High Temperature-humidity Index Research Articles

5-Aminolevulinic acid combined with sodium ferrous citrate mitigates effects of heat stress on bovine oocyte developmental competence.

High summer temperatures have deleterious effects on oocyte developmental competence. The antioxidant and autophagy-related properties of 5-aminolevulinic acid (5-ALA) gives the compound a broad range of biological activities. This study aimed to evaluate the effects of: 1) a high temperature-humidity index (THI) on the developmental competence of bovine oocytes, and 2) 5-ALA administration in combination with sodium ferrous citrate (SFC) during in vitro maturation (IVM) on bovine oocyte developmental competence evaluated at high THI. Bovine ovaries were collected from a local slaughterhouse at moderate environmental temperature (MT; THI of 56.2) and high environmental temperature (HT; THI of 76.7) periods; cumulus-oocyte complexes (COCs) were aspirated from medium-sized follicles, matured in vitro for 22 h, fertilized, and cultured for 10 days. For COCs collected during the HT period, 0 (control), 0.01, 0.1, 0.5, or 1 µM 5-ALA was added to the maturation medium in combination with SFC at a molar ratio of 1:0.125. The results showed that HT adversely affected blastocyst and hatching rates compared with MT. Adding 5-ALA/SFC (1 µM/0.125 µM) to the maturation medium of oocytes collected during the HT period improved cumulus cell expansion and blastocyst rates compared with the no-addition control. In conclusion, this study showed that high THI can disrupt bovine oocyte developmental competence. Adding 5-ALA to SFC ameliorates this negative effect of heat stress and improves subsequent embryo development.

Reproductive performance of northern Australia beef herds. 6. Risk factors associated with reproductive losses between confirmed pregnancy and weaning

Context High and variable fetal and calf loss in beef herds occurs across northern Australia. Reasons for the majority of these losses, a major cost to the industry, have remained unknown. Aims The research question was, which of the 58 region-, property-, management group-, and animal-level risk factors measured are associated with pregnant females failing to wean their calf? Methods An epidemiological study measured fetal and calf loss (consistently expressed as % points) between confirmed pregnancy and weaning and the major associated risk factors using a selected population from 55 commercial beef breeding herds representing 23 166 pregnancies in the mostly dry tropical environment of northern Australia. Key results Median fetal and calf loss was 9.5% with large variation. Achievable levels appeared to be <10% for Northern Forest herds, and <5% for Southern Forest, Central Forest and Northern Downs herds. The risk factors most strongly associated with fetal and calf loss were low-fertility country type interacting with phosphorus inadequacy (up to 10% increase), low body condition score interacting with phosphorus inadequacy (up to 8% increase), tall cows (up to 4% increase), and high temperature–humidity index around calving interacting with country type (up to 7% increase). These are nutritional and environmental risk factors and had the combined highest individual effect and frequency. Other risk factors associated with fetal and calf loss included first-lactation cows, which interacted with mustering around calving (up to 9% increase), having not reared a calf in the previous year interacting with cow age (up to 8% increase), low mustering efficiency (up to 9% increase), perceived predation by wild dogs (4–5% increase), high prevalence of Campylobacter fetus sp. venerealis antibodies (7% increase), recent infection with bovine viral diarrhoea virus (9% increase), and inadequate dry-season protein (4% increase). Conclusions The combined effects of environmental, nutritional and management risk factors on fetal and calf loss in northern Australia were large and additive and were much greater, collectively up to 30–40%, and more consistent than that due to either endemic infectious diseases or animal factors. Implications Opportunity for remedial action is high and, for the effect of non-infectious risk factors, should target milk delivery to neonatal calves.

Effect of seasonal variation in Temperature Humidity Index on milk production and its composition in Murrah buffaloes

The present study was aimed to evaluate the effect of seasonal variation in Temperature Humidity Index (THI) on milk production and composition in Murrah buffaloes. Eight adult lactating Murrah buffaloes of 3-5 years of age and insecond to fourth lactation were selected in summer and winter season. Meteorological variables such as ambient temperature and relative humidity were recorded and THI was calculated during the period of study. Milk samples were collected from Murrah buffaloes and evaluated for the concentration of milk fat, protein, SNF, lactose and salt. The data was analyzed using SPSS v.20. The results indicated that average milk production, milk fat, protein and SNF decreased significantly (p<0.05) in summer in comparison to winter, while lactose and salt did not differ significantly (p>0.05) in between seasons. From the present study it was concluded that high THI imposes significant heat stress and negatively affects milk production and composition in Murrah buffaloes. Hence, additional feed, shelter and management practices might be adopted to overcome the negative effects of thermal stress and also to optimize milk production of the animals.

