The influence of heat load on Merino sheep. 1. Growth, performance, behaviour and climate

2020 ◽  
Vol 60 (16) ◽  
pp. 1925
Author(s):  
A. M. Lees ◽  
M. L. Sullivan ◽  
J. C. W. Olm ◽  
A. J. Cawdell-Smith ◽  
J. B. Gaughan
Keyword(s):  
Middle East ◽  
Growth Performance ◽  
Water Intake ◽  
Feed Intake ◽  
Heat Load ◽  
Climatic Conditions ◽  
Temperature Humidity Index ◽  
Humidity Index ◽  
Dressing Percentage ◽  
Live Export

Context Annually, millions of sheep are exported from Australia to the Middle East, typically during the southern hemisphere winter to the northern hemisphere summer. During these voyages, sheep can be exposed to relatively rapid changes in ambient conditions within a short period of time (≤29 days); therefore, excessive heat load concerns can arise. Aims The aim of this study was to define the responses of sheep to incremental heat load under simulated live export conditions. The study herein describes (1) the heat load imposed, and (2) the effect of this heat load on the growth, performance and behavioural responses of sheep during periods of incremental heat load. Methods A total of 144 Merino wethers (44.02 ± 0.32 kg) were included in a 29-day climate controlled study using two cohorts of 72 sheep (n = 2), exposed to two treatments: (1) thermoneutral and (2) hot (HOT). Ambient temperature (°C) and relative humidity (%) for the HOT treatment were modelled from live export voyages from Australia to the Middle East in July. Climatic conditions within the climate control chambers were recorded at 10-min intervals, then used to calculate a temperature humidity index. Sheep posture, rumination, eating, drinking and demeanour (calm, agitated or depressed) were observed four times daily at 3-h intervals between 0800 hours and 1700 hours. Feed intake was recorded daily and water intake was measured using an automated meter. Sheep were weighed on Day 0 and then at 7-day intervals. Sheep were weighed at slaughter and carcass weights were obtained, these data were used to determine carcass dressing percentage. Data were analysed using a repeated measures model, with a compound symmetry covariance structure. Key results Climatic conditions in the HOT treatment increased incrementally between Day 1 (temperature humidity index ≥19) and Day 29 (temperature humidity index ≤34.7). Behaviour, feed intake, average daily gain (g/day), carcass weight (kg) and dressing percentage were not influenced by treatment (P > 0.05). Sheep in the HOT treatment group showed a 137% increase in water intake (P < 0.01) and on average consumed 2.15 L/sheep.day, whereas the thermoneutral group consumed 1.67 L/sheep.day. Conclusions These results suggest that these sheep were capable of maintaining feed intake and growth despite exposure to heat load, albeit with a 137% increase in water intake. Implications These results highlight the resilience of the Australian Merino genotype, as these sheep were capable of maintaining feed intake and growth during exposure to heat load. As the climatic conditions in this study were modelled based on typical live export vessel conditions, these results may suggest that the climatic conditions experienced by sheep during voyages may not be as critical as previously thought.

A practical future-scenarios selection tool to breed for heat tolerance in Australian dairy cattle

2017 ◽  
Vol 57 (7) ◽  
pp. 1488 ◽  
Author(s):  
Thuy T. T. Nguyen ◽  
Ben J. Hayes ◽  
Jennie E. Pryce
Keyword(s):  
Heat Tolerance ◽  
Milk Fat ◽  
Heat Load ◽  
Selection Index ◽  
Dairy Herd ◽  
Breeding Value ◽  
Future Scenarios ◽  
Selection Tool ◽  
Temperature Humidity Index ◽  
Humidity Index

