An effective way to incorporate temperature-humidity index to study effect of heat stress on milk yield by an XGBoost machine learning model.

The objective of this work was to examine the effect of heat stress on glucose and pH values in blood of high-yielding dairy cows in the early stage of lactation, as well as to determine whether the changes in these parameters are interdependent under such conditions. An experiment was performed on high-yielding dairy cows during the summer and the spring periods. Forty cows were selected, twenty each for the two periods under investigation. In the course of the experiment, the temperature humidity index (THI) was determined for the entire period of investigations, and then also the average daily THI, nightmorning THI (average value of hourly THI measured from 22h on the previous day until 10h of the current day), as well as the day-night THI (average value of hourly THI measured during the period from 10h to 22h of the current day). The pH and glucose concentration were determined in blood samples taken in the morning and afternoon of days 30, 60, and 90 of lactation during the spring and summer periods of the investigations. Based on the results for the THI, it was established that the animals were not exposed to the effect of extreme heat stress during the spring period of investigations, while they were periodically exposed to moderate but also extreme heat stress during the summer, in particular in the afternoon hours. It can be concluded from the results obtained for the blood pH that the cows were in respiratory alkalosis during the summer in the morning and afternoon hours on day 30, in the afternoon hours of days 60 and 90 of lactation, as well as in the afternoon on day 90 of lactation during the spring period of investigations. During the summer period, there were no statistically significant differences between the pH value determined in the morning and afternoon hours on day 30 of lactation, while the pH value was significantly higher in the afternoon hours than in the morning hours on days 60 and 90 of lactation. There were no significant differences between the average values for glucose during the spring period of investigations. During the summer, the average afternoon values for glucose on days 60 and 90 of lactation were significantly lower against the morning values. Glucose concentration measured on day 90 was statistically significantly lower than those for days 30 and 60 of lactation, both in the morning and in the afternoon. Glucose concentration on day 90 of lactation during the summer period was significantly lower against glucose concentration during the spring, both in the morning and in the afternoon hours. During the spring period, there was no significant correlation between blood glucemia and pH, while there was a negative correlation between the electrochemical reaction of blood and glucemia during the summer, but which was significant only in the afternoon hours. The decrease in glucemia in the afternoon hours of days 60 and 90 of lactation during the summer period can be explained by the strong influence of alkalosis on insulin secretion that leads to the increased utilization of glucose in peripheral tissues, which is why its concentration in blood is significantly decreased at that time. This is a form of the metabolism shifting under conditions of heat stress, when it uses glucose predominantly as a source of energy in the cells, as its oxidation releases significantly less heat energy in comparison with the combustion of other metabolites.

Abstract. This article studied the potential seasonal heat-stress of dairy ewes housed in a typical naturally ventilated sheep barn located close to the east coast of central Greece. Heat stress was assessed using the Temperature Humidity Index (THI) and the Seasonal THI-hrs index. Dairy ewes were exposed to potential heat-stress (THI ≥ 22.2) in 79%, 17%, and 11% of summer, autumn, and spring hours, respectively, whereas no heat-stress was present during winter. The monthly means of the daily maximum hourly THI values remained above the extreme severe heat-stress threshold (i.e. 25.6) during the summer months and above the severe heat-stress threshold (i.e., 23.3) during May and September. During all summer days the minimum daily maximum hourly THI value was 24.6 indicating that sheep experienced severe heat-stress (THI ≥ 23.3). THI levels remained very high (usually above the extreme severe heat-stress threshold) during daytime and dropped below the heat-stress threshold (i.e., 22.2) only for a few hours during night-time. The values of the Seasonal THI-hrs index under heat-stress conditions (THI ≥ 22.2) were 6596, 975, 0, and 516 during summer, autumn, winter, and spring, respectively. These findings suggest that under summer conditions in the east coast of central Greece, dairy ewes were exposed to severe or extremely severe heat-stress conditions, while they were also partially exposed to severe or extremely severe heat-stress conditions during autumn and spring.

Temperature humidity index (THI) is widely used to assess the effect of temperature and relative humidity on performance in animals. In summer the THI was between 74 – 89 with average value of 81.18. in winter months THI ranged between 49 -70 with the average of 60. The results showed a significant effect of heat stress on daily milk yield and milk composition. In the present study the daily milk yield decreases from 4.46 to 3.65kg, heat stress reduced milk yield by 18.2%. There was a significant effect of heat stress on milk composition. Heat stress significantly reduced milk fat content from 8.3% during the winter to 7.19% during the summer. Milk protein percentage significantly decreased as a result of summer heat stress (3.08 vs.2.9 %, respectively for the winter and summer). In the present study the SNF decreases from 9.08 to 9.05 %, heat stress reduced SNF % as the THI value went from ≤ 74 to ≥ 83 in summer. Results showed that milk production is a function of THI. The negative slope of regression line indicates that milk production fat%, protein% and SNF% decreases as THI increases. This regression indicates that in general for each point increase in THI value. There was decrease in milk yield of 0.028kg per buffalo per day. Heat stress environments have been associated with depression in milk fat%, protein% and SNF%. There was decrease in milk fat of 0.046% per buffalo per day. There was also decrease in milk protein of 0.00014 % per buffalo per day. The decrease in milk SNF of 0.0047 % per buffalo per day.