Association between heat stress during intrauterine development and the expression and regulation of ovarian steroid hormone receptors in adult Holstein cows.

Dairy cattle experience stressful environmental situations that affect production. Heat stress during gestation can influence the intrauterine development of offspring, resulting in long-term damage that can affect the reproductive life of the adult offspring. The aim of the present study was to evaluate changes in the expression and regulation of steroid hormone receptors in the ovary of Holstein cows gestated under different temperature-humidity index (THI) during their in utero development. Animals were classified by their exposure to temperature-humidity index (THI) ≥72 during their development in utero according to date of birth or date of effective service of their mother. This study was not carried out under controlled conditions, but the conditions to which the cows were naturally exposed during their development were considered retrospectively, controlling the variables in the statistical analyses (age as a covariate, dairy farm as a random factor). Gestation was divided into two periods (P1=days 0-150; and P2=day 151 to calving) and three trimesters (T1=days 0-90; T2=days 91-180; and T3=day 181 to calving), and the exposure to THI ≥72 was calculated in each one. The following characteristics were evaluated: gene expression of estrogen receptor (ESR) 1, ESR2 and progesterone receptor (PGR), CpG methylation in the 5'UTR of ESR1 and ESR2, and protein expression of ESR1, ESR2, PGR and coregulatory proteins in the dominant follicles of daughter cows in adulthood. We found associations between heat stress variables during gestation and the methylation status of CpG sites in the 5'UTR of ESR1 and ESR2 in dominant follicles. Results also showed association between exposure to high THI values during intrauterine development and expression of ESR1, ESR2 and PGR and coregulatory proteins in dominant follicles of adult cows. These results provide novel information about the impact of prenatal heat stress on molecular aspects at the ovary level in the offspring, during their adult life, which probably impacts the reproductive aspects of the herd.

Influence of dietary supplementation of selenium and vitamin E on bone morphometry and mineralization in broiler chicken under heat stress

A study on bone development under the influence of selenium and vitamin E supplementation was under taken in broiler chicken. Three levels of each selenium (0.15, 0.35, and 0.45 mg/kg diet) and vitamin E (50, 100, and 150 IU/ kg diet) were taken to formulate nine treatment groups in the form of broiler starter and finisher to evaluate the bone morphometry and bone mineralization of broiler chicken. The experiment was conducted in a high temperature humidity index (83.94) during the August-September period. The results revealed that bone morphometry parameters such as tibia bone proximal width, mid shaft width, distal width, and length were not influenced by dietary selenium and vitamin E supplementation. Similarly, the mean tibia bone weight (g), bone moisture (%), bone calcium (%), bone phosphorus (%), total ash (%), and bone Zn content (mg/kg) did not differ significantly due to selenium and vitamin E levels in the diet. Therefore, it can be concluded that the bone morphometry and bone mineralization in broiler chicken is not affected by different levels of selenium and vitamin E in the diet.

120 Effect of bull exposure to high temperature-humidity index levels on the quality of sperm selected through density gradient centrifugation for in vitro fertilisation.

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

Effect of injectable trace mineral supplementation on peripheral polymorphonuclear leukocyte function, antioxidant enzymes, health, and performance in dairy cows in semi-arid conditions

