Effects of heat stress on the well-being, fertility, and hatchability of chickens in the northern Guinea savannah zone of Nigeria: a review

Strategies to combat heat stress in poultry production-A review

The effects of heat stress (HS) caused by high temperatures continue to be a global concern in poultry production. Poultry birds are homoeothermic, however, modern-day chickens are highly susceptible to HS due to their inefficiency in dissipating heat from their body due to the lack of sweat glands. During HS, the heat load is higher than the chickens' ability to regulate it. This can disturb normal physiological functioning, affect metabolism and cause behavioural changes, respiratory alkalosis and immune dysregulation in birds. These adverse effects cause gut dysbiosis and, therefore, reduce nutrient absorption and energy metabolism. This consequently reduces production performances and causes economic losses. Several strategies have been explored to combat the effects of HS. These include environmentally controlled houses, provision of clean cold water, low stocking density, supplementation of appropriate feed additives, dual and restricted feeding regimes, early heat conditioning and genetic selection of poultry lines to produce heat-resistant birds. Despite all these efforts, HS still remains a challenge in the poultry sector. Therefore, there is a need to explore effective strategies to address this long-lasting problem. The most recent strategy to ameliorate HS in poultry is early perinatal programming using the in ovo technology. Such an approach seems particularly justified in broilers because chick embryo development (21 days) equals half of the chickens' posthatch lifespan (42 days). As such, this strategy is expected to be more efficient and cost-effective to mitigate the effects of HS on poultry and improve the performance and health of birds. Therefore, this review discusses the impact of HS on poultry, the advantages and limitations of the different strategies. Finally recommend a promising strategy that could be efficient in ameliorating the adverse effects of HS in poultry.

Transcriptomics analysis unveils key potential genes associated with brain development and feeding behavior in the hypothalamus of L-citrulline-fed broiler chickens

High ambient temperature is a major environmental stressor affecting poultry production, especially in the tropical and subtropical regions of the world. Nutritional interventions have been adopted to combat thermal stress in poultry, including the use of amino acids. L-citrulline is a nonessential amino acid that is involved in nitric oxide generation and thermoregulation, however, the molecular mechanisms behind L-citrulline's regulation of body temperature are still unascertained. This study investigated the global gene expression in the hypothalamus of chickens fed either basal diet or L-citrulline-supplemented diets under different housing temperatures. Ross 308 broilers were fed with basal diet (CON) or 1% L-citrulline diet (LCT) from day-old, and later subjected to 2 environmental temperatures in a 2 by 2 factorial arrangement as follows; basal diet-fed chickens housed at 24°C (CON-TN); L-citrulline diet-fed chickens housed at 24°C (LCT-TN); basal diet-fed chickens housed at 35°C (CON-HS), and L-citrulline diet-fed chickens housed at 35°C (LCT-HS) from 22 to 42 d of age. At 42-days old, hypothalamic tissues were collected for mRNA analyses and RNA sequencing. A total of 1,019 million raw reads were generated and about 82.59 to 82.96% were uniquely mapped to genes. The gene ontology (GO) term between the CON-TN and LCT-TN groups revealed significant enrichments of pathways such as central nervous system development, and Wnt signaling pathway. On the other hand, GO terms between the CON-HS and LCT-HS groups revealed enrichments in the regulation of corticosteroid release, regulation of feeding behavior, and regulation of inflammatory response. Several potential candidate genes were identified to be responsible for central nervous system development (EMX2, WFIKKN2, SLC6A4 Wnt10a, and PHOX2B), and regulation of feed intake (NPY, AgRP, GAL, POMC, and NMU) in chickens. Therefore, this study unveils that L-citrulline can influence transcripts associated with brain development, feeding behavior, energy metabolism, and thermoregulation in chickens raised under different ambient temperatures.

The synergistic impact of Spirulina and selenium nanoparticles mitigates the adverse effects of heat stress on the physiology of rabbits bucks