Korea, located in East Asia in the northern hemisphere, is experiencing severe climate changes. Specifically, the heat stress caused by global warming is negatively affecting the dairy sector, including milk production and reproductive performance, as the major dairy cattle Holstein-Friesian is particularly susceptible to heat stress. Here, we collected artificial insemination and pregnancy data of the Holstein and the Jersey cows from a dairy farm from 2014 to 2021 and analyzed the association between the conception rate and the temperature-humidity index, calculated using the data from the closest official weather station. As the temperature-humidity index threshold increased, the conception rate gradually decreased. However, this decrease was steeper in the Holstein breed than in the Jersey one at a temperature-humidity index threshold of 75. To evaluate the effects of heat stress on the oocyte quality, we examined the nuclear and cytoplasmic maturation of Holstein (n = 158, obtained from six animals) and Jersey oocytes (n = 123, obtained from six animals), obtained by ovum pick-up. There were no differences in the nuclear maturation between the different conditions (heat stress: 40.5°C, non- heat stress: 37.5°C) or breeds, although the Holstein oocytes seemed to have a lower metaphase II development (p = 0.0521) after in vitro maturation under heat stress conditions. However, we found that the Holstein metaphase II oocytes exposed to heat stress presented more reactive oxygen species and a peripheral distribution of the mitochondria, compared to those of the Jersey cattle. Here, we show that weather information from local meteorological stations can be used to calculate the temperature-humidity index threshold at which heat stress influences the conception rate, and that the Jersey cows are more tolerant to heat stress in terms of their conception rate at a temperature-humidity index over 75. The lower fertility of the Holstein cows is likely attributed to impaired cytoplasmic maturation induced by heat stress. Thus, the Jersey cows can be a good breed for the sustainability of dairy farms for addressing climate changes in South Korea, as they are more resistant to hyperthermia.

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.

Dairy cattle, particularly in Australia where dairy farming is predominantly pasture-based, are experiencing an increased incidence of heat stress through rising global temperatures, causing a detrimental impact on productivity and welfare. Improving the thermotolerance of dairy cows through genetic selection is a potential proactive solution for mitigating the impact of heat stress for the dairy industry. Although heat tolerance breeding values for milk yield traits have been available to Australian dairy producers since 2017, considerable potential remains to develop genetic evaluation for heat tolerance of fertility and understanding of the underlying genetic architecture for heat tolerance. The objective of this study was to investigate the effect of heat stress measured as temperature-humidity index (THI) on fertility traits and to identify genomic regions associated with heat tolerance in 2 specific fertility traits: first service nonreturn rate (FNRR) and successful calving rate to first service (SCRFS). In this study, we assembled more than 892K phenotypic records of Holstein cows with THI and fertility traits and identified specific periods with respect to service day. The effect of heat stress on fertility was assessed using a random regression sire model for estimating the change in genetic variance of fertility across various THI and obtaining heat tolerance solution (slope) for sires. Also, whole genome sequence GWAS were undertaken based on heat tolerance phenotypes of 5K Holstein bulls with at least 10 daughters with fertility data. The assessment of the different THI definitions based on different numbers of days before and after artificial service days on the fertility traits showed that the most prominent effect of THI on fertility outcomes was observed for THI 7 d preceding service (including the service day) and 6 d after service day. Heat tolerance (HT) traits with respect to FNRR and SCRFS are lowly heritable and ranged from 0.01 to 0.04 under moderate THI conditions ranging between 60 and 70. However, as the THI exceeded 70, the heritability increased to up to 0.08, indicating increased genetic variance as THI increased. Genetic correlations between extreme THI ranges were as low as 0.13, while correlations between consecutive THI ranges reached up to 0.98. This finding suggests the presence of genotype-by-environment interactions due to heat stress. Notable variation in heat stress sensitivity among sires was also observed for HT fertility. In total, 553 sequence variants were significantly associated with HT fertility, and 52 of them were identified as independent QTL. Some of the QTL regions were located near or within the genes that are involved in oxidative stress, inflammation, and fertility (e.g., TRPC5, CDK5RAP2, MGAT1, COMMD10, PRR7, GRK6, CUGBP1, MAFG, HERC2, NAPRT, HSD17B12, THRB, and EEF1D). The findings in this study will further aid in understanding genetic architecture and provide valuable information for improving the accuracy of genomic prediction of HT in dairy cattle.

