作用机理

温度对动物生殖机能具有重要的影响,本文分别阐述热应激对雌性动物发情、受胎率、胚胎成活率、产仔数以及对雄性动物繁殖性能的影响,并提出了热应激对动物生殖机能影响的可能作用机理。     

热应激对动物机体生理机能的影响

热应激对动物生产造成严重的不利影响.在热应激状态下,动物的生产性能、生理机能、生化代谢和内分泌机能等各种机能发生显著变化.文章论述了热应激对动物采食量、体温、呼吸、血清酶活性、血液蛋白质、糖、脂肪含量及代谢产物、K 、Na 、Ca2 、P等矿物质含量及甲状腺素、皮质醇、雌二醇等激素含量影响的研究进展.热应激对动物的生理生化机能可造成严重影响,通过研究热应激对动物生理机能的变化,可为研究热应激的发生机理及衡量抗热应激药物或饲料添加剂提供理论依据.     

热应激对种公牛精液品质的影响

任何生物都依赖于其所处的环境 ,它对气候变化的适应及利用有效资源的能力是其存活的关键 ,因此 ,各种环境因子均可造成动物的生理应激 ,从而给动物的生产带来不利影响 ,牛也不例外。从经济角度看 ,在各种应激反应中 ,对牛影响最大的是热应激 ,而热应激对牛生殖机能会产生非常重要的影响。在热应激的作用下 ,种公牛的精液品质和受精率均显著下降 ,体内的一些血液生化指标也会发生明显变化。本文参考近年来国内外研究热应激的文献 ,论述了其对公牛繁殖性能的影响 ,以便于生产中制定缓解种公牛热应激的技术措施。1　热应激对种公牛繁殖机能的…     

热应激影响动物生殖的表观遗传学机制研究进展

随着全球温室效应剧增,夏季高温作为一种热应激源对动物生殖产生越来越大的影响,对世界各国的畜牧生产带来严重损失,因此,亟需对热应激影响动物生殖的机制进行深入研究。同时,越来越多的报道指出,在动物生殖的诸多生理过程中,表观遗传机制起到广泛而又重要的作用。基于此,文章总结了近期国内外热应激影响动物生殖的表观机制的研究进展,以便为解决实际生产中的问题提供理论支持。     

热应激条件对雄性小鼠精液顶体反应相关酶活力的影响

为探讨全球变暖和局部极端高温气候对雄性动物繁殖能力的影响,利用智能光照恒温培养箱模拟持续的热应激环境,建立小鼠热应激模型,设立了31,34,37℃3个不同的热应激温度组和22℃常温对照组,并在不同的温度下设置了热应激1,3,5,7,14 d 5个时间组,在不同的温度和时间下分别检测了小鼠精液的HYD、LDH、ACP和ACE等酶活性.结果显示,热应激条件下精子顶体反应相关酶活性均出现异常变化,从而影响精子的顶体反应及受精过程,对雄性小鼠的生殖机能产生影响.     

热应激影响家畜繁殖机能的机理及其调控研究进展

大量的研究结果表明,热应激能够影响家畜的繁殖机能,给动物生产带来危害,严重损害畜牧生产者的经济利益。作者综述了热应激对母畜、公畜繁殖机能的影响、可能的作用机制及其调控措施。为畜牧生产者采取更有效的预防措施减少热应激对家畜繁殖机能的危害提供理论依据。     

热应激对动物机体生理机能的影响

随着全球气候温室效应的不断加剧及高度集约化动物生产的发展,热应激对动物生产造成了严重影响,引起了广大畜牧兽医工作者的高度重视。近年来,国内、外许多学者对热应激对各种动物生理机能的影响进行了大量研究,取得了很大进展。1采食量热应激对动物采食量的影响因动物种类、年龄和应激程度有较大差异。一般认为,热应激往往导致动物采食量明显下降。在热应激时,由于交感神经兴奋,导致胃肠蠕动减弱,消化液分泌减少,消化器官循环血量减少,胃肠黏膜发生病理损伤     

