High Temperature-humidity Index Research Articles

Estimation of Genotype by Environmental Interaction for Litter Traits by Reaction Norm Model in Taiwan Landrace Sows.

The negative effects of heat stress on swine reproduction have been well documented and the recent global warming trend caused by climate change is leading to more days with high temperatures every year. This has caused a reduction in litter trait performance of Landrace sows in Taiwan, a country extending across tropical and subtropical oceanic zones. Therefore, this study developed a modified model to determine which stages of pregnancy, before, early, middle, and late, had the largest impacts of heat stress on litter traits. A reaction norm model (RNM) was used to identify sows with high resilience to heat stress for litter traits followed by analysis of the modified model. Data from Landrace sows were collected from two farms in Taiwan between 2008 and 2021. A total of 11,059 records were collected for total number born (TNB), number born alive (NBA), and stillborn rate (STBR). The results showed that the heritabilities of TNB, NBA, and STBR were 0.170, 0.115, and 0.077, respectively. These results were similar between the conventional model and the modified model. In the modified model, the before and early stages of sow pregnancy were the significant periods for TNB and NBA (p<0.05), while the early and middle stages were significant for STBR (p<0.05). According to the RNM results, the heritability estimates for TNB, NBA, and STBR were 0.23-0.11, 0.18-0.08, and 0.10-0.04, respectively, showing a decrease from low temperature-humidity index (THI) to high THI. The minimum genetic correlations between the highest and the lowest THI for TNB, NBA, and STBR were 0.85, 0.64, and 0.80, respectively. The results of the RNM for breeding value showed re-ranking across THI values. In conclusion, similar results were obtained for heritability when the model was modified for heat stress estimation. Yet re-ranking of breeding values across THI could help farmers to select not only for improved litter trait performance but also for heat stress resilience of Landrace sows in Taiwan.

Heat Stress Effects on Physiological and Milk Yield Traits of Lactating Holstein Friesian Crossbreds Reared in Tanga Region, Tanzania.

Global warming caused by climate change is a challenge for dairy farming, especially in sub-Saharan countries. Under high temperatures and relative humidity, lactating dairy cows suffer from heat stress. The objective of this study was to investigate the effects and relationship of heat stress (HS) measured by the temperature-humidity index (THI) regarding the physiological parameters and milk yield and composition of lactating Holstein Friesian crossbred dairy cows reared in the humid coastal region of Tanzania. A total of 29 lactating Holstein Friesian x Zebu crossbred dairy cows with 50% (HF50) and 75% (HF75) Holstein Friesian gene levels in the second and third months of lactation were used. The breed composition of Holstein Friesians was determined based on the animal recording system used at the Tanzania Livestock Research Institute (TALIRI), Tanga. The data collected included the daily temperature, relative humidity, daily milk yield, and physiological parameters (core body temperature, rectal temperature, respiratory rate, and panting score). THI was calculated using the equation of the National Research Council. The THI values were categorized into three classes, i.e., low THI (76-78), moderate THI (79-81), and high THI (82-84). The effects of THI on the physiological parameters and milk yield and composition were assessed. The effects of the genotype, the parity, the lactation month, and the interaction of these parameters with THI on the milk yield, milk composition, and physiological parameters were also investigated. The results show that THI and its interaction with genotypes, parity, and the lactation month had a highly significant effect on all parameters. THI influenced (p ˂ 0.05) the average daily milk yield and milk fat %, protein %, lactose %, and solids-not-fat %. As the THI increased from moderate to high levels, the average daily milk yield declined from 3.49 ± 0.04 to 3.43 ± 0.05 L/day, while the fat % increased from 2.66 ± 0.05% to 3.04 ± 0.06% and the protein decreased from 3.15 ± 0.02% to 3.13 ± 0.03%. No decline in lactose % was observed, while the solid-not-fat % declined from 8.56 ± 0.08% to 8.55 ± 0.10% as the THI values increased from moderate to high. Also, the THI influenced physiological parameters (p ˂ 0.05). The core body temperature (CBT), rectal temperature (RT), respiratory rate (RR) and panting score (PS) increased from 35.60 ± 0.01 to 36.00 ± 0.01 °C, 38.03 ± 0.02 to 38.30 ± 0.02 °C, 62.53 ± 0.29 to 72.35 ± 0.28 breaths/min, and 1.35 ± 0.01 to 1.47 ± 0.09, respectively, as the THI increased from low to high. The THI showed a weak positive correlation with the average daily milk yield and fat percentage, whereas the protein, lactose, and solids-not-fat percentages showed negative relationships with THI (p ≤ 0.05). CBT, RT, RR, and PS showed positive relationships (p ≤ 0.05) with THI. These negative relationships indicate that there is an antagonistic correlation between sensitivity to HS and the level of production. It is concluded that the THI, the genotype, the parity, and the lactation month, along with their interactions with THI, significantly influenced the milk yield, milk composition, and physiological parameters of lactating Holstein Friesian dairy crosses at THI thresholds ranging from 77 to 84.

