Effect of ascorbic acid or increasing metabolizable energy level with or without supplementation of some essential amino acids on productive and physiological traits of slow-growing chicks exposed to chronic heat stress

Four hundred and twenty, 21-day-old slow-growing chicks were divided randomly into seven treatments, each containing five replicates. Each replicate was kept in a 1 × 1-m floor pen. One treatment was kept under thermo-neutral conditions in a semi-open house and fed a corn-soybean meal diet (positive control). The other six groups were kept under chronic heat stress (CHS) at 38 °C and 60% RH for 4 h from 12:00 to 16:00 pm for three successive days per week. Chicks in CHS treatments were fed a corn-soybean meal diet without (negative control) or with increasing metabolizable energy (ME) level by oil supplementation alone, or also with increasing some essential amino acids (EAA) such as methionine (Met), methionine and lysine (Met+Lys) or methionine, lysine and arginine (Met+Lys+Arg) or supplemented with 250 mg of ascorbic acid (AA)/kg. CHS impaired (p < 0.05) growth performance, increased plasma triglycerides and total serum Ca while decreasing (p < 0.05) plasma glucose and total serum protein. Meanwhile 250 mg AA/kg diet or an increasing ME without or with some EAA partially alleviated (p < 0.0001) the negative effect of CHS on growth while increasing (p < 0.05) feed intake and improving (p < 0.05) feed:gain ratio (F:G) and crude protein (CP) digestibility (p < 0.05). AA or increasing ME with or without EAA increased (p < 0.05) percentage dressing, liver and giblets to those of the positive control. AA or increasing ME with or without EAA partially alleviated the negative effect of CHS on blood pH, packed cell volume (PCV), haemoglobin (Hgb), total serum protein and total Ca, plasma glucose and triglyceride, rectal temperature and respiration rate. Increasing ME level improved chickens' tolerance to CHS without a significant difference from those supplemented with AA. However, increasing Met, Lys and Arg concentration did not improve performance over that recorded with increasing ME level alone. Under CHS, 250 mg AA/kg diet or increasing ME level by addition of 3% vegetable oil could be an useful approach to improve productive and physiological traits of slow-growing chicks, which may be applicable also to fast-growing one.     

热应激对山羊生理生化指标的影响

３只健康山羊置于人工热激环境中（环境温度３７．５～３８．５℃）,１小时后回到自然环境（２４．５～２６．５℃）。试验前及试验开始后第１５、６０、１８０分钟,分别测定心率、呼吸频率、体温、红细胞数（ＲＢＣ）、白细胞数（ＷＢＣ）、血糖、血清谷草转氨酶（ＧＯＴ）、谷丙转氨酶（ＧＰＴ）、肌酸激酶（ＣＫ）、总蛋白（ＴＰ）、清蛋白（Ａｌｂ）、尿素氮（ＢＵＮ）含量。结果表明,热应激时,山羊的心率、呼吸频率、血糖含量均有一定程度的上升;ＣＫ在热应激中有明显的上升;ＷＢＣ略有下降;ＲＢＣ和血清中ＧＯＴ、ＧＰＴ、ＴＰ、ＢＵＮ含量变化不显著。     

The influence of different doses of α-tocopherol and ascorbic acid on selected oxidative stress parameters in in vitro culture of leukocytes isolated from transported calves

The objective of the study was to assess in vitro the influence of various doses of two different antioxidants, α-tocopherol and ascorbic acid, on protective mechanisms against ROS in white blood cells obtained from calves exposed to transport, and to compare these results with those obtained from non-transported animals.The concentrations of lipid peroxidation products in leukocytes and in the retained medium were assessed by determining the level of ThioBarbituric Acid Reactive Substances (TBARS). Total antioxidant status in the leukocytes and the medium were estimated using a ferric-reducing ability of plasma (FRAP) assay. Leukocyte viability was determined using the trypan blue reduction test.The study demonstrated that after bovine leukocytes (WBC) were incubated in vitro with α-tocopherol and ascorbic acid, peroxidation intensity decreased and total antioxidant capacity increased. The results of the study reveal that these antioxidants in concentrations over 0.1 mg/ml have a major impact on free radical activity on bovine white blood cells and on cell viability during transport of animals.Based on this study, we suggest that incubation of the leukocytes with antioxidants decreases the oxidative stress development, which can be helpful in protection of the immunological cells during bovine respiratory disease.     