热应激对种公犬精液品质的影响

热应激通常是指在环境温度超过动物的适温区上限的影响下,因体内产热与散热失衡而导致的一系列生理与行为机能上的负面表现。 一、热应激对公犬精液品质的影响 （一）热应激影响公犬精液品质的机理 热应激使公犬采食量显著下降,营养物质供应不足,体内酸碱平衡调节受到影响,机体组织细胞机能和新陈代谢发生变化。种公犬在高温环境下阴囊和睾丸组织的温度升高,睾丸机能减退。     

热应激对雌鼠卵巢组织病理变化的影响

卵巢在繁殖中起着至关重要的作用,如果卵巢机能受到损害,将会引起排卵延迟或不排卵,更有甚者将会引起卵巢机能减退,导致动物暂时性或永久性不育.研究表明,在热应激下奶牛优势卵泡发育提前,到正式排卵时已经老化,从而影响受胎率.适宜的温度对卵子的生成是必需的.然而不同程度热应激对哺乳动物卵巢组织本身影响的报道却很少见.研究从个体及器官的水平揭示热应激下主要生殖器官卵巢的病理变化,评定热应激对雌性动物卵巢的损伤程度.有试验结果表明,热应激对小鼠的影响和损伤和对其他家畜的影响和损伤是相符的,由于小鼠对热应激非常敏感,经济价值低廉,故将其确定为试验的最佳受试动物.     

热应激对肉鸡免疫功能的影响

热应激是肉鸡生产中最常见的应激之一，它能够影响肉鸡免疫器官的生长发育，使体液免疫和细胞免疫功能也受到影响。１热应激的概念应激是动物从受刺激达到体内平衡的一种适应性反应眼１演。热应激是指环境温度超过动物能够对其适应的生理范围而产生的应激。肉鸡生产过程中经常会遇到各种应激，其中热应激造成的危害最大。它不仅影响肉鸡的生长、发育及生产性能，也可影响其免疫机能，是造成疾病发生流行的重要原因。因此，热应激影响肉鸡免疫功能的研究对避免这一情况的发生将会起到积极的作用眼２演。２热应激对肉鸡免疫功能的影响２．１鸡…     

家兔热应激研究进展

夏季高温高湿的气候极易引起家兔的热应激反应,导致生长性能、繁殖性能和抗氧化能力降低,阻碍兔产业的健康发展。文章综述热应激对家兔行为及生理生化指标、生产性能、繁殖性能等方面的影响,家兔热应激期的分子调控机制,以及热应激的营养调控措施,旨在为制定家兔热应激调控策略提供参考。     

热应激对奶牛生产性能的影响及缓解措施

奶牛经过不断选育,产奶量不断提高,但高产奶量增加了奶牛机体产生的热量,在周围环境温度和湿度不断增加的情况下,热量会积累加剧,进而导致热应激的发生。为了散热,奶牛启动一系列的适应机制,包括增加呼吸频率、出汗等,长期则导致生产性能和繁殖性能的下降,极大地影响了奶牛养殖业的发展。因此,本文通过对奶牛热应激评定、热应激对奶牛的影响及缓解热应激措施进行综述,以期为缓解奶牛热应激提供有效的综合方案。     

