Protective effect of soursop (Annona muricata linn.) juice on oxidative stress in heat stressed rabbits

"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.

Herbal inclusions ameliorate effect of heat stress on haematology, proinflammatory cytokines, adipokines and oxidative stress of weaned rabbit does in humid tropics

A study was designed to evaluate the effect of Moringa oleifera, Phyllanthus amarus and Viscum album leaf meal as herbal inclusions to alleviate the detrimental outcomes of heat stress in weaned female rabbits. Forty (40) weaned rabbit does (527.99 ± 10.35 g; 28 days old) were randomly allotted to four dietary groups consisting of Diet 1(control diet; without leaf meal), Diets 2 (supplemented with 10% V. album); 3 (supplemented with 10% M. oleifera) and 4 (supplemented with 10% P. amarus) in an 84 days trial at the peak of heat stress in Southwest Nigeria. At the end of the trial, blood samples were collected to assess physiological responses and oxidative status of the rabbit does. The results obtained revealed that rabbit does were exposed to heat stress; rabbit does fed control diet had higher leucocyte and neutrophil/lymphocyte ratio compared to rabbit does fed on herbal inclusions. The herbal inclusions enhanced oxidative stability of rabbit does by lowering lipid peroxidation and enhancing antioxidant activities during heat stress conditions. Rabbit does fed control-based diet had significantly higher heat shock protein 70, leptin and adiponectin compared to rabbit does on M. oleifera, P. amarus and V. album supplemented diets. The herbal inclusions tend to suppress proinflammatory cytokines in rabbit does during heat stress condition. In conclusion, the herbal inclusions suppress inflammation, adipokines and promotes oxidative stability of rabbit does exposed to heat stress conditions.

Potentials of Phyllanthus amarus, Viscum album and Moringa oleifera supplements to mitigate heat stress in female rabbits in humid tropics

Global warming is a key challenge subjecting animals to heat stress conditions resulting in multiple physiological alterations in tropical climate. Dietary approach seems to be the more friendly approach to curb the adverse effects of heat stress in rabbits. Some herbs have been categorized to have high potential for promotion of immune responses for amelioration of heat stress. Thus, this research aims to evaluate the potential of Mistletoe (Viscum album), Moringa (Moringa oleifera) and Phyllanthus (Phyllanthus amarus) leaf meal as herbal supplements for the alleviation of heat stress in female rabbits by measuring improvement in sex and stress hormonal responses in serum biochemistry. 80 Rabbit does were exposed to 4 dietary groups supplemented with each of Mistletoe, Moringa, Phyllanthus and a control in an 84-day trial at the summit of thermal stress in South west Nigeria. Growth indices were monitored throughout the study, blood samples were compiled at the end of the trial to assess serum biochemistry, stress and sex hormonal responses of the Does using standard protocols. The results revealed that final weight and weight gain of Does fed on Phyllanthus were significantly (p < 0.05) higher (11.46% and 14.25%, respectively) than Does on control. The herbal supplements enhance glucose, protein, albumin and globulin, reduced cholesterol, and creatinine of Does under heat stress conditions. Among the herbal treatment groups, mistletoe, moringa and phyllanthus had 12.42%, 18.39% and 16.90%, respectively, lower corticosterone than control groups which had 39.76ng/ml. Triiodothyronine of Does fed control were significantly (p < 0.05) lower than Does on Moringa oleifera and Phyllanthus amarus supplements. Estradiol and Follicle stimulating hormone of rabbit Does fed on moringa supplement were significantly (p < 0.05) higher than other treatments. In conclusion, the herbal supplements tend to mitigate the detrimental outcome of thermal stress on Does by suppressing stress hormones. Moringa oleifera and Phyllanthus amarus enhanced sex hormones while Phyllanthus amarus confered growth promoting effects on the Does.