Modulations in antioxidant defence system and expression of genes involved in antioxidant and apoptosis pathway helps ward-off heat stress incows reared in hot-arid ambience of Thar desert

The present study was designed to assess the seasonal perturbations in key antioxidant parameters: ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) scavenging activity, lipid per oxidation (LPO), uric acid and reduced glutathione (GSH) assay along with expression profile of genes that regulate the antioxidant pathway: manganese superoxide dismutase (SOD2), Glutathione Peroxidase 1 (GPX1) and apoptosis pathway: B-cell lymphoma 2 (BCL2) and Bcl-2-associated X protein (BAX) in the two crucial indicine cattle breeds- Sahiwal and Kankrej. The study was carried out in the hot-arid region of Rajasthan across four seasons, wherein, the meteorological parameters were recorded across seasons to calculate the prevailing temperature-humidity index (THI) to assess the extent of heat load on cows. The study revealed huge diurnal variations in the temperature across four seasons, while the THI during summer and hot-humid seasons was well in excess of 80, highlighting significant heat stress on cows. All the key antioxidant parameters, except GSH registered an increase with the incremental THI. The transcriptional profile of SOD2 and GPX1 mRNA expression revealed significantly higher expression during the higher THI months of both summer and hot-humid seasons. The expression pattern of BAX and BCL2 mRNA in PBMCs of Sahiwal cows revealed an initial induction during the month of summer season with significantly higher expression, followed by a decline by the hot-humid season. The findings highlight a crucial role played by antioxidant defence and genes regulating apoptosis pathway in thermotolerance of indicine cattle breeds.

Effect of extended heat stress in dairy cows on productive and behavioral traits

This study evaluates the response of dairy cows to short and extended heat stressing conditions (from 1 to 28 days), as expressed in changes in their behavior. Due to climate change, heat stress and strong heat waves are frequently affecting the productivity and behavior of dairy cows. In the five years under study from 2018 to 2022, two were characterized by extremely strong heat waves occurring in the region analyzed in this study (Northern Italy). The dairy cattle farm involved in this study is located in Northern Italy and includes about 1 600 Holstein Friesian lactating dairy cows. Phenotypic data were provided by the Afimilk system and compromised behavioral and productive traits. Behavioral traits analyzed were activity, rest time, rest bouts, rest ratio, rest per bout and restlessness. Production traits were daily milk yield, average milking time, somatic cell count, fat percentage, protein percentage and lactose percentage. Climate data came from the National Aeronautics and Space Administration/Prediction of Worldwide Energy Resources database. Heat stress was analyzed considering Temperature-Humidity Index (THI) averaged over 28 different time windows of continuous heat stress. Results showed that rest time and milk yield were the two traits most affected by the increased THI. Rest time was immediately affected by high THI, showing a marked decrease already from 1d window and maintaining this all over the other windows. Furthermore, results show that rest time and rest ratio were only slightly negatively correlated with milk yield (−0.14 and −0.15). In addition, heat stress has a different effect depending on parity and lactation stages on the studied traits. In conclusion, the results indicate that heat stress increases activity and compromises milk production, rest time and milk quality traits. Results further suggest that rest time can be a better parameter than activity to describe the effects of heat stress on dairy cattle. The novel approach used in this study is based on the use of different time windows (up to 28 days) before the emergence of undesired THI and allows to identify the traits that are immediately influenced by the undesirable THI values and those that are influenced only after a prolonged heat stress period.

