Effect of season on physiological, biochemical, hormonal, and oxidative stress parameters of indigenous sheep

"Unravelling the impacts of climatic heat events on cardiovascular health in animal models"

Climate change has led to an increase in high ambient temperatures, causing extreme heat events worldwide. According to the World Meteorological Organization (WMO), July 2023 marked a historic milestone as the Earth reached its hottest recorded temperature, precisely hitting the critical threshold of 1.5 °C set by the Paris Agreement. This distressing development led to a stark warning from the United Nations, signaling the dawn of what they call "an era of global boiling". The increasing global temperatures can result in high heat stress which leads to various physiological and biochemical alterations in the human body. Given that cardiovascular diseases (CVDs) are a leading cause of morbidity and mortality globally, heat events exacerbate this public health issue. While clinical and in-vitro studies have suggested a range of pathophysiological and biochemical mechanisms underlying the body's response to heat stress, the complex nature of organ-system level interactions makes precise investigation challenging. To address this knowledge gap effectively, the use of animal models exposed to acute or chronic heat stress can be invaluable. These models can closely replicate the multifaceted effects observed in humans during heat stress conditions. Despite extensive independent reviews, limited focus has been shed on the high heat-induced cardiovascular complications and their mechanisms, particularly utilizing animal models. Therefore, in this comprehensive review, we highlight the crucial biomarkers altered during heat stress, contributing significantly to various CVDs. We explore potential mechanisms underlying heat-induced cardiovascular dysfunction and damage, delving into various animal models. While traditional rodent models are commonly employed, we also examine less conventional models, including ruminants, broilers, canines, and primates. Furthermore, we delve into various potential therapeutic approaches and preventive measures. These insights hold significant promise for the development of more effective clinical interventions against the effects of heat stress on the human cardiovascular system.

Effect of Organic Selenium Supplementation on the Antioxidant Status, Immune Response, and the Relative Expression of IL-2 and IFN-γ Genes in Ewes During the Hot Season

This study was conducted to evaluate the effects of different doses of selenium (Se) from Sel-Plex© (selenium-enriched Saccharomyces cerevisiae yeast) supplement on the antioxidant status, the antibody titers against the foot-and-mouth disease virus, and the expression of interleukin-2 (IL-2) and interferon-γ (IFN-γ) genes in ewes during the hot season. Six ewes were kept at 25 °C and received basal diet (the negative control group), and 24 ewes were kept at 38 °C for 5 h per day and received no supplement (the positive control), 0.15, 0.30, and 0.45 mg Se/kg. Ewes in the positive control had higher (P<0.001) liver enzyme activity, malondialdehyde (MDA), and cortisol levels, and lower antibody titer than the negative control. The liver enzymes' lowest (P<0.001) activities were observed in ewes receiving 0.30 and 0.45 mg Se/kg. Ewes receiving 0.30 and 0.45 mg Se/kg had lower MDA levels than other treatments. Ewes receiving 0.30 and 0.45 mg Se/kg had higher (P<0.001) total antioxidant capacity levels than those receiving 0.15 mg Se/kg and the positive control. Se-supplemented groups had lower (P<0.001) relative expression of IL-2 and higher (P<0.04) expression of IFN-γ than the positive control. The antibody titer was the same in the positive control and the group receiving 0.15 mg Se/kg. Ewes fed a diet with 0.30 and 0.45 mg Se/kg had higher (P<0.011) antibody titer than the positive control. The Se supplementation can reverse the decrease of antioxidant capacity and immune function caused by heat stress, and 0.3 mg Se/kg from Sel-Plex©is the best dose.

Exploring candidate genes for heat tolerance in ovine through liver gene expression

Thermotolerance has become an essential factor in the prevention of the adverse effects of heat stress, but it varies among animals. Identifying genes related to heat adaptability traits is important for improving thermotolerance and for selecting more productive animals in hot environments. The primary objective of this research was to find candidate genes in the liver that play a crucial role in the heat stress response of Santa Ines sheep, which exhibit varying levels of heat tolerance. To achieve this goal, 80 sheep were selected based on their thermotolerance and placed in a climate chamber for 10 days, during which the average temperature was maintained at 36 °C from 10 a.m. to 4 p.m. and 28 °C from 4 p.m. to 10 a.m. A subset of 14 extreme animals, with seven thermotolerant and seven non-thermotolerant animals based on heat loss (rectal temperature), were selected for liver sampling. RNA sequencing and differential gene expression analysis were performed. Thermotolerant sheep showed higher expression of genes GPx3, RGS6, GPAT3, VLDLR, LOC101108817, and EVC. These genes were mainly related to the Hedgehog signaling pathway, glutathione metabolism, glycerolipid metabolism, and thyroid hormone synthesis. These enhanced pathways in thermotolerant animals could potentially mitigate the negative effects of heat stress, conferring greater heat resistance.

Heat stress adaptation in cows - Physiological responses and underlying molecular mechanisms

Heat stress is a key abiotic stressor for dairy production in the tropics which is further compounded by the ongoing climate change. Heat stress not only adversely impacts the production and welfare of dairy cows but severely impacts the economics of dairying due to production losses and increased cost of rearing. Over the years, selection has ensured development of high producing breeds, however, the thermotolerance ability of animals has been largely overlooked. In the past decade, the ill effects of climate change have made it pertinent to rethink the selection strategies to opt for climate resilient breeds, to ensure optimum production and reproduction. This has led to renewed interest in evaluation of the impacts of heat stress on cows and the underlying mechanisms that results in their acclimatization and adaptation to varied thermal ambience. The understanding of heat stress and associated responses at various level of animal is crucial to device amelioration strategies to secure optimum production and welfare of cows. With this review, an effort has been made to provide an overview on temperature humidity index as an important indicator of heat stress, general effect of heat stress in dairy cows, and impact of heat stress and subsequent response at physiological, haematological, molecular and genetic level of dairy cows.

Review of the Heat Stress-Induced Responses in Dairy Cattle

In the dairy cattle sector, the evaluation of the effects induced by heat stress is still one of the most impactful and investigated aspects as it is strongly connected to both sustainability of the production and animal welfare. On the other hand, more recently, the possibility of collecting a large dataset made available by the increasing technology diffusion is paving the way for the application of advanced numerical techniques based on machine learning or big data approaches. In this scenario, driven by rapid change, there could be the risk of dispersing the relevant information represented by the physiological animal component, which should maintain the central role in the development of numerical models and tools. In light of this, the present literature review aims to consolidate and synthesize existing research on the physiological consequences of heat stress in dairy cattle. The present review provides, in a single document, an overview, as complete as possible, of the heat stress-induced responses in dairy cattle with the intent of filling the existing research gap for extracting the veterinary knowledge present in the literature and make it available for future applications also in different research fields.

Seasonal patterns of oxidative stress markers in captive Asian elephants in Thailand and relationships to elephant endotheliotropic herpesvirus shedding

Introduction

Oxidative stress refers to an imbalance between oxidant and antioxidant activity and accumulation of reactive oxygen species, which can have detrimental effects on animal health. Annual fluctuations in oxidative stress status can occur, increasing disease susceptibility during certain time periods. However, a full understanding of factors related to oxidative stress in Asian elephants and how to mitigate the negative consequences is lacking.

Methods

This study measured six serum oxidative stress markers [reactive oxygen species (ROS), malondialdehyde (MDA), 8-hydroxydeoxyguanosine (8-OHdG), albumin, glutathione peroxidase (GPx), and catalase] and two stress markers [serum cortisol and fecal glucocorticoid metabolites (fGCM)] in 23 captive Asian elephants in Thailand over a 12 months period to examine relationships with age and season.

