Temperature-humidity Index Values Research Articles

Changes in genetic parameters for milk yield and heat tolerance in the Thai Holstein crossbred dairy population under different heat stress levels and over time

The objectives of this study were to investigate changes in genetic parameters for milk yield (MY) and heat tolerance of the crossbred Thai Holstein Friesian population under different heat stress levels over time, and to investigate the threshold point of heat stress manifestation on milk production. Genetic parameters were estimated using single-step genomic REML (ssGREML) and traditional REML models. Data included 58,965 test-day MY records from 1999 to 2008 (old data) and 105,485 test-day MY records from 2009 to 2018 (recent data) from the first parity of 24,520 cows. The pedigree included 55,168 animals, of which 882 animals had genotypes. Variance components were estimated with the REMLF90 program using a repeatability model with random regressions on a function of temperature-humidity index (THI) for additive genetic and permanent environmental effects. Fixed effects included farm-calving season combination, breed group-months in milk combination, and age at first calving. Random effects included additive genetic (intercept and slope) effects, permanent environmental (intercept and slope) effects, and herd-month-year of test. The phenotypic mean for MY was 13.33 ± 4.39 kg/d in the old data, and 14.48 ± 4.40 kg/d in the recent data. Estimates over different THI levels for the intercept additive genetic variance using old data ranged from 2.61 to 2.77 and from 5.02 to 5.38 using recent data with the REML method. In ssGREML analyses (performed with recent data only) the estimates for the intercept additive genetic variance ranged from 4.71 to 5.05. Estimates for the slope additive genetic variance were close to zero in all cases, with the largest values (0.024-0.030) at the most extreme THI value (80). Using REML, the covariance between the intercept and the slope additive genetic effects (THI from 72 to 80) ranged from -0.001 to 0.019 with old data and from 0.027 to 0.060 with recent data. The same covariance ranged from 0.026 to 0.057 in ssGREML analyses. The covariance between the intercept and the slope permanent environmental effects ranged from -0.42 to -0.67 for all data and THI levels. Across THI levels, the genetic correlation between MY and heat tolerance varied from -0.06 to 0.13 with old data, from 0.16 to 0.30 with recent data in REML analyses, and from 0.15 to 0.30 in ssGREML analyses, suggesting that in the current population the top animals for MY are more resistant to heat stress. This was expected, because of the introduction of Bos indicus genes in the last years. Heritability estimates for MY ranged from 0.19 to 0.21 (old data) and from 0.33 to 0.40 (recent data) for REML analyses. Heritability estimates for MY using ssGREML ranged from 0.31 to 0.38. A decline in MY was found when the animals' breed composition had more than 97.3% of Holstein genetics, and it was greatest at THI 80. The heritability and genetic correlations observed in this study show that selection for MY is possible without a negative correlated response for heat tolerance. Although the inclusion of genomic information is expected to increase the accuracy of selection, more genotypes must be collected for successful application. Future research should address other production and fitness traits within the Thai Holstein population.

Diurnal and seasonal fluctuations in cloacal temperature in helmeted guinea-fowl (Numida meleagris) and the effect of ascorbic acid

ABSTRACT The study evaluated ascorbic acid (AA) effects on diurnal fluctuations in cloacal temperature (CT) in guinea-fowls. Twenty guinea-fowls were each assigned to two groups: Group I was administered with distilled water and Group II was treated daily with AA (50 mg/kg) orally. Measurements of dry-bulb temperature (DBT) and relative humidity (RH), to obtain temperature-humidity index (THI), and CT of each guinea-fowl were taken concurrently in the pen thrice a day for 3 days, 1 week apart, during the rainy, cold-dry (harmattan) and hot-dry seasons. Values of THI during the rainy (26.16 ± 0.36) and hot-dry (28.50 ± 1.11) seasons were above the thermoneutral zone for avian species (21), indicating that the guinea-fowls were exposed to heat stress in the seasons. Values of CT were higher (P < 0.05) in controls than experimental guinea-fowls (rainy, 42.17 ± 0.06 vs 42.04 ± 0.08; hot-dry, 42.78 ± 0.11 vs 42.52 ± 0.04°C) and were outside the normal range for avian species. Administration of AA modulated CT fluctuations by decreasing the values in hot-dry season. In conclusion, the hot-dry season was the most stressful for guinea-fowls, and AA modulated considerably CT fluctuations during the season.

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

Changes 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.

