The present study was undertaken to investigate the association of the temperature-humidity index with physiological, biochemical and behavioural responses in Malabari, crossbred and Attappady black ...goats of Kerala, India. A positive correlation was noticed between in-house temperature (IT) and temperature-humidity index (THI) with respiration rates, rectal temperatures, heart rate and skin temperature levels of breeds at 2.00 PM and 5.00 PM. Biochemical and endocrines parameters, blood gases and electrolytes were analysed during the 2nd, 32nd and 60th day of the study. Alterations in physiological parameters were more significant in Malabari goats. However, a negative correlation was observed between in-house relative humidity and all physiological parameters during all the different times. Behavioural patterns were influenced by increased IT and THI and the breeds spent more time in standing position during heat stress. A significant difference was observed within the study period in the pO2, Na+, HCO3- and blood pH. A significant difference was observed between the breeds for K+, Cl- and HCO3- levels. A significantly higher glucose level on the 32nd day and a lower total cholesterol level in the latter half of the experimental period were noticed in Malabari and crossbred. Mean total protein levels of all the breeds were significantly increased on the 32nd day. Increased GGT levels were observed in the first half of the experimental period in all breeds. Higher cortisol levels in Malabari and crossbred could be estimated in the first half of the experiment. Although Malabari showed higher T3 levels on the 32nd day compared to other breeds, within the breeds no significant difference in T3 levels could be noticed. However, significantly higher T4 values were recorded on the 32nd day and 60th day only in Crossbred breeds when the IT and THI were high. Thus it has been shown that heat stress was affecting the physiology, metabolism and behaviour of breeds. The increase in respiratory rate and rectal temperature were the first signs of heat stress in these breeds. The physiological manifestations of stress were the greatest for Malabari goats and the least for Attappady black.
•The Malabari, Attappady black and crossbred goats were under stress during the periods of peak THI (89.65).•In-house temperature and THI are the major factors deciding thermal stress in breeds.•The physiological manifestations of stress were the greatest for Malabari and the least for Attappady black.•Increase in respiratory rate and rectal temperature were the first signs of heat stress in these breeds.•Heat stress was affecting the physiology, metabolism and behaviour of breeds.
Selection has been emphasized for increasing production traits with ignoring the fertility traits, which leads to a general loss of reproductive fitness. The aim of this study was to evaluate the ...reproductive performance of the pure Brown Swiss (BS), Holstein (HO), their first-generation crossbred (F1), and backcross (BC) cows under subtropical Egyptian conditions. The reproductive performance and health traits were measured in the pure BS, HO, their F1, and BC crossbred, in addition to investigating the impact of temperature–humidity index level (THI) on reproductive traits. Brown Swiss and her F1 had a better reproductive efficiency and health traits than in HO and BC. They possess a higher conception (34.1% and 36.9%, respectively) and pregnancy rates (32.8% and 31.1%, respectively), a shorter calving interval (401 and 420 days, respectively), and a lower average insemination per parturition (3.18 and 3.45, respectively), with a lower incidence of metritis (14.1% and 14.6%, respectively). Moreover, no difference has been detected in the fertility of BS with different THI levels, whereas F1 was slightly affected by increasing THI, especially for conception rate which declined from 43.1% at low to 24.1% at high THI. But the pregnancy rate did not change with different levels of THI. Our results indicate that BS and her F1 have a better reproductive performance and adaptability than pure HO and BC under subtropical Egyptian conditions. Furthermore, milk yield of the F1 crossbred is comparable to that of the pure HO cows.