Results

Seasonal variations were observed, with several markers exhibiting significantly higher concentrations in the summer (ROS, MDA, 8-OHdG, albumin) and lower values during the rainy/winter seasons (MDA, 8-OHdG, albumin, catalase). By contrast, GPx was the only marker to be highest during the rainy season. For the stress markers, higher fGCM concentrations were noted during the rainy season, which contrasts with earlier studies showing more activity in the winter (tourist season). Positive correlations were found between the temperature-humidity index and ROS, GPx, and fGCM, while a negative correlation was observed with serum albumin. Elephant endotheliotropic herpesvirus (EEHV) shedding events were associated with higher concentrations of ROS and MDA. A moderate negative correlation was observed between 8-OHdG and the PCR threshold cycle of EEHV shedding (Ct), indicating DNA damage may be involved in EEHV shedding in elephants.

Discussion

Results revealed significant age and seasonal effects on several oxidative stress markers, indicating those factors should be considered in study design and data interpretation. There also may be physiological adaptations in oxidative stress conditions in relation to environmental changes that could impact health outcomes.

Influence of Heat Stress on Body Temperatures Measured by Infrared Thermography, Blood Metabolic Parameters and Its Correlation in Sheep

The aim of this research is to examine the influence of heat stress (HS) on body temperature (BT) measured rectally (RT) or by infrared thermography (IRT) of the nose (NT), eye (ET), leg (LT) and abdominal (AT) regions in intensively and extensively breed sheep and to detect a correlation between body temperature and metabolic response in sheep. A total of 33 Wurttemberg × Sjenica Pramenka sheep breeds were examined, 17 ewes were from outdoors and 16 were from indoor housing systems during three experimental periods (thermoneutral period, severe HS and moderate HS). Sheep under HS have a higher BT, and the magnitude of BT measured by infrared thermography (IRT) was higher than RT. LT and AT showed positive linear correlations with the temperature-humidity index (THI), while other ways of measuring BT did not give statistically significant correlations. Sheep under HS showed higher cortisol, insulin, total protein, albumin, urea, creatinine, bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, alkaline phosphatase, lactate dehydrogenase, creatine kinase and index of insulin resistance, with lower values of triiodothyronine (T3), thyroxine (T4), non-esterified fatty acids, beta-hydroxybutyrate (BHB), glucose, calcium, inorganic phosphates, magnesium and cholesterol. BT and metabolic response were different in the function of the housing method of sheep. LT and AT showed a significant correlation with almost all blood parameters, and the strongest connections were made with T3, T4, BHB and the revised quantitative insulin sensitivity check index of insulin resistance. The abdomen and legs are good thermal windows because LT and AT are good summative responses to external ambient THI and internal metabolic changes in sheep under heat stress.

Growth traits, hematological, and ruminal fluid profile of sheep offered ensiled coffee skin replacing dried water spinach

Background and Aim

Developing simple, cost-efficient sheep feed will improve farmers' incomes. Including coffee skin in feed offers the most technical method of increasing sheep weight gain. This study aimed to evaluate varying proportions of ensiled coffee skin replacing dried water spinach and determine the optimal combination for the growth performance, physiological and hematological profiles, and rumen fluid of sheep.

Materials and Methods

Eighty-four animals were randomly allocated to the treatments, arranged in a randomized block design using the initial weight as a block. Seven treatment diets were adjusted and a 12-animal replication was used for each treatment. The treatments were as follows: T0: 30% maize stover, 30% dried water spinach, 5% pollard, 20% coffee skin; T1: 30% maize stover, 25% dried water spinach, 5% pollard, 5% ensiled coffee skin; T2: 30% maize stover, 20% dried water spinach, 5% pollard, 10% ensiled coffee skin; T3: 30% maize stover, 15% dried water spinach, 5% pollard, 15% ensiled coffee skin; T4: 30% maize stover, 10% dried water spinach, 5% pollard, 20% ensiled coffee skin; T5: 30% maize stover, 5% dried water spinach, 5% pollard, 25% ensiled coffee skin; T6: 30% maize stover, 5% pollard, and 30% ensiled coffee skin. The sheep were reared for 70 days.The parameters observed during the early stage included growth performance (initial body weight, LW gain, final body weight, and feed intake). At the end of periods, a representative sample of ruminal fluid (approximately 150 mL) was collected from slaughtered sheep, duplicated, and then incubated for 18 h and blood samples were collected from the sheep (jugular vein) in ethylenediaminetetraacetic acid tubes. Then, used to analyze various blood biochemical parameters.

Results

The final body weights showed a linear curve increasing as the treatment increased (p < 0.05). The ensiled coffee skin tended to increase at 6 h incubation time, producing reduced methane gas (p < 0.05). However, in general, the use of ensiled coffee skin did not significantly alter the blood biochemistry of crossbreed sheep (p > 0.05). There was no significant effect on the protozoal population (p > 0.05).

Conclusion

Increasing the level of ensiled coffee skin up to 30% replacing dried water spinach increased the final body weight of crossbreed sheep with no adverse effect.

Facial skin temperature and overall thermal sensation of sub-tropically acclimated Chinese subjects in summer

This study explored the facial skin temperature and thermal sensation of sub-tropically acclimated subjects in summer. We conducted a summer experiment that simulated the common indoor temperatures in Changsha, China. Twenty healthy subjects experienced five exposure conditions: 24, 26, 28, 30 and 32 °C with a relative humidity of 60%. During exposure (140min), the sitting participants documented their thermal sensation, comfort and acceptability of the environment. Their facial skin temperatures were continuously and automatically recorded by using iButtons. These facial parts include the forehead, nose, left and right ears, left and right cheeks and chin. The results found that the maximum facial skin temperature difference increased with air temperature reduction. The forehead skin temperature was the highest. Nose skin temperature is lowest when air temperature is not higher than 26 °C during summer. Correlation analysis confirmed that the nose is the potential facial part that is most suitable to evaluate thermal sensation. Based on the published winter experiment, we further explored their seasonal effects. The seasonal analysis showed that, compared with winter, thermal sensation is more sensitive to indoor temperature changes and facial skin temperatures were less susceptible to thermal sensation changes in summer. Facial skin temperatures were higher in summer under the same thermal conditions. It suggests that seasonal effects should be considered when facial skin temperature can be used as an important parameter for indoor environment control in the future through monitoring thermal sensation.

Placental Development and Physiological Changes in Pregnant Ewes in Silvopastoral and Open Pasture Systems during the Summer

This study aimed to analyze the reproductive and physiological changes in ewes subjected to heat stress during pregnancy at UTFPR-Brazil. Twenty-four pregnant crossbred ewes were kept in a silvopastoral system (SP) or an open pasture system (OP) throughout the final trimester of pregnancy. Both systems were stressful, but the SP system had lower air temperature than the OP system (26.0 ± 0.38 and 26.9 ± 0.41 °C, respectively; p = 0.0288). Moreover, the radiant thermal load of the two groups presented a difference of 34 Wm^-2 (p = 0.0288), and the grass temperature was also lower in the SP system compared to that in the OP system (23.4 ± 0.37 and 25.6 ± 0.44 °C, respectively; p = 0.0043). The respiratory and heart rates of animals from the OP group were higher than those from the SP group (p < 0.001), but no difference was observed in the mobilization of white blood cells (p = 0.4777), and the neutrophil count was only affected by time (p < 0.0001). As regards placental biometry, placentas in twin pregnancies had a greater membrane area (p = 0.0223), but no differences between the systems were observed in placental weight (p = 0.1522) and the number of cotyledons (p = 0.5457). We concluded that the type of rearing system used affects the thermal comfort of pregnant ewes, and that an SP system can offer more amenable microclimatic conditions, which result in greater comfort for the ewes.