Climate change will have an impact on dairy cow performance. When heat stressed, animals consume less feed, followed by a decline in milk yield. Previously, we have found that there is genetic variation in this decline. Selection for increased milk production, a major breeding objective, is expected to reduce heat tolerance (HT), as these traits are genetically unfavourably correlated. We aimed to develop a future-scenarios selection tool to assist farmers in making selection decisions, that combines the current national dairy selection index, known as the balanced performance index (BPI), with a proposed HT genomic estimated breeding value (GEBV). Heat-tolerance GEBV was estimated for 12 062 genotyped cows and 10 981 bulls, using an established genomic-prediction equation. Publicly available future daily average temperature and humidity data were used to estimate mean daily temperature–humidity index for each dairy herd. An economic estimate of an individual cow’s heat-tolerance breeding value (BV_HT) was calculated by multiplying head-tolerance GEBVs for milk, fat and protein by their respective economic values that are already used in the BPI. This was scaled for each region by multiplying BV_HT by the heat load, which is the temperature–humidity index units exceeding the threshold per year at a particular location. BV_HT were incorporated into the BPI as: BPI_HT = BPI + BV_HT; where BPI_HT is the ‘augmented BPI’ breeding value including HT. A web-based application was developed enabling farmers to predict the future heat load of a herd and take steps to aim at genetic improvement in future generations by selecting bulls and cows that rank high for the ‘augmented BPI’.

scholarly journals Thermoregulatory and Behaviour Responses of Dairy Heifers Raised on a Silvopastoral System in a Subtropical Climate

2020 ◽  
Vol 20 (2) ◽  
pp. 613-627 ◽  
Author(s):  
Frederico Márcio C. Vieira ◽  
Matheus Deniz ◽  
Edgar S. Vismara ◽  
Piotr Herbut ◽  
Jaqueline A. Pilatti ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Air Temperature ◽  
Water Intake ◽  
Time Of Day ◽  
Subtropical Climate ◽  
Silvopastoral System ◽  
Hair Coat ◽  
Dairy Heifers ◽  
Temperature Humidity Index ◽  
Humidity Index

AbstractIn this study, we investigated the influence of a silvopastoral system on the thermal environment, behaviour and thermoregulation of dairy heifers in a subtropical climate. The experiment was conducted on a dairy farm in Southwest Paraná, Brazil, during the summer of 2014. Crossbred Holstein × Jersey dairy heifers (n = 10) were used in a split-plot design. The fixed effects in this study include time of day (9:00–10:00, 13:00–14:00, and 17:00–18:00 h) under silvopastoral or open pastures conditions, which were the main-plot and split-plot factors, respectively. To assess the environmental conditions in both systems, air temperature, relative humidity and wind speed were recorded. In addition, the temperature-humidity index was calculated based on the microcli-mate measurements. Respiratory rate and hair coat surface temperature of heifers were measured in both groups during time of day (30 days). Diurnal behaviour using focal observations with 0/1 sampling was observed. Data were analysed using Bayesian inference with a mixed effects model. The air temperature was higher (P<0.05) in open pasture conditions than the silvopasture system. Temperature-humidity index values for the silvopasture system were lower than open pasture during the hottest hours of the day. Regarding thermoregulation responses, there was an interaction between time of day and pasture environment (P<0.05). Heifers showed lower respiratory rates and hair coat surface temperature values (P<0.05) when access to shade was provided, mainly during the hottest periods in the afternoon. In addition, there was also an interaction between rumination and water intake (P<0.05), which indicates a higher rumination frequency for animals in the silvopasture system during the hottest period, as well as a higher water intake frequency for heifers in open pasture during midday. These findings imply that the arrangement of trees in a silvopasture system provides better thermal comfort conditions for dairy heifers raised in a subtropical climate.

scholarly journals Microclimate in silvipastoral systems with eucalyptus in rank with different heights

2010 ◽  
Vol 39 (3) ◽  
pp. 685-694 ◽  
Author(s):  
Wander de Souza ◽  
Orlando Rus Barbosa ◽  
Jair de Araújo Marques ◽  
Marco Aurélio Teixeira Costa ◽  
Eliane Gasparino ◽  
...  
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Air Temperature ◽  
Thermal Load ◽  
Heat Load ◽  
Temperature Humidity Index ◽  
Heat Load Index ◽  
Humidity Index ◽  
Globe Temperature ◽  
Black Globe Temperature