5-Aminolevulinic acid combined with sodium ferrous citrate mitigates effects of heat stress on bovine oocyte developmental competence

High summer temperatures have deleterious effects on oocyte developmental competence. The antioxidant and autophagy-related properties of 5-aminolevulinic acid (5-ALA) gives the compound a broad range of biological activities. This study aimed to evaluate the effects of: 1) a high temperature-humidity index (THI) on the developmental competence of bovine oocytes, and 2) 5-ALA administration in combination with sodium ferrous citrate (SFC) during in vitro maturation (IVM) on bovine oocyte developmental competence evaluated at high THI. Bovine ovaries were collected from a local slaughterhouse at moderate environmental temperature (MT; THI of 56.2) and high environmental temperature (HT; THI of 76.7) periods; cumulus-oocyte complexes (COCs) were aspirated from medium-sized follicles, matured in vitro for 22 h, fertilized, and cultured for 10 days. For COCs collected during the HT period, 0 (control), 0.01, 0.1, 0.5, or 1 µM 5-ALA was added to the maturation medium in combination with SFC at a molar ratio of 1:0.125. The results showed that HT adversely affected blastocyst and hatching rates compared with MT. Adding 5-ALA/SFC (1 µM/0.125 µM) to the maturation medium of oocytes collected during the HT period improved cumulus cell expansion and blastocyst rates compared with the no-addition control. In conclusion, this study showed that high THI can disrupt bovine oocyte developmental competence. Adding 5-ALA to SFC ameliorates this negative effect of heat stress and improves subsequent embryo development.     

抗坏血酸引发对NaCl胁迫燕麦种子活力的影响

以燕麦种子为材料,通过对燕麦种子进行不同浓度(0、0.5、1.0、1.5和2.0 mmol·L^-1)的抗坏血酸(AsA)引发,然后在浓度为0、50、100和200 mmol·L^-1的NaCl胁迫下发芽,并分析其发芽率(G_p)、发芽指数(G_i)及平均发芽时间(MGT)的变化,以探讨外源AsA引发对盐胁迫种子活力的影响。结果表明:燕麦种子G_p、G_i和MGT在NaCl胁迫下显著(P<0.05)降低。随AsA浓度增加,燕麦种子G_p在浓度为100和200 mmol·L^-1的NaCl胁迫下呈先升后降的趋势,其G_i呈下降趋势,其MGT则呈增大趋势,而且不同AsA和NaCl浓度及两者的交互作用均对燕麦种子G_p、G_i和MGT影响极显著(P<0.01)。NaCl胁迫降低了燕麦种子的活力水平,而外源AsA引发可提高NaCl胁迫下燕麦种子的活力,该作用与AsA和NaCl的浓度具有密切关系。试验中1.0 mmol·L^-1的AsA引发对100和200 mmol·L^-1的NaCl胁迫效果最好。然而,外源AsA引发会延长燕麦种子在NaCl胁迫下的萌发时间。     