Heat stress has a detrimental effect on animal fertility, particularly testicular functions, including reduced sperm output and quality, which causes an economic loss in the production of rabbits. The present trial investigated the efficacy of dietary Spirulina (SP) (Arthrospira platensis), selenium nanoparticles (SeNPs), and their combination (SP-SeNPs) on semen quality, haemato-biochemical, oxidative stress, immunity, and sperm quality of heat-stressed (HS) rabbit bucks. Sixty mature bucks (APRI line) were distributed into 6 groups of ten replicates under controlled conditions. Bucks in the 1st group (control-NC) were kept under normal conditions (11-22°C; 40-45% RH% = relative humidity), while the 2nd group (control-HS) was kept under heat stress conditions (32±0.50°C; 60-66% RH %). The control groups were fed a commercial pelleted diet and the other four heat-stressed groups were fed a commercial pelleted diet with 1 g SP, 25 mg SeNPs, 1 g SP+25 mg SeNPs, and 1 g SP+50 mg SeNPs per kg diet, respectively. The dietary inclusion of SP, SeNPs, and their combinations significantly increased hemoglobin, platelets, total serum protein, high-density lipoproteins, glutathione, glutathione peroxidase, superoxide dismutase, and seminal plasma testosterone while decreased triglycerides, total cholesterol, urea, creatinine, and malondialdehyde compared with the control-HS. Red blood cells, packed cell volume, serum albumin, and testosterone significantly increased, while SeNPs, SP+SeNPs25, and SP+SeNPs50 significantly decreased low-density lipoproteins, aspartate, and alanine amino transferees. Total antioxidant capacity substantially increased in serum and seminal plasma, while seminal plasma malondialdehyde decreased in 25 or 50 mg of SeNPs+SP/kg groups. All supplements significantly improved libido, sperm livability, concentration, intact acrosome, membrane integrity, total output in fresh semen, and sperm quality in cryopreserved semen. SP-SeNPs50 had higher synergistic effect than SP-SeNPs25 on most different variables studied. In conclusion, the dietary inclusion of SP plus SeNPs50 has a synergistic effect and is considered a suitable dietary supplement for improving reproductive efficiency, health, oxidative stress, and immunity of bucks in the breeding strategy under hot climates.

Chronic Heat Stress Part 2: Increased Stress and Fear Responses in F1 Pekin Ducks Raised from Parents That Experienced Heat Stress

The effects of HS on the welfare of poultry have been reported to have a transgenerational effect on phenotype plasticity. The goal of our experiment was to determine whether parental exposure to HS would impair the performance, HPA axis response, or behavior of their offspring. We treated adult drakes and hens (n = 80 ducks/treatment) at peak lay with HS or the control temperature for 3 weeks and incubated eggs collected from the last 3 days of the experiment. We utilized 76 ducklings/parental treatment group: control (CON-F1) and HS (HS-F1). Weekly data for body weights, body condition scores (BCSs), and novel object test (NOT) were collected. At 3 weeks of age, the ducks (n = 6/treatment) were subjected to adrenocorticotropic hormone (ACTH/cosyntropin, 0.0625 mg/kg) challenge or vehicle as the control. Blood samples were collected at 0, 1, 2, 3, and 4 h relative to treatment for serum glucocorticoid and heterophil-to-lymphocyte ratio (HLR) analyses. All injected birds were euthanized with pentobarbital on the second day relative to ACTH administration, and the spleen and bursa were removed and weighed immediately. Duck level analyses were completed using one- or two-way ANOVA as appropriate. BCSs were analyzed using a chi-squared test. The HS-F1 ducks had a lower hatch weight (p < 0.05) compared with the CON-F1 ducks but no significant difference in growth rates during the 5-week period. NOT (n = 4) analyses showed that the HS-F1 ducks had a greater fear response (p < 0.001) compared with the CON-F1 ducks. Similarly, an ACTH stimulation test showed that the HS-F1 ducks had significantly (p < 0.05) heightened corticosterone and HLR responses compared with the CON-F1 ducks. The HS-F1 ducks showed altered baseline and ACTH-stimulated levels of cortisol compared with the controls. Our data suggest that parental exposure to HS impacts the HPA response and fearfulness of the F1 generation in Pekin ducks.

Blood hematology and biochemical of four laying hen strains exposed to acute heat stress

This study is aimed at defining physiological responses to heat stress (HS) in four different lines to better understand the underlying mechanisms of various responses in these genotypes when exposed to heat for a short period. At the age of 30 weeks, 176 laying hens (44 each from the Fayoumi, Golden Sabahia, White Leghorn, and Lohman Brown) were allotted to 2 groups (thermoneutral temperature (26.0 ± 1 °C) and HS (35 ± 1 °C) with relative humidity 55 ± 5% for 6 h/day). Blood samples were collected after 6 h of heat. According to the findings of this study, acute HS increased the concentration of LH in hens by 20.2% while decreasing the concentration of FSH by 4.24. Genotype was found to have a significant effect on blood hematology and most blood biochemical. Significant differences were found between heat stress and genotype in most of the blood parameters. Golden sabahia laying hens had significantly higher WBC, IgY, and LH levels than other groups under HS. The findings of the current study suggested that Lohman Brown was less tolerant to acute HS than another genotype.