Thermal characterization and ventilation assessment of a battery-caged laying hen housing in the humid tropic climate.

The indoor climate to which livestock are exposed is a critical factor influencing their performance and productivity. Elevated air temperature and relative humidity could result in heat stress for laying hens. This situation results in severe adverse effects such as weight loss and mortality. Egg fertility and hatchability are also impacted. Consequently, a study was carried out in a naturally ventilated battery-caged laying hen house to measure climatic variables (air temperature, relative humidity and air velocity). The degree of heat stress was assessed using the temperature-humidity index (THI), and the index of temperature and air velocity (ITV) was also evaluated. According to the results obtained, birds reared within the study building would spend most of their productive life under stressful thermal conditions, which could significantly hamper their performance. The air velocity was below 1.0 ms-1 for most of the internal part of the housing, meaning natural air movement at the location was insufficient to provide a suitable environment for the birds. A high THI was recorded for nearly the entire study period. This high THI could indicate high relative humidity about air temperature. The observed ITV values (ITV > 25) suggest that birds throughout the building could be perpetually uncomfortable. The thermal and velocity profile within the structure could further be assessed numerically using computational fluid dynamics. This would enable engineers to make modifications to improve living conditions within the building.

Effect of Temperature Humidity Index (THI) on resting pattern of dairy cows in different regions of Sri Lanka.

The ability to spend time resting is extremely important for dairy cattle welfare. Through this study, lying behaviour of dairy cows in to Up-Country (UP), Mid-Country (MC), Coconut-Triangle (CT) and Western-Province (WP) of Sri Lanka was studied to get an insight into their resting pattern. Resting pattern was assessed in 170 Holstein-Friesian/ Jersey crossed, tie-stalled lactating cows (UP = 49, MC = 49, CT = 48 and WP = 24) using electronic data loggers. Appropriate resting behaviours were attained in UP and MC regions, with longer lying time (11.7, 11.3 h/day) and lying bout durations (78.0, 84.9 min) respectively, where lower THI ranges were observed compared to other regions. WP and CT resulted with lower lying times (9.00, 9.26 h/day) and lying bout durations (48.3, 64.3 min) respectively with higher THI. There is a slight variation of the environmental temperature of each region with the time period of experiment. Cows in all regions prefer to lie on their left side (UP-6.1, MC-6.1, CT-4.4, WP-4.7 h/d) and with significant differences (P<0.05) between MC-WP, MC-CT, UP-CT and UP-WP. A negative significant (P<0.05) correlation was observed between THI and lying behaviours. There were significant effects of time (hour) and time × region interaction (P<0.05) on the lying down pattern. More lying down was observed in late night and early morning with a peak rest around the hours of 21:00-05:00. Overall, according to the results of the current study, the existing environmental conditions of four regions affected the resting pattern of dairy cows and, identification of possible mechanisms to modify the environment to enhance cow comfort is vital.

Housing conditions of dry cows: effects on teat contamination and somatic cells at the beginning of the subsequent lactation

The study investigated the effects of housing conditions and temperature-humidity index (THI) during the dry period on total bacteria counts of bedding material, animal cleanliness, and teat bacterial contamination on 212 cows from three farms. Additionally, milk yield, quality, total somatic cells, and leucocyte fractions were evaluated in the subsequent lactation on a subgroup of 119 cows. The results showed a relationship between persistent high THI, teat bacterial contamination, and pathogens on teat skin. Somatic cell count (SCC) in milk at the beginning of the next lactation was not affected by THI during the dry period. Multiple correlation analysis revealed a relationship among high milk SCC, high percentage of neutrophils, high bacterial count of bedding during the dry period, and high milk production at dry-off. The study confirms that critical environmental conditions, such as high THI and poor bedding hygiene, during the dry period, can affect teat bacterial contamination and increase the risks for high SCC in the next lactation. High milk production at dry-off may be another risk factor.