干旱胁迫下结缕草叶片抗坏血酸与相关生理指标变化的品种差异研究

通过盆栽试验,以日本结缕草与细叶结缕草为材料,研究了干旱胁迫下结缕草叶片AsA含量与相关生理指标的品种差异。结果表明,干旱胁迫下日本结缕草和细叶结缕草叶片中AsA含量与相关生理指标的动态变化规律基本相似,但品种间差异显著。干旱胁迫下2个品种的AsA含量和AsA/DHA均呈现先上升后下降的变化趋势,但日本结缕草下降的时间更早。干旱胁迫下叶片相对含水量、POD活性在2个品种中均呈下降趋势,但日本结缕草的下降趋势更明显,尤其在干旱胁迫后期。胁迫后日本结缕草叶绿素a与叶绿素b含量下降明显,而细叶结缕草变化不大。胁迫后两者的相对电导率和MDA含量均呈上升趋势,但日本结缕草增加的幅度更为显著。干旱胁迫后日本结缕草和细叶结缕草叶片Rubisco的含量均在第3天开始下降,胁迫后期日本结缕草Rubisco含量恢复到对照水平,而细叶结缕草Rubisco含量在胁迫后期显著高于对照。本研究结果表明,干旱胁迫下结缕草可以通过增加和维持叶片中AsA含量与POD活性来减缓Rubisco及叶绿素的降解,降低干旱胁迫对植株造成的氧化胁迫伤害程度,进而改善其抗旱能力。本研究结果进一步证实结缕草抗旱能力有品种差异,其中日本结缕草抗旱能力弱于细叶结缕草。     

甜菜碱日粮对热应激条件下肉鸭生长性能、血液指标及盲肠脂肪酸含量的影响

文章旨在评估甜菜碱对热应激条件下肉鸭血液指标、电解质、气体分压和盲肠短链脂肪酸含量的影响。试验选择平均体重为48.6g当天孵化的肉鸭400只,随机分为4组,每组5个重复,每个重复20只。试验日粮处理分为对照组和3个处理组,对照组饲喂基础日粮(自由采食),处理1组为热应激条件下添加1500mg/kg甜菜碱,处理2组为热应激条件下5点~10点以及17点~20点饲喂含1500mg/kg甜菜碱日粮,处理3组为热应激条件下17点~10点饲喂含1500mg/kg甜菜碱日粮,试验共进行42d。结果显示:饲喂甜菜碱日粮的肉鸭较对照组体重显著提高(P<0.05)。对照组肉鸭血液红细胞总数、红细胞压积、血红蛋白、红细胞平均体积、红细胞分布宽度、血小板计数、血小板压积、血小板平均体积均低于甜菜碱组(P<0.05)。不同饲喂时间的甜菜碱组肉鸭电解质浓度均高于对照组(P<0.05)。对照组肉鸭血液二氧化碳分压、氧气分压、细胞外液碱浓度、碳酸氢盐和总二氧化碳浓度均低于甜菜碱组(P<0.05)。与对照组相比,甜菜碱组肉鸭盲肠中总短链脂肪酸、乙酸、丙酸的浓度较高(P<0.05),而丁酸、异丁酸、戊酸和异戊酸含量较低(P<0.05)。因此,与自由采食相比,在上午和下午限制饲喂甜菜碱日粮或17~10点饲喂甜菜碱日粮显著提高了热应激条件下肉鸭的生长性能和生物学参数。     

