scholarly journals What is the best temperature-humidity index equation to indicate heat stress in crossbred dairy calves in a tropical environment?

2019 ◽  
Vol 49 (1) ◽  
Author(s):  
Fernanda Gatti de Oliveira Nascimento ◽  
Hellen Cris Pinto Aguiar ◽  
Gustavo Moya Rodrigues ◽  
Ednaldo Carvalho Guimarães ◽  
Mara Regina Bueno de Mattos Nascimento
Keyword(s):  
Heat Stress ◽  
Dew Point ◽  
Tropical Environment ◽  
Dairy Calves ◽  
Sensible Heat ◽  
Dew Point Temperature ◽  
Physiological Variables ◽  
Temperature Humidity Index ◽  
Humidity Index ◽  
The One

ABSTRACT: The aim of this study was to determine among nine temperature-humidity index (THI) equations, the one that best represents the effects of heat stress on crossbred dairy calves reared in a tropical environment. Twelve male and female calves, aged 20 to 60 days, and raised in a tropical pen were evaluated. Respiratory (RR) and heart rates (HR), rectal (RT), body surface (BST), dry bulb (Tdb) and wet bulb (Tbw) temperatures, partial vapor pressure (Pv), relative humidity (RH) and dew point temperature (Tpo) were quantified in the morning and afternoon. Nine THI equations were calculated. The highest correlation between physiological variables and this was used to select the best THI equation. Averages for nine THI equations, Tdb, Twb, Pv, Tdp, RR, HR, RT, and BST were higher in the afternoon than in the morning, whereas that for RH was the opposite. The highest values for RT occurred at temperatures above 26.4°C and when humidity was below 55.5%. The Tdb and Pv correlations with RR (0.697 and 0.707), RT (0.703 and 0.706) and BST (0.818 and 0.817) were significant and positive, whereas the RH correlations with the same physiological variables were significant and negative (-0.622, -0.590 and -0.638, respectively). The best index was the THI sensible heat-based ( T H I = 3.43 + 1.058 x T d b - 0.293 x R H + 0.0164 x T d b x R H + 35.7), which was significantly correlated with RR (r=0.668 and r²=0.446), HR (r=0.259 and r²=0.067), RT (r=0.693 and r²=0.479) and BST (r=0.807 and r²=0.650). In conclusion, the THI sensible heat-based equation best represents the effects of heat stress on crossbred dairy calves reared in a tropical environment.

scholarly journals Experiments on Energy-Efficient Evaporative Cooling Systems for Poultry Farm Application in Multan (Pakistan)

2021 ◽  
Vol 13 (5) ◽  
pp. 2836
Author(s):  
Khawar Shahzad ◽  
Muhammad Sultan ◽  
Muhammad Bilal ◽  
Hadeed Ashraf ◽  
Muhammad Farooq ◽  
...  
Keyword(s):  
Heat Stress ◽  
Low Cost ◽  
Evaporative Cooling ◽  
Thermal Exposure ◽  
Climatic Conditions ◽  
The Body ◽  
Dew Point ◽  
Sweat Glands ◽  
Cooling Systems ◽  
Humidity Index

Poultry are one of the most vulnerable species of its kind once the temperature-humidity nexus is explored. This is so because the broilers lack sweat glands as compared to humans and undergo panting process to mitigate their latent heat (moisture produced in the body) in the air. As a result, moisture production inside poultry house needs to be maintained to avoid any serious health and welfare complications. Several strategies such as compressor-based air-conditioning systems have been implemented worldwide to attenuate the heat stress in poultry, but these are not economical. Therefore, this study focuses on the development of low-cost and environmentally friendly improved evaporative cooling systems (DEC, IEC, MEC) from the viewpoint of heat stress in poultry houses. Thermodynamic analysis of these systems was carried out for the climatic conditions of Multan, Pakistan. The results appreciably controlled the environmental conditions which showed that for the months of April, May, and June, the decrease in temperature by direct evaporative cooling (DEC), indirect evaporative cooling (IEC), and Maisotsenko-Cycle evaporative cooling (MEC) systems is 7–10 °C, 5–6.5 °C, and 9.5–12 °C, respectively. In case of July, August, and September, the decrease in temperature by DEC, IEC, and MEC systems is 5.5–7 °C, 3.5–4.5 °C, and 7–7.5 °C, respectively. In addition, drop in temperature-humidity index (THI) values by DEC, IEC, and MEC is 3.5–9 °C, 3–7 °C, and 5.5–10 °C, respectively for all months. Optimum temperature and relative humidity conditions are determined for poultry birds and thereby, systems’ performance is thermodynamically evaluated for poultry farms from the viewpoint of THI, temperature-humidity-velocity index (THVI), and thermal exposure time (ET). From the analysis, it is concluded that MEC system performed relatively better than others due to its ability of dew-point cooling and achieved THI threshold limit with reasonable temperature and humidity indexes.