Tropical and sub-tropical climates are characterized by high temperature and humidity, during at least part of the year. Consequently, heat stress is common in Holstein cattle and productive and ...reproductive losses are frequent. Our objectives were as follows: (1) to quantify losses in production and quality of milk due to heat stress; (2) to estimate genetic correlations within and between milk yield (MY) and milk quality traits; and (3) to evaluate the trends of genetic components of tolerance to heat stress in multiple lactations of Brazilian Holstein cows. Thus, nine analyses using two-trait random regression animal models were carried out to estimate variance components and genetic parameters over temperature-humidity index (THI) values for MY and milk quality traits (three lactations: MY×fat percentage (F%), MY×protein percentage (P%) and MY×somatic cell score (SCS)) of Brazilian Holstein cattle. It was demonstrated that the effects of heat stress can be harmful for traits related to milk production and milk quality of Holstein cattle even though most herds were maintained in a modified environment, for example, with fans and sprinklers. For MY, the effect of heat stress was more detrimental in advanced lactations (-0.22 to -0.52 kg/day per increase of 1 THI unit). In general, the mean heritability estimates were higher for lower THI values and longer days in milk for all traits. In contrast, the heritability estimates for SCS increased with increasing THI values in the second and third lactation. For each trait studied, lower genetic correlations (different from unity) were observed between opposite extremes of THI (THI 47 v. THI 80) and in advanced lactations. The genetic correlations between MY and milk quality trait varied across the THI scale and lactations. The genotype×environment interaction due to heat stress was more important for MY and SCS, particularly in advanced lactations, and can affect the genetic relationship between MY and milk quality traits. Selection for higher MY, F% or P% may result in a poor response of the animals to heat stress, as a genetic antagonism was observed between the general production level and specific ability to respond to heat stress for these traits. Genetic trends confirm the adverse responses in the genetic components of heat stress over the years for milk production and quality. Consequently, the selection of Holstein cattle raised in modified environments in both tropical and sub-tropical regions should take into consideration the genetic variation in heat stress.
Temperature and humidity levels above a certain threshold decrease milk production in dairy cattle, and genetic variation is associated with the amount of lost production. To enable selection for ...improved heat tolerance, the aim of this study was to develop genomic estimated breeding values (GEBV) for heat tolerance in dairy cattle. Heat tolerance was defined as the rate of decline in production under heat stress. We combined herd test-day recording data from 366,835 Holstein and 76,852 Jersey cows with daily temperature and humidity measurements from weather stations closest to the tested herds for test days between 2003 and 2013. We used daily mean values of temperature-humidity index averaged for the day of test and the 4 previous days as the measure of heat stress. Tolerance to heat stress was estimated for each cow using a random regression model with a common threshold of temperature-humidity index=60 for all cows. The slope solutions for cows from this model were used to define the daughter trait deviations of their sires. Genomic best linear unbiased prediction was used to calculate GEBV for heat tolerance for milk, fat, and protein yield. Two reference populations were used, the first consisted of genotyped sires only (2,300 Holstein and 575 Jersey sires), and the other included genotyped sires and cows (2,189 Holstein and 1,188 Jersey cows). The remainder of the genotyped sires were used as a validation set. All animals had genotypes for 632,003 single nucleotide polymorphisms. When using only genotyped sires in the reference set and only the first parity data, the accuracy of GEBV for heat tolerance in relation to changes in milk, fat, and protein yield were 0.48, 0.50, and 0.49 in the Holstein validation sires and 0.44, 0.61, and 0.53 in the Jersey validation sires, respectively. Some slight improvement in the accuracy of prediction was achieved when cows were included in the reference population for Holsteins. No clear improvements in the accuracy of genomic prediction were observed when data from the second and third parities were included. Correlations of GEBV for heat tolerance with Australian Breeding Values for other traits suggested heat tolerance had a favorable genetic correlation with fertility (0.29–0.39 in Holsteins and 0.15–0.27 in Jerseys), but unfavorable correlations for some production traits. Options to improve heat tolerance with genomic selection in Australian dairy cattle are discussed.
Heat stress exerts a substantial effect on dairy production. The temperature and humidity index (THI) is widely used to assess heat stress in dairy operations. Herein, we review the effects of high ...temperature and humidity on body temperature, feed intake, milk production, follicle development, estrous behavior, and pregnancy in dairy cows. Analyses of the effects of THI on dairy production have shown that body temperature is an important physiological parameter in the evaluation of the health state of dairy cows. Although THI is an important environmental index and can help to infer the degree of heat stress, it does not reflect the physiological changes experienced by dairy cows undergoing heat stress. However, the simultaneous measurement of THI and physiological indexes (e.g., body temperature) would be very useful for improving dairy production. The successful development of automatic detection techniques makes it possible to combine THI with other physiological indexes (i.e., body temperature and activity), which could help us to comprehensively evaluate heat stress in dairy cows and provide important technical support to effectively prevent heat stress.
