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1.
AIM: To identify the contributions of stationary periods and external climatic environments to thermal stress conditions for sheep on livestock transport vehicles during journeys in summer. METHODS: Two livestock transport vehicles carrying sheep, operating under commercial conditions in New Zealand, were monitored during February and March 2002. Temperature and humidity were logged in five pens inside each vehicle, as well as externally. From these data, the temperature-humidity index (THI) was calculated. Global positioning equipment was used to log the location of the vehicle and whether it was moving or stationary. Regression analysis was used to identify factors that made a significant contribution to the THI within the vehicle. Regression models included the effects of vehicle, journey, initial ambient temperature or THI, pen position and duration of each stationary period. RESULTS: The THI in the livestock pens generally increased when vehicles were stationary. The highest THI value (95) was recorded in a vehicle on an enclosed deck of a Cook Strait ferry. Ambient conditions, the initial THI of a pen, and duration of the stationary period were all significant contributors to increases in the THI. Some increases in the THI occurred in stationary vehicles despite ambient conditions being mild, suggesting that lack of airflow was a critical factor. During stationary periods, 34% of THI readings exceeded 75, and, on average, the THI increased by 0.16 for every minute of a stationary period. CONCLUSIONS: Increases in the THI that could be detrimental to the welfare of sheep could occur on stationary sheep transport vehicles at most daytime ambient temperatures during summer. For a given stocking density and vehicle design, the THI of a pen increased in proportion to the duration of the stationary period. Mild ambient conditions (<25 degrees C) provided some protection against excessive THI increases if the duration of the stop was limited, but drivers are best advised to park their vehicles where there is airflow, and to minimise the duration of stops where possible. Livestock transport vehicles during summer should not be placed on enclosed ferry decks where airflow is absent or minimal.  相似文献   

2.
AIM: The aim of this study was to evaluate the potential of variations in stock crate design (especially ventilation) and stocking density on road transport vehicles for reducing the risk of environmental stress for lambs during long-haul transport in hot weather. METHODS: In Experiment 1, lambs were transported on vehicles fitted with either a newer-design aluminium crate comprising a three-deck truck and four-deck trailer, or an older-design, more open, steel crate of a three-deck truck and three-deck trailer. In Experiment 2, lambs were transported on newer-design vehicles at either standard stocking density (0.20 m2 per 35 kg lamb) or at a 20% lower density (0.26 m2 per 35 kg lamb). In each experiment, each journey was replicated twice and consisted of travel periods and stationary periods designed to emulate conditions associated with an inter-island ferry crossing. Air ammonia concentrations and temperature and humidity were monitored within six pens on each vehicle, and the temperature-humidity index (THI) was calculated. RESULTS: Ammonia concentrations were variable and generally 50 ppm, and did not vary significantly with treatment. The THI increased when the vehicles were stationary, especially under conditions designed to emulate an enclosed ferry deck. The ambient temperature during Experiment 1 was moderate (up to 21 degrees C), and THI was slightly lower in the older-design crate. High ambient temperatures (up to 33 degrees C) were present during Experiment 2, and THI was significantly lower at the lower stock density. During a 3-h stationary period, the peak THI at standard stocking density was 91.0, compared with 84.9 for the low density treatment (p<0.001). CONCLUSIONS: For standard road transport vehicles used for long-haul transport of lambs, lowered loading density may be of considerable benefit in alleviating conditions that increase the risk of lamb deaths during inter-island transport on hot days.  相似文献   