Evaluation of heat stress responses in Holstein and Jersey cows by analyzing physiological characteristics and milk production in Korea.

We evaluated the effects of heat stress on physiological responses and milk production in Holstein and Jersey cows reared in Korea. The mean average temperature-humidity index (THI) increased significantly from May to August and then decreased until October. The mean average rectal temperature (RT) was increased in Holstein cows compared with Jersey cows, as the THI values increased from 61 to 85. The average respiratory rate (RR) was increased in Jersey cows compared with Holstein cows when the THI value increased from 61 to 85. The average surface temperature of the rumen and udder was higher in Jersey cows than in Holstein cows when the THI value increased from 61 to 85. No significant difference was noted with respect to relative serum volumes between the breeds and THI ranges, but we measured significant changes in serum pH in Holstein and Jersey cows when the THI value increased from 61 to 85. Milk production was not significantly changed in Holstein cows when the THI increased from 61 to 85, but milk production and milk protein content were significantly altered in Jersey cows when the THI increased from 61 to 85. Current study suggests that Holstein cows still have an advantage in terms of the economic returns of dairy farms in Korea. Therefore, further research is required regarding the heat tolerance of Jersey cows in Korean climatic conditions.

English

The magnitude of heat stress in dairy cattle is assessed using temperature humidity index (THI) widely in the world. The present study was conducted to assess the appropriateness of incorporating THI in recommending dairy cattle breeds to different areas of Sri Lanka. The study considered 10 different cattle genotypes commonly reared for milk production in the country.&nbsp; Daily THI values were computed by employing a thermal model, THI = Tdb - [0.55 - (0.55 &times; RH/100)] &times; (Tdb - 58) using data collected from 26 meteorological stations from 2005-2014. The THI values for different regions and the threshold THI values for milk production of 10 genotypes were used to produce THI maps. Among the crosses, Jersey crossbreds, except Jersey &times; Friesian cross, showed a high coping ability with comparatively high milk production capacity. Local cattle were not affected within the THI range observed in the country. THI based recommendation for distribution of dairy cattle could be made by identifying the variation of coping ability of cattle genotype and minimizing the vulnerability to climate change. Therefore, costly management interventions needed to mitigate the heat stress and related low productivity of dairy cattle under smallholder production systems could be abated. Key words: Climate change, dairy cattle breeds, heat stress.

Impact of heat stress on Holstein breeding performance conducted in a semi-arid Mediterranean climate. Case of Western Algeria.

The dairy cattle husbandry systems in semi arid climate require adapting as a response to climate change. In this study, we focus on semi arid climate of Mediterranean region to assess the effect of heat stress on productive and physiological parameters of Holstein cows. The temperature-humidity index (THI), calculated as a combination of ambient temperature and relative humidity, was used to characterize heat stress. The averages of index (THI) are 71.7, 83.6 and 72.6 respectively for spring; summer and autumn. when the THI increased from average value 12 unit between spring and summer, the cows decreased their daily milk production (DMP) and dry matter intake (DMI) by 17.6 % kg/day and 22 % respectevelly. THI value was negatively correlated to DMP with regression equation DMP (kg /day) = -0,36THI+40.8 (r2 =0.72). in semi arid condition a daily increase was observed for RT, RR an HR respectively when the THI value increased from 71.7 to 83.6 (RT 38.6˚C to 39.1˚C; RR 49.3 inspiration/min to 71.6 inspiration/min and HR 52.6beat/min to 72.7 beat/min for spring and summer respectively) with positive correlation between THI and RR, HR and RT. significant seasonal variation was detected for all physiological parameters for spring, summer and autumn period. Summer heat stress affected the physiological functions of lactating Holstein cows reared under semi arid Mediterranean climatic conditions. The Holstein breed cows are sensitive to heat stress in semi arid conditions. In the context of cow breeding practiced in conditions of semi-arid heat stress, it is necessary to find alternatives in terms of management or genetic improvement, in order to alleviate the impact of climatic stress on performance and physiological parameters.