The roles of temperature and humidity in shaping diurnal retreat site occupation and short-term movements in amphibians in desert environments have scarcely been studied. In this work, we ...investigated retreats and movements in the painted frog (Discoglossus pictus auritus) that inhabits oases in arid southern Tunisia, by using a composite temperature-humidity index (THI). Our results show non-random occupation of retreat sites with respect to prevailing temperature-humidity conditions. When leaving retreat sites with THI values above or below their preferred levels, painted frogs tended to move to sites with THI levels more similar to their preferred conditions. We also found that large individuals tended to occupy retreat sites offering similar THI levels, while small individuals moved between sites with very different THI levels, a pattern that could be driven by age-dependent experience. However, there was no significant relationship between the distance moved by painted frogs and the magnitude of the change in the THI between occupied sites. In summary, our findings evidence the role of temperature-humidity conditions in shaping the patterns of diurnal retreat site use in an arid zone amphibian. They also underline the usefulness of composite temperature-humidity indices when assessing amphibian-habitat relationships.
•Effects of temperature and humidity on shelter use by an arid zone frog are studied.•Retreat site occupation varies according to temperature-humidity conditions.•Temperature-humidity conditions do not seem to affect nocturnal frog movements.•Retreat site selection is influenced by individual past experiences.•Composite temperature-humidity indices are useful in amphibian-habitat studies.
In the experiment were detected changes of air temperature and relative humidity inside the free-stall barn. It is affecting the welfare of stabled dairy cows of two different groups according to the ...stage of lactation during the summer. The effects of microclimate individual parameters in the barn were assessed on the basis of the temperature-humidity index in relation to milk production. From the research, it was found that the animals are housed in suitable microclimate conditions barn were not subject to heat stress without major loss of milk production. The contribution includes information about the values of decrease or increase milk production, depending on the temperature-humidity index. It highlights the importance of determining the temperature-humidity index of stables. Temperature-humidity index can be a useful tool for determining of thermal stress in different sections of the barn. However, it would be appropriate this method of calculating the temperature-humidity index improved and supplemented with the other climatic factors.
The objective of this study was to investigate the relationship between temperature-humidity index (THI) and rumination time (RT) in order to possibly exploit it as a useful tool for animal welfare ...improvement. During summer 2015 (1 June to 31 August), data from an Italian Holstein dairy farm located in the North of Italy were collected along with environmental data (i.e. ambient temperature and relative humidity) recorded with a weather station installed inside the barn. Rumination data were collected through the Heatime® HR system (SCR Engineers Ltd., Hadarim, Netanya, Israel), an automatic system composed of a neck collar with a Tag that records the RT and activity of each cow. A significant negative correlation was observed between RT and THI. Mixed linear models were fitted, including animal and test day as random effects, and parity, milk production level and date of last calving as fixed effects. A statistically significant effect of THI on RT was identified, with RT decreasing as THI increased.
The aim of this study was to investigate the effects of heat stress on milk traits in South Korea using comprehensive data (dairy production and climate). The dataset for this study comprised ...1,498,232 test-day records for milk yield, fat- and protein-corrected milk, fat yield, protein yield, milk urea nitrogen (MUN), and somatic cell score (SCS) from 215,276 Holstein cows (primiparous: n = 122,087; multiparous: n = 93,189) in 2,419 South Korean dairy herds. Data were collected from July 2017 to April 2020 through the Dairy Cattle Improvement Program, and merged with meteorological data from 600 automatic weather stations through the Korea Meteorological Administration. The segmented regression model was used to estimate the effects of the temperature-humidity index (THI) on milk traits and elucidate the break point (BP) of the THI. To acquire the least-squares mean of milk traits, the generalized linear model was applied using fixed effects (region, calving year, calving month, parity, days in milk, and THI). For all parameters, the BP of THI was observed; in particular, milk production parameters dramatically decreased after a specific BP of THI (p < 0.05). In contrast, MUN and SCS drastically increased when THI exceeded BP in all cows (p < 0.05) and primiparous cows (p < 0.05), respectively. Dairy cows in South Korea exhibited negative effects on milk traits (decrease in milk performance, increase in MUN, and SCS) when the THI exceeded 70; therefore, detailed feeding management is required to prevent heat stress in dairy cows.
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