3.
A 20-min van journey increased plasma cortisol concentrations to 15-25 ng/ml in male goats, blood glucose concentrations were not affected, but respiratory rates and heart rates were increased, the latter by 40 beats per min. A 2-h van journey increased plasma cortisol to greater than 25 ng/ml and blood glucose to greater than 5 mmol/l. Respiratory rates were increased to greater than 40 breaths per min and heart rates by greater than 100 beats per min. Xylazine alone (0.01 mg/kg) suppressed resting plasma cortisol concentrations, increased blood glucose concentrations to 4.5 +/- 0.8 mmol/l and suppressed respiratory rates by 5-10 breaths per min and heart rates by 20 beats per min. Cortisol concentrations were suppressed by xylazine treatment if given before a 20-min van journey, and for approximately 60 min if given 20 min after the start of a 2-h journey. When combined with transport, xylazine caused an additive effect on glucose concentrations, but suppressed respiratory and heart rates. However, for the latter criteria the timing of suppression was different depending on the time of onset and duration of the stressor. Injection of 50 micrograms ovine corticotrophin releasing factor (CRF) caused an immediate elevation of cortisol concentrations (but not glucose) which lasted for at least 6 h compared with the return to baseline within 60 min after either length of journey. Xylazine pretreatment did not alter the cortisol response to CRF, suggesting that xylazine must act centrally above pituitary level when blocking the cortisol response to transport. It is proposed that under resting conditions the hypothalamus is under alpha 2-adrenergic suppression. Stimulation of cortisol secretion in response to a stressor can be inhibited by an alpha 2-adrenergic agonist.  相似文献   

4.
Comparisons were made of the behaviour, physiology and meat quality of 24-week-old male veal calves (mean live weight 234 kg) that were slaughtered either at the veal unit (the control group) or following 3 h transportation at space allowances of either 0.7 or 0.95 m2 calf−1 and 1.5 h of lairage. Compared with nontransported calves, transported calves had a greater heart rate during the journey and during lairage; greater plasma cortisol concentration immediately after the journey, but not after 1.5 h of lairage; and greater plasma creatine kinase activity immediately after the journey and after 1.5 h of lairage. The transported calves did not lie down during the journey. There was no effect of space allowance on either the heart rate or frequency of potentially traumatic events during the journey or the plasma cortisol concentration and plasma creatine kinase activity sampled after the journey. There was no effect of transport on either carcase bruising or muscle pH 24 h after slaughter. Although compared with ‘on-farm’ slaughter, the transport and handling associated with the journey to the slaughterhouse were stressful to the calves; there were no adverse effects of transport on either carcase bruising or meat quality.  相似文献   

5.
The aim of this study was to investigate the effects of long-distance road transport (19 h, from Poland to Italy) during 2 seasons (summer vs. winter) on clinical and hematological variables in calves. The environmental temperature range that could compromise the thermoregulation system (thermal stress) of the calves was tested. For the 7 Holstein calves in each transport, the BW and rectal temperature (RT) were measured, and blood samples were collected at the farm of origin, before loading at the transit center (T2), after unloading at the farm of destination (T3), and 1, 2, 3, and 4 d after arrival. The body temperature (BT) and heart rate (HR) were continuously monitored from T2 to T3. The data were statistically analyzed according to a mixed model that considered the fixed effects of transport (repeated measurements), season of journey, and their interaction. Within the observed temperature-humidity index (THI) range (30 to 80), effective thermoregulation allowed the calves to maintain their BT with small physiologic changes to prevent thermal stress, particularly in the summer. With no seasonal differences, the HR was greater at loading than unloading (120 vs. 115 beats per min; P = 0.012). As for the transport effect, the BW was less (P < 0.001) after unloading, and the RT was greater (P = 0.004). This effect was more marked in summer. The hematological variables indicated a moderate effect of transport on the hydration condition, reactive and muscular systems, and metabolism, although hematocrit (P = 0.004), erythrocytes, cortisol, NEFA, β-hydroxybutyrate, lactate, creatine kinase, lactate dehydrogenase, and aspartate aminotransferase activity (P < 0.001), and total protein (P = 0.007) were greater after unloading. This was confirmed by a moderate decrease in total leukocytes (P = 0.031) and glucose concentration (P = 0.002). The changes in the clinical variables were similar for both seasons even though in the summer, hematocrit (P < 0.001), urea (P = 0.008), and total protein (P = 0.010) increased and glucose concentration (P = 0.038) decreased. In conclusion, the data did not show a pronounced effect attributable to the season of the journey. Long-distance road transport leads to notable changes in clinical and hematological variables at the end of the journey. However, these variables remained within their physiological ranges and returned to basal values within a few days after the journey.  相似文献   