The aim of this work was to verify if the presence of trees and its height in formed silvipastoral systems with eucalyptus planted in rank can modify the microclimate and improve the environment for bovine raising during the day in summer. It was evaluated the microclimate of the environment in formed silvipastoral systems in rank of eucalyptus with 8 m, 18 m and 28 meters of height, compared to a system no shade in the summer. The experimental design was a split plot with six hour time in sub parcels. The systems are made up of parcels and the months as block in four replications and the interaction hour × system. The air temperature, black globe temperature, relative humidity and wind speed were observed to create the following indexes for thermal comfort: temperature-humidity index; black globe-humidity index; heat load index and the radiant thermal load. Excepted for the relative humidity, there was interaction for time × system for all variables and indexes. Interaction occurred for: air temperature at 10 a.m. and 6 p.m.; wind speed from 8 a.m. to 4 p.m.; temperature humidity index at 10 a.m. and 12 p.m.; black globe temperature, black globe humidity index, heat load index, and radiant thermal load at all the hours. During the summer, the system with shade of 28 m trees had the lowest average of black globe temperature; wind speed; black globe humidity index; radiant thermal load index; and heat load index. There was a reduction of wind speed average in systems 8 m, 18 m and 28 m trees in, respectively, 20.7; 50.0 and 48.0% in relation to no shade system; however it was not proportional to the height, with influence of the rank porosity and pantries height. Nevertheless, for radiant thermal load index the reduction was proportional to the height of the trees with 10.24; 12.49 and 20.76%, respectively, for 8 m, 18 m and 28 meters of height. There was a reduction of the thermal stress in the environment due to the presence of trees, being the heat load index thermal the index that better demonstrated the effect, despite of not being proportional to the rank height.

scholarly journals Effects of Suckling Schedule on Growth Characteristics of Saanen Kids

2008 ◽  
Vol 51 (1) ◽  
pp. 55-63 ◽  
Author(s):  
F. Diken ◽  
F. Ugur ◽  
C. Tolu ◽  
M. Dosay Akbulut
Keyword(s):  
Growth Performance ◽  
Water Intake ◽  
Feed Intake ◽  
Live Weight ◽  
Growth Characteristics ◽  
Weight Increase ◽  
Training Centre ◽  
Significant Difference ◽  
The Right ◽  
And Training

Abstract. This study was carried out with single-born Saanen kids raised at Uvecik Research and Training Centre of Canakkale Onsekiz Mart University. In the study, the kids were raised according to two suckling program. In the first program, the kids suckled full-udder of their dams for 30 min at 08.00 and 18.00. In the second program, the right lob of the udder of the kid’s dams was milked by hand, and then the kids were allowed to suckle their dams for 30 min at 08.00 and 18.00. The kids in the both groups were weaned at 5 weeks of the study. The live weights of the kids of the first and second program were 10963.0±274.4 and 10384.9±285.1 g (P>0.05) at 5 weeks of the study and 17932.9±676.3 and 17482.7±702.8 g (P>0.05) at 12 weeks of the study, respectively. The height at withers and heart girth of the kids of the first and second program were 51.7±0.9 and 51.1±0.9 cm (P>0.05), and 61.1±0.8 and 58.5±0.8 cm (P≤0.05) at 12 weeks of the study, respectively. The live weight increase between 1-5 and 1-12 weeks of the kids of the first and second program were determined as 192.0±9.5 and 178.6±9.9 g (P>0.05), and 160.2±8.4 and 157.0±8.7 g (P>0.05), respectively. No significant difference was found between the programs in terms of roughage intake (P>0.05), concentrate feed intake (P>0.05), water intake (P>0.05), rumination (P>0.05) behaviors. In conclusion, the growth performance and behaviors of kids which were raised according to two suckling program were found similar.