The objective of this study was to evaluate the effect of subcutaneous injections of 15 mg/mL Cu, 5 mg/mL Se, 60 mg/mL Zn, and 10 mg/mL Mn on health, performance, polymorphonuclear leukocyte (PMNL) function, circulating glutathione peroxidase (GPx) and superoxide dismutase (SOD) concentrations, and inflammation of dairy cows undergoing the transition period in high temperature-humidity index. A total of 923 multiparous cows from 2 commercial dairy farms were randomly allocated into 1 of 2 treatment groups as follows: control and injectable trace mineral supplementation (ITMS). Cows in the ITMS group received 7 mL of subcutaneous injections at dry-off (208 ± 3 d of gestation), 260 ± 3 d of gestation, and at 35 ± 3 d in milk (DIM). Data regarding health traits, reproductive performance, milk yield, and survivability were extracted from farm database software, and animals were followed-up until 300 DIM. For a subset of 142 cows from one herd, blood samples were collected at enrollment, and at 3 ± 1, 7 ± 1, 10 ± 1, and 35 ± 3 DIM to evaluate hematology, PMNL function, GPx and SOD concentrations, and circulating haptoglobin. Logistic regression was used to assess health and pregnancy per artificial insemination at first service. Cox proportional hazards models were used to evaluate hazard of pregnancy and culling. Mixed linear regression models accounting for repeated measures were used to assess all continuous variables collected over time. Parity, twinning, and previous gestation length were considered as potential confounders. Farm was included as a random effect. The ITMS cows tended to have lower incidence of metritis and stillbirth compared with control group. However, ITMS treatment did not influence the incidence of other diseases (e.g., mastitis, retained placenta), milk yield, reproductive performance, culling, and leukocyte count. Neutrophil-to-lymphocyte ratio, PMNL phagocytosis, and oxidative burst as well as intensity of the oxidative burst were greater for ITMS-treated cows in comparison to control cows. The ITMS cows had decreased expression of the adhesion molecule L-selectin on PMNL surface. The serum concentration of GPx and SOD were not affected by ITMS treatment. In conclusion, ITMS tended to reduce the incidence of metritis and stillbirth parturition, improved PMNL function, and improved the inflammatory status of dairy cows undergoing the transition period in high temperature-humidity index conditions. However, these findings did not translate into improved milk yield, reproductive performance, and survivability.

Impact of temperature humidity index (THI) on physiological responses and milk yield of Tharparkar and Karan Fries cows exposed to controlled environment

Tharparkar and Karan Fries cows were exposed to 25°C, 35°C and 42°C with relative humidity of 50±5%, corresponding to THI of 72.2, 85.3 and 91.0, respectively for three hours continuously for three days consecutively in the control climatic chamber. At THI of 91.0, physiological responses i.e. RR/ min, PR/min and RT (°F) increased by 14, 13, and 1.18 in Tharparkar and 23, 14 and 2.98 in Karan Fries cows, respectively over pre exposure values. At THI of 91.0, the surface body temperature was increased over THI 72.2 by 5.21 to 7.52°C in Tharparkar and 7.45 to 8.42°C in Karan Fries cows. Skin blood flow of Karan Fries cows was increased by 4.98, 4.15 and 3.95 PU at THI 85.3 and 6.84, 9.18 and 8.04 PU at 91 THI over the pre exposure values of respective THI at dorsal, ventral and ear part of body, respectively. The decrease in milk yield was calculated in the THI range of 72.2 - 91.0, the milk yield was decrease (per unit increase in THI) by 135.11ml in Karan Fries and 51.60 ml in Tharparkar cows. The results of the study clearly indicated the more sensitivity of Karan Fries compared to Tharparkar cows at higher THI. Therefore, Karan Fries cows needs protection from extreme heat for sustained production performance.

PSXII-6 Landscape genetics used to identify gene bank beef cattle collection completeness and gaps

Abstract Gene banks (GB) primary goal is to capture genetic diversity among livestock breeds. Genetic diversity assessments by US GB have used pedigrees and genetic markers. Landscape genetics (LG), is a third approach for evaluating germplasm collections and genetic resources. We evaluated the GB’s beef collection using LG for the purpose of assessing collection gaps/completeness by using geographic information systems. The current beef cattle collection contains 3,916 animals from 11 Bos indicus (including composite, BI), and 40 Bos taurus British (BTB) and Bos taurus continental (BTC) breeds. Each GB animal was georeferenced by latitude and longitude. In addition, county level satellite imagery of the continental US was obtained and included: temperature, humidity, precipitation, and normalized difference vegetation index (NDVI). Temperature–humidity index (THI) was computed from temperature and humidity by county. In addition, USDA beef cattle statistics by county were used in mapping overlays. There was a high correspondence between in-situ cattle density and GB collection throughout the mid-west and extending to both borders. Evaluating genetic groups demonstrated that BI were derived from the Gulf Coast region, while BTB and BTC shared a distribution throughout the mid-west. The collection’s BTB were also sourced from the inter-mountain west. All environmental parameters were combined to identify similar environmental conditions where germplasm had already been collected. Through this process future geographies for sampling genetic groups were apparent. New collection areas should include the Great Basin, west Texas, New Mexico and Arizona. Further BI collections should be performed in low THI score areas and BTB and BTC collections in high THI areas is needed. Using GIS/LG adds a new perspective and resolution for future collections to ensure cattle that are adapted to a particular environment are added to the collection.