Relationship between Temperature-humidity Index and Milk Production of Dairy Cows in Tropical Climate

Background: Dairy cattle in many tropical, subtropical and semi-arid regions are subject to high ambient temperature and relative humidity for extended periods of time. This compromises the ability of the lactating cows to dissipate heat, resulting in heat stress and decreasing milk production. The objective of this study was to evaluate the effect of the temperature-humidity index (THI) on milk production in cows in the study area. Methods: Data on monthly milk production (2017 to 2019) was collected from the Department of Animal Production and Health, Batticaloa District, Sri Lanka and the monthly weather data (2017 to 2019) required for the study was collected from the Meteorological Observatory Station in Batticaloa, Sri Lanka. SPSS version 26 was used to analyze interaction between milk production and weather parameters. The monthly THI values were determined for each year.Result: Statistically significant negative relationship (p less than 0.05) was found between milk production and THI in 2017, 2018 and from 2017 to 2019 except 2019 due to the sudden death of cattle in Batticaloa district. Results of all three years indicated that milk production decreases as THI increases. It is concluded that the milk yield of cows is influenced significantly by heat stress during the dry season from April to August between 2017 and 2019, proper management strategies could be helpful to minimize heat stress to attain optimal performance of dairy cows.

Tingkat Kenyamanan Termal Ruang Terbuka Hijau dengan Pendekatan Temperature Humidity Index (THI)

This study aims to examine the level of thermal comfort of Tanjungpura University's green open space. The method used is to measure air temperature and humidity at seven green open spaces with three observation periods and then analyze it by calculating the Temperature Humidity Index (THI) value at each location. The results showed that the overall thermal comfort of green open space was still in the uncomfortable and partially uncomfortable category, with THI values between 25.61 to 28.93. In conclusion, there is a need for the development and enrichment of green open space vegetation in the Tanjungpura University area to increase thermal comfort for the academic community.&#x0D; Keywords: Thermal Comfort, Green Open Space, Temperature Humidity Index

Impact of heat stress on Holstein breeding performance conducted in a semi-arid Mediterranean climate. Case of Western Algeria.

&#x0D; The dairy cattle husbandry systems in semi arid climate require adapting as a response to climate change. In this study, we focus on semi arid climate of Mediterranean region to assess the effect of heat stress on productive and physiological parameters of Holstein cows. The temperature-humidity index (THI), calculated as a combination of ambient temperature and relative humidity, was used to characterize heat stress. The averages of index (THI) are 71.7, 83.6 and 72.6 respectively for spring; summer and autumn. when the THI increased from average value 12 unit between spring and summer, the cows decreased their daily milk production (DMP) and dry matter intake (DMI) by 17.6 % kg/day and 22 % respectevelly. THI value was negatively correlated to DMP with regression equation DMP (kg /day) = -0,36THI+40.8 (r2 =0.72). in semi arid condition a daily increase was observed for RT, RR an HR respectively when the THI value increased from 71.7 to 83.6 (RT 38.6˚C to 39.1˚C; RR 49.3 inspiration/min to 71.6 inspiration/min and HR 52.6beat/min to 72.7 beat/min for spring and summer respectively) with positive correlation between THI and RR, HR and RT. significant seasonal variation was detected for all physiological parameters for spring, summer and autumn period. Summer heat stress affected the physiological functions of lactating Holstein cows reared under semi arid Mediterranean climatic conditions. The Holstein breed cows are sensitive to heat stress in semi arid conditions. In the context of cow breeding practiced in conditions of semi-arid heat stress, it is necessary to find alternatives in terms of management or genetic improvement, in order to alleviate the impact of climatic stress on performance and physiological parameters.&#x0D;

Thermal Work Limit Index in Cattle Farm

The survey was conducted in workers in dairy farming in Bulgaria. In the survey were not reported Thermal Work Limit (TWL) index values, which require cessation of employment and constitute a danger to human health. The lowest values of TWL were registered during the summer and spring months, respectively 229.3 and 258.4 W/m2. The highest are normally registered in the autumn and winter months - 318.3 and 312.2 W/m2. Outdoor the lowest average TWL values were reported in the summer and spring months 236 and 287.9 W/m2, respectively, and the highest in the autumn and winter months - 316.4 and 317.2 W/m2. An inverse dependency was found between the calculated values of Temperature-humidity index (THI) and the TWL.

Modelling THI effects on milk production and lactation curve parameters of Holstein dairy cows.