scholarly journals Negative relationship between dry matter intake and the temperature-humidity index with increasing heat stress in cattle: a global meta-analysis

2021 ◽  
Author(s):  
J. Chang-Fung-Martel ◽  
M. T. Harrison ◽  
J. N. Brown ◽  
R. Rawnsley ◽  
A. P. Smith ◽  
...  
Keyword(s):  
Heat Stress ◽  
Feed Intake ◽  
Dry Matter ◽  
Heat Waves ◽  
Meta Analysis ◽  
Negative Relationship ◽  
Dry Matter Intake ◽  
Temperature Humidity Index ◽  
Lactation Stage ◽  
Humidity Index

AbstractChanges in frequency and severity of heat waves due to climate change pose a considerable challenge to livestock production systems. Although it is well known that heat stress reduces feed intake in cattle, effects of heat stress vary between animal genotypes and climatic conditions and are context specific. To derive a generic global prediction that accounts for the effects of heat stress across genotypes, management and environments, we conducted a systematic literature review and a meta-analysis to assess the relationship between dry matter intake (DMI) and the temperature-humidity index (THI), two reliable variables for the measurement of feed intake and heat stress in cattle, respectively. We analysed this relationship accounting for covariation in countries, breeds, lactation stage and parity, as well as the efficacy of various physical cooling interventions. Our findings show a significant negative correlation (r =  − 0.82) between THI and DMI, with DMI reduced by 0.45 kg/day for every unit increase in THI. Although differences in the DMI-THI relationship between lactating and non-lactating cows were not significant, effects of THI on DMI varied between lactation stages. Physical cooling interventions (e.g. provision of animal shade or shelter) significantly alleviated heat stress and became increasingly important after THI 68, suggesting that this THI value could be viewed as a threshold for which cooling should be provided. Passive cooling (shading) was more effective at alleviating heat stress compared with active cooling interventions (sprinklers). Our results provide a high-level global equation for THI-DMI across studies, allowing next-users to predict effects of heat stress across environments and animal genotypes.

scholarly journals Iklim Mikro dan Respon Fisiologis Sapi Pesisir di Dataran Rendah dan Dataran Tinggi Sumatera Barat

2020 ◽  
Vol 20 (2) ◽  
Author(s):  
Yetmaneli Yetmaneli ◽  
B. P. Purwanto ◽  
Rudi Priyanto ◽  
Wasmen Manalu
Keyword(s):  
Heat Tolerance ◽  
Physiological Responses ◽  
Climatic Conditions ◽  
T Test ◽  
Mild Stress ◽  
Physiological Variables ◽  
Temperature Humidity Index ◽  
West Sumatra ◽  
Humidity Index ◽  
Environmental Measures