6.
Pentobarbitone inhibits the stress response to transport in male goats   总被引：2，自引：0，他引：2  
Pentobarbitone (20 mg/kg i.v.) blocked plasma cortisol release when administered either before a 20 min journey or during a 2 h journey. This confirms that pentobarbitone can block stimulated, as well as resting, cortisol secretion. In general, blood glucose concentrations were not increased above 90 mg/100 ml until at least 30 min after the start of transport; however, this increase was also blocked by pentobarbitone administered 30 min into the 2 h journey. Significant increases in respiratory and heart rates occurred within 15 min of the start of transport; pentobarbitone caused an immediate decrease in these parameters. In conclusion, pentobarbitone was shown to reverse many metabolic changes induced by transport.  相似文献   

7.
The environmental temperature increased during summer and decreased during winter to the limits that might negatively affect animal and human reproduction. The responses of Egyptian rams to either hot or cold climatic conditions were studied in six mature rams subjected to weekly testicular Doppler ultrasonographic examination, blood sampling, seminal plasma collection and semen evaluation. The maximum environmental temperature and the relative humidity were used to classify the climatic condition according to the heat stress equation of sheep into hot months where temperature–humidity index (THI) was >26 (31.67 ± 0.54), and cold months where THI was <22 (18.39 ± 0.41). Testosterone, estradiol, superoxide dismutase (SOD), glutathione peroxidase (GPX) and lipid peroxide product (malondialdehyde, MDA) were measured in both blood and seminal plasma, while catalase (CAT) and reduced glutathione (GSH) were measured in blood and seminal plasma, respectively. Results revealed that, during the hot months, rams displayed significantly decreased testicular blood flow, increased seminal plasma MDA, decreased seminal plasma (SOD, GPx and GSH) and blood CAT antioxidant enzymes. The present study evidenced two novel findings: (a) the marked decrease in testicular blood flow volume, that is remarkable increase in both resistive index (RI) and pulsatility index (PI) values, during hot months could be negatively affected both seminal plasma enzymatic activities and seminal attributes, and (b) the SOD and GPx activities in seminal plasma of such animals were suitable predictive markers for seminal attribute evaluation.  相似文献   

8.
The effect of Temperature Humidity Index (THI) on dairy cows’ willingness to be on pasture was examined. Information for 2 years regarding weather, milk production, and time for voluntarily passing a gate between the barn and pasture of cows milked with an automatic milking system was studied. When the THI exceeded 72 during the day, more cows spent time on pasture compared to when the THI was less than 72 (27.0% vs. 19.2% of cows on pasture, respectively). However, the time of day influenced the proportion of cows on pasture, and when the THI exceeded 72, more cows were on pasture at night and less during the afternoon compared to days when the THI was less than 72. In conclusion, even under Swedish conditions, THI might have an effect on cows’ behaviour. However, when the cows have free access to roughage and pasture, an increased THI does not affect milk production.  相似文献   