The main objective of this study was to determine the potential impact of heat stress (HS) on milk production and lactation curve parameters of Holstein dairy cows. Milk, fat, protein, and somatic cell count test-day records collected between 2013 and 2019 from 947 cows in 23 herds were combined with THI calculated from meteorological data recorded between 2013 and 2019. The temperature-humidity index (THI) was used to investigate the effect of heat stress. The severity of heat stress was measured using the temperature-humidity index (THI) and the impacts of different THIs-low (≤68), moderate (68-72), and high (≥72) on production performance and lactation curve parameters were measured. The nonlinear model of Wood was applied for modeling the lactation curve. Analysis of variance was applied to test the effects of three levels of THI on milk production, its composition, and lactation curve parameters. Results showed losses due to heat stress. A decrease in milk yield and fat and protein content was reported. Fat and protein contents tended to decrease steadily with increasing values of THI. Milk yield ranged from 17.882±0.064 (68<THI<72) to 16.503±0.035kg/j (THI>72), fat and protein contents ranged from 3.551±0.041 to 3.449±0.026 and from 3.246±0.031%, to 3.113 (0.029) for 68<THI<72 and THI>72, respectively. Somatic cell score was marked by an increase (from 4.143 to 4.358) at the highest ranges of THI>72 and decreased values (from 4.143 to 3.857) at the lowest ranges of THI. Heat stress showed a significant effect on the parameters of the lactation curve. The increased value of THI showed a significant effect on milk yield THI was in a significant negative correlation with the yield, and quality of milk. The effect of THI was highly significant (P<0.05) for all parameters of the lactation curve and milk yield. Cows exposed to THI between 68 and 72 achieved the highest peak milk yields and the highest total yield of 305 days of lactation (Y305).

Physiological, Biochemical, and Growth Parameters of Fogera Cattle Calves to Heat Stress during Different Seasons in Sub-Humid Part of Ethiopia.

Simple SummaryEvaluation of Fogera cattle breed during the different seasons would help to determine their response to heat stress. This would assist in designing intervention strategies for the anticipated climate change. Therefore, this study aimed to determine physiological, hematological, biochemical, and growth parameters of Fogera cattle calves to heat stress in different seasons. We observed that the heart rate and respiration rate were increased by six beats per minute and four breaths per minute when the temperature-humidity index increased from 66 to 78, respectively. The positive relationship between the temperature–humidity index and physiological parameters further confirms that calves were good at thermoregulation at a temperature–humidity index value of 66. Thus, the temperature-humidity index value of 66 can be considered as optimum for high weight gain and normal physiological response to heat stress in Fogera cattle calves under their current production system. However, some more amelioration strategies such as better nutrition, availability of shade, and routine health management practice will further strengthen the resilience of the breed to heat stress in the future.Fogera cattle are among indigenous breeds of cattle in the northern part of Ethiopia. However, their response to heat stress (HS) under different seasonal variations has not been well investigated. This study was aimed to determine physiological, hematological, biochemical, and growth parameters of Fogera cattle calves to HS during dry season, short rainy, and long rainy. A total of 72 calves (24 for each season) that were 6 months of age with an equal number of males and females were evaluated for physiological, hematological, biochemical, and growth parameters. Daily ambient temperature (AT) and relative humidity (RH) were recorded two times per day during the study periods from which the daily average temperature–humidity index (THI) was calculated. The study revealed higher AT and THI during dry and short seasons while higher RH was observed during the long rainy season. Physiological parameters except rectal temperature were affected by the seasons. Hematological parameters were also affected by season except for packed cell volume. Biochemical and growth parameters were also significantly affected by the seasons. THI was positively related with physiological but negatively with growth parameters. Thus, the THI value of 66 can be considered as optimum for high weight gain and normal physiological response to HS in Fogera cattle calves under their current production system.

Thermal comfort assessment over the past two decades in different landscape areas within Palembang City

Urbanization has an impact on changing landscapes to built-up land so that it triggers changes in microclimate conditions and potentially disrupts the thermal comfort of urban communities. For two decades, the condition of air temperature and thermal comfort at two locations (Sukarami and Sako) in Palembang city with different landscape changes have been assessed in this study. The variations of air temperature over the past two decades were reported. The Temperature Humidity Index (THI) was an indicator for assessing thermal comfort and its values are categorized as comfortable, quite comfortable, and uncomfortable. The results showed that the air temperature in Sako increased by about two times greater than the increase at Sukarami which was 1.1 °C and 0.5 °C. This study clearly reveals that thermal comfort conditions have worsened in the last two decades. During 1999, the THI values were dominated by quite comfortable categories at both locations. After two decades, in 2019, the percentage of days in the quite comfortable category of both locations decreased by almost 60% at Sukarami and more than 80% at Sako. The main factor this difference occurs is the landscape changes with depletion of vegetation area at both locations.

