热应激对鸡新城疫疫苗免疫效果的影响

本试验利用伊莎蛋雏鸡,分别接种新城疫油乳剂灭活苗和Ｎ－７９弱毒苗,油乳剂灭活苗免疫的各试验组抗体滴度稍有下降,与对照组间无明显的差异;Ｎ－７９弱毒苗免疫的各试验组,高温处理２４小时的雏鸡,抗体滴度稍低于对照组,但无明显差异;而高温处理４８小时的各组,抗体滴度均显著低于对照组（ｐ＜０．０５）。     

冷、热应激对水禽的影响及营养调控研究进展

应激可通过神经-体液相关激素的基因和蛋白质、肠道微生物群、脂质氧化等,影响水禽的生理状态和生产性能,导致经济损失.水禽常见的应激包括热应激和冷应激.生产上可以通过控制环境温度、在饲粮中添加营养物质缓解水禽冷、热应激.文章以鸭、鹅为水禽代表,对冬、夏季节水禽生产中面临的冷、热应激主要的影响机制及营养调控措施进行综述,旨在...     

慢性冷热应激对放牧西门塔尔牛抗氧化功能及HPA轴、SAM轴激素分泌的影响

为研究慢性冷热应激对放牧条件下西门塔尔牛生理指标、抗氧化功能及下丘脑-垂体-肾上腺皮质轴(HPA)、交感-肾上腺-髓质轴(SAM)激素分泌的影响,选取内蒙古锡林郭勒盟苏尼特左旗某家庭牧场体质量相近、体况健康的西门塔尔牛20头,试验期间测定试验牛生理指标,于试验期最后一天清晨进行颈静脉采血并制备血清,采用ELISA方法检...     

Zinc alleviates the heat stress of primary cultured hepatocytes of broiler embryos via enhancing the antioxidant ability and attenuating the heat shock responses

Zinc (Zn) has been shown to attenuate the adverse effects of heat stress on broilers, but the mechanisms involving this process remain unclear. We aimed to investigate possible protective mechanisms of Zn on primary cultured hepatocytes of broiler embryos subjected to heat stress. Three experiments were conducted. In Exp. 1, hepatocytes were treated with 0, 50, 100, 200, or 400 μmol/L added Zn as inorganic Zn sulfate (iZn) for 12, 24 or 48 h. In Exp. 2, cells were exposed to 40 °C (a normal temperature [NT]) and 44 °C (a high temperature [HT]) for 1, 2, 4, 6, or 8 h. In Exp. 3, cells were preincubated with 0 or 50 μmol/L Zn as iZn or organic Zn lysine chelate (oZn) for 8 h under NT, and then incubated with the same Zn treatments under NT or HT for 4 or 6 h. The biomarkers of antioxidative status and heat stress in cells were measured. The results in Exp. 1 indicated that 50 μmol/L Zn and 12 h incubation were the optimal conditions for increasing antioxidant ability of hepatocytes. In Exp. 2, the 4 or 6 h incubation under HT was effective in inducing heat shock responses of hepatocytes. In Exp. 3, HT elevated (P < 0.01) malondialdehyde content and expressions of heat shock protein 70 (HSP70) mRNA and protein, as well as HSP90 mRNA. However, Zn supplementation increased (P < 0.05) copper zinc superoxide dismutase (CuZnSOD) activity and metallothionein mRNA expression, and effectively decreased (P < 0.05) the expressions of HSP70 mRNA and protein, as well as HSP90 mRNA. Furthermore, oZn was more effective (P < 0.05) than iZn in enhancing CuZnSOD activity of hepatocytes under HT. It was concluded that Zn (especially oZn) could alleviate heat stress of broiler hepatocytes via enhancing their antioxidant ability and attenuating heat shock responses.     