Chronic heat stress part 1: Decrease in egg quality, increase in cortisol levels in egg albumen, and reduction in fertility of breeder pekin ducks

Global warming poses detrimental effects on poultry production leading to substantial economic losses. The goal of our experiment was to test the hypothesis that heat stress (HS) would alter welfare and egg quality (EQ) of breeder ducks. Furthermore, we wanted to test if HS would increase cortisol levels in egg albumen. Adult Pekin ducks were randomly assigned to two different rooms at 85% lay with 60 hens and 20 drakes per room. Baseline data including body weight, body condition scores (BCS), and egg production/quality were collected the week preceding heat treatment. Ducks were subjected to cyclic HS of 35°C for 10h/day and 29.5°C for the remaining 14h/day for 3 weeks while the control room was maintained at 22°C. Eggs were collected daily and analyzed weekly for quality assessment, and for albumen glucocorticoid (GCs) levels using mass spectrometry. One week before the exposure to HS, 10 hens and 5 drakes were euthanized and the same number again after 3 weeks and birds necropsied. Data analyses were done by 1- or 2-way ANOVA as appropriate with a Tukey-Kramer post hoc test. BCS were analyzed using a chi-squared test. A p ≤ 0.05 was considered significant. Circulating levels of corticosterone were significantly (p < 0.01) elevated at week 1 only in the HS hens. The circulating levels of cortisol increased significantly at week 1 and 2 (p < 0.05), and week 3 (p < 0.01) in the hens and at weeks 2 and 3 only (p < 0.05) in the drakes. Feather quality scores (p < 0.01), feather cleanliness scores (p < 0.001) and footpad quality scores (p < 0.05) increased significantly in the HS group. HS elicited a significant (p < 0.001) decrease in egg production at weeks 1 and 3. Hens in the HS group showed significantly decreased BW (p < 0.001) and number of follicles (p < 0.05). Shell weight decreased significantly at week 1 only (p < 0.05) compared to controls. Yolk weight decreased significantly at week 3 (p < 0.01) compared to controls. HS elicited a significant increase in albumen cortisol levels at week 1 (p < 0.05) and week 3 (p < 0.05). Thus, cortisol may provide critical information to further understand and to improve welfare.

Influence of Heat Stress on Poultry Growth Performance, Intestinal Inflammation, and Immune Function and Potential Mitigation by Probiotics

Simple Summary

The poultry industry sustains severe economic loss under heat stress conditions. Heat stress adversely affects the productivity, physiological status, and immunity of birds. To date, several mitigation measures have been adopted to minimize the negative effects of heat stress in poultry. Nutritional strategies have been explored as a promising approach to mitigate heat stress-associated deleterious impacts. Of these, probiotic feeding has a strong potential as a nutritional strategy, and this approach warrants further investigation to improve thermotolerance in poultry.

Abstract

Heat stress has emerged as a serious threat to the global poultry industry due to climate change. Heat stress can negatively impact the growth, gut health, immune function, and production and reproductive performances of poultry. Different strategies have been explored to mitigate heat stress in poultry; however, only a few have shown potential. Probiotics are gaining the attention of poultry nutritionists, as they are capable of improving the physiology, gut health, and immune system of poultry under heat stress. Therefore, application of probiotics along with proper management are considered to potentially help negate some of the negative impacts of heat stress on poultry. This review presents scientific insight into the impact of heat stress on poultry health and growth performance as well as the application of probiotics as a promising approach to alleviate the negative effects of heat stress in poultry.

Influence of Heat Stress on Intestinal Epithelial Barrier Function, Tight Junction Protein, and Immune and Reproductive Physiology

The potential threat of global warming in the 21^st century is on the ecosystem through many aspects, including the negative impact of rising global temperature on the health of humans and animals, especially domestic animals. The damage caused by heat stress to animals has been more and more significant as the worldwide climate continues to rise, along with the breeding industry's expanding scale and stocking density, and it has become the most important stress-causing factor in southern China. In this review, we described the effects of heat stress on animal immune organs and immune system. The much-debated topic is how hyperthermia affects the tight junction barrier. Heat stress also induces inflammation in the body of animals causing low body weight and loss of appetite. This review also discussed that heat stress leads to hepatic disorder, and it also damages the intestine. The small intestine experiences ischemia, and the permeability of the intestine increases. Furthermore, the oxidative stress and mitogen-activated protein kinase (MAPK) pathways have a significant role in stress-induced cellular and organ injury. The study has shown that MAPK activity in the small intestine was increased by heat stress. Heat stress caused extreme small intestine damage, enhanced oxidative stress, and activated MAPK signaling pathways.