Establishment of Hematological and Plasma Biochemical Reference Values and Analysis of Risk Factors for Pet Sugar Gliders (Petaurus breviceps) in Taiwan

Hematological and plasma biochemical examination are crucial in the veterinary care of sugar gliders, which are increasingly popular in Taiwan and the United States. However, published research of the species' reference interval and related influencing factors were rare. The objectives of this study were to establish the hematological and plasma biochemical reference values for captive sugar gliders in Taiwan and to evaluate the influence of factors including age, gender, neuter status, location, season, diet, caging arrangement, and other pets in the household. A total of 42 clinically healthy pet sugar gliders were recruited. Morphometrical measurements and physiological data were collected, and hematological and plasma biochemical examinations were performed. The reference value of each index was calculated using Reference Value Advisor (RVA) software, following the American Society for Veterinary Clinical Pathology (ASVCP) guidelines. Normality of data distribution was tested, and data transformation was conducted. The parametric method and robust method were used to determine reference limits. Univariate analysis was performed, and multiple regression models were built for each hematological and plasma biochemical parameter. Red blood cell, hematocrit, and hemoglobin levels were higher in males, compared to females, while they were lower in the neutered group, compared to the intact group. Relative neutrophil counts were higher in elder sugar gliders, while relative lymphocyte counts were lower. Aspartate transaminase levels were higher in elder sugar gliders, while albumin levels were lower. Blood urea nitrogen levels were highest in spring. The blood profile and related effects presented in this study can provide useful information for veterinary care in pet sugar gliders.

Thermal stress-related physiological, behavioral, and serum biochemical responses in indigenous pigs adapted to Eastern Himalayan region

Introduction

The current study was carried out to investigate the effect of micro-environmental variations on physiological, behavioral, and serum biochemical parameters of indigenous (Niang Megha), Hampshire, and crossbred (75% Hampshire X 25% Niang Megha).

Methods

Rectal temperature (T_R), skin surface temperature (T_SS), respiration rate (RR), and heart rate (HR) were recorded at 0,900 and 1,600 h weekly once for 2 months for each season in grower pigs of each genotype. CCTV video cameras were utilized to observe the behavioral changes. Five milliliters of blood samples was collected to estimate different biochemical parameters.

Results

Season affected (p < 0.05) all physiological parameters which generally increased during summer except T_R and RR of indigenous pig. T_R, T_SS, RR, and HR were significantly (p < 0.05) higher for Hampshire than for indigenous and crossbred in the summer season. The frequency and behavioral activities to heat loss or to conserve heat such as shivering and wallowing were lower except for physical activity that was higher at all times in indigenous pigs. Seasonal variations influenced metabolic activity and serum activity of alkaline phosphatase (ALP) and alanine transaminase (ALT), which rose in summer in all genotypes. Serum ALP and thyroxine (T₄) were significantly (p < 0.05) higher for indigenous pig in both the seasons. The insulin level was significantly (p < 0.05) higher in indigenous pigs with no significant difference between Hampshire and crossbred in summer whereas there was significant difference among the genotypes in winter. However, superoxide dismutase (SOD) showed no significant difference in the study. Indigenous pigs had the lowest serum cortisol concentrations, whereas Hampshire had the highest.

Conclusion

The current study's findings on several parameters of three different genotypes suggest that indigenous pigs in this region are more adaptable to the region's changing climatic conditions.

Influence of Cold Environments on Growth, Antioxidant Status, Immunity and Expression of Related Genes in Lambs

Cold climates may be a risk to the health and welfare of lambs during winter because cold environments alter the physiological processes of lambs, and we used cold environments with three different temperature gradients—an indoor heating control group (IHC) using electric heating; an indoor temperature group (IT) with intermittent and slight degrees of stimulation of coldness; an outdoor temperature group (OT) exposed to cold environments in an external natural environment. The results showed that the lambs in the OT group had a greater decrease in the average daily gain (ADG) and increase in the average daily feed intake (ADFI) and the feed-to-gain ratio (F:G) compared to the other two groups. The decrease in immunoglobulin A (IgA) and interleukin 2 (IL-2) contents and IL-2 gene expression, and the increase in tumor necrosis factor α (TNF-α) content and TNF-α and nuclear factor kappa-B p65 (NF-κB p65) gene expressions in the OT group suggested that the lambs had a compromised immune status in cold environments. Moreover, the decrease in catalase (CAT), glutathione peroxidase (GPx), total superoxide dismutase (T-SOD), and total antioxidant capacity (T-AOC) levels, and CAT, GPx, SOD1, SOD2, and nuclear factor-erythroid 2-related factor 2 (Nrf2) gene expressions, and the increase in malondialdehyde (MDA) in the OT group suggested that the lambs had a lower antioxidant defense capacity in cold environments. Thus, in extreme cold, lambs kept outdoors could reduce growth, immune function and antioxidant status. However, shelter feeding in winter could relieve the stress of cold environments on lambs, and housing with heating equipment was more conducive to the improve growth, immune, and antioxidant function of the lambs.

Effects of High Heat Load Conditions on Blood Constituent Concentrations in Dorper, Katahdin, and St. Croix Sheep from Different Regions of the USA

Forty-six Dorper (DOR), 46 Katahdin (KAT), and 43 St. Croix (STC) female sheep (initial body weight of 58, 59, and 46 kg, respectively, SEM = 1.75; 3.3 ± 0.18 years of age, 2.6−3.7), derived from 45 commercial farms in four regions of the USA (Midwest, Northwest, Southeast, and central Texas), were used to evaluate responses in blood constituent concentrations to increasing heat load index (HLI) conditions. There were four sequential 2 weeks periods with target HLI during day/nighttime of 70/70 (thermoneutral zone conditions), 85/70, 90/77, and 95/81 in period 1, 2, 3 and 4, respectively. A 50% concentrate pelletized diet was fed at 53.3 g dry matter/kg body weight0.75. The analysis of most constituents was for samples collected on the last day of the second week of each period at 13:00 h; samples for cortisol, thyroxine, and heat shock protein were collected in week 2 and 8. Previously, it was noted that resilience to high HLI conditions was greatest for STC, lowest for DOR, and intermediate for KAT. There were few effects of region. Other than hemoglobin concentration, there were no interactions between breed and period. Blood oxygen concentration was greatest (p < 0.05) among breeds for STC (5.07, 5.20, and 5.53 mmol/L for DOR, KAT, and STC, respectively; SEM = 0.114) and differed among periods (4.92, 5.26, 5.36, and 5.52 mmol/L for period 1, 2, 3, and 4, respectively; SEM = 0.093). There were breed differences (i.e., main effects; p < 0.05) in glucose (50.0, 52.6, and 52.1 mg/dL; SEM = 0.76), urea nitrogen (17.2, 17.3, and 19.4 mg/dL; SEM = 0.33), creatinine (0.991, 0.862, and 0.802 mg/dL; SEM = 0.0151), total protein (6.50, 6.68, and 6.95 g/l; SEM = 0.017), triglycerides (28.4, 29.1, and 23.5 mg/dL; SEM = 0.87), and cortisol (6.30, 8.79, and 6.22 ng/mL for DOR, KAT, and STC, respectively; SEM = 0.596). Differences among periods (p < 0.05) were observed for lactate (27.9, 25.3, 27.8, and 24.0 mg/dL; SEM = 0.99), creatinine (0.839, 0.913, 0.871, and 0.917 mg/dL; SEM = 0.0128), total protein (6.94, 6.66, 6.60, and 6.65 g/l; SEM = 0.094), and cholesterol (60.2, 56.5, 58.3, and 57.6 mg/dL for period 1, 2, 3, and 4, respectively; SEM = 1.26). In addition, the concentration of cortisol (7.62 and 6.59 ng/mL; SEM = 0.404), thyroxine (5.83 and 5.00 µg/dL; SEM = 0.140), and heat shock protein (136 and 146 ng/mL for week 2 and 8, respectively; SEM = 4.0) differed between weeks (p < 0.05). In conclusion, the lack of interaction between breed and period with different HLI conditions suggests that levels of these blood constituents were not highly related to resilience to high HLI.