9.
The effects of floor space on the trailer and journey time during transport from the farm to the packing plant on indicators of stress (open-mouth breathing, muscle tremors, and skin discoloration) and on the incidence of transport losses (dead on arrival, nonambulatory, noninjured, and nonambulatory, injured) were evaluated in a study involving 160 loads of market-weight pigs (BW 124.7 ± 4.38 kg) using a split-plot design with a 2 × 6 factorial arrangement of treatments: 1) journey time [main plot; short (<1 h) and long (3 h)] and 2) floor space (subplot; 0.396, 0.415, 0.437, 0.462, 0.489, and 0.520 m(2)/pig, which is equivalent to 0.317, 0.332, 0.350, 0.370, 0.391, and 0.416 m(2)/100 kg of BW, respectively). Two consecutively loaded trailers were randomly allotted to journey time treatment. Floor space treatments were compared in the front 3 compartments on the top and bottom decks of the trailer and were created by varying the number of pigs per compartment, which confounds the effect of floor space with group size. Of the 17,652 pigs transported in 954 test compartments, 0.24% died or became nonambulatory. Neither journey time nor floor space had an effect (P > 0.05) on the incidence of dead and nonambulatory, injured pigs, or on total transport losses. There were interactions (P < 0.05) between journey time and floor space treatments for the incidences of nonambulatory, noninjured pigs and open-mouth breathing. For 2 of the smallest floor spaces (0.415 and 0.437 m(2)/pig), the incidence of nonambulatory, noninjured pigs was greater on short than on long journeys; for the other 4 floor spaces there was no effect (P > 0.05) of journey time. The incidence of open-mouth breathing for the 3 smallest floor spaces was greater (P < 0.05) for short than long journeys, whereas there was no effect (P > 0.05) of journey time for the 3 greatest floor spaces. The frequency of skin discoloration was greater (P < 0.001) for pigs transported at the 2 smallest floor spaces compared with the other 4 floor spaces. In summary, short journey time increased the frequency of indicators of stress after unloading at the plant for pigs transported at smaller floor spaces and also increased the incidence of nonambulatory, noninjured pigs at 2 of the 3 smallest floor spaces. However, neither transport floor space nor journey time had an effect on total losses.  相似文献   

10.
Dehydration and increased risk of respiratory problems are common outcomes of transport, and both appear to be related to journey duration, emotional effects, such as fear, and challenging environmental conditions. Welfare may be improved by familiarising equines with transport vehicles and loading procedures before travel starts, and by providing thermally comfortable and well ventilated conditions during the journey. For long road journeys, rest breaks with drinking water should be given. Both trained and unhandled animals should have sufficient space and freedom to adjust their posture and to lower their heads, but maximum safe space allowances are unknown. Mares and foals should be transported together. Injury during transport is relatively common, particularly in groups of horses travelling to slaughter, and is usually associated with driver error, internal fittings and vehicle type or design, but also with mixing of animals of different sex and weight leading to fighting. There needs to be better training and monitoring to prevent such avoidable risks to horse welfare. There is also a need for more research into appropriate prophylaxis and post transport therapy as knowledge of accumulated stress and depressed immune function following prolonged and repeated transport is poorly understood.  相似文献   

11.
Ten years of calving records were examined from Bos taurus crossbred cows (mean of 182 cows/yr) to quantify the effects of environmental conditions during the breeding season on pregnancy rate. Estimated breeding dates were determined by subtracting 283 d from the calving date. Relationships were determined between the proportion of cows bred during the periods from the beginning of the breeding season until d 21, 42, and 60 of the breeding season and the corresponding environmental variables. Weather data were compiled from a weather station located approximately 20 km from the research site. Average daily temperature and relative humidity were used to calculate daily temperature-humidity index (THI). Daily averages for each environmental variable were averaged for each period. Minimum temperature (MNTP) and THI for the first 21 and 42 d of the breeding season were negatively associated (P < 0.001) with pregnancy rate. For the 0-to 21-d, 0- to 42-d, and 0- to 60-d breeding periods, respective r2 for average temperatures were 0.32, 0.37, and 0.11, whereas r2 for MNTP were 0.45, 0.40, and 0.10 and r2 for THI were 0.38, 0.41, and 0.11, respectively, for the same breeding periods. The negative associations of temperature and THI with pregnancy rate are most pronounced during the first 21 d of the breeding season, with a -3.79 and -2.06% change in pregnancy rate for each unit of change in MNTP and THI, respectively. A combination of environmental variables increased the R2 to 0.67. In this analysis, windspeed was found to be positively associated with pregnancy rate in all equations and increased the R2 in all breeding periods. Optimum MNTP for the 0- to 21-d, 0- to 42-d, and 0- to 60-d breeding periods was 12.6, 13.5, and 14.9 degrees C, respectively. For the 0- to 60-d breeding period, optimum THI was 68.0, whereas the THI threshold, the calculated level at which cattle will adapt, was found to be 72.9. Reductions in pregnancy rate are likely when the average MNTP and THI equal or exceed 16.7 degrees C and 72.9, respectively, and for Bos taurus beef cows that are pasture bred during a 60-d spring-summer period.  相似文献   