‘Can They Take the Heat?’—The Egyptian Climate and Its Effects on Livestock

Egypt already has conditions in summer that cause heat stress for livestock, and predicted climate changes suggest that these will be exacerbated over the course of this century. As well, extreme climatic events make the mitigation of climate change difficult but important to understand. Apart from neonates, farm animals have upper critical temperatures in the region of 25–30 °C, whereas temperatures in summer regularly exceed 40 °C for prolonged periods. The temperature and humidity data were collected half hourly to calculate Temperature Humidity Indices and demonstrate that Egyptian livestock at two centers of livestock production in the country would experience heat stress in summer for extended periods of each day. The impact of rising temperatures on livestock in Egypt was reviewed, where extensive resources to mitigate the impact are not often available. It was found that, although there are some prospects to mitigate some heat stress, by using agroforestry systems of production for example, these are unlikely to have a major impact, and reduced food security may ensue over the course of this century.

Climate Change and Livestock Production: A Literature Review

Globally, the climate is changing, and this has implications for livestock. Climate affects livestock growth rates, milk and egg production, reproductive performance, morbidity, and mortality, along with feed supply. Simultaneously, livestock is a climate change driver, generating 14.5% of total anthropogenic Greenhouse Gas (GHG) emissions. Herein, we review the literature addressing climate change and livestock, covering impacts, emissions, adaptation possibilities, and mitigation strategies. While the existing literature principally focuses on ruminants, we extended the scope to include non-ruminants. We found that livestock are affected by climate change and do enhance climate change through emissions but that there are adaptation and mitigation actions that can limit the effects of climate change. We also suggest some research directions and especially find the need for work in developing country settings. In the context of climate change, adaptation measures are pivotal to sustaining the growing demand for livestock products, but often their relevance depends on local conditions. Furthermore, mitigation is key to limiting the future extent of climate change and there are a number of possible strategies.

Effects of heat stress and a low energy diet on blood parameters and liver hsp70 and iNOS gene expressions in local chickens

Two experiments were conducted to compare effects of heat stress and its combination with low dietary energy on blood indices, liver hsp70 and iNOS gene expressions in three Tanzanian local chicken ecotypes. In experiment one, five weeks old Kuchi (K), Ching'wekwe (C) and Morogoro medium (M) were randomly allocated to separate pens in a 3 × 2 factorial design in two adjacent rooms with controlled temperature. The study had three replicates consisting of 39 chickens per room, 13 per ecotype per pen making a total of 234 chickens. In one room, temperature was maintained at 26.5 ± 0.5 °C while in another it was maintained at 32±1 °C for 7 days and thereafter 37±1 °C for 10 days. A similar design was used in experiment two except that chickens were fed 55% less energy. In experiment one, serum corticosterone levels increased (p<0.05) in C and K. Gene expressions for hsp70 and iNOS were unchanged though hsp70 levels for K were higher (p<0.05). In experiment two, corticosterone levels were significantly elevated (p<0.05) in all ecotypes. Heterophil/lymphocyte ratios were markedly increased and changes in Hb and Hct at higher temperatures showed ecotype differences. Serum triglycerides were significantly reduced in all ecotypes. Hsp70 and iNOS levels were up-regulated in all ecotypes with levels in K higher (p<0.05) than in M. In both experiments, there were marked reductions in serum total protein. These results suggest that ecotype-based differences exist in local chickens’ responses to heat stress and its combination with low energy diets. M and C demonstrated better tolerance than K when only heat stress was applied but a synergistic effect of heat stress and low dietary energy suggested M is more tolerant.

Delay in puberty is dependent on heat shock protein B1 expression in native cross layers of Punjab under heat stress

Small heat shock protein B1 (HspB1) has been reported to play an essential role in thermotolerance. This study aimed to determine a correlation (if any) between HspB1 expression and age at first egg lay (puberty) in a native cross-layer poultry of Punjab under heat stress. Forty native cross-layer birds were reared in two different seasons, viz. summer (THI was more than 27), classified as the heat-stressed group (n = 20) and winter season (THI was less than 21), classified as the control group (n = 20). Blood was collected from both the groups of birds in their 15^th week of age and at puberty. Serum catalase and superoxide dismutase activities, reduced glutathione and corticosterone concentration and lipid peroxidation were measured to assess the oxidative stress in both the groups of birds. The serum antioxidants significantly decreased whilst corticosterone levels and lipid peroxidation significantly elevated in birds in response to summer heat stress. Moreover, in summer season, the activities of the antioxidant enzymes further decreased and lipid peroxidation further increased significantly in birds from their pre-pubertal stage to puberty, which was not observed during the winter season. A clone of chicken HspB1 in BL21 (DE3) cells was revived, and recombinant HspB1 was purified using Ni-NTA agarose column. Serum HspB1 concentration was estimated in different groups of birds by indirect ELISA that has been standardized using the recombinant chicken HspB1. Compared to the control, birds under heat stress had significantly higher serum HspB1 levels. The delay in puberty of all the heat-stressed birds was significantly associated with the increase in their serum HspB1 levels. Taken together, the expression of HspB1 was found to be associated with age at puberty in the native cross poultry layers of Punjab.