Heat stress response in slick vs normal-haired Criollo Limonero heifers in a tropical environment.

To assess the effect of hair type on the heat stress response, 20 Criollo Limonero heifers with slick (n = 11) or normal hair (n = 9) were studied. Under a high temperature-humidity index (THI) environment, heat stress response was assessed through physiological variables that included respiration rate (RR), heart rate (HR), ruminal frequency (RMF), rectal temperature (RT), saliva pH (SPH), and lymphocyte count (LC) in the morning (5:00 AM, 27.4°C, 64% relative humidity, THI = 77) and afternoon (1:00 PM, 34.5°C, 70% relative humidity, THI = 88). A case-control study using a split plot design was used. Data were analyzed using ANOVA (PROC MIXED SAS 2010) and a statistical model comprising the fixed effects of hair length, sampling hour, interaction of hair length by sampling hour, and the random effect of animal nested within hair type on physiological variables associated with heat stress response. Sampling hour influenced (P < 0.0001) RR, RT, and (P < 0.003) SPH. Hair length influenced RR (P < 0.01) and RT (P < 0.04) and tended to influence LC (P < 0.07). The interaction of sampling hour by hair influenced RR (P < 0.04), RT (P < 0.0002), and both SPH and LC (P < 0.05). During afternoon hours, slick-haired heifers had lower values for RR (81 ± 4.2 vs 102 ± 4.7bpm; P < 0.01), RT (39.5 ± 0.1 vs 40.3 ± 0.1 C°; P < 0.002), and LC (60 ± 3.2 vs 72.3 ± 3.6; P < 0.09) than normal-haired heifers. In normal-haired heifers, SPH increased during afternoon compared to morning-hours (8.66 ± 0.1 vs 9.11 ± 0.1; P < 0.04). It was concluded that slick-coated heifers exhibited an enhanced capability to cope with heat stress compared to normal-haired heifers likely due to an enhanced capacity for heat dissipation.

Semen analysis of boars under intertropical conditions reveals the relevance of proximal and distal cytoplasm droplets for sperm functional integrity.

This work aimed to establish whether the temperature humidity index (THI) under different intertropical zones affects the retention of cytoplasmic droplets (CDs), sperm function and DNA integrity in boars. With this purpose, two separate studies were devised. In the first one, 49 boars from six farms were collected every 45days (230 ejaculates). THI were measured daily, and sperm parameters were evaluated. Boars were classified into three groups based on the incidence of ejaculates having more than 25% spermatozoa with CDs: persistent (at least three consecutive ejaculates), moderate (less than three ejaculates) and absent (no ejaculate having ≥25% spermatozoa with CDs). Farms were classified based on THI through cluster analysis into two groups. In the second study, 32 liquid-stored semen samples were classified based on three cluster analysis: low and high incidence of proximal (PCDs), distal (DCDs) CDs and a combination of PCD and DCDs. high THI farms presented significantly (p<.05) higher proportions of boars with moderate and persistent incidence of CD than those with low THI. In study 2, the presence of PCDs was negatively correlated with sperm DNA integrity (r=-0.691; p<.01). However, differences between groups were more apparent when ejaculates were classified based on both PCDs and DCDs than when PCDs or DCDs were considered separately. In conclusion, classification of boars according to the severity and persistence of CDs in boars allows understanding more clearly the dynamics of CD retention and the effects of ambient temperature and relative humidity. Additionally, the joint analysis of both PCDs and DCDs is necessary in routine sperm quality analyses.