12.
This study examined the effects of transporting calves less than four weeks of age on a journey at the limit of the maximum time laid down by recent EU legislation. In both summer and winter, 45 calves were transported by road for 19 hours. The journey included a one-hour break on the lorry in which the calves were given either a glucose/electrolyte solution, water, or nothing at all. Control groups of 15 calves remained on farm and were fed normally. The effects of the journey were greater during winter when liveweight loss was greater and more prolonged, and the calves suffered a depression in body temperature. Mid-journey feeding was of minimal benefit. Feeding electrolytes reduced the extent of dehydration as measured by changes in plasma total protein and albumin concentrations, but there was some indication that giving water alone was detrimental. Most of the variables which changed during the journey had recovered in line with the values in the control animals within 24 hours of the end of the journey, but the calves' liveweight and plasma creatine kinase activity took up to seven days to stabilise. The study highlighted the problem that young calves have in maintaining body temperature during transport, especially during colder weather.  相似文献   

13.
本试验采用实时跟踪摄像和颈静脉血管瘘连续采样,观察二花脸断奶仔猪在2h运输过程中的行为表现,并测定血浆皮质醇水平的动态变化。结果表明:运输前期(出发后15min)仔猪的探究行为和异常行为发生次数较多且持续时间较长,运输中期(出发后60~75min)此类行为显著减少(P<0.05),而到运输后期(最后15min)几乎观察不到此类行为;仔猪的躺卧行为在运输前期和中期发生次数较少,持续时间较短,而在运输后期仔猪大部分时间都处于躺卧状态(P<0.05);运输至中期仔猪大部分时间处于站立状态,而到运输后期站立行为显著减少(P<0.05);仔猪蹲坐行为发生的次数和持续时间在运输的前中后无显著差异(P>0.05)。仔猪上车后皮质醇水平迅速上升(P<0.05),出发15min升至峰值,且保持该高水平直到2h运输结束,下车后15min皮质醇水平迅速下降至上车前15min的基础水平。  相似文献   

14.
Factors affecting the mortality of pigs being transported to slaughter   总被引：1，自引：0，他引：1  
A multilevel logistic regression model was used to identify and quantify the effects of factors affecting the mortality of pigs being transported to slaughter under commercial conditions. A survey of 739 journeys to 37 slaughterhouses in five eu countries was carried out, and information potentially related to the welfare and mortality of the pigs and the number of injuries were recorded. The average temperature during the journey, its duration, the average loading time per pig, the recorded injuries, fasting before transport, and the interaction between fasting and journey duration were used in the final model. The average mortality was 0.11 per cent and the average proportion of injured pigs was 0.36 per cent, and these figures were significantly correlated (P<0.001). In 29 per cent of the journeys the pigs were not fasted before being loaded, which doubled the risk of mortality irrespective of whether the pigs were injured or not. The risk of mortality increased with average temperature. In journeys with fasted pigs that did not have any recorded injury, average temperature was more important than the duration of the journey. The risk of mortality increased as the average time taken to load them decreased, and the risk was highest when the pigs were not fasted and when injuries were recorded. Other factors such as the country, loading density, availability of drinking water and type of ventilation did not affect the risk of mortality.  相似文献   