Effect of prenatal ambient temperature on the performance physiological parameters, and oxidative metabolism of Japanese quail (Coturnix coturnix japonica) layers exposed to heat stress during growth

A strategy to mitigate the negative effects of stress on animals is to enhance their ability to beneficially respond to stressful conditions. This study aimed to assess whether prenatal ambient temperature influences the response of Japanese quail (Coturnix coturnix japonica) chicks to environmental challenges during growth. The experiment was conducted in a 2 × 2 factorial arrangement: two temperature conditions for the mothers (thermoneutral and heat stress by continuous exposure to 32 °C) and two offspring ambient temperature conditions (thermoneutral and heat stress by intermittent exposure to 34 °C for 6 h/day from 15 to 35 days of age). Heat stress in mothers led to lower laying rate, egg mass, expression of methionine sulfoxide reductase A (MSRA) gene, and antioxidant capacity as well as higher chick mortality rate (1-15 days of age). Maternal heat stress led to lower weight gain and total antioxidant capacity and higher feed conversion ratio. Maternal temperature × Offspring temperature interaction effects were observed on carbonylated protein content and HSP70, GSS, and MSRA gene expression. It was observed that, for chicks hatched from heat-stressed mothers, exposure to heat stress led to higher carbonylated protein content and HSP70 expression than exposure to thermoneutral conditions. Maternal heat stress was also responsible for increasing GSS expression in chicks grown under thermoneutral conditions. Chicks hatched from non-stressed mothers and subjected to heat stress had higher MSRA expression compared to chicks maintained in a thermoneutral environment. Our results show that, although maternal heat stress had no negative effects on performance or oxidative metabolism of offspring grown under thermoneutral conditions, it was associated with lower performance and higher protein oxidation in offspring exposed to heat stress during growth. These results could be due in part to alterations in the expression of genes related to antioxidant capacity.

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.

Heat stress and poultry production: impact and amelioration

Globally, the poultry industry is gaining significant importance among the agricultural and its allied sectors. However, heat stress was found to negatively affect the poultry production particularly in the tropical regions. This review is therefore an attempt to generate information pertaining to the impacts of heat stress on poultry production and its amelioration. Heat stress reduces the growth, reproductive performance, and egg production in poultry birds. The reduction in productive potential of poultry birds on exposure to heat stress may be attributed to the deviation of energy resources from production to adaptation pathway. There are different approaches pertaining to relieving the adverse impacts of heat stress on poultry production. These approaches can be broadly categorized under genetic, management, and nutritional strategies. These approaches may reduce the negative effects of heat stress and enhance the productive performance of poultry birds. The management strategies include appropriate shelter design, providing shade, using sprinklers, implementing cooling devices, and using fans and ventilation systems. The recommended floor space for mature birds weighing 1.7 kg is 0.06 m²/bird while it is 0.13 m²/bird for the birds weighing 3.5 kg with 27.8 kg/m² bird density in either case. The nutritional interventions comprise ration balancing and providing essential micronutrients to improve the productive and reproductive performance in poultry birds. Fat, antioxidants, yeast, and electrolyte supplementations are some of the most commonly used nutritional strategies to ensure optimum production in the poultry industry. Furthermore, providing adequate water supply and disease surveillance measures may help to ensure optimum meat and egg production in the birds. The advanced biotechnological tools may aid to identify suitable genetic markers in poultry birds which might help in developing new strains of higher thermo-tolerance by designing suitable breeding program involving marker-assisted selection. These strategies may help to optimize and sustain poultry production in the changing climate scenario.

Climate change and heat stress: Impact on production, reproduction and growth performance of poultry and its mitigation using genetic strategies

Heat stress is an important environmental determinant which adversely affects the performance of poultry worldwide. The present communication reviews the impact of heat stress on production, reproduction and growth performance of poultry, and its alleviation using genetic strategies. The adverse effects of high environmental temperature on poultry include decrease in growth rate, body weight, egg production, egg weight, egg quality, meat quality, semen quality, fertility and hatchability, which cause vast financial losses to the poultry industry. High ambient temperature has an antagonistic effect on performance traits of the poultry. Thus, selection of birds for high performance has increased their susceptibility to heat stress. Additionally, heat burden during transportation of birds from one place to another leads to reduced meat quality, increased mortality and welfare issues. Molecular markers are being explored nowadays to recognize the potential candidate genes related to production, reproduction and growth traits for selecting poultry birds to enhance thermo-tolerance and resistance against diseases. In conclusion, there is a critical need of formulating selection strategies based on genetic markers and exploring more genes in addition to HSP25, 70, 90, H1, RB1CC, BAG3, PDK, ID1, Na, F, dw and K responsible for thermoregulation, to improve the overall performance of poultry along with their ability to tolerate heat stress conditions.