Reducing the Fermentability of Wheat with a Starch Binding Agent Reduces Some of the Negative Effects of Heat Stress in Sheep

The objective of this study was to investigate the effects of reducing the fermentability of grains on thermoregulatory responses in heat stressed (HS) lambs. To achieve this, wheat grain treated with a commercial starch binding agent, Bioprotect, is compared to maize, which has already demonstrated effects in ameliorating heat stress-induced thermoregulation responses and untreated wheat grains. An initial in vitro experiment was conducted to examine cumulative gas production from the fermentation of wheat grain with different dosages of the commercial starch binding agent, Bioprotect. Based on the in vitro results, an in vivo lamb experiment was conducted using 24 Merino lambs (1 year old; 42.6 ± 3.6 kg BW). The lambs were offered one of three dietary treatments: a wheat-based diet (WD), a Bioprotect treated wheat-based diet (BD), and a maize-based diet (MD). Three successive 1-week experimental periods were conducted with lambs from all dietary groups (P1, P2, and P3). During P1, lambs were exposed to a TN environment and fed a 1.7× Maintenance feed intake (MF) level; in P2, lambs were kept in a HS environment and fed a 1.7× MF level; and in P3, animals were kept in a HS environment and fed a 2× MF level. The in vitro experiment revealed a reduction in cumulative gas production (p < 0.05) from the Bioprotect treated wheat compared to untreated wheat samples. In the in vivo component of the study, the replacement of wheat with maize or 2% Bioprotect-treated wheat reduced the respiration rate (p < 0.001) and heart rate (p ≤ 0.01) of lambs during HS. There was a reduction in the concentration of blood gas variables such as a base excess of blood (BE(b)) and extracellular fluid (BE(ecf)), bicarbonate (CHCO3−), the partial pressure of carbon dioxide (pCO2), the total concentration of carbon dioxide (ctCO2), and sodium (Na+) (p ≤ 0.001 for all) during the periods of HS compared to the thermoneutral conditions. Moreover, BD- and MD-fed lambs had a higher blood potassium concentration (K+) than the WD-fed lambs (p = 0.008). The results of the present study suggest that Bioprotect can be a viable feed treatment strategy for treating rapidly fermentable grains such as wheat to alleviate the effects of HS. Further, Bioprotect-treated wheat could be an option to replace maize in concentrate rations in jurisdictions where maize is cost-prohibitive or unavailable.

Heat Stress: Effects on Rumen Microbes and Host Physiology, and Strategies to Alleviate the Negative Impacts on Lactating Dairy Cows

Heat stress (HS) in dairy cows causes considerable losses in the dairy industry worldwide due to reduced animal performance, increased cases of metabolic disorders, altered rumen microbiome, and other health problems. Cows subjected to HS showed decreased ruminal pH and acetate concentration and an increased concentration of ruminal lactate. Heat-stressed cows have an increased abundance of lactate-producing bacteria such as Streptococcus and unclassified Enterobacteriaceae, and soluble carbohydrate utilizers such as Ruminobacter, Treponema, and unclassified Bacteroidaceae. Cellulolytic bacteria, especially Fibrobacteres, increase during HS due to a high heat resistance. Actinobacteria and Acetobacter, both acetate-producing bacteria, decreased under HS conditions. Rumen fermentation functions, blood parameters, and metabolites are also affected by the physiological responses of the animal during HS. Isoleucine, methionine, myo-inositol, lactate, tryptophan, tyrosine, 1,5-anhydro-D-sorbitol, 3-phenylpropionic acid, urea, and valine decreased under these conditions. These responses affect feed consumption and production efficiency in milk yield, growth rate, and reproduction. At the cellular level, activation of heat shock transcription factor (HSF) (located throughout the nucleus and the cytoplasm) and increased expression of heat shock proteins (HSPs) are the usual responses to cope with homeostasis. HSP70 is the most abundant HSP family responsible for the environmental stress response, while HSF1 is essential for increasing cell temperature. The expression of bovine lymphocyte antigen and histocompatibility complex class II (DRB3) is downregulated during HS, while HSP90 beta I and HSP70 1A are upregulated. HS increases the expression of the cytosolic arginine sensor for mTORC1 subunits 1 and 2, phosphorylation of mammalian target of rapamycin and decreases the phosphorylation of Janus kinase-2 (a signal transducer and activator of transcription factor-5). These changes in physiology, metabolism, and microbiomes in heat-stressed dairy cows require urgent alleviation strategies. Establishing control measures to combat HS can be facilitated by elucidating mechanisms, including proper HS assessment, access to cooling facilities, special feeding and care, efficient water systems, and supplementation with vitamins, minerals, plant extracts, and probiotics. Understanding the relationship between HS and the rumen microbiome could contribute to the development of manipulation strategies to alleviate the influence of HS. This review comprehensively elaborates on the impact of HS in dairy cows and introduces different alleviation strategies to minimize HS.

Impacts of short-term water restriction on Pelibuey sheep: physiological and blood parameters

One of the projected effects of climate change is a reduction in rainfall in certain regions of the world. Hence, the agricultural and livestock sectors will have to cope with increasing incidences of water shortage while still maintaining productivity levels to feed an ever increasing global population. This short communication reports on the effect of a 2-week water stress on Pelibuey sheep in Cuba. Three treatments were compared, viz. supply of water ad libitum, water supplied once every 3 or 6 days. Following exposure to the water stress, the results showed no changes in sheep body weight or rectal temperature. However, respiration frequency was affected with water stress causing a reduction from 23.3 to 13.3 respirations per min in control and water-deprived animals, respectively. Furthermore, there was evidence for hemoconcentration in response to water stress (levels of hemoglobin increased from 9.2 to 13.1 g L^-1 and hematocrits from 27.6 to 39.3% in the control group and animals restricted to water once every 6 days. The imposed water stress was also evident in the reduction of lymphocytes (from ±63 to 43%), and in increase of neutrophils (from approximately 38 to 54%) and leukocytes (from 3133 to 4933 per mm³). The results indicated a decline in the levels of antioxidants, i.e., SOD from approximately 13 to 10 U mg^-1 protein and CAT activity from 23 to 9 U mg^-1 protein. To the best of our knowledge, this is the first report on the response of Pelibuey sheep to short-term water shortage stress under Cuban environmental conditions.