15.
Environmental factors influencing heat stress in feedlot cattle   总被引：8，自引：0，他引：8  
Data from 3 summer feedlot studies were utilized to determine the environmental factors that influence heat stress in cattle and also to determine wind speed (WSPD; m.s(-1)) and solar radiation (RAD; W.m(-2)) adjustments to the temperature-humidity index (THI). Visual assessments of heat stress, based on panting scores (0 = no panting to 4 = severe panting), were collected from 1400 to 1700. Mean daily WSPD, black globe temperature at 1500, and minimums for nighttime WSPD, nighttime black globe THI, and daily relative humidity were found to have the greatest influence on panting score from 1400 to 1700 (R2 = 0.61). From hourly values for THI, WSPD, and RAD, panting score was determined to equal -7.563 + (0.121 x THI) - (0.241 x WSPD) + (0.00082 x RAD) (R2 = 0.49). Using the ratio of WSPD to THI and RAD to THI (- 1.992 and 0.0068 for WSPD and RAD, respectively), adjustments to the THI were derived for WSPD and RAD. On the basis of these ratios and the average hourly data for 1400 to 1700, the THI, adjusted for WSPD and RAD, equals [4.51 + THI - (1.992 x WSPD) + (0.0068 x RAD)]. Four separate cattle studies, comparable in size, type of cattle, and number of observations to the 3 original studies, were utilized to evaluate the accuracy of the THI equation adjusted for WSPD and RAD, and the relationship between the adjusted THI and panting score. Mean panting score derived from individual observations of black-hided cattle in these 4 studies were 1.22, 0.94, 1.32, and 2.00 vs. the predicted panting scores of 1.15, 1.17, 1.30, and 1.96, respectively. Correlations between THI and panting score in these studies ranged from r = 0.47 to 0.87. Correlations between the adjusted THI and mean panting score ranged from r = 0.64 to 0.80. These adjustments would be most appropriate to use, within a day, to predict THI during the afternoon hours using hourly data or current conditions. In addition to afternoon conditions, nighttime conditions, including minimum WSPD, minimum black globe THI, and minimum THI, were also found to influence heat stress experienced by cattle. Although knowledge of THI alone is beneficial in determining the potential for heat stress, WSPD and RAD adjustments to the THI more accurately assess animal discomfort.  相似文献   

16.
The effects of transporting Holstein Friesian bulls (n=72; bodyweight 403+/-3.5 kg) for 12h by road were examined. Adrenal, haematological and immune responses, body temperature and performance were recorded. The animals had been previously housed for 96 days at three space allowances (1.2, 2.7 or 4.2m(2) per bull). The bulls were allocated to one of two treatments: T (transport for 12h; n=16 per space allowance) and C (control; n=8 per space allowance). Basal cortisol plasma concentrations and interferon (IFN)-gamma production from cultured lymphocytes did not show any statistically significant difference (P>0.05) following the housing period. Removing bulls from their home pens and walking them to the pre-loading crush facility, loading onto the transporter, and unloading following the 12h road journey, significantly (P<0.001) increased plasma cortisol concentration. The bulls housed at 4.2m(2) had greater (P<0.05) plasma cortisol concentrations than bulls housed at 1.2m(2) at loading, unloading, or on return to the crush holding facility; those housed at 1.2m(2) had greater (P<0.05) plasma cortisol concentrations than bulls housed at 2.7 and 4.2m(2) in their home pens after transport. There was an increased (P<0.05) plasma cortisol response in the T than in the C bulls following adrenocorticotrophic hormone administration. Transport significantly reduced (P<0.05) IFN-gamma production, lymphocyte % and body weight and significantly increased (P<0.05) neutrophils, eosinophils, packed cell volume, red blood cell numbers and haemoglobin. In conclusion, housing bulls for 96 days in a range of space allowances did not affect basal cortisol response or immune function parameters. Whereas transport increased plasma cortisol and reduced the immune response in the short-term, the changes were transient and within normal physiological ranges, suggesting that 12h road transport had no adverse effect on welfare status over the longer term. Furthermore, transport of bulls housed at increased space allowance (4.2m(2)/bull) resulted in a greater plasma cortisol response, albeit still within normal physiological range.  相似文献   

17.
Factors affecting the number of weaned piglets found dead after commercial transport between farms were studied by means of multilevel Poisson regression. Information relating to 58,682 piglets during 109 journeys in different EU countries was collected at the end of each journey by means of questionnaires. Overall, 0.07 per cent of all the transported piglets were found dead on arrival, and deaths of piglets were recorded in 13.8 per cent of journeys. The final regression model, which was calculated using the complete records from 105 journeys, included the total duration of the journey, the mean outside temperature during the journey, whether the piglets were fasted before transport, whether drinking water was provided, the type of ventilation in the vehicle and the interaction between journey duration and the mean outside temperature. The duration of the journey and the mean outside temperature showed a significant interaction effect, with a gradual increase in the predicted number of dead piglets with increasing journey duration as the outside temperature increased. Providing the piglets with drinking water and having mechanically assisted ventilation (fans) in the vehicle during the journey significantly reduced the number of deaths, as did fasting the piglets before transport.  相似文献   