Organ Histopathology and Hematological Changes Associated With Heat Exposure in Australian Desert Birds

An inability of the body to appropriately respond to extreme temperatures will result in pathological changes to vital organs and adverse hematological changes. Mild heat exposure of a bird to a temperature above the zone of thermoneutrality can induce subclinical heat stress, which may be a precursor to illness. The ability to identify subtle changes that may be associated with subclinical heat stress can be important in early diagnosis and treatment of heat stress in birds. Pathological changes to internal body organs, post-heat exposure, were microscopically examined in 13 budgerigars (Melopsittacus undulatus), 15 zebra finches (Taeniopygia guttata), and 8 diamond doves (Geopelia cuneata) as model species for the bird orders Psittaciformes, Passeriformes, and Columbiformes, respectively. There was mild to moderate congestion of the lungs of 28/36 birds examined, including all of the budgerigars and diamond doves. In 8/15 zebra finches no significant lung congestion was noted. Interstitial and pulmonary hemorrhage was in observed in one diamond dove. The most common hepatic pathologic change identified was micro- and macro-vesicular hepatocellular vacuolation (4/15 zebra finches, 5/13 budgerigars, and 8/8 diamond doves). There was mild to moderate congestion in the kidneys of 1/15 zebra finch, 2/ 13 budgerigars, and 4/8 diamond doves, as well as in the gastrointestinal tract of 1/15 zebra finch and 7/8 budgerigars. Budgerigars showed a decrease in hematocrit and a significant change in the numbers of heterophils and lymphocytes following heat exposure. The basophil population of cells remained relatively stable in both budgerigars and diamond doves. These findings indicate avian species differences in body organ and hematological changes following exposure to similar elevations in environmental temperatures.

Analysis of the metabolic pathways affected by hot-humid or dry climate based on fecal metabolomics coupled with serum metabolic changes in broiler chickens

Air temperature and relative humidity (RH) are 2 important climatic elements that affect animal welfare and health. The prevailing hot and humid or dry climate is one of the major constraints for optimum poultry production, especially in the tropics and subtropical regions. Many studies have suggested that exposure to hot-humid or dry climate is associated with a high risk of metabolic imbalance; however, the underlying metabolic changes caused by low or high RH climate is not yet well understood. Therefore, we used a comprehensive ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry–based metabolic profiling of fecal samples to explore the effects of hot-humid and dry climate on metabolic pathways in broilers. A total of 180 twenty-eight-day-old Arbor Acres broilers were randomly allocated to 3 treatments, each containing 6 replicates of 10 birds per treatment, using a completely randomized design. Birds were reared at 35, 60, or 85% RH at 32°C (temperature increased by 3°C every 3 d from 20°C to 32°C within 15 d: 20°C, 23°C, 26°C, 29°C, 32°C) for 15 d. Results showed that significant changes in the levels of 36 metabolites were detected. Evidence of changes in gluconeogenesis associated to pyruvate metabolism, galactose metabolism, and ABC transporter was observed. In addition, hot-humid and dry stress also affected the protein translation process caused by aminoacyl-tRNA biosynthesis, which may be associated with protein synthesis and hormone secretion disorders. Furthermore, we observed significant changes in primary bile acid biosynthesis and taurine and hypotaurine metabolism, which indicated that fat synthesis was affected. We also observed significant changes in arginine and proline metabolism and histidine metabolism, which were associated with skin vasodilation and blood flow. These results provide biochemical insights into metabolic changes due to hot-humid or dry climate.

Heat shock protein B1 expression is associated with age at sexual maturity in Rhode Island Red and Punjab Red layers under heat stress

Heat shock proteins (Hsp) aid in protein folding and also to combat stress in all cellular organisms. HspB1 is a member of the small HSP family that has a significant role in thermo-tolerance. In this study, we aimed to determine the relationship (if any) between age at sexual maturity of layer poultry (Rhode Island Red and Punjab Red) and HspB1 expression both at mRNA and protein levels under heat stress. The mRNA expression of hspB1 was checked by real-time PCR. Delay in sexual maturity of the birds was found to be directly associated with the hspB1 mRNA expression in both the bird varieties under heat stress. No significant regression (association) of hspB1 mRNA expression with age at sexual maturity was observed in case of control, non-heat stressed birds. The serum levels of HspB1 were measured by indirect ELISA, using recombinant HspB1 that was expressed using pET-32b(+) vector in BL21(DE3) cells. Serum HspB1 concentration increased significantly (p ≤ 0.001) in heat-stressed birds as compared with control ones. A significant association was found between the increase in serum HspB1 concentration and delay in sexual maturity of all the birds under heat stress while no such association was found in control birds. In conclusion, HspB1 mRNA and protein expression were found to be associated with age at sexual maturity in Punjab Red and RIR layers under heat stress.