Association between a pyroelectric infrared sensor monitoring system and a 3-dimensional accelerometer to assess movement in preweaning dairy calves

The objective of this study was to correlate movement assessed by a pyroelectric infrared sensor system in preweaning dairy calves with lying and standing time assessed by a 3D accelerometer considering the temperature-humidity index (THI). A total of 35 dairy calves (1–7 d of age) were enrolled in the study and 20 calves were included in the final analyses. The lying and standing time of the calves was monitored with a 3D accelerometer (Hobo Pendant G Data Logger, Onset Computer Corporation, USA), which was used as the gold standard reference. The infrared sensor monitoring system (IMS; Calf Monitoring System, Futuro Farming GmbH, Germany) was fixed to the fence of the calf hutch within the calf's reach. Temperature-humidity was monitored with 2 validated THI sensors inside and on outside of each calf hutch. Additionally, one THI sensor was located near the calf hutches. The observation period lasted 14 consecutive days. The average standing time assessed by the 3D accelerometer was 13.4 ± 12.7 (mean ± standard deviation) min/h and the average lying time was 46.6 (±12.7) min/h. The median (25th percentile; 75th percentile) number of movements measured by the IMS was 360 (60; 919) movements per hour. Number of movements per hour measured by the IMS was compared with data obtained with a validated 3D accelerometer. The Pearson correlation coefficient between both standing and lying time and the number of movements was r = 0.85 and r = −0.85, respectively. The Pearson correlation coefficients were only slightly influenced by THI (low THI [<68]: r = 0.86; medium THI [68–72]: r = 0.85; high THI [>72]: r = 0.81). Our data show that the number of movements of dairy calves measured by IMS were highly correlated with the chosen gold standard reference method. High THI slightly affects the measurement accuracy of IMS.

Seasonal effects on multiparous dairy cow behavior in early lactation

Controlled studies have shown that heat stress abatement positively influences health, productivity, behavior, and reproductive performance of dairy cows during all stages of the lactation cycle. Based on previous findings, the present study focused on a better understanding of how seasonal changes affect the behavior of multiparous lactating dairy cows kept in typical free-stall housing with the objective to aid in the management of lactating cows exposed to variable environmental conditions. Automated monitoring devices (Nedap, the Netherlands) were used to assess behavioral activity of mature Holstein dairy cows during the “hot season” (HS; n = 19; July, August, and September) and the “cool season” (CS; n = 15; December, January, and February) under normal management conditions. Cows received a leg tag to measure daily lying time, and number of steps and standing bouts, and a neck tag to measure eating and rumination time. All cows were housed in sand-bedded freestall barns equipped with cooling systems (soakers and fans). Behavior, milk production and milk components were recorded for the first 9 wk of lactation after calving. Average temperature-humidity index (THI) was 78.2 ± 0.4 (± standard error) in the HS and 54.4 ± 0.2 in the CS. Fat-corrected milk yield was greater in the CS compared with HS during the first 5 wk of lactation. Milk protein percentage was lower in CS during the first 2 wk of lactation. In contrast with HS, milk fat percentage was greater in the CS. Compared with CS, overall, during HS cows spent less time eating, lying down, and tended to spend less time ruminating. In addition, exposure to high THI resulted in increases in standing bouts, and overall standing time in HS relative to CS. No differences in number of steps were observed between HS and CS. In summary, exposure to high THI during lactation seems to negatively affect the behavior and consequently the daily time budget of lactating Holstein cows, even under housing conditions with active cooling. A better understanding on how different seasons affect the daily time budget of lactating dairy cows may contribute to the development of more effective management strategies to decrease the negative effects of heat exposure.