18.
试验旨在比较分析南方地区发酵床奶牛舍四个季节舍内环境卫生指标。主要测定了舍内温度、相对湿度、噪音、细菌密度、氨气浓度和温湿度指数等指标并分析了其间的相关性。结果表明:温度在四季间差异显著(P<0.05),夏季高达32.43℃,冬季低至1.53℃;春季、夏季和秋季的相对湿度显著高于冬季(P<0.05);温湿度指数(THI)在四季间差异显著(P<0.05);夏季和冬季的噪音显著高于春季和秋季(P<0.05);春季和秋季的细菌密度显著高于夏季和冬季(P<0.05);夏季氨气浓度为3.92 mg/m^3,显著高于其他季节的(P<0.05)。相关分析表明,一年中,牛舍温度与THI呈正高度相关关系(P<0.01),其余指标间相关性不高(|r|<0.70)或不相关(P>0.05)。另外,季节内的环境指标相关性分析表明:秋、冬季的温度和THI间皆呈正相关(P<0.01),冬季的温度与细菌密度呈正相关(P<0.05);春季的THI、噪音和细菌密度三者之间均呈正相关(P<0.05);秋季的氨气浓度与噪音高度也呈正相关关系(P<0.01)。综上,南方地区发酵床奶牛舍内,四季的环境卫生指标均达到了卫生标准,但夏季THI较高为85.36,奶牛易处于中度热应激状态。  相似文献   

19.
Not all parameters are trustworthy and practical to use as parameters to determine heat stress in dairy cattle. The temperature-humidity index (THI) is still the best, simplest and most practical index (parameter) for measurement of environmental warmth which cause heat stress in dairy cattle. It is practical, easy to determine and relatively trustworthy to use body temperature and respiratory rate as parameters to determine heat stress in dairy cattle. These physiological parameters must always be used together with THI values to determine and evaluate heat stress in dairy cattle. For practical purposes, plasma cortisol concentration and milk composition cannot be used as parameters to determine heat stress in dairy cattle although good indications of acute or chronic heat stress can be obtained. Vanillic acid is a break-down product of adrenalin found in milk, but before its concentration in milk can be used as an indicator/parameter of heat stress in dairy cows, more about the pharmacodynamics of adrenaline in the milk has to be known. Selection and breeding of dairy cows on the basis of their adaptibility to heat stress using the most practical heat stress parameters will ensure that their offspring will have superior performance in the prevailing environmental conditions.  相似文献   

20.
The relationship between mortality and stressful weather is not only a complex health, social and environmental issue, but also becomes an economical problem when considering livestock. Future-climate scenarios suggest that higher global mean temperatures could result in marked changes in the frequency of extreme temperatures. The relationship between high temperature and mortality is well known in people living in urban areas, but it has been poorly investigated in livestock such as dairy cows. The aim of this study was to quantify the relationship between heat and mortality from all causes among dairy cows in Italy. We studied 6697 adult (≥24 months) dairy cows that died during the summer in the 5-year period 2002-2006 in three Italian districts (Brescia, Cuneo, Rome) which were selected because of the high livestock production and the availability of weather data for these geographical areas. A case-crossover design was applied using the temperature-humidity index (THI) as exposure of interest. Pooled odds ratio (OR) of mortality at high exposure values versus low exposure values was estimated. An exposure over the THI cut-off increased the risk of mortality by 1.6 times, with a 4% increase in mortality for each THI degree increase above the threshold. We found no effect modification for age-class, herd size or breed, but a certain degree of geographical heterogeneity was identified. The increased dairy cow mortality highlighted in this study should be considered when adopting animal welfare and farm management measures. This phenomenon can be prevented by adopting appropriate interventions to mitigate environmental thermal challenges.  相似文献   

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