Climate sensitivity of milk production traits and milk fatty acids in genotyped Holstein dairy cows

The aim of this study was the evaluation of climate sensitivity via genomic reaction norm models [i.e., to infer cow milk production and milk fatty acid (FA) responses on temperature-humidity index (THI) alterations]. Test-day milk traits were recorded between 2010 and 2016 from 5,257 first-lactation genotyped Holstein dairy cows. The cows were kept in 16 large-scale cooperator herds, being daughters of 344 genotyped sires. The longitudinal data consisted of 47,789 test-day records for the production traits milk yield (MY), fat yield (FY), and protein yield (PY), and of 20,742 test-day records for 6 FA including C16:0, C18:0, saturated fatty acids (SFA), unsaturated fatty acids (UFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA). After quality control of the genotypic data, 41,057 SNP markers remained for genomic analyses. Meteorological data from the weather station in closest herd distance were used for the calculation of maximum hourly daily THI. Genomic reaction norm models were applied to estimate genetic parameters in a single-step approach for production traits and FA in dependency of THI at different lactation stages, and to evaluate the model stability. In a first evaluation strategy (New_sire), all phenotypic records from daughters of genotyped sires born after 2010 were masked, to mimic a validation population. In the second strategy (New_env), only daughter records of the new sires recorded in the most extreme THI classes were masked, aiming at predicting sire genomic estimated breeding values (GEBV) under heat stress conditions. Model stability was the correlation between GEBV of the new sires in the reduced data set with respective GEBV estimated from all phenotypic data. Among all test-day production traits, PY responded as the most sensitive to heat stress. As observed for the remaining production traits, genetic variances were quite stable across THI, but genetic correlations between PY from temperate climates with PY from extreme THI classes dropped to 0.68. Genetic variances in dependency of THI were very similar for C16:0 and SFA, indicating marginal climatic sensitivity. In the early lactation stage, genetic variances for C18:0, MUFA, PUFA, and UFA were significantly larger in the extreme THI classes compared with the estimates under thermoneutral conditions. For C18:0 and MUFA, PUFA, and UFA in the middle THI classes, genetic correlations in same traits from the early and the later lactation stages were lower than 0.50, indicating strong days in milk influence. Interestingly, within lactation stages, genetic correlations for C18:0 and UFA recorded at low and high THI were quite large, indicating similar genetic mechanisms under stress conditions. The model stability was improved when applying the New_env instead of New_sire strategy, especially for FA in the first stage of lactation. Results indicate moderately accurate genomic predictions for milk traits in extreme THI classes when considering phenotypic data from a broad range of remaining THI. Phenotypically, thermal stress conditions contributed to an increase of UFA, suggesting value as a heat stress biomarker. Furthermore, the quite large genetic variances for UFA at high THI suggest the consideration of UFA in selection strategies for improved heat stress resistance.

Characterization of Short-Term Heat Stress in Holstein Dairy Cows Using Altered Indicators of Metabolomics, Blood Parameters, Milk MicroRNA-216 and Characteristics

Simple SummaryIn this study, we characterize the influence of short-term (4 days) heat stress on Holstein cows during early lactation. The use of indicators, such as production performance, physiological variables, blood parameters, micro-RNA expression, and metabolomes, in heat-stressed cows during early lactation—which is a high-stress phase—may provide insights into how to deal with the level of damage to dairy cows, through appropriate nutritional and management strategies. We identify that short-term heat stress has a negative effect, to some extent, on feed and water intake, rectal temperature, heart rate, blood hematology and metabolites, milk characteristics, miRNA expression in milk, and metabolomics in blood.This study aims to characterize the influence of short-term heat stress (HS; 4 day) in early lactating Holstein dairy cows, in terms of triggering blood metabolomics and parameters, milk yield and composition, and milk microRNA expression. Eight cows (milk yield = 30 ± 1.5 kg/day, parity = 1.09 ± 0.05) were homogeneously housed in environmentally controlled chambers, assigned into two groups with respect to the temperature humidity index (THI) at two distinct levels: approximately ~71 (low-temperature, low-humidity; LTLH) and ~86 (high-temperature, high-humidity; HTHH). Average feed intake (FI) dropped about 10 kg in the HTHH group, compared with the LTLH group (p = 0.001), whereas water intake was only numerically higher (p = 0.183) in the HTHH group than in the LTLH group. Physiological parameters, including rectal temperature (p = 0.001) and heart rate (p = 0.038), were significantly higher in the HTHH group than in the LTLH group. Plasma cortisol and haptoglobin were higher (p < 0.05) in the HTHH group, compared to the LTLH group. Milk yield, milk fat yield, 3.5% fat-corrected milk (FCM), and energy-corrected milk (ECM) were lower (p < 0.05) in the HTHH group than in the LTLH group. Higher relative expression of milk miRNA-216 was observed in the HTHH group (p < 0.05). Valine, isoleucine, methionine, phenylalanine, tyrosine, tryptophan, lactic acid, 3-phenylpropionic acid, 1,5-anhydro-D-sorbitol, myo-inositol, and urea were decreased (p < 0.05). These results suggest that early lactating cows are more vulnerable to short-term (4 day) high THI levels—that is, HTHH conditions—compared with LTLH, considering the enormous negative effects observed in measured blood metabolomics and parameters, milk yield and compositions, and milk miRNA-216 expression.