Influence of induced heat stress on HSP70 in buffalo lymphocytes

Heat stress in farm animals, such as cattle and buffalo during summer and post-summer seasons is a problem for livestock producers. The effect of heat stress becomes pronounced when heat stress is accompanied with ambient humidity impairing the immune status, growth, production and reproductive performance of animals. Increase in HSP70 levels from cell cultures in presence of different stressors often does not reflect the physiological adaptability of animals governing thermal regulation. In this study we directly compared the effect of different heat stress conditions with the immune status and HSP70 expression patterns from buffalo lymphocytes both in vivo and in vitro. Murrah buffalo calves were exposed to induced heat stress with two experimental treatments: hot-dry (42 °C with existing relative humidity) or hot humid (35 °C with 70% relative humidity) condition in psychometric chamber, 4 h daily for 12 days and compared with control animals maintained in an experimental shed under natural conditions. There was >200-fold increase in serum-HSP70 levels in both heat stress conditions compared with control. Furthermore, the immune status of the calves failed to activate the level of HSP70 expression in serum lymphocytes. Lymphocytes cultured in vitro at higher temperature exert 2.5-fold increase in HSP70 concentration. This study is the first of its kind to demonstrate more complex expression pattern of buffalo serum-HSP70 level as a thermo adaptive response compared with in vitro treated cells. Results from this study indicate that serum-HSP70 levels could be used as a sensitive biomarker for heat stress management in large farm animals.     

Effect of mineral mixture and antioxidant supplementation on growth,reproductive performance and adaptive capability of Malpura ewes subjected to heat stress

This study was conducted to evaluate the effect of mineral and antioxidant supplementation on growth, reproductive performance and physiological adaptability of heat‐stressed Malpura ewes. The study was conducted for a period of 21 days in 21 adult Malpura ewes. The ewes were randomly divided into three groups with seven animals each viz. GI (control; n = 7), GII (heat stress; n = 7) and GIII (heat stress + mineral and antioxidant supplementation; n = 7). The animals were stall fed ad libitum with the diet consisting of 70% roughage and 30% concentrate. GI ewes were maintained under normal controlled condition in the shed, while GII and GIII ewes were subjected to heat stress by exposing them to 42 °C in the climatic chamber. The parameters studied were feed intake (FI), water intake (WI), body weight, body condition score (BCS), physiological, biochemical and endocrine responses. Heat stress significantly altered FI, water intake, BCS, respiration rate and rectal temperature in the afternoon, oestrus duration, estradiol, progesterone, Hb, PCV, plasma glucose, total protein, cortisol, T₃ and T₄ levels while mineral and antioxidant supplementation ameliorated this heat stress effect on the parameters studied. Further, the adverse effect of heat stress on the productive and reproductive efficiency of Malpura ewes was reduced considerably by mineral mixture and antioxidant supplementation. This is evident from the non‐significant difference in BCS, oestrus duration and plasma estradiol between GI and GIII in this study. Hence, it is very pertinent to conclude from this study that mineral mixture and antioxidant supplementation were able to protect Malpura ewes against heat stress.     

夏季热应激对奶牛的影响及预防措施

夏季热应激会降低奶牛的生产性能,影响养殖行业的经济效益,严重制约畜牧业的发展。因此牧场热应激的防控工作显得尤为重要。本文就热应激对奶牛的行为、采食量、繁殖性能的影响等进行综述,探讨缓解热应激的措施,以期帮助牧场管理人员制定预防热应激的策略。     

Effect of Repeated Stress Treatments During the Follicular Phase and Early Pregnancy on Reproductive Performance of Gilts