Dietary selenium levels modulates antioxidant, cytokine and immune response and selenoproteins mRNA expression in rats under heat stress condition

This research paper focuses on time-lagged heat stress (HS) effects from an across-generation perspective. Temperature × humidity indexes (THI) from the last 8 weeks of pregnancy were associated with subsequent female offspring performances. The offspring dataset considered 172 905 Holstein dairy cows from calving years 2002-2013 from 1,968 herds, located in the German federal state of Hesse. Production traits included milk yield (MKG), protein percentage (PRO%), fat percentage (FAT%), somatic cell score (SCS) and milk urea nitrogen (MUN) from the first official test-day in first lactation. Female fertility traits were the non-return-rate after 56 d (NRR56) in heifers and the interval from calving to first insemination (ICFI) in first parity cows. Longevity traits were the length of productive life (LPL), lifetime productivity in milk yield (LTP-MKG) and milk yield per day of life (MKG-DL). The association analyzes for 10 traits combined with meteorological data from 8 single weeks before calving implied in total 80 different runs. THI ≥50 from all single 8 weeks before calving had unfavorably significant effects on FAT%, ICFI and LPL. Heat stress in terms of THI ≥60 from the last 3 weeks before calving impaired MKG. NRR56 decreased with increasing THI, as observed for all 6 weeks before calving. LTP-MKG and MKG-DL decreased due to high THI in the last 4 weeks before calving. Heat stress (THI ≥60) during late pregnancy had no significantly unfavorable impact on PRO% and MUN. Interestingly, SCS in offspring declined with increasing THI during late pregnancy. In conclusion, for most of the primary and functional traits, unfavorable impact of HS from the dry period on time-lagged performances in offspring was identified, even on longevity. From a practical perspective, our data suggest to provide HS abatement to late gestation dams to avoid long-term adverse effects on the offspring.

BackgroundAutomatic noninvasive oscillometric blood pressure (NIBP) devices measure mean arterial pressure (MAP); systolic and diastolic blood pressure (SBP, DBP) are algorithmically derived from MAP. The most invalid NIBP measure is SBP, yet stroke practitioners use it to manage blood pressure (BP) in accordance with thrombolysis guidelines. We determined agreement between SBP, DBP, and MAP measured manually and by NIBP in patients treated with alteplase.MethodsA multisite prospective observational study of NIBP and manual BP agreement was conducted in patients treated with alteplase immediately after bolus and infusion initiation using methods established in guidelines for the assessment of device agreement. Dual auscultatory stethoscopes were used by 2 investigators to ensure agreement with each manual BP variable and MAP was calculated using the standard formula for manual BP measures. Data were analyzed using Bland–Altman analyses and Lin concordance correlation coefficient.ResultsA total of 7 hospitals participated, collecting 5 sets of manual/NIBP BPs in 95 patients treated with alteplase (475 paired measures). Range in limits of agreement were SBP: −28.91 to 21.41 mmHg with Lin's concordance correlation coefficient 0.8; DBP: −21.0 to 19.0 mmHg with Lin's concordance correlation coefficient 0.69; and MAP: −27.5 to 16.5 mmHg with Lin's concordance correlation coefficient 0.7. There was no difference in device agreement by BP device manufacturer brand. Differences in SBP, DBP, and MAP between NIBP and manual sphygmomanometry failed to reach guideline recommendations requiring 80% of measures to fall within a 5 mmHg difference and 95% of measures to fall within a 10 mmHg difference.ConclusionNIBP devices produce significantly different BP measures then manual sphygmomanometry auscultated BP. Because NIBP devices rely on the MAP and do not directly measure SBP and DBP, definition of what constitutes safe MAP boundaries in patients treated with alteplase should be determined when automatic BP measurement is used in clinical practice.

The data set for this study comprised 1,488,474 test-day records for milk, fat, and protein yields and fat and protein percentages from 191,012 first-, second-, and third-parity Holstein cows from 484 farms. Data were collected from 2001 through 2007 and merged with meteorological data from 35 weather stations. A linear model (M1) was used to estimate the effects of the temperature-humidity index (THI) on production traits. Least squares means from M1 were used to detect the THI thresholds for milk production in all parities by using a 2-phase linear regression procedure (M2). A multiple-trait repeatability test-model (M3) was used to estimate variance components for all traits and a dummy regression variable (t) was defined to estimate the production decline caused by heat stress. Additionally, the estimated variance components and M3 were used to estimate traditional and heat-tolerance breeding values (estimated breeding values, EBV) for milk yield and protein percentages at parity 1. An analysis of data (M2) indicated that the daily THI at which milk production started to decline for the 3 parities and traits ranged from 65 to 76. These THI values can be achieved with different temperature/humidity combinations with a range of temperatures from 21 to 36°C and relative humidity values from 5 to 95%. The highest negative effect of THI was observed 4 d before test day over the 3 parities for all traits. The negative effect of THI on production traits indicates that first-parity cows are less sensitive to heat stress than multiparous cows. Over the parities, the general additive genetic variance decreased for protein content and increased for milk yield and fat and protein yield. Additive genetic variance for heat tolerance showed an increase from the first to third parity for milk, protein, and fat yield, and for protein percentage. Genetic correlations between general and heat stress effects were all unfavorable (from −0.24 to −0.56). Three EBV per trait were calculated for each cow and bull (traditional EBV, traditional EBV estimated with the inclusion of THI covariate effect, and heat tolerance EBV) and the rankings of EBV for 283 bulls born after 1985 with at least 50 daughters were compared. When THI was included in the model, the ranking for 17 and 32 bulls changed for milk yield and protein percentage, respectively. The heat tolerance genetic component is not negligible, suggesting that heat tolerance selection should be included in the selection objectives.