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 seasonal thermal stress on oxidative status, immune response and stress hormones of lactating dairy cows.

This study aimed to assess the impact of seasonal thermal stress on oxidative stress, immune response, and stress hormones of lactating dairy cows in subtropical regions with different levels of temperature-humidity index (THI). A total of 32 healthy lactating Holstein dairy cows experienced 4 seasons (8 cows/season). The physiological parameters were categorized into low THI (LTHI, THI = 42.97 ± 0.95) in winter, moderate THI (MTHI, THI = 61.84 ± 0.42) in spring and autumn, and high THI period (HTHI, THI = 86.09 ± 0.23) in summer. The blood samples were collected twice in each season to measure oxidative stress, inflammatory and hormonal parameters. Our results showed THI had a positive correlation with the rectal temperature (R2 = 0.821, P < 0.001) and respiratory rate (R2 = 0.816, P < 0.001). Dry matter intake, milk yield and fat percentage also significantly differed among groups (P < 0.05). Compared with the MTHI group, the LTHI group exhibited a significant increase in malondialdehyde (MDA) level (P < 0.001), and the HTHI group displayed a significant increase in levels of cortisol, interleukin (IL)-10, IL-1β and tumor necrosis factor-α (P < 0.001). Opposite changes in serum endotoxin and immunoglobulin G levels were observed with the increasing THI (P < 0.001). LTHI notably increased the triiodothyronine level, although the thyroxine level was reduced by LTHI and HTHI compared with the MTHI group. In conclusion, LTHI and HTHI conditions may induce different degrees of oxidative stress, inflammation response, and stress hormone imbalances on lactating dairy cows, therefore environmental management is necessary for the health of dairy cows in extreme weather conditions.

Heat stress effects in primiparous and multiparous lactating crossbred cows under a warm environment and their responses to a cooling treatment

Context In temperate climates, multiparous cows are more susceptible to heat stress (HS) than are primiparous cows. However, these differences in susceptibility may vary in warm environments, where the overall production level is lower, cow size is smaller, and adaptation to HS increases. Aim The different effects of HS and its alleviation on primiparous and multiparous cows was tested in crossbred cows (3/4 Holstein × 1/4 Brahman) in a warm environment. Method Twelve cows during the rainy season (August–September 2014) and 12 cows during the dry season (March–April 2015; six primiparous, six multiparous) were monitored for rectal temperature and respiration rate, indicators of HS, and milk yield (MY) in a dairy farm in El Salvador. Ambient temperature and relative humidity were recorded hourly to estimate temperature–humidity index throughout the day. During the rainy season, all cows were housed in a pen without cooling treatment. During the dry season, fans and sprinklers were installed in the pen and provided cooling to the herd in two 15-day periods, alternated with two periods without cooling (Control). Key results Primiparous cows were more susceptible to HS. Cooling alleviated HS, resulting in an increased feed intake and MY, with a greater impact on primiparous cows. During the cooling treatment, HS parameters increased overnight after the last cooling cycle of the day. This indicated that, despite the cooling treatment, cows still suffered from HS outside the hottest hours of the day. Furthermore, despite a higher temperature–humidity index during the rainy season, rectal temperature and MY remained similar in both the dry and the rainy season for cows without cooling, indicating that animals effectively lower their body temperature by increasing their respiration rate. Conclusions The cooling only partially helped alleviate HS in both multiparous and primiparous cows, with the effects being greater on the latter. However, the increments in MY were proportional to the increases in feed intake, indicating that the efficiency of feed utilisation was likely to be not improved. Implications More attention should be given to the susceptibility of primiparous cows to HS, as well as to the adjustment of cooling protocols towards alleviating HS in early morning and late afternoon hours.