Effects of temperature-humidity index on blood metabolites of German dairy cows and their female calves

Heat stress (HS) impairs productivity, health, and welfare in dairy cows, and additionally causes metabolic changes. Hence, specific metabolites could be used as HS biomarkers. Consequently, the aim of the present study was to compare blood metabolite concentrations of German Holstein dairy cows and of their female calves suffering from high temperature-humidity index (THI) during late gestation (cows) or during their first week of life (calves) or not. According to the mean daily THI (mTHI) at the day before blood sampling, animals were classified into 2 groups: high mTHI ≥60 (hmTHI) and low mTHI <60 (lmTHI). To perform a standard cross-sectional 2-group study, cow groups (n = 48) and calf groups (n = 47) were compared separately. Differences in metabolite concentrations between hmTHI and lmTHI animals were inferred based on a targeted metabolomics approach. In the first step, processed metabolomics data were evaluated by multivariate data analysis techniques, and were visualized using the web-based platform MetaboAnalyst V5.0. The most important metabolites with pronounced differences between groups were further analyzed in a second step using linear mixed models. We identified 9 thermally sensitive metabolites for the cows [dodecanedioic acid; 3-indolepropionic acid; sarcosine; triglycerides (14:0_34:0), (16:0_38:7), (18:0_32:1), and (18:0_36:2); phosphatidylcholine aa C38:1; and lysophosphatidylcholine a C20:3] and for the calves [phosphatidylcholines aa C38:1, ae C38:3, ae C36:0, and ae C36:2; cholesteryl esters (17:1) and (20:3); sphingomyelins C18:0 and C18:1; and p-cresol sulfate], most of them related to lipid metabolism. Apart from 2 metabolites (3-indolepropionic acid and sarcosine) in cows, the metabolite plasma concentrations were lower in hmTHI than in lmTHI groups. In our heat-stressed dry cows, results indicate an altered lipid metabolism compared with lactating heat-stressed cows, due to the missing antilipolytic effect of HS. The results also indicate alterations in lipid metabolism of calves due to high mTHI in the first week of life. From a cross-generation perspective, high mTHI directly before calving seems to reduce colostrum quality, with detrimental effects on metabolite concentrations in offspring.

PHYSIOLOGICAL RESPONSES OF FEMALE BEEF CATTLE AGAINST PEATLAND MICROCLIMATE STRESS IN CENTRAL KALIMANTAN

This study aimed to evaluate the physiological response of female beef cattle to peatland microclimate stress in Central Kalimantan. This study used direct observation on small holder beef cattle farm. Microclimate data on 41 units cattle barns and physiological parameters of female cattle were collected in the morning, at noon and in the afternoon. The physiological parameter measurements involved 215 female beef cattle, consisting of 119 Bali and 96 crossbred cattle with different physiological stages including pregnant cows, lactating cows, dry cows, heifers and calves. The microclimate condition within cattle barns on peatland of Central Kalimantan is not the comfort zone for beef cattle. It is characterized by high air temperature and relative humidity, and low wind speed, which result in high temperature humidity index (THI). The barn with gable roof type and asbestos materials gave the lowest THI. This Microclimate caused heat stress to beef cattle reared on the peatlands, indicated by the high rectal temperature, heart rate, respiratory rate, and heat tolerance coefficient, although it was still categorized as mild to moderate stress. Bali cattle showed better physiological responses to microclimate stress than crossbred cattle. Pregnant crossbred cows were the most susceptible to peatland microclimate stress.

Use of Innovative Tools for the Detection of the Impact of Heat Stress on Reticulorumen Parameters and Cow Walking Activity Levels.