ABSTRAK. Penelitian bertujuan melihat potensi iklim mikro dan respon fisiologis sapi Pesisir yang dipelihara di dataran rendah (Kota Padang (0-300 m dpl )) dan dataran tinggi (BPTU Padang Mengatas ( 600 m dpl)) Sumatera Barat. Materi yang digunakan dalam penelitian ini 8 ekor sapi Pesisir, variabel yang diukur terdiri dari 2 aspek yaitu lingkungan abiotik dan aspek fisiologis sapi Pesisir. Aspek lingkungan abiotik berupa suhu lingkungan (Ta), kelembapan udara (RH) serta Temperature Humidity Index (THI). Variabel fisiologis sapi meliputi suhu rektal (Tr), suhu kulit (Ts), frekuensi pernapasan (RR) dan denyut jantung (HR). Tr dan TS digunakan menghitung suhu tubuh sapi (Tb). Tr dan RR digunakan menghitung Heat Tolerance Coefficient (HTC). Uji beda (t-test) digunakan untuk mengetahui ada tidaknya perbedaan kondisi iklim dan respon fisiologis sapi Pesisir di dataran rendah dan tinggi Sumatera Barat. Hasil penelitian menunjukkan potensi iklim di dataran rendah adalah rerata suhu lingkungan 29,96°C, rerata kelembapan 64,22%, rerata THI 79,96 sedangkan potensi iklim di dataran tinggi adalah rerata suhu lingkungan 25,42°C, rerata kelembapan 69,48%, rerata THI 74,3. Rerata daya tahan panas sapi di dataran rendah 1,78 dan dataran tinggi 1,82. Kesimpulan penelitian menunjukkan potensi iklim dataran rendah untuk pemeliharaan sapi termasuk zona cekaman panas sedangkan dataran tinggi dalam cekaman ringan. Kondisi fisiologis sapi Pesisir di dataran rendah yang berbeda dengan sapi yang di dataran tinggi adalah suhu rektal, suhu kulit, suhu tubuh dan denyut jantung sedangkan frekuensi pernapasan didapatkan sama di kedua dataran. Daya tahan panas sapi Pesisir cukup baik ditemui di kedua dataran Sumatera Barat. (Microclimate and physiological responses of Pesisir cattle at lowland and highland of West Sumatra) ABSTRACT. This research aimed to investigate the potential of microclimate and physiological responses of Pesisir cattle that are maintained in lowland (Padang City (0-300 m asl)) and highland (Padang Mengatas BPTU ( 600 m asl)) in West Sumatra. The experimental animals were 8 pesisir cattle. The measured variables were abiotic environment and physiological responses of Pesisir cattle. Abiotic environmental measures were ambient temperature (Ta), humidity (RH) and Temperature Humidity Index (THI). Physiological variables were rectal temperature (Tr), skin temperature (Ts), respiratory rate (RR), and heart rate (HR). Tr and Ts were used to determine body temperature (Tb). Tr and RR are variables for calculating Heat Tolerance Coefficient (HTC). To determine whether there are differences in climatic conditions and physiological values in the two regions, the data were analyzed using a t-test. The results showed that climate potential in the lowlands was the average Ta 29.96° C, the average Rh 64.22% with an average THI 79.96 while the potential climate in the highlands was the average Ta 25.42°C, the average Rh 69, 48% with a mean THI of 74.3. The average HTC of cattle in the lowlands is 1.78 and the highlands is 1.82. The conclusion showed the climate potential of lowland for raising beef cattle includes heat stress zones, while the highlands there was mild stress. The physiological conditions of Pesisir cattle in the lowlands different from the highlands are Tr, Ts, Tb, and HR while RR is found the same in both plains. HTC of Pesisir cattle is good in both plains of West Sumatera.

The influence of heat load on Merino sheep. 3. Cytokine and biochemistry profiles

2020 ◽  
Vol 60 (16) ◽  
pp. 1940
Author(s):  
A. M. Lees ◽  
G. Wijffels ◽  
R. McCulloch ◽  
S. Stockwell ◽  
H. Owen ◽  
...  
Keyword(s):  
Middle East ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Heat Load ◽  
Controlled Study ◽  
Blood Samples ◽  
Inflammatory Status ◽  
Biochemical Profiles ◽  
Hemisphere Winter ◽  
Live Export