scholarly journals Critical Temperature-Humidity Index Thresholds for Dry Cows in a Subtropical Climate

2021 ◽  
Vol 2 ◽  
Author(s):  
Véronique Ouellet ◽  
Izabella M. Toledo ◽  
Bethany Dado-Senn ◽  
Geoffrey E. Dahl ◽  
Jimena Laporta
Keyword(s):  
Heat Stress ◽  
Respiration Rate ◽  
Rectal Temperature ◽  
Dry Matter ◽  
Dry Matter Intake ◽  
Subtropical Climate ◽  
Dry Period ◽  
Environmental Indices ◽  
Temperature Humidity Index ◽  
Humidity Index

The effects of heat stress on dry cows are profound and significantly contribute to lower overall welfare, productivity, and profitability of the dairy sector. Although dry cows are more thermotolerant than lactating cows due to their non-lactating state, similar environmental thresholds are currently used to estimate the degree of heat strain and cooling requirements. Records of dry cow studies conducted over 5 years in Gainesville, Florida, USA were pooled and analyzed to determine environmental thresholds at which dry cows exhibit signs of heat stress in a subtropical climate. Dry-pregnant multiparous dams were actively cooled (CL; shade of a freestall barn, fans and water soakers, n = 107) or not (HT; shade only, n = 111) during the last 7 weeks of gestation, concurrent with the entire dry period. Heat stress environmental indices, including ambient temperature, relative humidity, and temperature-humidity index (THI), and animal-based indices, including respiration rate, rectal temperature and daily dry matter intake were recorded in all studies. Simple correlations were performed between temperature-humidity index and each animal-based indicator. Differences in respiration rate, rectal temperature and dry matter intake between treatments were analyzed by multiple regression. Using segmented regression, temperature-humidity thresholds for significant changes in animal-based indicators of heat stress were estimated. Stronger significant correlations were found between the temperature-humidity index and all animal-based indices measured in HT dry cows (−0.22 ≤ r ≤ 0.35) relative to CL dry cows (−0.13 ≤ r ≤ 0.19). Although exposed to similar temperature-humidity index, rectal temperature (+0.3°C; P < 0.001) and respiration rate (+23 breaths/min; P < 0.001) were elevated in HT dry cows compared with CL cows whereas dry matter intake (−0.4 kg of dry matter/d; P = 0.003) was reduced. Temperature-humidity index thresholds at which respiration rate and rectal temperature began to change were both determined at a THI of 77 in HT dry cows. No significant temperature-humidity threshold was detected for dry matter intake. At a practical level, our results demonstrate that dry cow respiration rate and rectal temperature increased abruptly at a THI of 77 when provided only shade and managed in a subtropical climate. Therefore, in the absence of active cooling, dry cows should be closely monitored when or before THI reaches 77 to avoid further heat-stress related impairments during the dry period and the subsequent lactation and to mitigate potential carry-over effects on the offspring.

scholarly journals Effect of Temperature-Humidity-Index on Milk Performances of Local Born Holstein Dairy Cows Under Saharan Climate

2021 ◽  
Vol 24 (2) ◽  
pp. 24-36
Author(s):  
Lazoumi Ouarfli ◽  
Abdelmadjid Chehma
Keyword(s):  
Heat Stress ◽  
Dairy Cows ◽  
Environmental Conditions ◽  
Arid Regions ◽  
Effect Of Temperature ◽  
Significant Drop ◽  
Temperature Humidity Index ◽  
Lactation Length ◽  
Humidity Index ◽  
Milking Frequency