The aim of this study was to evaluate the influence of the temperature and humidity index on reticulorumen parameters such as temperature, pH, rumination index, and cow walking activity levels. Throughout the experiment, the following parameters were recorded: reticulorumen pH (pH), reticulorumen temperature (RR temp.), reticulorumen temperature without drinking cycles, ambient temperature, ambient relative humidity, cow walking activity levels, heat index, and temperature-humidity index (THI). These parameters were registered with particular smaXtec boluses. SmaXtec boluses were applied on 1 July 2022; 24 days were the adaptation period. Measurements started at 25 July 2022 and finished at 29 August 2022. The THI was divided into two classes: THI < 72 (comfort zone) and THI ≥ 72 (higher risk of thermal stress). Cows assigned to the 2nd THI class had lower average values for pH, temperature, and rumination index, but not walking activity levels. The mean differences ranged from 0.36 percent in temperature to 11.61 percent in walking activity levels (p < 0.01). An analysis of the THI revealed a significant positive linear relation with hours, where the THI had a tendency to increase on average by 0.2403. The reticuloruminal pH showed a negative linear relation with hours, where the reticuloruminal pH had a tendency to decrease on average by 0.0032, p < 0.001. Data analysis revealed a significant positive linear relationship between walking activity levels and hours, where walking activity levels had a tendency to increase on average by 0.0622 steps per hour, p < 0.001. The rumination index was not significantly related to hours (p < 0.005), although the rumination index had a tendency to increase by 0.4376 per hour, p > 0.05. The influence of HS on reticulorumen parameters increased the risk of acidosis and cows' activity levels. HS had a negative impact on reticulorumen pH, temperature, and the rumination index. A higher THI (≥72) increased the risk of ruminal acidosis and decreased cows' physical activity levels. From a practical point of view, we can use innovative tools for the detection of HS and its impact on reticulorumen parameters and cow walking activity levels.

Comparing thermal conditions inside and outside lactating dairy cattle barns in Canada

The health, longevity, and performance of dairy cattle can be adversely affected by heat stress. This study evaluated the in-barn condition [i.e., temperature, relative humidity, and resulting temperature-humidity index (THI)] at 9 dairy barns with various climates and farm design-management combinations. Hourly and daily indoor and outdoor conditions were compared at each farm, including both mechanically and naturally ventilated barns. On-site conditions were compared with on-farm outdoor conditions, meteorological stations up to 125 km away, and NASA Power data. Canadian dairy cattle face periods of extreme cold and periods of high THI, dependent on the regional climate and season. The northernmost location (53°N) experienced about 75% fewer hours of THI >68 compared with the southernmost location (42°N). Milking parlors had higher THI than the rest of the barn during milking times. The THI conditions inside dairy barns were well correlated with THI conditions measured outside the barns. Naturally ventilated barns with metal roofs and without sprinklers fit a linear relationship (hourly and daily means) with a slope <1, indicating that in-barn THI exceeded outdoor THI more at lower THI and reached equality at higher THI. Mechanically ventilated barns fit nonlinear relationships, which showed the in-barn THI exceeded outdoor THI more at lower THI (e.g., 55-65) and approached equality at higher THI. In-barn THI exceedance was greater in the evening and overnight due to factors such as decreased wind speed and latent heat retention. Eight regression equations were developed (4 hourly, 4 daily) to predict in-barn conditions based on outdoor conditions, considering different barn designs and management systems. Correlations between in-barn and outdoor THI were best when using the on-site weather data from the study, but publicly available weather data from stations within 50 km provided reasonable estimates. Climate stations 75 to 125 km away and NASA Power ensemble data gave poorer fit statistics. For studies involving many dairy barns, the use of NASA Power data with equations for estimating average in-barn conditions in a population is likely appropriate especially when public stations have incomplete data. Results from this study show the importance of adapting recommendation on heat stress to the barn design and guide the selection of appropriate weather data depending on the aim of the study.

Negative association between high temperature-humidity index and milk performance and quality in Korean dairy system: big data analysis.

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.

5-Aminolevulinic acid/sodium ferrous citrate improves the quality of heat-stressed bovine oocytes by reducing oxidative stress.