Common and Differential Dynamics of the Function of Peripheral Blood Mononuclear Cells between Holstein and Jersey Cows in Heat-Stress Environment

Simple SummarySeasonal change, particularly changing to hot and humid season, has a negative effect on dairy cows in various ways, including productivity, reproduction, metabolism, and immunity. In high-temperature and humid weather, dairy cows are vulnerable to diseases by weakened immune system. However, the cause of this has not been fully described. Therefore, this study aims to understand changes of specific gene expression and immune pathways based on transcriptome analysis from peripheral blood mononuclear cells of Holstein and Jersey dairy cows between normal and heat-stress environmental conditions. We observed that the two breeds of dairy cow have common and different immune shifts according to the changes of temperature and humidity condition. Overall, the findings of this study improve the understanding of the underlying mechanisms by which seasonal changes affect dairy cow immunity.Heat stress has been reported to affect the immunity of dairy cows. However, the mechanisms through which this occurs are not fully understood. Two breeds of dairy cow, Holstein and Jersey, have distinct characteristics, including productivity, heat resistance, and disease in high-temperature environments. The objective of this study is to understand the dynamics of the immune response of two breeds of dairy cow to environmental change. Ribonucleic acid sequencing (RNA-seq) results were analyzed to characterize the gene expression change of peripheral blood mononuclear cells (PBMCs) in Holstein and Jersey cows between moderate temperature-humidity index (THI) and high THI environmental conditions. Many of the differentially expressed genes (DEGs) identified are associated with critical immunological functions, particularly phagocytosis, chemokines, and cytokine response. Among the DEGs, CXCL3 and IL1A were the top down-regulated genes in both breeds of dairy cow, and many DEGs were related to antimicrobial immunity. Functional analysis revealed that cytokine and chemokine response-associated pathways in both Holstein and Jersey PBMCs were the most important pathways affected by the THI environmental condition. However, there were also breed-specific genes and pathways that altered according to THI environmental condition. Collectively, there were both common and breed-specific altered genes and pathways in Holstein and Jersey cows. The findings of this study expand our understanding of the dynamics of immunity in different breeds of dairy cow between moderate THI and high THI environmental conditions.

Effect of pad water flow rate on evaporative cooling system efficiency in laying hen housing

An experiment was conducted in three commercial laying hen houses with 32-week-old hens in the summer of 2017 in a commercial farm in Gharbia Province, Egypt (31.06ºN, 31.16ºE) using an evaporative pad cooling system to determine the most suitable water flow rate for maintaining indoor air temperature within the thermal comfort zone. The experiment was conducted using three different water flow rates, i.e. 4.76, 5.65, and 6.35 L min–1.m–2, to assess the effect of different water flow rates on evaporative pad cooling system performance and determine the most suitable water flow rate for maintaining the thermal comfort zone of laying hens. The evaporative pad cooling system maintained the mean indoor air temperature below 28°C. The mean indoor air relative humidity during the experimental period ranged from 72.6 to 73.8%. The 4.76 L min–1.m–2 water flow rate resulted in the highest saturation efficiency (ca. 73.75%). In contrast, the 6.35 L min–1 m–2 water flow rate resulted in the lowest saturation efficiency (70.63%). The mean cooling energy values were 69.11, 66.0, and 66.65 kwh for water flow rates of 4.76, 5.56, and 6.35 Lmin–1m–2, respectively. The highest temperature-humidity index was 27.78°C, which indicated that birds were not stressed in all treatments.