热应激对猪的影响研究进展

夏季南方高温高湿的气候条件极易使猪产生热应激,特别是集约化高密度的饲养环境,热应激带来的损失已经十分明显,因此研究行之有效的方法缓解热应激问题,降低损失,对养殖也具有重要经济意义。     

Effect of daidzein on production performance and serum antioxidative function in late lactation cows under heat stress

Forty Chinese Holstein cows were randomly divided into 4 groups according to birth, milk yield, and close lactation. The cows in 4 groups were fed with basic diet, basic diet plus 200, 300, 400 mg/day daidzein, respectively; and the experimental period was 60 days. The milk yield in all cows was monitored everyday and the quality of milk was examined regularly. Blood was collected on days 0, 10, 30, 60 of experiment to isolate serum, and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), malondialdehyde (MDA) content, and total antioxidant capacity (TAC) in the serum were measured. Results showed that the milk yield and the percentage of milk fat were significantly higher after feeding daidzein (P<0.01), and the percentage of milk protein was significantly elevated on day 60 in three daidzein groups (P<0.05 or P<0.01), especially in 400 mg/day daidzein group (P<0.01). Compared with the control group (basic diet), the TAC and activities of SOD, GSH-Px and CAT were markedly elevated in three daidzein groups (P<0.05 or P<0.01), while the MDA content was significantly reduced in three daidzein groups (P<0.05 or P<0.01). All data suggest that daidzein has positive effects on increasing the production performance and antioxidative activity in late lactation cows, and enhancing the body adaptability and resistance to heat stress.     

Effects of short-term cooling on pregnancy rate of dairy heifers under summer heat stress

Thermal stress in cattle results in major decreases in dairy production and reproduction. A study was designed to evaluate the influence of temporary cooling on pregnancy rate in Holstein heifers during summer heat stress. Estrus was synchronized with two injections of prostaglandin (PG), administrated 11 d apart, and all heifers were housed in a shaded enclosed structure at the time of the second PG injection. After estrus detection, heifers were randomly divided into three groups: Control (C; n = 30), Sprinkler (S; n = 30) or Sprinkler and Fan (SF; n = 30). Rectal temperatures were measured 2.5 hours before AI, at the time of AI, and 1.5 and 3.5 hours after AI. Group C heifers receive no further treatment, but heifers in S and SF groups were exposed to short-term cooling from 2 hours before until 2 hours after AI with a sprinkler (S) or sprinkler and a fan (SF), respectively. Estrus detection and AI were performed by a single skilled technician; semen was from a bull of known fertility. Rectal temperature did not differ among groups 2.5 hours before AI, but at the time of AI was lower (P < 0.05) in SF group (39.3 ± 0.0°C) than in S (39.5 ± 0.0°C) and C (39.9 ± 0.1°C) groups which also differed (P < 0.05). At 1.5 and 3.5 hours after AI, rectal temperature remained lower in SF group (38.9 ± 0.0 and 38.7 ± 0.0°C, respectively) than in the S (39.4 ± 0.0 and 39.2 ± 0.0°C, respectively) and C (39.3 ± 0.0 and 39.3 ± 0.0°C, respectively) groups, which no longer differed. Pregnancy rate following AI was higher (P < 0.05) in SF group (56.7%) than in the C group (23.3%) with the S group (40%) intermediate and not different from either. The present study results indicate that cooling of dairy heifers for a short time before and after AI, especially with sprinkler and fan, can increase pregnancy rate during heat stress.     

Impact of heat stress,nutritional restriction and combined stresses (heat and nutritional) on growth and reproductive performance of Malpura rams under semi‐arid tropical environment

A study was conducted to assess the combined effect of heat stress and nutritional restriction on growth and reproductive performances in Malpura rams. Twenty‐eight adult Malpura rams (average body weight (BW) 66.0 kg) were used in this study. The rams were divided into four groups: CON (n = 7; control), HES (n = 7; heat stress), NUS (n = 7; nutritional stress) and COS (n = 7; combined stress). The study was conducted for a period of 2 months. CON and HES rams had ad libitum access to their feed while NUS and COS rams were under restricted feed (30% intake of CON rams) to induce nutritional stress. The HES and COS rams were kept in climatic chamber at 42 °C and 55% relative humidity for 6 h a day between 10 : 00 h and 16 : 00 h to induce heat stress. Body weight increased significantly (p < 0.05) in CON as compared to NUS and COS. When compared within groups, scrotal width morning, scrotal width afternoon, scrotal circumference morning and scrotal circumference afternoon were significantly (p < 0.05) larger in CON while smaller in COS rams. The higher testicular length was recorded both during morning (p < 0.05) and afternoon (p < 0.01) in COS rams while the lowest in NUS rams. The highest plasma testosterone concentration was recorded in CON and lowest in COS rams. Semen volume and mass motility also differed significantly (p < 0.05) between the groups. The highest semen volume and mass motility was recorded in CON and NUS while lowest in both HES and COS rams. It can be concluded from this study that when two stressors occur simultaneously, they may have severe impact on reproductive performance of rams.     