Hemato-Biochemical Responses Of Rats Co-Exposed To Heat Stress And Trichloroethylene Vapors

Aim — The present study was aimed to measure some hemato-biochemical parameters of male Sprague-Dawley rats co-exposed to different levels of heat stress and Trichloroethylene (TCE) exposure. Methods — All male rats were randomly divided into nine equal groups of 5 animals each. They were exposed to heat stress and TCE vapors in a subacute manner (8 hr/day for 10 days) according to experimental design. Blood samples were taken from the heart of all animals at the end of the 10th day of exposure. Hematology and biochemical parameters were determined using the automated hematology analyzer and an automated biochemistry, respectively. Results — The values of WBC, RBC and HB significantly decreased after co-exposure 250 ppm TCE and extreme heat stress; although, this exposure condition lead to statistically significant increase in mean levels of MCV, RDW, ALP, CPK and LDH. Our findings indicated that there were the subtractive and independent interactions for the hematological parameters and the additive, subtractive and independent interactions for biochemical parameters based on the exposure level to trichloroethylene and heat stress. Conclusion — Heat stress may increase sensitivity of workers to trichloroethylene and the simultaneous effects of exposure provide the circumstances for the occurrence of a variety of disorders.

Non-Invasive Determination of Annual Fecal Cortisol, Androstenedione, and Testosterone Variations in a Herd of Male Asian Elephants (Elephas maximus) and Their Relation to Some Climatic Variables

Simple Summary

Studies of physiology, animal welfare, and behavior in endangered species are gaining more importance with the aim of contributing to their conservation, and studies that use non-invasive methods for hormonal determinations are especially valuable. In this study, feces were used to assess whether the adrenal and gonadal hormones showed variation in male Asian elephants in a 14-month period and to evaluate whether there were any influences of climatic variables with respect to hormonal secretion. We show here that the use of non-invasive methods to measure the levels of steroid hormones in Asian elephant feces allows us to obtain useful results without having to subject the animals to stressful activity or requiring specific training to obtain the samples. Additionally, this research provides a deeper understanding of endocrine regulation in captive Asian elephants (Elephas maximus) in order to enhance reproduction programs in captivity and conserve the species.

Abstract

The measurement of stress and reproductive hormones in wild animal species by non-invasive methods is of special interest. To assess whether the adrenal and gonadal hormones show annual variations in male Asian elephants (Elephas maximus) and to evaluate whether there is any influence of climatic variables on hormonal secretion, fecal samples were taken from a herd of 7 Asian elephants over a 14-month period to subsequently determine the concentrations of testosterone (T), androstenedione (A4), and cortisol (C) by a validated immunoassay technique. Data referring to three climatic variables in the place and period of study were collected, namely monthly mean values of temperature, humidity and rainfall. Levels of T and A4 showed two major increases in July (T: 1088.35 ± 131.04 ng/g; A4: 480.40 ± 50.86 ng/g) and October (T: 825.09 ± 31.60 ng/g; A4: 319.96 ± 32.69 ng/g) (p < 0.05). Our results show a secretion of fecal androgens dependent on temperature (T and A4), and humidity (T). Male musth was detected during the initial increases of T and A4 levels. The highest concentrations of C were observed in September (156.67 ± 60.89 ng/g) (p < 0.05), probably due to the stressful fights that occurred during the musth period. The observed results of the fecal levels of T, A4 and C were similar to those obtained by invasive methods. In conclusion, fecal secretion of the three hormones in these captive male Asian elephants showed variations related in some cases to different weather factors.

Adaptive profiles of Nellore sheep with reference to farming system and season: physiological, hemato-biochemical, hormonal, oxidative-enzymatic and reproductive standpoint

This paper outlines the effect of farming systems with reference to season on the body condition score (BCS) and adaptive profile (physiological, hemato-biochemical, hormonal, enzymatic and reproductive parameters) of Nellore sheep. In trial 1, sixty ewe-lambs were allotted to extensive, semi-intensive, and intensive rearing systems (n = 20) and evaluated for BCS at puberty, mating, 2 weeks pre-lambing and 2, 4, 8, and 12 weeks post-lambing. In trial 2, eighteen rams were distributed evenly to three farming systems (n = 6) and evaluated for physiological, hemato-biochemical, hormonal, enzymatic, and reproductive parameters concerning three seasons. Although the scores did not differ among the groups, the Kruskal-Wallis ranks of BCS revealed a higher energy status of intensive ewes at different physiological conditions. The sheep reared under extensive and semi-intensive systems displayed higher temperature, pulse rate and respiratory rate with predominant effects in summer season. Similarly, both systems exhibited higher WBC and lower haemoglobin, PCV, and RBC contents without affecting MVC, MCH, MCHC, and differential leucocyte count. The percent haemoglobin and RBC count were higher in winter compared to summer months, whereas WBC count followed an exactly opposite pattern. The sheep reared in intensive system showed higher glucose, total protein, albumin, cholesterol, T3, T4, calcium, and phosphorus; however, the globulin, creatinine, uric acid, aspartate amino transferase (AST), alanine amino transferase (ALT), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase, and catalase levels were elevated in extensive and semi-intensive systems. The dartos muscle extension (DME) and scrotum sweating rate (SSR) were higher for the sheep reared under extensive system, especially during summer season; while the seminal parameters viz., total sperm count, progressive sperm motility, and plasma membrane integrity were lower for extensive and semi-intensive sheep. No interactions were noticed for any of the parameters, except for cortisol, DME, and SSR, which showed significant interactions for rearing system vs. season. Our results showed dynamic adaptive mechanisms of the Nellore sheep in relation to different stressors like grazing for long distances, inadequate nutrition, and heat stress, revealing the heat resilient ability in harsh environmental conditions. Further, the analyzed vector plot showed that the AST, GPx, Cortisol, SOD, Catalase, WBC, PR, T4, total abnormalities, and major abnormalities were the major contributors for adapting during combined stressors.

Effects of Feed Supplementation on Nesfatin-1, Insulin, Glucagon, Leptin, T3, Cortisol, and BCS in Milking Ewes Grazing on Semi-Natural Pastures

This study aimed to investigate the effects of feed supplementation on body condition score (BCS) and different metabolic hormones concentration in lactating sheep reared in Italian Central Apennine pastures during the grazing summer period. In this study, 24 Comisana x Appenninica pluriparous ewes from June until August were divided into two homogenous groups: the control group (UNS) was free to graze, while the other group (SUP), in addition to grazing, was supplemented with 600 g/day/head of cereals. At the start of the supplementation and at an interval of 9-10 days until the end of experimentation, BCS evaluation and blood withdrawal to assay nesfatin-1, insulin, glucagon, leptin, triiodothyronine and cortisol levels were performed. Univariable analysis showed no remarkable differences between the groups, while multivariable analysis suggested that the UNS group was characterized by a lower BCS and greater nesfatin-1 than the SUP group. These findings can be considered in relation to milk production, which shows a clear better persistence in the SUP group. Our results indicate that nutritional supplementation has protected ewes from the usual lowering of the body state linked to lactation and provides a good maintenance of milk production, determining also a better overall body and metabolic state of the animals, which is important at the beginning of the sexual season.