In pig husbandry, stress is being considered an important cause of impaired reproductive performance. Therefore, an experiment was performed to quantify effects of repeated stressors during the follicular phase and/or during early pregnancy on reproductive performance of gilts. Eighty-one cyclic gilts were assigned to one of four treatments, namely, stress treatment during the follicular phase (n = 20), stress treatment during early pregnancy (n = 20), stress treatment during both phases (n = 21) and no stress treatment (n = 20). All gilts were housed individually, but gilts in the stress treatments had no opportunity for visual or physical contact with other gilts. Further, animals in a stress-treatment were grouped for half an hour at the start of the treatment and during the treatment period nose-sling and an unpredictable feeding scheme were applied regularly. The extent of stress was monitored using heart rate measurements, behavioural observations and saliva cortisol levels during nose-sling fixation. Of the 81 gilts, 93% showed oestrus and were inseminated. Of these, 93% were pregnant at day 35, having 17.9 +/- 0.3 ovulations and 15.6 +/- 0.3 foetuses. These parameters were not affected by treatment. The stress treatment during the follicular phase tended to shorten cycle length (stress: 20.8 +/- 0.20; control: 21.2 +/- 0.17 days, p = 0.07) and weight of foetuses at day 35 (stress: 4.47 +/- 0.08 g; no stress: 4.69 +/- 0.08 g, p = 0.06); stress during early pregnancy did not affect any of the reproduction parameters. Percentage stereotypic behaviour, heart rate and saliva cortisol levels varied greatly between animals and between days, but did not differ between the treatments. No relationships were found between any of the reproductive parameters and any of the stress parameters (heart rate, cortisol, stereotypic behaviour). These results indicate that the repeatedly applied acute stressors did not generate a chronic stress-response and that these stressors during the follicular phase and/or during early pregnancy did not affect reproductive processes. It is not clear how these findings relate to suggested effects of stress(ors) on reproductive performance in pig husbandry.     

三价铬对畜禽繁殖性能的影响及其作用机制

三价铬是动物需要的微量元素之一,具有缓解应激、改善肉质的功能,对动物的繁殖也有重要作用。铬通过缓解应激对繁殖的损伤和调节机体的内分泌等方面影响畜禽的繁殖性能。本文就铬对畜禽繁殖性能的影响及其可能的机制作一综述,以期为三价铬在种用畜禽上的合理应用提供理论支持。     

Sow line differences in heat stress tolerance expressed in reproductive performance traits

The objectives of this study were 1) to investigate if there were differences in the relation between temperature and reproductive performance traits in 2 different sow lines, a Yorkshire line producing mainly in temperate climates and a Large White line producing mainly in warm climates, and 2) to determine the upper critical temperature (UCT) for the reproductive performance of these 2 lines. Sows are exposed to heat stress when temperature exceeds the UCT of the thermo-neutral zone. Data included 32,631 observations on reproductive performance from 11,935 sows on 20 farms in Spain, collected from 2003 to 2005. Sows belonged to 2 different purebred sow lines, named D (Yorkshire sow line, producing mainly in temperate climates) and I (Large White sow line, producing mainly in warm climates). Only first insemination records per parity were used and were combined with the maximum outside temperature at day of insemination. Upper critical temperatures were studied for 3 reproduction traits: farrowing rate (0 or 1), litter size (range from 1 to 25), and total number of piglets born per first insemination (combination of farrowing rate and litter size, range from 0 to 25). Data were corrected for fixed effects, which included parity, service sire, and an interaction between farm and year. Corrected data were used as observations in the models to study the effect of outside temperature on reproductive performance. Two models were compared for goodness of fit: a linear regression model and a plateau-linear model with the plateau representing the thermo-neutral zone and a linear decrease above that zone. Farrowing rate of I-line sows was not affected by temperature. For litter size and total number born per first insemination of I-line sows no UCT could be estimated. These traits were linearly affected by temperature. For all 3 reproduction traits of the D-line the best model was the plateau-linear model; the UCT for the D-line sows was estimated to be 19.2 degrees C for farrowing rate, 21.7 degrees C for litter size, and 19.6 degrees C for total number born per first insemination. The decrease in reproductive performance of I-line sows with increasing outside temperature was less than in D-line sows. From this study it can be concluded that there are differences in heat stress tolerance between sow lines as measured by the differences in reproductive performance. These differences are an indication of genetic differences in heat stress tolerance in sow lines.     

热应激对奶牛机体的影响及防控措施

随着全球气候变暖,以及奶牛产奶性能的提高,热应激成了影响我国奶牛生产的一大难题,尤其在南方高温高湿的夏季,奶牛极易发生热应激。本文就热应激对奶牛产奶量、乳品质和繁殖性能的影响等方面进行了综述,并提出了一些预防奶牛热应激的措施,以期指导生产实践,提高奶牛养殖的经济效益。