Metabolic adaptations to heat stress in growing cattle

To differentiate between the effects of heat stress (HS) and decreased dry matter intake (DMI) on physiological and metabolic variables in growing beef cattle, we conducted an experiment in which a thermoneutral (TN) control group (n = 6) was pair fed (PF) to match nutrient intake with heat-stressed Holstein bull calves (n = 6). Bulls (4 to 5 mo old, 135 kg body weight [BW]) housed in climate-controlled chambers were subjected to 2 experimental periods (P): (1) TN (18 °C to 20 °C) and ad libitum intake for 9 d, and (2) HS (cyclical daily temperatures ranging from 29.4 °C to 40.0 °C) and ad libitum intake or PF (in TN conditions) for 9 d. During each period, blood was collected daily and all calves were subjected to an intravenous insulin tolerance test (ITT) on day 7 and a glucose tolerance test (GTT) on day 8. Heat stress reduced (12%) DMI and by design, PF calves had similar nutrient intake reductions. During P1, BW gain was similar between environments and averaged 1.25 kg/d, and both HS and PF reduced (P < 0.01) average daily gain (-0.09 kg/d) during P2. Compared to PF, HS decreased (P < 0.05) basal circulating glucose concentrations (7%) and tended (P < 0.07) to increase (30%) plasma insulin concentrations, but neither HS nor PF altered plasma nonesterified fatty acid concentrations. Although there were no treatment differences in P2, both HS and PF increased (P < 0.05) plasma urea nitrogen concentrations (75%) compared with P1. In contrast to P1, both HS and PF had increased (16%) glucose disposal, but compared with PF, HS calves had a greater (67%; P < 0.05) insulin response to the GTT. Neither period nor environment acutely affected insulin action, but during P2, calves in both environments tended (P = 0.11) to have a blunted overall glucose response to the ITT. Independent of reduced nutrient intake, HS alters post-absorptive carbohydrate (basal and stimulated) metabolism, characterized primarily by increased basal insulin concentrations and insulin response to a GTT. However, HS-induced reduction in feed intake appears to fully explain decreased average daily gain in Holstein bull calves.     

热应激对雄鼠生殖器官及精子发生的影响

每天在固定时间用不同梯度温度(42℃,37℃和33℃)处理实验组鼠1 h,热应激前后分别记录小鼠的肛温和体重.在应激的第8 d、13 d分别处死受试鼠后分离睾丸、附睾并分别称量其重量,计算睾丸、附睾与体重指数,将睾丸和附睾组织切片后镜检.结果表明,应激组小鼠的肛温显著升高(P＜0.05);睾丸和附睾内的精子数量、生精细胞上皮层数显著减少,精母细胞数量减少,且排列混乱,细胞的凋亡数量增多;而睾丸、附睾与体重指数无明显变化.     

Central and peripheral effects of repeated noise stress on hypothalamic-pituitary-adrenocortical axis in pigs