Effects of transport and altitude on hormones and oxidative stress parameters in sheep

In study, it was aimed to determine the stress effects that can be caused by transporting and altitude in sheep. Karayaka sheeps were used in the study. Karayaka sheeps are a valuable breed of meat quality and fleece, which is raised in the Black Sea region. The live weight of the sheep (n = 30) while hungry was determined before transport and sea level. Average live weight was determined as 55.64 ± 4.66 kg. Blood samples were collected just before (sea level) and just after transport (1500 meters above sea level). Transportation distance was approximately 182 km and duration was 5 hours. According to the findings, cortisol was not affected by transport stress and altitude (P>0.05) and Triiyodotironin (T3) (P<0.039) and Tyrosine (T4) (P<0.000) were affected significantly. Malondialchehyche (MDA), which is one of the oxidative stress parameters, was significantly affected (P<0.039) and Protein Carbonyl (PC) values were not affected by transport and altitude (P>0.184). As a result of this study, it was determined that transportation and altitude in sheep causes stress. Stress-reducing measures should be taken in the exposure of sheep to altitude differences and in transportation. Antioxidant nutritional supplements should be made in order not to negatively affect the meat quality in sheep.

Comparative Assessment of Thermotolerance in Dorper and Second-Cross (Poll Dorset/Merino × Border Leicester) Lambs

Simple Summary

Selection of animal breeds that are adapted to extreme climatic conditions may help to sustain livestock production in the face of climate change. We measured the thermotolerance of 4–5-month-old Dorper and second-cross lambs (Poll Dorset × (Border Leicester × Merino)) by assessing feed intake, physiological, blood biochemical and prolactin responses. Heat stress reduced feed intake only in second-cross lambs but not in Dorpers. As expected, heat stress also increased water intake, respiration rate, rectal temperature, and skin temperature in both genotypes, but to a lesser extent in Dorpers. The comparatively lower influence of heat stress on thermotolerance indices in Dorper indicates adaptability of this breed to heat challenge.

Abstract

The objective of this study was to compare the thermotolerance of second-cross (SC; Poll Dorset × Merino × Border Leicester) and Dorper lambs. Dorper and SC lambs (4–5 months of age) were subjected to cyclic heat stress (HS) (28–40 °C). The temperature was increased to 38–40 °C between 800 and 1700 h daily and maintained at 28 °C for the remainder of the day (30–60% relative humidity (RH)) in climatic chambers for 2 weeks (n = 12/group), with controls maintained in a thermoneutral (TN) (18–21 °C, 40–50% RH) environment (n = 12/group). Basal respiration rate (RR), rectal temperature (RT) and skin temperature (ST) were higher (p < 0.01) in SC lambs than in Dorpers. HS increased RR, RT and ST (p < 0.01) in both genotypes, but the levels reached during HS were lower (p < 0.01) in Dorpers. HS increased (p < 0.01) water intake to a greater extent in SC lambs, while feed intake was reduced (p < 0.05) by HS in SC lambs but not in Dorpers. HS increased (p < 0.01) blood urea nitrogen and creatinine in SC lambs only. Plasma non-esterified fatty acid concentrations were reduced (p < 0.05) by HS in SC lambs but increased (p < 0.05) in Dorpers. There was no effect of HS on pO₂, cHCO₃⁻ and cSO₂, but higher (p < 0.01) blood pH and lower (p < 0.01) pCO₂ were recorded under HS in both genotypes. Blood electrolytes and base excess were reduced (p < 0.01) under HS, while a genotype difference (p < 0.05) was only observed in blood K⁺ and hemoglobin concentrations. Basal plasma prolactin concentrations were lower (p < 0.01) in Dorpers but were elevated at a similar level during HS (p < 0.01) in both genotypes. Dorper lambs are more resilient to HS than SC lambs. Future research should focus on confirming whether the better heat tolerance of Dorpers is translated to better returns in terms of growth performance and carcass traits over the summer months.

Gastrointestinal parasite infection intensity and hematological parameters in South African communal indigenous goats in relation to anemia

Aim:

The study was conducted to determine the intensity of gastrointestinal parasite (GIP) infections and hematological parameters in South African communal indigenous goats in relation to anemia.

Materials and Methods:

A total of 288 goats were randomly sampled in areas representing four agro-ecological zones. Fecal and blood samples were collected from the rectum and jugular vein, respectively, of each animal. The number of eggs per gram (EPG) and oocysts per gram (OPG) of feces and the hematological parameters were determined using the modified McMaster technique and a BC-2800Vet® automatic hematology analyzer, respectively. Data were analyzed using the repeated measures techniques of Minitab 17, modeling the covariance structure of the observed data.

Results:

Based on EPG and OPG, goats in humid zone were significantly infected (p<0.05) with strongyles, Eimeria, Moniezia, and Trichuris spp. Hematological parameters of goats in arid and humid zone were lower (p<0.05) than those in semi-arid and dry sub-humid zone. GIP infection intensities were higher (p<0.05) in young animals than in adult and suckling goats. GIP infection intensity was similar between goat sexes, while hematological parameters were higher (p<0.05) in females. Higher (p<0.05) infection intensities for strongyles (302.90 EPG) and Eimeria (216.09 EPG) were observed in winter compared to summer (strongyles: 302.90, Eimeria: 216.09 EPG). Higher (p<0.05) values for the hematological parameters were observed during summer compared to that in winter.

Conclusion:

GIP infection intensity in the winter could be associated with hypochromic and normocytic anemia which likely to affects suckling goats while in the summer could be associated with normochromic and normocytic anemia which likely to affect young goats.

Effects of heat stress on antioxidant status and immune function and expression of related genes in lambs

The study was conducted to evaluate the effects of heat stress on antioxidant status, immune response, and related gene expression of lambs. Eighteen male lambs were randomly allocated into three treatment groups that were as follows: indoor temperature control group furnished with an air-conditioner (ITC), indoor temperature non-control group suffered intermittent and varying degrees of heat stress (ITNC), outdoor temperature non-control group in the external natural environment (OTNC). ITNC group presented a more severe and prolonged exposure to thermal stress than the other two groups. The trial lasted 28 days. Blood samples were collected on days 14 and 28 to analyze total superoxide dismutase (T-SOD), catalase (CAT), glutathione peroxidase (GPx) activities, malondialdehyde (MDA) concentrations, total antioxidant capacity (T-AOC), interleukin-1 (IL-1), interleukin-2 (IL-2), tumor necrosis factor-alpha (TNF-α), immunoglobulin A (IgA), immunoglobulin G (IgG), and immunoglobulin M (IgM) concentrations and gene expressions of SOD1, SOD2, GPx, CAT, nuclear factor erythroid 2-related factor 2 (Nrf2), IL-1β, IL-2, and TNF-α. Results showed that on day 14 an elevated temperature reduced (p < 0.05) the level of GPx, T-SOD, T-AOC, and IgG, whereas significantly increased (p < 0.05) CAT, MDA, IgA, and TNF-α levels. Gene expressions of SOD1 and GPx were down-regulated (p < 0.05). On day 28, ITNC group significantly decreased (p < 0.05) CAT, GPx, T-SOD, T-AOC, IgG, and IL-2 levels and increased (p < 0.05) MDA, IL-1, and TNF-α levels, accompanying by the reducing or increasing (p < 0.05) of their relative gene expression apart from CAT and IL-1β gene (p > 0.10). In addition, in ITNC and OTNC groups, the level of CAT, T-SOD, T-AOC, IgG, IgM, and IL-2 and the expression of CAT, SOD2, and IL-2 reduced (p < 0.05), whereas IL-1 and TNF-α levels and IL-1β expression increased (p < 0.05) on day 28 compared with day 14. In ITC group, the level of IgA, IL-1, and TNF-α and the expression of IL-1β and TNF-α increased (p < 0.05), while the content of IgG and IgM reduced (p < 0.05) on day 28 compared with day 14. These results indicated that heat stress negatively affected the antioxidant status and immune response of lambs, and the negative effects of heat stress are not only related to the stress duration but also associated with the stress severity.