抗坏血酸和水杨酸丸衣对NaCl胁迫下紫花苜蓿种子发芽特性的影响

为探究抗坏血酸（AsA）和水杨酸（SA）丸衣对NaCl胁迫下紫花苜蓿种子萌发的缓解效应,以紫花苜蓿种子为试验材料,采用不同浓度的AsA（1、2、4、8 mmol·L^-1）和SA（1、5、10、20 mmol·L^-1）对紫花苜蓿种子拌种后进行丸衣处理（未丸衣种子为CK₁,不做拌种处理的丸衣种子记为CK₂）,分析丸衣种子在NaCl胁迫下发芽特性的变化,以期获得能有效缓解紫花苜蓿种子盐胁迫效应的种子丸衣配方。结果表明,1.25%和1.50%的NaCl胁迫显著（P<0.05）降低了紫花苜蓿未丸衣种子的发芽率、发芽势、种苗长和种苗重,延长了平均发芽时间。AsA在1.25%NaCl胁迫下缓解效果不明显,4 mmol·L^-1AsA拌种后丸衣处理,能提高1.50%NaCl胁迫下紫花苜蓿种子的发芽率、种苗长。1 mmol·L^-1SA拌种后丸衣处理,能提高1.50%NaCl胁迫下紫花苜蓿种子的发芽势、发芽率和种苗长,而20 mmol·L^-1SA拌种后丸衣处理降低了紫花苜蓿种子的发芽率。说明AsA和SA丸衣对NaCl胁迫的缓解作用与其拌种浓度和NaCl胁迫浓度有关。本试验筛选出4 mmol·L^-1AsA和1 mmol·L^-1SA拌种丸衣配方对NaCl胁迫的缓解作用最优,该结果为AsA和SA丸衣应用于紫花苜蓿种子缓解NaCl胁迫提供依据。     

Presence of chlorogenic acid during in vitro maturation protects porcine oocytes from the negative effects of heat stress

Chlorogenic acid (CGA) is known to protect oocytes from oxidative stress. Here we investigated the effects of CGA on porcine oocyte maturation under heat stress and subsequent embryonic development after parthenogenetic activation. For in vitro maturation (IVM) at 41.0°C (hyperthermic condition), supplementation of the maturation medium with 50 μM CGA significantly improved the percentage of matured oocytes and reduced the rate of apoptosis relative to oocytes matured without CGA (p < .05). CGA treatment of oocytes during IVM under hyperthermia tended to increase (p < .1) percentage of blastocyst formation after parthenogenesis and significantly increased (p < .05) the total cell number per blastocyst relative to oocytes matured without CGA. For IVM at 38.5°C (isothermic condition), CGA significantly improved the rate of blastocyst development compared with oocytes matured without CGA (p < .05), but did not affect oocyte maturation, apoptosis rate or the number of cells per embryo. Omission of all antioxidants from the IVM medium significantly reduced the rate of oocyte maturation, but the rate was restored upon addition of CGA. These results demonstrate that CGA is a potent antioxidant that protects porcine oocytes from the negative effects of heat stress, thus reducing the frequency of apoptosis and improving the quality of embryos.     

In ovo injection of ascorbic acid and higher incubation temperature modulate blood parameters in response to heat exposure in broilers

1. This study analysed whether in ovo injection of ascorbic acid before incubation and at high incubation temperature influenced blood characteristics and performance in broilers reared in different temperature conditions.

2. A total of 3,000 fertile eggs from broiler breeders (Cobb®) were randomly divided into three incubation treatments: no ascorbic acid injection and egg incubation at 37.5°C (control); no ascorbic acid injection and egg incubation at 39°C; in ovo ascorbic acid injection prior to incubation (6 µg AA/100 µl water) and egg incubation at 39°C.

3. Male chicks hatched from the three incubation treatments were submitted to three distinct rearing temperatures (control, cold and hot) from the third week of age onwards (540 chicks were divided into 6 treatments with 5 replicates per treatment).

4. Measurements at 42 d showed that, after egg incubation at 39°C, the haematocrit, haemoglobin values, ionised calcium and glucose concentrations were increased and base excess values were reduced. However, in ovo injection of ascorbic acid normalised all these parameters.

5. Partial CO₂ and O₂ pressure were higher with increased rearing temperature. Blood pH was lower when eggs were incubated at 39°C and injected with ascorbic acid. In ovo injection of ascorbic acid induced leucocytosis due to lymphocytosis and heterophilia, restored basophils rate and led to monocytopoenia. Leucocytosis was triggered by hot rearing temperature due to lymphocytosis, eosinophilia and heterophilia.

6. The results obtained in this study showed that in ovo injection of ascorbic acid before incubation may serve as a long-term stimulator and modulator of the broiler immune system, and that high incubation temperatures induce adaptations in the electrolytic balance, minimising or avoiding the occurrence of respiratory alkalosis under hot rearing temperature.     