The present study was performed to examine the effects of a repeated noise exposure (4 weeks) on basal and noise-induced plasma adrenocorticotrophin (ACTH), cortisol and corticosteroid binding globulin (CBG) levels, brain glucocorticoid receptors (GR) and corticotropin-releasing hormone (CRH) concentrations as well as on the morphology of adrenal glands in German Landrace pigs. Chronically cannulated pigs were exposed to either a daily stimulation with broad-band noise (2 h, 90 dB) (N1), or to the same stimulus three times a week (N2), or to an equal handling procedure without noise stimulation. Noise exposure caused an increase of basal CBG concentrations in N1 animals in the first week. During noise session, an increase of plasma ACTH and cortisol levels in N1 animals was measured in week 1 followed by a subsequent decrease until week 4. The ACTH and cortisol response of the N2 animals increased after week 1 and was significantly elevated in week 4. Furthermore, noise stress caused an increased hippocampal GR binding of N2 pigs, but had no effects on GR binding in the amygdala and on hypothalamic CRH levels. There were also significant structural modifications in the adrenal gland of N1 pigs resulting in differentiated effects on the adrenal cortex and medulla. The present results show that repeated noise exposure of pigs causes considerable alterations at different levels of the HPA system in association with the frequency of noise stimulation. This may have substantial impact on the general vulnerability of the animal with respect to productivity, health and welfare.     

The impact of maternal overnutrition and obesity on hypothalamic-pituitary-adrenal axis response of offspring to stress

We evaluated the effect of maternal obesity before and throughout gestation on offspring hypothalamic-pituitary-adrenal axis function. Multiparous Rambouillet by Columbia crossbred ewes were fed either 100% of National Research Council (NRC) recommendations (control, C) or 150% of NRC recommendations (obese, OB) from 60 d before mating until lambing. Ten lambs born to OB ewes (five males and five females), and eight lambs born to C ewes (three male and five female) were studied. From delivery to weaning lambs were maintained with their mothers, who were all fed 100% NRC recommendations. After weaning, all lambs were group housed and fed the same diet to meet NRC requirements. At 19 mo of age lambs were placed in individual pens and fed a pelletized diet to meet maintenance requirements. Jugular vein catheters were placed and 2 d later lambs received an intravenous (i.v.) adrenocorticotropic hormone (ACTH) challenge followed by an i.v. corticotropin-releasing hormone (CRH)/arginine vasopressin (AVP) challenge 1 d later. Thirty d later offspring were again catheterized and placed into metabolism crates for 2 d before receiving an isolation stress test. ACTH and cortisol responses to the isolation stress test and CRH/AVP challenge and cortisol responses to ACTH challenge were determined. Cortisol was quantified via radioimmunoassay and ACTH was quantified using an Immulite 1000; both were analyzed using repeated measures using the MIXED procedure of SAS. Offspring from OB ewes had elevated basal plasma ACTH and cortisol compared with C offspring before all three challenges (P < 0.05). Offspring from OB mothers tended (P = 0.06) to have a greater ACTH response after an i.v. CRH/AVP injection than offspring from C mothers (12,340 ± 1,430 vs 8,170 ± 1,570 area under the curve, respectively). Cortisol response to the CRH/AVP and ACTH challenges was not influenced by maternal nutrition (P = 0.46) and averaged 4.77 ± 0.2 μg/dL and 1.94 ± 0.01 μg/dL, respectively. The ACTH response following the isolation stress test was also similar (P = 0.82) for OB and C offspring (147 ± 20 pg/mL), and cortisol response during the isolation stress test was similar between C and OB offspring (P = 0.64, 5.25 ± 0.3 μg/dL). These findings suggest that maternal obesity before and during gestation does not affect stress responses by the offspring, but has an impact on hypothalamic-pituitary-adrenal sensitivity. The lack of differences in cortisol release under the influence of difference concentrations of ACTH during the CRH/AVP challenge could indicate adrenal dysfunction in OB offspring.     

Effect of cooling Holstein cows during the dry period on postpartum performance under heat stress conditions

Two experiments were completed to determine whether cooling Holstein cows during their 60-day prepartum period improved their immediate physiological status as well as subsequent postpartum performance. In Experiment 1, 38 cows were divided into two pens that were not cooled, or where the cows were moved twice daily to be cooled by soaking until their body was completely wet. Prepartum respiration rate (RR) and rectal temperatures (RT) did not differ between groups, indicating that the cooling system was largely ineffective, which was consistent with differences that only numerically favored the treated group in postpartum productive (milk production, milk fat content and related response variables), and reproductive (services per conception and days open) performance. In Experiment 2, 52 Holstein cows were used over 3 years (n = 24 in year one; n = 12 in year two; n = 16 in year three) and cows were housed in pens either not cooled or cooled with water spray and fans. Cooled cows had lower RR and RT prepartum at 14:00 and 18:00 h vs. non-cooled cows, indicating that the cooling system was effective, and this was consistent with improved productive (milk production, milk fat content and related response variables), and reproductive (services per conception and days open) performance postpartum. In addition, there was a trend (P = 0.10) to higher birth weights of calves from cooled mothers (which was consistent with a numeric difference in Experiment 1). Use of effective cooling systems under hot and dry conditions during the dry period can improve postpartum productive and reproductive performance of Holstein cows.     