High ambient temperature directly decreases milk synthesis in the mammary gland in Saanen goats

The mammary gland is a privileged organ for mammals. Because of their high capacity for milk synthesis, dairy ruminants have been distributed throughout the world. In tropical areas, dairy animals face high ambient temperatures (HTa). The indirect effect of HTa on milk synthesis is mediated in part by a reduction in feed intake. The current experiment focused on the direct natural effect of HTa on mammary function. Multiparous Saanen goats were used in this study. The physiological responses for HTa were evaluated from the control period during the winter and from the natural HTa during the summer. Milk samples were collected for isolation of the goat milk cells to study the expression of the β-1,4 galactosyltransferase (β-GALT1), Akt, and heat shock protein 70 (HSP70) genes. Although goats in the summer maintained rectal temperature and plasma cortisol levels similar to those observed in the winter, the higher respiratory rate and lower feed intake and milk yield (MY) from the goats in the summer indicated that the goats in the summer were exposed to a higher degree of HTa. This was supported by the significantly higher level of plasma glutathione peroxidase (GPX) activity. Moreover, the relative expression levels of β-GALT1 and Akt were not different. The relative expression of HSP70 during the summer was significantly higher than what was observed in cells isolated in the winter. In conclusion, the HTa effect on MY during the summer was related to its indirect effect on feed intake. The direct HTa effect might be related to HSP70 gene expression in goat milk cells and to plasma GPX activity. However, the natural HTa did not affect the expression of Akt or β-GALT1.

m6A mRNA methylation analysis provides novel insights into heat stress responses in the liver tissue of sheep

N⁶-methyladenosine (m⁶A) mRNA methylation varies in response to stress. However, no map of m⁶A mRNA methylation has been obtained for sheep, nor is it known what effect this has on regulating heat stress in sheep. Here, we obtained m⁶A methylation maps of sheep liver tissues with and without heat stress by MeRIP-seq. In total, 8306 m⁶A peaks associated with 2697 genes were detected in the heat stress group, and 12,958 m⁶A peaks associated with 5494 genes were detected in the control group. Peaks were mainly enriched in coding regions and near stop codons with classical RRACH motifs. Methylation levels of heat stress and control sheep were higher near stop codons, although methylation was significantly lower in heat stress sheep. GO and KEGG revealed that differential m⁶A-containing genes were significantly enriched in the stress response and fat metabolism. Our results showed that m⁶A mRNA methylation modifications regulate heat stress in sheep.

Effect of season and SNPs of HSP90 and HSP70 genes on the biochemical traits in Indian sheep (Ovis aries) breeds

Heat shock proteins (HSPs) are evolutionary conserved family of proteins produced by living cells in response to various biological stresses, including heat shock. Heat stress affects the productivity of the livestock species, which causes severe economic losses to the animal keepers. The present study was undertaken to establish reference baseline values for thyroid (T3 and T4) and adrenal gland (cortisol) hormones in four indigenous sheep breeds (Chokla, Marwari, Magra and Madras Red). The effect of the seasons and genotypes of the HSP90 and HSP70 genes on the functions of the thyroid gland as well as cortisol levels were examined in plasma samples of these sheep breeds. A total of 80 plasma samples (10 animals per breed for the summer and winter season) were analyzed. The least square analysis revealed significant seasonal effect on Triiodothyronine (T3) and Thyroxine (T4). Significantly higher T3 and T4 levels were observed in the winter with a low temperature humidity index (THI) than in summer with high THI. Cortisol was non-significantly higher in the summer than in winter season. Overall, the influence of the breeds on these three parameters was non-significant. Genotypes of SNP1 (HSP90 gene) and SNP2 (HSP70 gene) had significant effect on T3 level. These SNP markers may be useful for identifying animals that are more adaptable to heat stress following a thorough association analysis over a large sample size.

Impact of thermal stress exposure on seminal quality, antioxidant defence system, TNF-α and TIMP-3 in Ossimi ram

Heat stress (HS) occupies huge importance nowadays as it leads to severe economic losses especially in livestock. Preserving sheep against HS is one of the governmental scopes where it represents huge percentage of global ruminant. The present research was conducted to study semen quality, some stress and inflammatory markers in Ossimi rams under both hot and mild climatic conditions. The current study was conducted on selected 46 ram samples divided into two groups during summer and winter. Semen analysis, testosterone (TES), cortisol (COR) and blood glucose (BG) levels, and lipid and protein profiles were done. Concentrations of tumour necrosis factor alpha (TNF-α), tissue inhibitor of metalloproteinase-3 (TIMP-3), nitric oxide (NO), malondialdehyde (MDA) and reduced glutathione (GSH) and specific activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD) were assessed. The results in summer compared to winter revealed significant elevation of total defects and number of dead sperms; however, there was reduction in sperm total motility and concentration and external epididymal tail duct diameter. Histological study of epididymal tail lumen exhibited azoospermia. Further, TES, TIMP-3 and GSH levels were decreased and COR, TNF-α, NO and MDA were raised. Specific activities of GPx and SOD were also declined. Additionally, there was a significant increase in concentrations of BG and lipid profiles except high-density lipoprotein. Our data concluded that there were new insights into TNF-α and TIMP-3 as biomarkers can be used in diagnosis of sheep suffering from HS, but further studies are recommended to do in future work about such aspect.

Resilience of Small Ruminants to Climate Change and Increased Environmental Temperature: A Review

Simple Summary

Small ruminants are critical for food security and livelihood, especially under extreme stressful and diverse climatic environments. Generally, sheep and goats are farmed on grazing land in relatively large groups relying on low inputs in terms of feed, water and labor, and possess high thermotolerance compared to large ruminants such as cattle. Climate change has been recognized as a harmful factor influencing sheep and goat production. Small ruminants are vulnerable to direct and indirect effects of climate change, including heat stress, limited and low-quality pasture availability and emerging infectious diseases. In this context, selection of animals for thermotolerance is one viable strategy that exploits natural variation within and between breeds for desirable traits. The various biological markers used to improve thermotolerance in small ruminants include behavioral (feed intake, water intake), physiological (respiration rate, rectal temperature, sweating rate), hormonal (T3, T4 and growth hormone) responses and the response of molecular regulators.

Abstract

Climate change is a major global threat to the sustainability of livestock systems. Climatic factors such as ambient temperature, relative humidity, direct and indirect solar radiation and wind speed influence feed and water availability, fodder quality and disease occurrence, with production being most efficient in optimal environmental conditions. Among these climatic variables, ambient temperature fluctuations have the most impact on livestock production and animal welfare. Continuous exposure of the animals to heat stress compromises growth, milk and meat production and reproduction. The capacity of an animal to mitigate effects of increased environmental temperature, without progressing into stress response, differs within and between species. Comparatively, small ruminants are better adapted to hot environments than large ruminants and have better ability to survive, produce and reproduce in harsh climatic regions. Nevertheless, the physiological and behavioral changes in response to hot environments affect small ruminant production. It has been found that tropical breeds are more adaptive to hot climates than high-producing temperate breeds. The growing body of knowledge on the negative impact of heat stress on small ruminant production and welfare will assist in the development of suitable strategies to mitigate heat stress. Selection of thermotolerant breeds, through identification of genetic traits for adaption to extreme environmental conditions (high temperature, feed scarcity, water scarcity), is a viable strategy to combat climate change and minimize the impact on small ruminant production and welfare. This review highlights such adaption within and among different breeds of small ruminants challenged by heat stress.