Atenuación del estrés calórico en pollos con la suplementación de un producto de cromo orgánico

Objetivos. Determinar la existencia de un estrés calórico en pollos de engorda y evaluar la efectividad de la suplementación con un producto orgánico de Cr en la disminución de este. Materiales y Métodos. Se determinó la existencia de un estrés calórico mediante la medición del comportamiento de la temperatura y la humedad relativa durante el experimento. Estos indicadores se registraron diariamente, con frecuencia de una hora, utilizando termohigrómetros digitales. Se utilizaron 45 pollos de engorda Ross 308 sexados machos, desde 1 d de edad, provenientes de un experimento de comportamiento productivo con 300 animales. Estos se distribuyeron en tres tratamientos (control,200y400ppbCr/kg-de-dieta) según un diseño completamente aleatorizado, con 4 repeticiones de 25 pollos cada una. Al finalizar el ciclo productivo se determinó la concentración de cortisol en suero sanguíneo de 15 animales por tratamiento, como indicador de estrés. Cada animal constituyó una unidad experimental. Para el análisis de los resultados, se utilizó el paquete estadístico computarizado INFOSTAT. Resultados. Los valores del índice de confort de temperatura y humedad durante los últimos 32 días de duración de la prueba oscilaron entre 112.53 y 115.26. Las concentraciones promedio de cortisol para los tres tratamientos evaluados fueron de 9.45, 8.91y7.66 nmol/L, respectivamente, sin mostrar diferencias significativas entre ellos. Conclusiones. El producto orgánico de Cr fue efectivo en la reducción del estrés calórico al disminuir la concentración de cortisol, aunque no significativamente, en suero sanguíneo de los pollos de engorda. Se ratificó la existencia de un estrés generado por calor durante la realización del experimento.

Use of Principal Component Analysis to Combine Genetic Merit for Heat Stress and for Fat and Protein Yield in Spanish Autochthonous Dairy Goat Breeds.

Simple SummaryTolerance to heat stress (HS) is an important economic trait in goats to maintain dairy farm profitability. We studied the effect of a climatological index of temperature and relative humidity (THI) on test day record (TD) of fat and protein yield (fpy) in the three main Spanish dairy goat breeds (Florida, 126.825 TD, Malagueña, 141.856 TD and Murciano Granadina, 62.834 TD), analysing the nature of the fpy response throughout the THI on the weeks of lactation (DIM) trajectories. The results showed the existence of a double genotype environment interaction between DIM and THI and a depression in the fpy level in animals kept in the hot zone (THI > 25) compared with those in the cold zone (THI ≤ 16). This negative impact is equivalent to 13 to 30 days in production. We propose an alternative to select animals by using a principal analysis of the estimated breeding value for each goat breed across DIM and THI scales. The results of this study show that this procedure is a powerful tool to select the most productive and heat-tolerant animals, thus contributing to the increased profitability of autochthonous Spanish goat breeds.We studied the effect of the Temperature Humidity Index (THI) (i.e., the average of temperature and relative humidity registered at meteorological stations) closest to the farms taken during the test day (TD), for total daily protein and fat yields (fpy) of the three main Spanish dairy goats. The data were from Florida (11,244 animals and 126,825 TD), Malagueña (12,215 animals and 141,856 TD) and Murciano Granadina (5162 animals and 62,834 TD) breeding programs and were studied by different linear models to estimate the nature of the fpy response throughout the THI and the weeks of lactation (Days in Milk, DIM) trajectories. The results showed an antagonism between THI and DIM, with a marked depression in the fpy level in animals kept in the hot zone of the THI values (THI > 25) compared with those in the cold zone (THI ≤ 16), with a negative impact equivalent to production of 13 to 30 days. We used a Reaction Norm model (RN), including THI and DIM as fixed covariates and a Test Day Model (TDM), to estimate the genetic (co)variance components. The heritability and genetic correlations estimated with RN and TDM showed a decreased pattern along the scale of THI and DIM, with slight differences between breeds, meaning that there was significant genetic variability in the animal’s ability to react to different levels of THI, which is not constant throughout the DIM, showing the existence of genotype-environment interaction. The breeding values (BV) of all animals for each level of THI and DIM were subject to a principal component analysis, and the results showed that 89 to 98% of the variance between the BV was explained by the two first eigenvalues. The standardized BV were weighted with the corresponding eigenvector coefficients to construct an index that showed, in a single indicator, the most complete expression of the existing genetic variability in the animals’ ability to produce fpy along the trajectories of THI and DIM. This new option will make it easier to select animals which are more productive, and with better adaptability to heat stress, as well as enabling us to exploit genetic variations in the form of the response to heat stress to be adapted to different production systems.