Context Approximately 2 million sheep are exported from Australia on live export voyages annually. As voyages travel from a southern hemisphere winter to a northern hemisphere summer, production and welfare issues associated with excessive heat load may arise. Aims The aim of this study was to evaluate the responses of sheep to incremental heat load under simulated live export conditions, specifically the influence of heat load on the metabolic and inflammatory status of sheep. Methods A total of 144 Merino wethers (44.02 ± 0.32 kg) were used in a 29-day climate controlled study using two cohorts of 72 sheep (n = 2), exposed to two treatments: (1) thermoneutral, and (2) hot. Sheep in the hot treatment were exposed to heat load simulated from live export voyages from Australia to the Middle East. Blood samples were collected from all sheep (n = 144) on Day 1, then at 7-day intervals (n = 5) for the duration of each 29-day period. Blood samples were analysed to determine the cytokine, biochemistry and haematology (data not presented here) profiles. Cytokine and biochemical profiles were analysed using a repeated measures model assuming a compound symmetry covariance. The model fitted included terms for cohort and treatment (hot, thermoneutral), and a term for sample collection day (day) and a treatment × day interaction. The subject factor corresponded to the cohort × treatment combinations. Key results There were no consistent trends in plasma cytokine and biochemical profiles. Bicarbonate was the only parameter that was influenced by cohort (P = 0.0035), treatment (P = 0.0025), collection (P = 0.0001) and treatment × collection (P = 0.0025). Furthermore, interleukin-6 and glutamate dehydrogenase were the only parameters that were not influenced by cohort (P &gt; 0.295), treatment (P = 0.2567), collection (P &gt; 0.06) or treatment × collection (P = 0.34). Conclusions Overall, these data highlight that the metabolic and inflammatory status of sheep exposed to incremental heat load, during a simulated live export voyage from a southern hemisphere winter to a northern hemisphere summer, were not markedly altered. Implications These results provide a preliminary evaluation of the inflammatory and metabolic status of sheep on arrival in the Middle East.

Identification of best temperature humidity index model for assessing impact of heat stress on milk constituent traits in Murrah buffaloes under subtropical climatic conditions of Northern India

2017 ◽  
Author(s):  
Rajalaxmi Behera ◽  
A. K. Chakravarty ◽  
A. Sahu ◽  
N. Kashyap ◽  
S. Rai ◽  
...  
Keyword(s):  
Heat Stress ◽  
Least Squares ◽  
Milk Composition ◽  
Climatic Conditions ◽  
Index Model ◽  
Monthly Average ◽  
Temperature Humidity Index ◽  
Murrah Buffaloes ◽  
Humidity Index ◽  
The Impact

The present study was conducted to identify the most suitable temperature humidity index (THI) model among seven reported THI models for analyzing the impact of thermal stress on monthly test day fat % (MTDF%),monthly test day SNF% (MTSNF%), monthly test day fat yield (MTDFY) and monthly test day SNF yield (MTDSNFY) of Murrah buffaloes at subtropical climatic conditions of Karnal, India. A total of 8868 MTDF% and 8606 MTDSNF% records from 1107 lactational records of Murrah buffaloes under five parities were included in the present study and weather information on dry bulb temperature (Tdb), wet bulb temperature (Twb) and relative humidity (RH in %) for the corresponding period of 20 years (March 1994- December 2013) were collected from ICAR-NDRI and ICAR-CSSRI, Karnal, respectively. The overall least-squares means for MTDF% ranged from 7.71 ± 0.067 in TD1 to 8.10 ± 0.08 in TD 9 and MTDSNF% ranged from 9.61 ± 0.01 in TD5 and TD 6 to 9.65 ± 0.01 in TD 8. The overall least squares means of MTDFY (g) ranged from 411.23 ± 14.74 to 745.98 ± 13.57 while for MTDSNFY (g) the value ranged from 491.90 ± 17.21 to 922.16 ± 15.17. Monthly average THI was computed for each of the seven models. The lowest monthly average THI value was found in January, while either May, June or July showed the highest average THI value for all seven THI models. Regression analysis was performed for identifying the best THI to assess the impact of heat stress on milk constituent traits under study anda negative association was found between the milk constituent traits and monthly average THI values.The THI model[THI = (0.55 × Tdb + 0.2 × Tdp) × 1.8 + 32 + 17.5]developed by NRC(1971)was identified as the most suitable THI model to assess the impact of heat stress on milk composition traits of Murrah indicating maximum decline in MTDF% (-0.005), MTDFY (-0.68 g),MTDSNF% (b=-0.0008) and MTDSNFY (-2.25 g) per unit rise in THI.

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