The role of different dietary Zn sources in modulating heat stress-related effects on some thermoregulatory parameters of New Zealand white rabbit bucks

The present work was conducted to assess the effect of diets supplementation to heat-stressed buck rabbits with different zinc (Zn) sources on the thermoregulatory and hematobiochemical parameters, and antioxidant status. A total of 24 mature buck rabbits (32-36 weeks of age) were randomly distributed into four groups (6 each). Group 1, non-heat-stressed control (NHSC), was reared in the absence of heat stress (HS) conditions and received the basal diet only. The other three groups (groups 2, 3 and 4) were kept in HS conditions. Group 2, heat-stressed control (HSC), received the basal diet only. The diet supplemented with 75 mg Zn/kg diet either in the inorganic form (Zn sulfate) or in the organic form (Zn picolinate) for groups 3 and 4, respectively. Zn supplementation to rabbits' diets lowered the heat stress-related increase of serum urea, alanine transaminase and malondialdehyde (MDA) concentration. These supplementations also increased the concentration of testosterone under HS conditions. Zn picolinate was more effective than Zn sulfate in restoring serum concentrations of urea, testosterone, and MDA. In conclusion, Zn addition to rabbits' diets from different sources, especially Zn picolinate, exhibits an ameliorative effect against the harmful impact of HS on hematobiochemical parameters and antioxidant status.

Ramifications of Heat Stress on Rabbit Production and Role of Nutraceuticals in Alleviating Its Negative Impacts: An Updated Review

Heat stress has become a widespread concern worldwide, which is a major environmental stress that causes substantial economic loss in the rabbit industry. Compared to other agricultural animals, rabbits are more sensitive to heat stress as they have fewer sweat glands and a thicker coat of fur, increasing the heat dissipation complexity. Thus, heat stress hurts rabbits' productivity, meat quality, reproductive performance, antioxidative properties, immune responsiveness, intestinal histomorphology, and microbiome. Nutraceuticals include vitamins, minerals, antioxidants, organic acids, fatty acids, probiotics, prebiotics, synbiotics, enzymes, and medicinal plants due to the possible impacts on maintaining common biological situations, strengthening immune response, and preventing illness, which ultimately led to an increase in productivity. Nutraceuticals have recently attracted a lot of attention to alleviate the adverse impacts of heat stress in rabbit farms. The objective of the current review is to provide acquaintance with the recent findings about the impact of heat stress on rabbit productivity and the advantages of dietary supplementation of nutraceuticals in mitigating it.

Herbal supplements suppress pro-inflammatory cytokines, boost humoral immunity, and modulate adipokines to enhance the productivity traits of rabbit bucks in hot climatic conditions

Thermal stress is the main stressor accounting for reduced productivity, compromised immunity, and collapse of thermoregulatory measures in rabbits in the tropics. The current climate change depicts worsening assault of heat stress in the time ahead; hence, the need to develop combative measures for animal productivity. This research investigates the influence of herbal supplements of three tropical herbs Viscum album (mistletoe), Moringa oleifera (Moringa), and Phyllanthus amarus (Phyllanthus) on immune response, oxidative status, adipokines, and growth of eighty weaned rabbits during heat stress in tropical climate. The bucks were fed with four standard diets; a control and others supplemented with each of Moringa, Phyllanthus, and mistletoe for an eight-week feed trial. Performance indicators were monitored and blood were sampled and assayed for hematology, pro-inflammatory cytokines, adipokines, and oxidative status. The result shows that the performance of bucks fed with Phyllanthus and mistletoe supplements was superior to other groups. The neutrophil/lymphocyte ratio was significantly (p < 0.05) lower in the bucks fed with Moringa supplement, with significantly (p < 0.05) highest values obtained in the control group. Total antioxidant activity of the bucks fed with supplements was significantly (p < 0.05) higher than those on control, with the significantly (p < 0.05) highest value recorded in bucks fed with Phyllanthus. Serum lipid peroxidation of the bucks on control was significantly (p < 0.05) highest and significantly (p < 0.05) least value was obtained in bucks on mistletoe. Heat shock protein 70, adiponectin, and leptin of the bucks on control were significantly (p < 0.05) higher than bucks on herbal supplements. Interleukin 6, interleukin β, and tumor necrosis factor α of bucks on control were significantly (p < 0.05) higher than bucks fed on herbal supplements. In conclusion, the inclusion of herbal supplements Moringa, Phyllanthus, or mistletoe suppressed pro-inflammatory cytokines, boost humoral immunity, enhance the anti-oxidative status, and promote the growth of rabbit bucks during thermal discomfort.