A high temperature-humidity index during summer has deleterious effects on mitochondrial function, reducing oocyte developmental competence. 5-Aminolevulinic acid (5-ALA) and sodium ferrous citrate (SFC) are both known to support mitochondrial function and have strong anti-oxidant and anti-apoptotic activities. This study aimed to determine the mechanism of action of 5-ALA/SFC on oocyte quality. Bovine oocytes were collected from medium-sized follicles during summer (July-September, temperature-humidity index:76.6), cultured with 0, 1, 2, 4, and 8 µM 5-ALA with SFC at a molar ratio of 1:0.125, fertilized, and cultured for 10 days. The addition of 8/1 µM 5-ALA/SFC had a deleterious effect on oocyte cleavage rate in comparison with control oocytes, but did not affect the blastocyst rate, while 1/0.125 µM 5-ALA/SFC had a significantly higher increase in blastocyst rate than 8/1 µM 5-ALA/SFC. The addition of 1/0.125 and 2/0.25 µM 5-ALA/SFC improved oocyte quality by increasing the mitochondrial distribution pattern and metaphase-II oocytes, reducing reactive oxygen species and upregulating nuclear factor erythroid-2-related factor 2, heme oxygenase-1, and superoxide dismutase-1 in oocytes, and nuclear factor erythroid-2-related factor 2 and mitochondrial transcription factor A in cumulus cells. These results indicate that 1/0.125 and 2/0.25 µM 5-ALA/SFC may support oocyte quality and developmental competence and provide anti-oxidant actions in cumulus-oocyte complexes.

Impact of heat stress on dairy cow rumination, milking frequency, milk yield and quality in a pasture-based automatic milking system

Context Heat stress is an increasing concern for the Australian dairy industry. Aims This study aimed to evaluate the effect of temperature–humidity index (THI) on rumination time (RT), milk yield and quality, and milking frequency in a pasture-based voluntary-movement automatic milking system (AMS). Methods Data were collected from the University of Melbourne Dookie College AMS farm for 3 years (June 2016 to March 2019). Daily RT was collected through the transponder collar (Qwes-HR, Lely). Climatic data (maximum ambient temperature and relative humidity) were obtained from the Dookie Meteorological station to calculate daily maximum THI (THImax). Key results Daily milk yield increased with a rising THImax to 65, then declined after THImax 65. Milking frequency was highest at THImax 90, followed by a steady decline afterwards. Rumination time was maximum at mid-range THImax and declined for high and low values. Conclusions The findings of this study clearly indicated that under pasture-based voluntary-movement AMS, high THI resulted in a drop in the milk yield, milking frequency and RT. Implications With the provision of automation of data collection from AMS, further study with mathematical modelling describing the daily patterns and thresholds in conjunction with the different heat stress levels can be useful for assessing animal welfare and to mitigate heat stress and seek alternative management strategies.

Genotype by environment interaction due to heat stress in Brown Swiss cattle

Due to its geographical position and a highly variable orography, Italy is characterized by several climatic areas and thus, by many different dairy cow farming systems. Brown Swiss cattle, in this context, are a very appreciated genetic resource for their adaptability and low metabolic requirement. The significant heterogeneity in farming systems may consist of genotype by environment (G × E) interactions with neglected changes in animals' rank position. The objective of this study was to investigate G × E for heat tolerance in Brown Swiss cattle for several production traits (milk, fat, and protein yield in kilograms; fat, protein, and cheese yield in percentage) and 2 derivate traits (fat-corrected milk and energy-corrected milk). We used the daily maximum temperature-humidity index (THI) range, calculated according to weather stations' data from 2008 to 2018 in Italy, and 202,776 test-day records from 23,396 Brown Swiss cows from 639 herds. Two different methodologies were applied to estimate the effect of the environmental variable (THI) on genetic parameters: (1) the reaction norm model, which uses a continuous random covariate to estimate the animal additive effect, and (2) the multitrait model, which splits each production pattern as a distinct and correlated trait according to the first (a thermal comfort condition), third (a moderate heat stress condition), and fifth (a severe heat stress condition) mean THI value quintile. The results from the reaction norm model showed a descending trend of the additive genetic effect until THI reached the value of 80. Then we recorded an increase with high extreme THI values (THI 90). Permanent environmental variance at increasing THI values revealed an opposite trend: The plot of heritability and the ratio of animal permanent environmental variance to phenotypic variance showed that when the environmental condition worsens, the additive genetic and permanent environmental component for production traits play a growing role. The negative additive genetic correlation between slope and linear random coefficient indicates no linear relationship between the production traits or under heat stress conditions, except for milk yield and protein yield. In tridimensional wireframe plots, the extreme margin decreases until a minimum of ∼0.90 of genetic correlation in the ECM trait, showing that the magnitude of G × E interaction is greater than the other traits. Genetic correlation values in Brown Swiss suggest the possibility of moderate changes in animals' estimated breeding value in heat stress conditions. Results indicated a moderate G × E interaction but significant variability in sire response related to their production level.