Oxidative Status of Goats with Different CSN1S1 Genotypes Fed ad Libitum with Fresh and Dry Forages

Forty late-lactation Girgentana goats were used to study the effect of diets fed ad libitum and αS1-casein (CSN1S1) genotype on redox balance. The goats genotyped at CSN1S1 locus (A/A, A/F) were subjected to four feeding treatments different for percentage inclusion of dry and fresh forage: DAF100 (98% of Dry Alfalfa Forage), DAF65 (65% of Dry Alfalfa Forage), FSF100 (100% of Fresh Sulla Forage) and FSF65 (65% of Fresh Sulla Forage). Blood samples were analyzed for superoxide dismutase (SOD) and glutathione peroxidase (GPX) activity, reactive oxygen metabolites (ROMs), biological antioxidant potential (BAP) and non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA), albumin, glucose and cholesterol contents. The oxidative stress index (OSI) was calculated as percentage ratio of ROMs to BAP. Redox balance was improved by Sulla inclusion, as reflected in the lower OSI values found in FSF100 and FSF65 groups. DAF100 group displayed the highest GPX activity, while other groups exhibited the highest SOD activity. Fresh forage diets increased albumin concentration while no effect of tested factors was noted on glucose, NEFA, BHBA and cholesterol contents. The interaction diet × genotype was significant only for GPX activity. GPX and albumin were negatively correlated and were correlated positively and negatively with ROMs, respectively. Diet rather than genotype affects redox balance in dairy goats and a possible role of forage polyphenol compounds on oxidative status needs to be tested in future studies.

Dietary supplementation of brown seaweed (Sargassum latifolium) alleviates the environmental heat stress-induced toxicity in male Barki sheep (Ovis aries)

Heat stress (HS) is the most potent environmental stressors for livestock in tropical and subtropical regions. HS induced splanchnic tissue hypoxia and intestinal oxidative damage, leading to endotoxemia and systemic inflammation. The present study evaluated and compared the modulatory effects of feeding Barki male sheep (Ovis aries) on a standard concentrated diet containing 2% or 4% of the brown seaweed (Sargassum latifolium) followed by roughage for 40 consecutive days on the toxicity-induced by exposure to severe environmental HS (temperature-humidity index = 28.55 ± 1.62). The present study showed that the diet containing Sargassum latifolium (especially 4%) modulated significantly (P < 0.05-0.001) almost all changes shown in the HS-exposed sheep including the increase in the thermo-respiratory responses (skin and rectal temperatures, and respiration rate) and the resulted dyslipidemia, anemia, and systemic inflammation (blood leukocytosis, the elevation in the erythrocyte sedimentation rate, and the increase in serum proinflammatory cytokines and heat shock protein-70 concentrations). In addition, Sargassum latifolium improved significantly (P < 0.05-0.001) the body-weight gain, kidney functions (especially at the high dose), and blood antioxidant defense system (total antioxidant capacity, and the activities of catalase and superoxide dismutase) in the HS-exposed sheep, as well as protected the animals from oxidative tissue damage and the risk of atherosclerosis. In conclusion, feeding sheep with the diet containing 4% of Sargassum latifolium was safe and suitable for animal nutrition, as well as efficiently alleviated the harmful effects of the environmental HS in Barki sheep through improving the animal antioxidant defense system, and regulating the thermo-respiratory and inflammatory responses.

Infrared thermography and feeding behavior of lambs fed increasing levels of safflower grains

ABSTRACT The objective was to evaluate the feeding behavior, physiological responses, and rumen heat emission of lambs fed with safflower grains. Eighteen lambs were randomly distributed in a completely randomized design. Safflower grain was added to the diets in the proportions of 0.0; 7.5 and 15%. The safflower grain did not change the patterns of eating, leisure, or rumination; however, it improved the efficiency of NDF ingestion, by 26%. The head temperature decreased by 1.5 ° C to include 7.5% safflower; and the rectal temperature decreased quadratically with the addition of safflower (39.5 and. 39.08 ° C). There was a linear trend of decreasing head temperature as the inclusion of safflower increased. The temperature of the eyeball decreased by 1.1 ° C when 7.5% of safflower DM was added to the diet and increased by 0.6 ° C when a 15% safflower was added. The ruminal temperature increased linearly for the addition of safflower (1.8 ° C). Safflower improves the efficiency of the use of NDF and the inclusion of 15% safflower can be used without effects on ingestive behavior. The head, eye, and left flank areas can be used; however, the left flank appears to be the best region for this type of study. Infrared thermography can be useful as a non-invasive assessment of lambs' diets.

Transcriptomic Analysis Provides Novel Insights into Heat Stress Responses in Sheep

Simple Summary

The general increase in global temperatures has meant that heat stress has become an increasingly significant problem for sheep. This has both direct and indirect impact on their physiological functions, productivity, and health of sheep. Sheep generally live in high-temperature environments; however, the genes and pathways that play regulatory roles in the heat stress responses of sheep remain unclear. In this study, we applied RNA-Seq technology to analyze liver tissues of sheep from heat-stressed and control groups, and screened genes and pathways related to sheep heat stress. This work provides a theoretical foundation for the breeding and production of heat-resistant sheep.

Abstract

With the intensified and large-scale development of sheep husbandry and global warming, sheep heat stress has become an increasingly important issue. However, little is known about the molecular mechanisms related to sheep responses to heat stress. In this study, transcriptomic analysis of liver tissues of sheep in the presence and absence of heat stress was conducted, with the goal of identifying genes and pathways related to regulation when under such stress. After a comparison with the sheep reference genome, 440,226,436 clean reads were obtained from eight libraries. A p-value ≤ 0.05 and fold change ≥ 2 were taken as thresholds for categorizing differentially expressed genes, of which 1137 were identified. The accuracy and reliability of the RNA-Seq results were confirmed by qRT-PCR. The identified differentially expressed genes were significantly associated with 419 GO terms and 51 KEGG pathways, which suggested their participation in biological processes such as response to stress, immunoreaction, and fat metabolism. This study’s results provide a comprehensive overview of sheep heat stress-induced transcriptional expression patterns, laying a foundation for further analysis of the molecular mechanisms of sheep heat stress.

Biomarkers of oxidative stress in saliva of sheep: Analytical performance and changes after an experimentally induced stress

Oxidative stress can affect animal's health and the quality of its final products. The oxidative status can be evaluated by the measurement of both oxidant and antioxidant biomarkers. The use of saliva as a sample is preferable to blood, as individuals with limited training can collect it easily and non-invasively with minimal stress to the animal. The aim of this study was to perform an analytical validation of automated assays of the ferric reducing ability of plasma (FRAP), the cupric reducing antioxidant capacity (CUPRAC), the Trolox equivalent antioxidant capacity (TEAC) and uric acid as antioxidant biomarkers and of the advanced oxidation protein products (AOPP) and hydrogen peroxide (H₂O₂) as oxidant biomarkers in saliva samples of sheep, and to evaluate their possible changes after stress induced by shearing. All assays produced acceptable results in the analytical validation, from which it can be concluded that oxidative stress biomarkers such as FRAP, CUPRAC, TEAC, uric acid and AOPP and H₂O₂ can be measured in sheep saliva. In addition, acute stress due to shearing could produce an oxidative stress response in sheep and subsequently increase antioxidants in order to protect cells from damage.