Performance, hemato-biochemical indices and oxidative stress markers of broiler chicken fed phytogenic during heat stress condition

Thermal stress is a tremendous health predicament encountered by poultry farmers with adverse effects on the performance, product stature, health condition, survival, and overall welfare of poultry birds, and so requires urgent dietary user-friendly strategy to curb. This study was conducted with 200-day old broilers for the purpose of investigating the potential of phytogenics in refining the negative effects of heat stress on broiler chicken. Moringa, Phyllanthus and mistletoe leaves were processed as phytogenic supplements and incorporated into standard ration for broilers as treatments B1 (control), B2, B3 and B4 diet during the peak of thermal discomfort in humid tropics. Growth and carcass indices were monitored in a 49-day trial and blood samples were harvested at the end of the ordeal period to assess haematology, serum biochemical and oxidative stress markers with the use of standard procedures. The results obtained showed that the prevailing environmental condition in the study site indicated that the birds were exposed to heat stress. Birds fed on moringa and mistletoe supplements had higher performance index than birds without supplementation during heat stress condition, while birds fed on mistletoe supplement had the highest survival rate across the treatments. The liveweight, slaughter weight, dressed weight and eviscerated weight of heat stressed birds fed on moringa, phyllanthus and mistletoe supplements were significantly higher than birds on control treatment. Heterophyl/lymphocyte ratio of heat stressed birds without supplement were higher than birds on phytogenic supplements, with least values recorded in phyllanthus and mistletoe fed birds. Birds on phytogenic supplement tend to have lower cholesterol profile, lipid peroxidation and better antioxidant profile than birds on control treatment during heat stress conditions. Mistletoe supplementation in broiler ration enhances the survival rate, as well as promotes growth indices better among the phytogenic supplements. However, phytogenic supplements did ameliorate the negative effects of thermal discomfort on performance, physiological and oxidative stress in heat-stressed broiler chicken.

Impacts of Heat Stress on Rabbit Immune Function, Endocrine, Blood Biochemical Changes, Antioxidant Capacity and Production Performance, and the Potential Mitigation Strategies of Nutritional Intervention

Heat stress has become a widespread concern in the world, which is one of the major environmental stressors and causes substantial economic loss in the rabbit industry. Heat stress leads to multiple damages to the health of rabbits, such as organ damage, oxidative stress, disordered endocrine regulation, suppressed immune function and reproductive disorders, ultimately, induces the decreased production performance and increased mortality. Nutritional approaches, including feeding strategies, adjusting feed formula, and supplementing vitamins, minerals, electrolytes, Chinese herbal medicines, and functional active substances to the feed, were reported to mitigate the detrimental effects of heat stress in rabbits. Therefore, elucidating the damage of heat stress to rabbits; proper management and nutritional approaches should be considered to solve the heat stress issue in rabbits. This review highlights the scientific evidence regarding the effects of heat stress on rabbit's immune function, endocrine, blood biochemical changes, antioxidant capacity and production performance, and the potential mitigation strategies of nutritional intervention to alleviate heat stress in rabbits; which could contribute to develop nutritional strategies in relieving heat stress of rabbits.

Environmental heat stress in rabbits: implications and ameliorations

Profitable production of rabbit meat requires comfortable environment for expression of good quality traits embedded in the genetic components of rabbits. One of the major problems facing rabbit production is heat stress, especially in hot regions of the world. This is further aggravated by global warming being experienced as a result of climate change. Rabbits have no or few sweat glands, complicating the problem of heat dissipation, thereby predisposing the animals to heat stress (HS). Heat stress adversely affect welfare and adaptation, feed consumption and utilization, immunity and health status, growth, reproduction, and milk production in rabbits. Rabbits are homoeothermic animals. They should be capable of body temperature regulation within a narrow range. Thermoregulation is extremely poor in rabbits because of lack of sweat glands. Rabbits are highly sensitive to high ambient temperature. The presence of thick insulator fur on the skin further impedes heat loss in rabbits. This review summarizes data available literatures in the last two decades (2000-2020). Short compilation on management techniques adopted in rearing rabbits under hot conditions is included.