抗坏血酸对高氮条件下高羊茅草坪草耐热性的影响

本试验以冷季型草坪草高羊茅“猎狗５号”为材料,研究了抗坏血酸对高氮条件下草坪草耐热性的影响。结果表明,抗坏血酸处理显著提高了高羊茅的叶绿素、类胡萝卜素和可溶性蛋白质含量,提高了超氧化物歧化酶（ＳＯＤ）、过氧化氢酶（ＣＡＴ）和过氧化物酶（ＰＯＤ）活性,显著降低了脯氨酸和丙二醛（ＭＤＡ）含量,进而增加了植株含水量、单蘖干重、绿叶比和单株分蘖数,增强高羊茅耐热性和延缓植株衰老,有利于其安全越夏。     

Physiological stress in broilers: Ramifications on nutrient digestibility and responses

Physiological stress is one of many concerns facing the modern broiler producer. Research has yet to reveal mechanisms that would allow the producer to efficiently minimize the detrimental impacts of physiological stress on broiler performance. One possible approach for improvement in this area is to elucidate the effects of different nutrient regimens on stressed broilers. Sufficient prior knowledge of the effects of stress on metabolism and nutrient digestibility, as well as effective stress induction models, is essential to any researcher interested in delineating the effects of nutrients on stressed broilers. This review examines the physiological mechanisms that activate and control stress, as well as the effects of stress on immunity, metabolism, and broiler performance. Validation procedures for stress induction models are also examined. Additionally, this review examines available research focused on amino acid digest-libility in the presence of stress, digestibility assays necessary for this research, and nutrients that have been shown to have the potential for stress reduction or amelioration.     

外源抗坏血酸对铜胁迫菊苣幼苗生长的缓解效应

为探究外源抗坏血酸(AsA)对铜(Cu)胁迫下菊苣幼苗生长的缓解效应,本研究以普那菊苣为试验材料,采用溶液培养法研究外源AsA对50μmol·L?1 Cu胁迫下菊苣幼苗的生长、Cu积累和生理特性的影响.结果表明,50μmol·L?1 Cu胁迫严重抑制了菊苣幼苗的叶绿素含量、光合作用和生物量的积累,加剧了细胞膜脂质过氧化...     

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.     

Both experimental hypo- and hyper-thyroidism exacerbate the adverse effects of chronic heat stress in broilers

1. The effects of hypo- and hyper-thyroidism in mitigating or exacerbating the negative changes of chronic heat stress (HS) in broilers were investigated.

2. Three-week-old broilers were distributed into six groups (n = 13 per group). Three groups were housed at ambient room temperature: control group (CN), propylthiouracil-treated group (AN) and thyroxine-treated group (TN). The other three groups were exposed to HS at 33 ± 1°C for 2 weeks: control heat stress (CH), propylthiouracil + heat stress (AH) and thyroxine + HS (TH).

3. Induced hypothyroidy significantly decreased cloacal temperature and body weight gain in the birds in both the normal and HS groups (AN, AH). Conversely, hyperthyroidy resulted in a significant elevation in cloacal temperature in the TN and TH groups and a significant decline in weight gain in the TH group. Hyperthyroidy exacerbated the HS-induced degenerative changes in jejunal mucosa and caused noticeable vascular changes. A significant increase in the expression levels of jejunal nutrient transporter genes was observed in the AH and TH groups. The hyperthyroidic state significantly upregulated the HSP70 expression level in the TH group and the reverse occurred with propylthiouracil (PTU) treatment in the AH group.

4. PTU supplementation to chicks reared under HS significantly decreased the triiodothyronine level, antibody (Ab) titre, and increased the heterophil-lymphocyte ratio. Furthermore, it induced higher hepatic glutathione peroxidase (GSH-Px) activity in the AN and AH groups and decreased the malondialdehyde content (MDA) in the AN group. Hyperthyroidy significantly increased triiodothyronine concentration, H/L ratio and decreased Hb concentration and Ab titres in the TH group. Additionally, this status increased the MDA content and decreased the GSH-Px activities.