断奶仔猪氧化应激模型的建立及其营养调控的研究进展

随着养殖业的迅速发展和养猪规模的不断扩大,早期断奶技术在现代化养猪生产中已经普及。仔猪早期断奶会造成仔猪体内产生大量的自由基,引起氧化应激。本文以断奶仔猪氧化应激的产生及危害为切入点,着重阐明仔猪氧化应激模型的构建方式,主要介绍了氧化鱼油、Diquat、H2O2攻毒这三种造模方法,最后从营养调控角度提出添加植物提取物、复合抗氧化剂、微量元素、中草药添加剂等物质对缓解仔猪氧化应激的重要意义,以期为断奶仔猪的营养调控提供一定的理论依据。     

Effect of seasonal thermal stress on oxidative status,immune response and stress hormones of lactating dairy cows

This study aimed to assess the impact of seasonal thermal stress on oxidative stress, immune response, and stress hormones of lactating dairy cows in subtropical regions with different levels of temperature-humidity index (THI). A total of 32 healthy lactating Holstein dairy cows experienced 4 seasons (8 cows/season). The physiological parameters were categorized into low THI (LTHI, THI = 42.97 ± 0.95) in winter, moderate THI (MTHI, THI = 61.84 ± 0.42) in spring and autumn, and high THI period (HTHI, THI = 86.09 ± 0.23) in summer. The blood samples were collected twice in each season to measure oxidative stress, inflammatory and hormonal parameters. Our results showed THI had a positive correlation with the rectal temperature (R² = 0.821, P < 0.001) and respiratory rate (R² = 0.816, P < 0.001). Dry matter intake, milk yield and fat percentage also significantly differed among groups (P < 0.05). Compared with the MTHI group, the LTHI group exhibited a significant increase in malondialdehyde (MDA) level (P < 0.001), and the HTHI group displayed a significant increase in levels of cortisol, interleukin (IL)-10, IL-1β and tumor necrosis factor-α (P < 0.001). Opposite changes in serum endotoxin and immunoglobulin G levels were observed with the increasing THI (P < 0.001). LTHI notably increased the triiodothyronine level, although the thyroxine level was reduced by LTHI and HTHI compared with the MTHI group. In conclusion, LTHI and HTHI conditions may induce different degrees of oxidative stress, inflammation response, and stress hormone imbalances on lactating dairy cows, therefore environmental management is necessary for the health of dairy cows in extreme weather conditions.     

热应激对奶牛血液中内毒素含量和抗氧化指标的影响

选用16头健康的中国荷斯坦奶牛,随机分为两个处理（夏季组和冬季组）,每个处理8个重复,每个重复1头牛。当夏季组奶牛牛舍温湿度指数（THI）〉72的时间连续达到15d,冬季组牛舍THI〈72的时间连续达到15d时,颈静脉采血15mL制备血清,检测血清中内毒素、超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）的活性,以及丙二醛（MDA）的含量。结果表明：夏季热应激可导致奶牛血清内毒素、MDA含量极显著升高,SOD和GSH-Px活性极显著和显著（P〈0.05）下降。     

热应激对蛋鸭产蛋性能和蛋品质的影响研究

为探讨热应激对蛋鸭产蛋性能、蛋品质的影响,试验选用健康状况良好、体重相近、食欲正常的360日龄金定鸭200羽,随机分为适温组(20～25℃)、热应激组(32～36℃),每组4个重复,每个重复25羽.试验预试期7d,正试期28 d.结果 表明:(1)试验28 d适温组产蛋率、总蛋重、平均蛋重显著升高(P＜0.05);高温...     

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。