Interaction of supplementary L-carnitine and dietary energy levels on feed utilization and blood constituents in New Zealand White rabbits reared under summer conditions

In the summer season, the harmful effects of high ambient temperatures on rabbit productivity have attained global interest. Therefore, the use of new nutritional strategies to improve heat tolerance in rabbits has become highly needed. In the current experiment, the effect of the addition of L-carnitine (LC) to normal (NE) or high-energy (HE) diets of growing rabbits reared under summer conditions on their productive performance, physiological indicators, and carcass characteristics was assessed. For this purpose, a 2 × 2 factorial arrangement of treatments was used with two dietary levels of energy of 10.00 and 11.22 MJ kg^-1 diet of NE and HE, respectively, which was fortified with 0 or 50 mg of LC kg^-1 of diet (LC0 and LC50, respectively). The feeding trial was conducted using 80 male rabbits (initial body weight, 630.7 ± 1.3 g; 35-day-old), and it lasted for 56 days. Throughout the experiment, the average temperature humidity index was 35.49 reflecting very severe heat stress conditions. Rectal temperature, heart rate, and respiration rate decreased significantly in rabbits fed NE+LC50, HE+LC0, and HE+LC50 diets compared with those fed NE diets without supplementation. Simultaneously, growth indices and feed conversion ratio were enhanced significantly. Rabbits fed NE+LC50, HE+LC0, and HE+LC50 diets showed significantly higher blood hemoglobin, white blood cell counts, total protein, glucose, and red blood cell counts, compared with those fed a NE+LC0 diet. Rabbits fed NE+LC50 and HE+LC50 showed higher economic efficiency. In conclusion, growing rabbits reared under summer conditions responded positively to LC supplementation and HE diets, in terms of the highest growth performance, feed conversion, and physiological and biochemical indicators, making them potentially safe to use.

Heat stress on microbiota composition, barrier integrity, and nutrient transport in gut, production performance, and its amelioration in farm animals

Livestock species experience several stresses, particularly weaning, transportation, overproduction, crowding, temperature, and diseases in their life. Heat stress (HS) is one of the most stressors, which is encountered in livestock production systems throughout the world, especially in the tropical regions and is likely to be intensified due to global rise in environmental temperature. The gut has emerged as one of the major target organs affected by HS. The alpha- and beta-diversity of gut microbiota composition are altered due to heat exposure to animals with greater colonization of pathogenic microbiota groups. HS also induces several changes in the gut including damages of microstructures of the mucosal epithelia, increased oxidative insults, reduced immunity, and increased permeability of the gut to toxins and pathogens. Vulnerability of the intestinal barrier integrity leads to invasion of pathogenic microbes and translocation of antigens to the blood circulations, which ultimately may cause systematic inflammations and immune responses. Moreover, digestion of nutrients in the guts may be impaired due to reduced enzymatic activity in the digesta, reduced surface areas for absorption and injury to the mucosal structure and altered expressions of the nutrient transport proteins and genes. The systematic hormonal changes due to HS along with alterations in immune and inflammatory responses often cause reduced feed intake and production performance in livestock and poultry. The altered microbiome likely orchestrates to the hosts for various relevant biological phenomena occurring in the body, but the exact mechanisms how functional communications occur between the microbiota and HS responses are yet to be elucidated. This review aims to discuss the effects of HS on microbiota composition, mucosal structure, oxidant-antioxidant balance mechanism, immunity, and barrier integrity in the gut, and production performance of farm animals along with the dietary ameliorations of HS. Also, this review attempts to explain the mechanisms how these biological responses are affected by HS.