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

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.

Genetic basis of thermotolerance in 2 local dairy sheep populations in the Iberian Peninsula

Sheep milk production in the Northern Mediterranean countries heavily relies on local breeds subject to selection schemes to improve milk production. Climate change may shift the range of thermal loads on the animals and challenge their adaptation to the new thermal gradient. The objective of this study was to characterize the genetic component of thermal tolerance of 2 local breeds from the Iberian Peninsula, Latxa and Manchega, belonging to different genetic types that have evolved under different climatic environments (Oceanic for Latxa and Continentalized Mediterranean for Manchega). A total of 79,243 and 2,388,853 test day monthly records of milk, fat and protein yields from 12,882 and 277,904 ewes of Latxa and Manchega breeds, respectively, along a 12-yr period, were matched with the value of the average temperature-humidity index (THI) on the day of milk recording of the closest weather station to the flocks. These data were used to fit individual reaction norms (Legendre polynomials) describing changes in yields along the THI gradient. Genetic values for thermal tolerance were obtained from the slopes of those reaction norms under cold or heat stress and variances and covariances between yield and thermal tolerance were derived from the (co)variance matrices of the polynomial random regression coefficients. Results showed differing patterns in the 2 breeds. The Latxa breed showed clearer signs of genotype by environment interaction than did Manchega. Estimated correlations between yields under extremes of cold and heat were always above 0.8 for Manchega and around 0.4 for Latxa for all traits. Estimates of correlations between comfort and thermal stress were again over 0.8 for Manchega and lower for the higher (hot end) values (down to 0.6) than for the lower (cold end) values (down to 0.84) of the THI gradient for Latxa, indicating greater thermal stress expected from high than from low temperatures in this breed. Substantial variability in thermal tolerance under the more extreme THI values was found in both breeds. Estimated genetic correlations between yield and thermal tolerance were close to 0 and 0.2 for Latxa and Manchega in the cold and down to -0.6 and -0.3 in the heat end, although small variation was observed for fat in Latxa. Estimated realized trends from the average estimated breeding value, by year of birth, showed a positive response for yields in both breeds [around 0.1 standard deviation (SD) unit], but a detrimental correlation for thermal tolerance (down to -0.03 SD units for heat tolerance in Latxa). These results can be used to design optimal selection strategies for sustainable improvement of productivity under a rising-temperature scenario associated with climate change.

Association between heat stress during intrauterine development and the calving-to-conception and calving-to-first-service intervals in Holstein cows

Heat stress has been widely studied in relation to its effects on the production and reproduction of dairy cattle. However, the long-term effects of heat stress during intrauterine development on adult cows have been scarcely considered. Thus, the aim of this study was to evaluate possible changes in the reproductive performance of Holstein cows gestated under different values of the Temperature-Humidity Index (THI) during their intrauterine development. Data collected from a database of reproductive and productive records of 10,790 Holstein cows from the central region of Argentina and the THI data from the agrometeorological station of the Instituto Nacional de Tecnología Agropecuaria (INTA) EEA Rafaela, Santa Fe, Argentina, were used. The gestation of the cows evaluated was divided into trimesters, in which the highest THI cycles (sum of three or more consecutive days of exposure to a THI ≥72 during each trimester) and number of days with a THI ≥ 72 were calculated. The calving-to-conception and calving-to-first-service intervals of the cows evaluated were considered as reproductive variables associated with their first lactation. Generalized Linear Mixed Models were used, considering the cow’s dairy farm as a random factor within the model. The exposure of the animals to environments with a THI ≥72 during the first trimester of gestation had a negative impact on the reproductive efficiency parameters analyzed. The results obtained indicate that the exposure of pregnant females to high THI values has a long-term impact on their daughters, which may contribute to a decrease in their reproductive performance, possibly through inherited epigenetic characteristics that remain in later generations through fetal programming.