Pathophysiological Changes in Female Rats with Estrous Cycle Disorder Induced by Long-Term Heat Stress

High-temperature exposure is detrimental to women's reproductive health; however, the impact caused by long-term high temperature is not comprehensive, and a stable model of estrous cycle disorder induced by a high temperature is yet lacking. Herein, we aimed to establish a stable and effective model of estrous cycle disorder in female rats induced by long-term heat stress to study its physiological and pathological characteristics and explore the underlying mechanism. In the present study, female Sprague-Dawley rats with normal estrous cycles were exposed to the temperature of 38 ± 0.5°C, relative humidity (RH) of 55 ± 5% (2 h/d, 1 time/d) hot cabin at more than 90 days. Consequently, after long-term heat stress, no difference was detected in body weight and rectal temperature, but the estrus cycle was prolonged, the uterine organ index was increased, pathological changes occurred, the increase latitude of stress hormones heat shock protein 70 (Hsp70) and corticosterone (CORT) decreased, estradiol (E₂) and luteinizing hormone (LH) levels decreased, follicle stimulating hormone (FSH) and prolactin (Prl) levels increased, gonadotropin-releasing hormone (GnRH) and thyroid hormone (T₄) showed no difference, and insulin (INS) decreased significantly. Moreover, the mRNA expression of the sex hormone receptor in the uterus and ovary was altered. Therefore, the estrous cycle disorder in female rats can be induced by regular heat stress for 90 days, which can be considered the pioneer method. Subsequently, prominent physiological and pathological characteristics and disruption in the hypothalamic-pituitary-gonadal (HPG) axis were noted.

Effects of in ovo injection of nano-selenium and nano-zinc oxide and high eggshell temperature during late incubation on antioxidant activity, thyroid and glucocorticoid hormones and some blood metabolites in broiler hatchlings

This experiment was conducted to evaluate the effects of in ovo injection of nano-selenium (Nano-Se) and nano-zinc oxide (Nano-ZnO) and high eggshell temperature (EST) during late incubation on blood parameters of broiler hatchlings. A total of 750 fertile eggs, were weighed and randomly distributed among 5 treatment groups on each of 5 replicate tray levels. The injection was performed on 17 d of incubation. Treatments included of: 1) Eggs not injected and incubated at normal EST (control); 2) Eggs not injected and incubated at high EST; 3) Eggs injected NaCl solution and incubated at high EST (sham); 4) Eggs injected NaCl solution containing 40 µg Nano-Se and incubated at high EST; 5) Eggs injected NaCl solution containing 500 µg Nano-ZnO and incubated at high EST. EST of 37.8ºC (normal) or 38.9ºC (high) was applied from d 19 to 21 of incubation. In ovo injection of Nano-Se and Nano-ZnO significantly increased activity of GSH-Px and SOD and total protein, but decreased the levels of corticosterone, cortisol, T4 and T3 at high EST. Injection of Nano-Se and Nano-ZnO had a significant role in alleviating the negative effects of high temperature incubation and heat stress by increased antioxidant activity and reduced oxidative stress.

Genetic polymorphisms in part of intron 7 and exon 8 of HSP90AA1 gene and its association with heat tolerance traits in two exotic layer chicken strains

Chickens, like other vertebrates, react to stress conditions through their cultured cells by expressing heat shock proteins (HSPs). Genetic association of single-nucleotide polymorphisms (SNPs) in HSPs with desirable traits will reveal their importance as potential genetic markers. Blood samples were collected from 50 birds per strain for DNA extraction, polymerase chain reaction amplification and sequencing of the HSP90AA1 gene. SNPs were detected using Codoncode Aligner. Association of each SNP with heat tolerance traits was analysed using generalized linear model procedure of SAS. A total of seven SNPs were detected, four SNPs; A7T, A160T, T223A and C134T were detected in part of intron 7 to exon 8 of HSP90AA1 gene of BRD while three A160T, T223A and C134T were detected in HYL. SNPC134T, a synonymous variant, was detected in exon 8. Only SNPA7T was in Hardy-Weinberg equilibrium (X² = 0.03) but had no association with the traits measured. Polymorphic information content calculated showed SNPA160T to be moderately polymorphic; other SNPs were lowly polymorphic. Heterozygosity for SNPs-A160T and T223A of BRD showed moderate genetic variation while the other SNPs and those in HYL recorded low genetic variation. The study concluded that the SNPs detected were majorly lowly polymorphic and also the SNP locus A7T in intron 7 of HSP90AA1 of BRD had no genetic association with heat tolerance traits.