Potential of watermelon (Citrullus lanatus) to maintain oxidative stability of rooster semen for artificial insemination

Fruits with antioxidant enrichment can be an economically affordable supplement for mitigating oxidative damage prone spermatozoa membrane pathologies. Computer-assisted sperm analyzer and oxidative status were utilized to evaluate the impact of watermelon (Citrullus lanatus) fortification of dextrose saline as diluent for rooster semen and fertility response of hens inseminated. Watermelon juice and dextrose saline were used to formulate diluent of 7 treatments consisting of unextended semen (positive control), 10%, 20%, 30%, 40%, 50% and only dextrose saline (negative control) designated as Treatments 1-7. Pooled semen was obtained from fertile roosters and equilibrated with diluents at ratio 1:2 in the various treatments and were evaluated using computer software coupled microscope and seminal oxidative status assay. 168 laying hens randomly divided into 7 treatment of 8 replicates and 3 hen per replicate. Hen were everted, and semen (2 × 10⁸ Spermatozoa) deposited intra-vagina and eggs collected over 8 weeks to assess fertility and hatchability of eggs laid. The result obtained revealed that watermelon-dextrose saline rooster semen diluent enhanced progressive motility, sperm kinetics and lowered non-progressive motility in T2-T6 compared to T7 over the 3 hours of evaluation. Watermelon addition to rooster semen diluent enhance the antioxidant capacity of rooster semen and lowered lipid peroxide generation. The percentage fertility was highest in T3 (81.01%) and T4 (81.24%) with lowest value obtained in T7 (73.46%). The hatchability of eggs set of hens inseminated with undiluted semen (71.46%) was lower than values for hens inseminated with watermelon inclusive extended semen (75.71%-80.39%). The optimal inclusion of 30%-40% watermelon in dextrose saline diluent enhance rooster semen kinetics, seminal oxidative stability and egg fertility.

Liver Transcriptome Changes of Hyla Rabbit in Response to Chronic Heat Stress

Simple Summary

It has been widely acknowledged in farm animals that environmental heat stress would have comprehensive influences on many kinds of physiological aspects, including the metabolic characteristics, production performances, welfare concerns, etc. The rabbit is a small herbivore and needs to regulate the body temperature in a fine mechanism. Little is known, however, about the genes and pathways that are involved in the regulatory responses under chronic heat stress conditions. In the present study, we investigated the liver transcriptome changes in response to chronic heat stress for Hyla rabbit, that is a commercial meat breed recently introduced into China. We successfully revealed the differentially expressed genes that were significantly enriched in heat stress related biological processes. The results would help us for better understanding the molecular mechanisms underlying physiological responses against heat stress in rabbits.

Abstract

Rabbit is an economically important farm animal in China and also is a widely used animal model in biological researches. Rabbits are very sensitive to the environmental conditions, therefore we investigated the liver transcriptome changes in response to chronic heat stress in the present study. Six Hyla rabbits were randomly divided into two groups: chronic heat stress (HS) and controls without heat stress (CN). Six RNA-Seq libraries totally yielded 380 million clean reads after the quality filtering. Approximately 85.07% of reads were mapped to the reference genome. After assembling transcripts and quantifying gene expression levels, we detected 51 differentially expressed genes (DEGs) between HS and CN groups with thresholds of the adjusted p-value < 0.05 and |log2(FoldChange)| > 1. Among them, 33 and 18 genes were upregulated and downregulated, respectively. Gene ontology analyses further revealed that these DEGs were mainly associated with metabolism of lipids, thyroid hormone metabolic process, and cellular modified amino acid catabolic process. The upregulated ACACB, ACLY, LSS, and CYP7A1 genes were found to be inter-related through biological processes of thioester biosynthetic process, acyl-CoA biosynthetic process, acetyl-CoA metabolic process, and others. Six DEGs were further validated by quantitative real-time PCR analysis. The results revealed the candidate genes and biological processes that will potentially be considered as important regulatory factors involved in the heat stress response in rabbits.