Effect of dietary protein level on egg production and egg-quality characteristics of Japanese quail (

Context Quail production is increasingly emerging as a low-capital, cheap, alternative source for supplementing protein intake among peoples in tropical countries such as Nigeria. Aims To increase animal protein sources, promote their availability to rural people, and reduce the unit cost of protein to the people, the effect of dietary crude protein on feed consumption, egg productivity and egg-quality characteristics of quail in the high-altitude Ekiti area of Nigeria was evaluated. Methods In total, 142 mature Japanese quails, divided into four groups with four replicates per group, were fed with four diets differing in dietary protein concentration with a near-isocaloric maize–groundnut cake–soybean meal-based diets for 10 weeks. Three experimental diets (18%, 22% and 24% crude protein (CP)) were tested and compared with a control 20% CP diet, in a completely randomised design of four replicates per treatment. Each consisted of 10 quails/cage at 5 weeks of age. Parameters measured on each quail included feed intake, egg number and egg-quality characteristics. Data were subjected to general linear model, regression and Duncan multiple-range procedures for means separation by SAS®v9.4 (2013). Key results Increasing dietary protein from 18% to 24% in the diet of experimental quails decreased daily feed intake, hen-day egg production (HDP) and average egg mass (AEM; P &lt; 0.05) during egg lay, whereas egg weight and diameter, egg shell weight, albumen weight, height and percentage, and yolk height increased significantly (P &lt; 0.05). The 18% CP diet produced the highest HDP and AEM responses (P &lt; 0.05). The 20% CP diet produced the highest numerical shell and yolk percentages (P &gt; 0.05). Birds on 22% CP diet consumed the lowest quantity of feed (daily feed intake, P &lt; 0.05) and had the lowest feed conversion ratio (FCR, P &gt; 0.05). Birds on 24% CP diet produced the highest egg weight and diameter, egg shell weight, albumen weight, height and percentage, and yolk height (P &lt; 0.05). Haugh unit values were high and uninfluenced by an increasing dietary protein concentration (P &gt; 0.05). The high and above-threshold environmental temperature–humidity index value of the test station resulted in heat stress during egg production, and was considered major cause of the generally low productivity and low egg-trait values obtained. Conclusions The 18% CP diet produced the highest HDP and AEM, while the 22% CP diet was the most efficiently utilised diet, and 24% CP diet stimulated higher egg-weight and egg-quality traits. Implications Massive quail egg production could be sustained among rural people with the 18% CP diet, with adequate energy level, and without adverse effects on egg quality.

The Impact of Temperature and Humidity on the Performance and Physiology of Laying Hens.

Simple SummaryThe present study investigated whether the temperature-humidity index (THI) influences the production parameters and physiology of laying hens. Two environmental conditions combining high temperature with low relative humidity (TLHH75) or vice versa (THHL75), with the same THI value (75), were considered. The same THI value indicated equal thermal stress for laying hens. Neither TLHH75 nor THHL75 affected laying performance, including egg production, egg weight, and egg mass, feed intake, feed conversion ratio, plasma biochemical parameters, and stress indicators. Our study suggests that laying hens exposed to the same THI values will receive similar thermal stresses. The results of this study will serve as a scientific basis for management decisions and handling laying hens under thermally challenging conditions.We investigated the effect of different ambient temperatures and relative humidity (RH) with the same temperature-humidity indices (THI) on laying performance, egg quality, heterophil to lymphocyte ratio (H/L ratio), corticosterone (CORT) concentration in blood, yolk, and albumen, and plasma biochemical parameters of laying hens. Commercial hens (Hy-Line Brown; n = 120), aged 60 weeks, were allocated to two environmental chambers. Laying hens were subjected to either one of two thermal treatments—26 °C and 70% RH (TLHH75) or 30 °C and 30% RH (THHL75) for 28 days—with the same THI of 75. Neither TLHH75 nor THHL75 affected laying performance, including egg production, egg weight, egg mass, feed intake, and feed conversion ratio (p > 0.05). Plasma biochemical parameters such as total cholesterol, high-density lipoprotein cholesterol, triglycerides, calcium, magnesium, and phosphorus were not altered by the environmental treatments (p > 0.05). As for stress indicators, both environmental regimes failed to affect blood H/L ratio and CORT levels in plasma, yolk, and albumen (p > 0.05), although albumen CORT levels were elevated (p < 0.05) in TLHH75 group at day 7. Hence, our study suggests that laying hens performed and responded similarly when exposed to either TLHH75 or THHL75 characterized by the same THI. These results can serve as a scientific basis for management decisions and handling laying hens under thermally challenging conditions.