5. In conclusion, manipulation of thyroid status is not a remedy to overcome the undesirable effects of HS in broilers.     

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。     

日粮中添加硫辛酸对热应激条件下母兔的影响

选择体况良好的新西兰母兔20只,随机分为4组,日粮中分别添加硫辛酸200mg/kg、400mg/kg、600mg/kg,对照组不添加。每组5个重复(每个单笼饲养的兔子为一个重复)。探索日粮中添加硫辛酸对热应激条件下母兔影响。试验结果表明,在高温应激情况下,在日粮中添加硫辛酸:①可使母兔血清中丙二醛(MDA)的含量显著降低(P0.05);②可提高母兔的血清中超氧化物歧化酶(SOD)和GSH-Px的活性(P0.05);③可增加母兔血清总抗氧化能力(P0.05)。从相关理化参数可见,以日粮中添加600mg/kg的硫辛酸抗热应激效果最好。     

Alterations of endotoxin distribution across different biofluids and relevant inflammatory responses by supplementing L-theanine in dairy cows during heat stress

The present trial was performed to reveal the regulatory effects of L-theanine on the levels of lipopolysaccharide (LPS) endotoxin within different biofluids, as well as relevant inflammatory responses of dairy cattle under heat stress conditions. Thirty lactating Chinese Holstein dairy cattle (189 ± 47 d in milk, and 2 ± 1 parities) were allocated in a completely randomized design to each of 3 dietary treatments: the control (CON, 0 g/d per cow L-theanine), the low L-theanine dosage treatment (LL, 16 g/d per cow L-theanine), and the high L-theanine dosage treatment (HL, 32 g/d per cow L-theanine). This trial consisted of 38 d (7 d for adaption and 31 d for data and sample collection), and sample collection for rumen liquid, blood plasma or serum, and milk were conducted on the d 27 and 38, respectively. Dairy cattle were constantly exposed to environmental heat stress during this experiment according to the recorded temperature-humidity index (THI). In the LL treatment, LPS concentration in rumen liquid was higher (P < 0.05), whilst LPS densities in plasma and milk were lower (P < 0.05) than those of the CON. Supplementing L-theanine at 2 dosages both significantly lowered (P < 0.05) the level of interleukin (IL)-1β in the serum. Results of the present study suggested that L-theanine could be a promising additive in reducing the detrimental effects of heat stress on dairy cows, and L-theanine supplementation at 16 g/d per cow is preferred because it reduced the LPS translocation into the peripheral blood and LPS accumulation in the milk, as well as mitigated LPS-induced inflammatory reactions in dairy cows during heat stress. Further studies are necessitated to investigate the underlying mechanisms of L-theanine in LPS alteration and inflammation alleviation.     

水分胁迫及复水对虉草生理生化特性的影响

通过温室盆栽控水试验,研究了虉草在自然干旱与复水过程中生理生化指标的变化规律,旨在探讨虉草对于水分变化的响应特性及耐旱能力。结果显示,1)干旱胁迫期间,尽管土壤含水量下降迅速,但是叶片相对含水量在水分胁迫前8 d仍维持在正常水平,直到第12天时才显著下降。2)在持续干旱过程中,可溶性蛋白与丙二醛含量不断增加。3)叶绿素、叶绿素a、类胡萝卜素含量及Chla/Chlb与Car/Chl的比值整体上均随干旱胁迫时间的延长而呈上升趋势。4)干旱胁迫后期,叶绿素荧光参数Fo、NPQ增加,Fm、Fv/Fm、Fv/Fo与qP均有所下降。5)复水后,各指标均能迅速得到不同程度恢复。研究结果初步表明,虉草具备较强的保护与损伤修复能力,使其能够适应较大程度的干旱逆境。     

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.