Abstract The objective is to study the effect of heat stress on milk yield (MY) relative to milking records (n=18178) of native Holsteins (n=187), in the region of Ghardaia, according to periods of HS, using the temperature-humidity index (THI). With THI >72 during 07 months in the study area, which significantly (P<0.001) decrease the MY (-15.5% corresponding to 21.73 kg). Also, calving periods led to a significant drop (P < 0.001) in overall MY (7030.35 kg) of the order of (-14.6%), and over the lactation length (353.43 d), which explains 41% of the variations in MY. In addition, the non-significant effect (P=0.212) of the lactation range on the increase in MY, moreover, the lactation length shows a non-significant (P = 0.108) decrease (-4.68%) during heat stress (HS). Furthermore, the significant effect (P <0.001) of the interaction (Milking frequency × THI) on MY, when THI variates from < 74 to > 84, with regression of (-16.82% and -08.82%) of the MF (2X and 3X), respectively. Again, the NH cow is less sensitive to hyperthermia, so THI explains only 2% of the variation in MY levels. Thus, NH in arid regions have the ability to acclimatize to Saharan environmental conditions.

Reassessment of temperature-humidity index for measuring heat stress in crossbred dairy cattle of a sub-tropical region

2019 ◽  
Vol 82 ◽  
pp. 99-106 ◽  
Author(s):  
Rakhshan Jeelani ◽  
Dipanjali Konwar ◽  
Asma Khan ◽  
Dhirendra Kumar ◽  
Dibyendu Chakraborty ◽  
...  
Keyword(s):  
Heat Stress ◽  
Dairy Cattle ◽  
Tropical Region ◽  
Temperature Humidity Index ◽  
Humidity Index ◽  
Crossbred Dairy Cattle

scholarly journals Environmental source of stress in livestock productivity - a study of Minna climate data

2018 ◽  
Vol 34 (2) ◽  
pp. 159-170 ◽  
Author(s):  
Sikiru Babatunde ◽  
Egena Acheneje ◽  
Alemede Comfort ◽  
Makinde John
Keyword(s):  
Oxidative Stress ◽  
Heat Stress ◽  
Livestock Production ◽  
Mitigation Strategies ◽  
Climate Data ◽  
Stress Genes ◽  
Temperature Humidity Index ◽  
Humidity Index ◽  
Livestock Productivity ◽  
The Tropics

Stress emanating from environment is a factor limiting livestock productivity in the Tropics because of elevated temperature year round; hence this study took a look at Minna climate data for evaluation of Temperature-Humidity- Index (THI) as a way of identifying climate source of stress on livestock production. Climate Normals for Minna between years 1961 and 2018 were obtained, and the data were analyzed using general formulae for calculating Temperature-Humidity-Index for livestock production. Relationships between production parameters on commercial farms and the THI data indicated that heat stress is a potential cause of oxidative stress in the area. The THI showed that the environmental conditions in the study area has potential for heat stress on animals, and that it can aggravate oxidative stress in livestock under production in the study area, hence there is need for further studies to identify the pathophysiological mechanisms of heat stress so as to develop mitigation strategies for improved animal performance and productivity. The study suggested that instead of the penchant for importing exotic breeds of livestock with the aim of upgrading the indigenous breeds, the way forward could be the utilization of genetic expression of heat and oxidative stress genes in animals as candidate markers for improvement of their productive potentials.

scholarly journals Efectos de la tensión calórica en la época seca sobre algunos índices fisiológicos y el estado general en lactación y crecimiento en ganado lechero cruzado

2016 ◽  
Vol 3 ◽  
pp. 34
Author(s):  
Edil E. Arauz
Keyword(s):  
Heat Stress ◽  
Polynomial Regression ◽  
Dry Season ◽  
Average Weight ◽  
Physiological Variables ◽  
Lactating Cows ◽  
Time Period ◽  
Respiratory Index ◽  
Humidity Index ◽  
The University