Thermoregulatory response and oxidative stress indices of rabbit bucks administered ascorbic acid and sodium bicarbonate in a humid tropical environment

Abstract Background This study aimed to assess the effect of ascorbic acid and sodium bicarbonate on thermoregulatory response and oxidative stress markers of rabbit bucks during highest temperature-humidity index in a humid tropical environment as a mitigation strategy against impact of high ambient temperature on the animals. Twenty-eight exotic rabbit bucks of 9 months old weighing 2.54 ± 0.23 kg were randomly allotted to four treatments consisting of T1 (Control-2 ml of sterile water), T2 (2 ml of 300 ppm ascorbic acid), T3 (2 ml of 0.30% sodium bicarbonate) and T4 (2 ml mixture of 150 ppm ascorbic acid + 0.15% sodium bicarbonate, administered orally at 48 h interval for 12 weeks. After a month of administration, rectal temperature, ear temperature, respiratory rate and pulse rate were monitored twice daily (8:00 am and 4:00 pm). Semen samples were collected from all bucks weekly for seminal lipid peroxidation and total antioxidant activity assay. Blood samples were collected from all bucks and serum obtained using standard procedure to assay for lipid peroxidation and total antioxidant activity. Results The result revealed that the rabbits were exposed to very severe heat stress for greater part of the day. At week 5, bucks on T2, T3 and T4 had increased respiratory rate at 8 am than those on T1, similar trend was observed at week 4 and 6. At 4 pm, the pulse rate was significantly (p &lt; 0.05) different among the treatments at weeks 11, bucks on T2, T3 and T4 had significantly lowered (p &lt; 0.05) pulse rate than those on T1. The administration of ascorbic acid, sodium bicarbonate and its combination did not significantly (p &gt; 0.05) influence the ear and rectal temperature of the bucks. At week 11, seminal total antioxidant activity of bucks on T1, T2 and T3 was significantly (p &lt; 0.05) lower than bucks on control T4. Lipid peroxidation level was significantly (p &lt; 0.05) lower in bucks on T2, T3 and T4 than those bucks on the control. Conclusion The administration of ascorbic acid, sodium bicarbonate and its combination had enhanced seminal total antioxidant and reduced lipid peroxidation in heat-stressed bucks.

75 Influence of paternal exposure to high temperature-humidity index on the oxygen consumption rate of

Reproduction, Fertility and Development is an international journal publishing original research , review and comment in the fields of reproduction and developmental biology in humans, domestic animals and wildlife

The seasonal effect on the performance of pigs reared in a backyard pig farm in Thailand: retrospective study

This study aimed to determine the seasonal effect on the performance of pigs reared in open-barn housing in Thailand. This retrospective study was performed using two years of recorded pig perfor-mance, including average birth weight, litter size, percentage of born alive and dead piglets, weaning weight, average daily gain (ADG), percentage of weaned alive and dead piglets and meteorological data. Data were grouped based on 3 different seasons: winter, summer and the rainy season, and the differences were compared. The highest temperature–humidity index (THI) was found during summer (85.3 ± 0.2) and the THI of the rainy season was higher than that in winter (between 82.3 ± 0.2 and 77.2 ± 0.4) (p &lt; 0.05). The piglet growth performance was affected by season (p &lt; 0.05). The weaning weight of piglets in the rainy season was higher than that in winter but not different from that in sum-mer. The highest ADG was observed in the rainy season. In summary, growth performance of suckling pigs reared in open-barn housing in Thailand was affected by the season. The optimal climate promot-ing growth of nursery pigs was determined to be the rainy season.