Şanlıurfa İli Süt Sığırı İşletmelerindeki Süt Verim Kaybına Isı Stresinin Etkisi

Bu çalışma, Şanlıurfa ilinin ilçelerine ait sıcaklık nem indekslerini (SNİ) hesaplayarak ısı stresinin süt kayıpları üzerindeki etkisini belirlemek amacıyla yapılmıştır. Araştırmanın veri setini Diyarbakır Meteoroloji Bölge Müdürlüğünden temin edilen Şanlıurfa ilinin 10 ilçesine ait 1999-2019 yılları arasındaki meteorolojik veriler ile Türkiye İstatistik Kurumu’ndan (TUİK) alınan 2019 yılı sağmal inek sayıları oluşturmuştur. Araştırmada, ilin tüm ilçelerine ait mayıs-eylül ayları arasındaki SNİ değerleri, SNİ değerinin alansal dağılımı, inek başına günlük süt kayıpları ile günlük toplam süt kayıpları belirlenmiştir. Araştırmada, SNİ değerlerinin kritik değerleri aştığı ay ve ilçeler dikkate alındığında yüksek SNİ değerlerine bağlı olarak oluşan inek başına günlük süt kaybının en yüksek olduğu ilçe ağustos ayında 10.828 g ile Şanlıurfa merkez, en düşük olduğu ilçe ise haziran ayında 163 g ile Hilvan olarak tespit edilmiştir. Böylece SNİ kaynaklı süt kayıplarının en fazla temmuz ve ağustos aylarında şekillendiği ve en çok etkilenen ilçelerin ise Şanlıurfa Merkez ve Akçakale olduğu belirlenmiştir. Ayrıca TUİK’ten alınan Şanlıurfa il ve ilçelerinin 2019 yılına ait 2 yaşın üstündeki toplam süt inek sayıları kullanılarak elde edilen toplam ortalama günlük süt kayıplarının en fazla yaşandığı ilçe ağustos ayında 27283 kg ile Siverek, en az yaşandığı ilçe ise haziran ayıda 71 kg ile Bozova olarak tespit edilmiştir. Söz konusu aylarda en fazla kaybın yaşandığı ilçeler süt ineği popülasyonuna bağlı olarak Şanlıurfa merkez, Akçakale ve Siverek olmuştur. Sonuç olarak, Şanlıurfa süt işletmelerinde, özellikle temmuz ve ağustos aylarında, ısı stresi nedeniyle önemli süt verim kayıplarının yaşandığı belirlenmiştir. Isı stresi ve süt kaybını önlemek için yüksek çevre sıcaklığının olduğu dönemlerde bakım-yönetim uygulamalarının iyileştirilmesi faydalı olacaktır.

Rumen-Reticular Temperature During Estrus and Ovulation Using Automated Activity Monitors in Dairy Cows.

This study aimed to determine changes in rumen-reticular temperature (RRT) at estrus or ovulation and determine if these changes are associated with the intensity of estrous expression. Cows were equipped with an automated activity monitor (AAM) and a rumen-reticular bolus thermometer. A total of 190 estrus episodes were used where physical activity data was recorded using the AAM and ovulation was determined via ultrasonography of the ovaries at alert and twice daily, for a maximum of 60 h. Estrous expression was assessed using the maximum activity and duration in which activity remained above the AAM threshold; both characteristics were categorized using the median. Temperature data was collected for the duration of estrus, as well as for the interval of time where ovulation was determined to occur. Three measures of temperature were calculated: (1) positive area under the curve (AUC), (2) maximum positive temperature change (PTC), (3) maximum negative temperature change (NTC) at estrus (AUCE/ PTCE/ NTCE) and around ovulation (AUCO/PTCO/ NTCO). Both AUC and PTC were greater during estrus than around ovulation (2.7 ± 0.2 and 1.1 ± 0.3°C2 for AUCE and AUCO; 0.55 ± 0.03 and 0.26 ± 0.04°C for PTCE and PTCO, respectively). In contrast, NTC was lower around ovulation than estrus (−0.28 ± 0.05 and −0.60 ± 0.06°C for NTCE and NTCO). Cows with greater estrous expression had greater AUC and PTC during estrus than around ovulation, but cows with lesser estrous expression had similar AUC and PTC. Increases in AUC [High THI (Temperature Humidity Index): High activity: 4.7 ± 0.5, Low activity: 1.5 ± 0.4; Low THI: High activity: 3.1 ± 0.2, Low activity: 1.4 ± 0.2 °C2] and PTC (High THI: High activity: 0.79 ± 0.08, Low activity: 0.36 ± 0.07; Low THI: High activity: 0.60 ± 0.04, Low activity: 0.47 ± 0.04°C) associated with estrous expression were found to be greater on days with higher THI. Alerts created using standard deviations from the mean were unable to detect estrus or ovulation with acceptable precision. Further research is required to determine how changes in RRT can be used successfully to predict estrus and ovulation.