Reducing rumen starch fermentation of wheat with 3% NaOH does not reduce whole tract starch digestibility and increases energy utilization in wethers during heat stress

Calving location preference and changes in lying and exploratory behavior of preparturient dairy cattle with access to pasture

This study examined the effects of heat stress (HS) on mid-lactating (100 ± 14 DIM) Holstein cows. Cows were assigned to either HS (temperature-humidity index [THI] 74-80; n = 7) or thermoneutral (pair-fed PFTN; THI 64; n = 8) conditions for 4 d. Exposure to HS reduced milk (4.34 ± 1.62 kg/d), protein (0.18 ± 0.04 kg/d), and fat (0.18 ± 0.05 kg/d) yields, highlighting the negative impacts of HS on production and homeostasis. To explore main molecular responses, mammary gland tissue samples were collected for transcriptomic analysis. Transcriptomic analysis revealed 54 upregulated and 74 downregulated genes in HS conditions. Upregulated genes included heat shock proteins (HSPA1A, HSPH1) and other stress-responsive genes (HSPA4L, SPINK4, ZNF772). Downregulated genes involved DNA repair (GADD45G and FEN1) and mitochondrial function (ND6 and ND5). Gene Ontology (GO) enrichment analysis indicated significant enrichment in protein quality control and stress response processes. Protein-protein interaction (PPI) of differentially expressed genes (DEG) analysis underscored networks of molecular chaperones and protein quality control pathways. Heat stress activates proteostasis-related pathways and molecular chaperone systems in the bovine mammary gland, reflecting cellular efforts to mitigate protein misfolding and maintain homeostasis.

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An experiment was conducted to determine the effects of heat stress and different cage densities on blood indices and Immune response. The hypothesis that, commercial layers, caged at lower densities, react less intensely, to heat stress, than would the hens caged at higher densities was also tested. A total of 936, Lohman Selected Leghorn (LSL) hens, fifty eight weeks old, were used in this experiment. These hens were originally housed, at eighteen weeks of age, as follows: 1- The first group (468 hens) was housed in a conventional open-sided house (Heat Stressed). 2The second group (468 hens) was housed in a conventional open-sided house with desert cooling systems (Control). Pullets were placed at 4, 5, 6, 7, 8 and 9 birds per cage in wire cages (60 cm wide by 50 cm deep and 40 cm height). At 58 weeks of age, the first group was exposed to high environmental temperatures, ranging from 4042 O C and 65-70% relative humidity (five hours daily for seven consecutive days). After each daily heat exposure, the hens were exposed to the normal ambient temperature of the season (20-26 O C and 60-65% relative humidity). The control group was exposed to the ambient temperatures of the season, ranging from 20-26 O C and 60-65% relative humidity. Data were collected during the period of heat stress exposure . Results indicated that rectal temperature and Heterophil: Lymphocyte ratios (H:L ratios) of heat-stressed birds, increased significantly as compared to the control group, at the first and last days of heat stress. However, red blood cell count, packed cell volume, hemoglobin concentration, plasma total protein, globulin and serum potassium levels, of heat stressed birds, decreased significantly as compared to the control ones, when tested at both the first and last day of heat stress. Plasma albumin and serum calcium levels, of heat stressed birds, decreased significantly as compared to the control group, only at the first day of heat stress. Also, heat exposure reduced antibody titers against sheep red blood cell's (SRBC's) on 3, 5 and 7 days post immunization. No significant detrimental effects, due to heat stress, on serum calcium and potassium levels, were observed, when hens were housed at the lowest cage density (4 hens/cage), at the first day of heat stress. At the last day of heat stress, plasma proteins, serum calcium and potassium levels, and H:L ratio, were also not affected, when hens were housed at the lowest cage density. Antibody titers against SRBC's, were significantly reduced due to heat stress, when hens were housed at 9 per cage,