The test was conducted, at the facilities of the Dual Purpose Dairy Program of the University of Panama in Chiriqui, Panama, to quantify the main climatic variables during the dry season and their effect on so me physiological indexes of lactating and growing hybrid dairy cattle. The physiological variables were analyzed using the split-plot experimental design in time and contrast of polynomial regression. Ten lactating hybrid cows, with and average weight of 446 kg and a milk production of 6.8 kg/cow/day, and ten calves weighing 118 kg each were used. The animals were Holstein/Brown Swiss X Zebu crossbreeds. The micro-climatic characterization, based on solar radiation, ambient temperature and the temperature-humidity index, indicated that the day time period during the dry season is the representative type of effective climatic heat stress,lactating cows and calves were affected by heat stress, and quadratic and cubic increases were observed in rectal temperature and the respiratory index over the normal physiological pattern.

scholarly journals The results of morphological examination of blood of cows under heat stress depending on the stages of temperature-humidity index

2020 ◽  
Author(s):  
M. Koshсhavka ◽  
◽  
N. Boyko ◽  
М. Tzvilikhovsky ◽  
◽  
...  
Keyword(s):  
Heat Stress ◽  
Respiratory Rate ◽  
Absolute Number ◽  
Normative Values ◽  
Morphological Examination ◽  
Holstein Breed ◽  
Temperature Humidity Index ◽  
Morphological Studies ◽  
Humidity Index ◽  
Severe Heat Stress

The results of morphological studies of the blood of cows under heat stress indicate that the temperature - humidity index (THI) of animals in comfortable conditions (THI - 68-71) the number of erythrocytes is 5.78 ± 0.13 T / l, the hematocrit - 24.98 ± 1.02%, hemoglobin content - 89.96 ± 2.63 g / l, MCV - 39.76 ± 2.31 fl; MCH - 15.56 ± 1.32 pg; MCHC - 39.14 ± 1.95 g / dl. The total number of leukocytes in the blood of cows is 7.17 ± 0.54 G / l. The relative content (leukogram) and the absolute number of certain types of leukocytes in the blood of cows has no abnormalities. This suggests that the morphological parameters of the blood of cows in the comfortable conditions of THI meet the normative values for cattle and, in particular, Holstein breed. Under moderate heat stress (THI -72-78), in the blood of cows, along with a significant increase in respiratory rate and heart rate, there is a tendency to increase the number of erythrocytes to 5.82 ± 0.69 T / l, there is a significant increase in hematocrit and MCV by 20 and 47%, and a significant decrease in hemoglobin, MCH and MCHC - by 32, 35 and 55%, respectively, relative to control. However, in the blood of cows there is a tendency to decrease the number of leukocytes, with the simultaneous appearance of metamyelocytes, an increase in the number of eosinophils and rod neutrophils, and a significant decrease in the number of lymphocytes by 27% compared to control. Under severe heat stress (THI - 80-90), when the pulse in cows fluctuates between 88-140 beats per minute, and the respiratory rate is 82.0 ± 3.76 respiratory movements, the number of erythrocytes in the blood of cows tends to decrease and is 5.01 ± 0.91 T / l. The hematocrit value is 21% significantly (p≤0.05) less than in cows under moderate heat stress, and is almost the same as in cows under comfortable conditions. The content of hemoglobin in the blood of cows in this period is significantly lower by 28% (p≤0.05) compared to that in cows under comfortable conditions with a slight tendency to increase compared to this figure in cows under moderate heat stress. Color indices indicate that in the blood of cows under severe heat stress there is a large number of young erythrocytes-macrocytes (MCV - 53.69 ± 3.22 fl), which are poor in hemoglobin (MSN - 12.95 ± 3.48 pg) and impaired hemoglobin formation (MCHC - 24.11 ± 2.23 g / dl). The total number of leukocytes in the blood of cows under severe heat stress is 10.80 ± 1.55 G / l, which is 78% (P≤0.01) more than under moderate heat stress and increases due to the appearance of young and an increase of almost in twice rod-shaped and segment-nuclear neutrophils and eosinophils with a simultaneous decrease in the percentage of lymphocytes.

scholarly journals Characterizing heat stress on livestock using the temperature humidity index (THI)—prospects for a warmer Caribbean

2018 ◽  
Vol 18 (8) ◽  
pp. 2329-2340 ◽  
Author(s):  
Cicero H. O. Lallo ◽  
Jane Cohen ◽  
Dale Rankine ◽  
Michael Taylor ◽  
Jayaka Cambell ◽  
...  
Keyword(s):  
Heat Stress ◽  
Temperature Humidity Index ◽  
Humidity Index
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