Changes in feed consumption and water intake among broiler chickens subjected to melatonin treatment during the hot-dry season

The experiment was conducted to evaluate changes in feed consumption and water intake among broiler chickens subjected to melatonin treatment during the hot-dry season. A total of 300 broiler chicks were selected and assigned into three groups, by simple random sampling, comprising 100 chicks each: group I was exposed to natural photoperiod of about 12-h light and 12-h darkness cycle (12D/12L), without melatonin supplementation; group II was kept under 24-h continuous lighting (CL), without melatonin supplementation; and group III was raised under 24-h CL and administered daily with melatonin orally at 0.5 mg/kg (CL + MEL). Live weight (LW), feed consumption, and water intake for each group were obtained at weekly intervals over a period of 8 weeks. On day 42 of age, the LW of 2420 ± 50 g/bird was obtained in group III administered with melatonin (CL + MEL), while LW values recorded in the 12D/12L and CL groups not administered with melatonin were 1470.00 ± 30.00 and 1907.00 ± 38.00 g/bird, respectively. The mean weight gain in CL + MEL (345.00 ± 21.01 g) was significantly (P < 0.05) higher than those of the 12D/12L (244.99 ± 18.67 g) and CL (307.48 ± 18.14 g) groups. Feed consumptions were significantly (P < 0.05) different in all the groups. Group II, raised on CL without melatonin supplementation, had the highest feed consumption value of 25.14 ± 0.51 g/bird from day 14, and attained the peak value of 206.77 ± 7.82 g/bird at day 56. The highest overall amount of water intake was recorded in the melatonin-treated group. In conclusion, melatonin administration to broiler chickens enhanced water intake but decreased feed consumption with increase in LW during the hot-dry season.

Effect of Supplementation with Trimethylglycine (Betaine) and/or Vitamins on Semen Quality, Fertility, Antioxidant Status, DNA Repair and Welfare of Roosters Exposed to Chronic Heat Stress

In this study, we investigated the influence of betaine (Bet, 1000 mg/kg), with or without vitamin C (VC, 200 mg/kg ascorbic acid) and/or vitamin E (VE, 150 mg/kg α-tocopherol acetate) on semen quality, seminal and blood plasma constituents, antioxidants' status, DNA repair, and the welfare of chronic heat stress (CHS)-exposed roosters. A total of 54 roosters were divided into six groups of nine replicates. One group was kept under thermoneutral conditions, whereas the other five were kept under CHS. One of the five groups served as an unsupplemented CHS group, and was fed with a basal diet. The other four CHS groups were supplemented with Bet, Bet + VC, Bet + VE, and Bet + VC + VE, respectively. Our data indicate that supplementation with Bet, Bet + VC, Bet + VE, and Bet + VC + VE, resulted in complete recovery of the CHS effect on sperm concentration and livability, semen pH, and fertility compared to the thermoneutral group. Seminal plasma total antioxidant capacity (TAC) was significantly (p < 0.05) increased with Bet, with or without vitamins, compared to the thermoneutral and CHS groups. Urea and blood plasma malondialdehyde (MDA) were totally recovered with Bet, with or without vitamin treatments. Both the jejunum and ileum DNA were partially recovered following Bet, with or without vitamin supplementation. In conclusion, Bet, at 1000 mg/kg feed, may be a useful agent for increasing semen quality, fertility, welfare, and to improve the breeding strategy of breeder males in hot climates.

Avian Liver: The Forgotten Organ

Simple Summary

The liver is a multi-purpose organ, with involvement in bile secretion, and lipid, carbohydrate and protein metabolism, as well as a number of other metabolic functions. This organ can adapt easily to changes in feed and the environment. Being at the centre of a number of digestive, metabolic and productive activities, it is essential to have a better understanding of this organ and the factors affecting liver functionality.

Abstract

Despite having huge responsibilities in avian species, published reports on the influence of dietary factors and other possible constraints on the size, development and function of liver are limited. Consideration of the factors that could influence and alter liver function is therefore of critical relevance. In the current review, aspects of liver structure and function, and the influence of feed restriction, anti-nutritional factors, structural components and feed additives on liver are discussed. Effects of feed technology techniques such as thermal treatment and pelleting, feed particle size and whole grain feeding on the liver are also reviewed. A discussion of lipogenesis and lipid storage in poultry is presented to provide a better understanding and to differentiate the normal pathways of lipid metabolism from abnormal (i.e., disordered) pathways. The liver is the main site of fat synthesis in poultry, but under certain conditions, excessive fat can accumulate in the liver and cause problems. Factors contributing to the fatty liver syndrome are also examined.

Physiological responses to heat stress in two genetically distinct chicken inbred lines

High ambient temperature is one of the most important environmental factors negatively impacting poultry production and health. Genetics is an important contributor in mitigating the stress response to heat. Two genetically distinct highly inbred lines of similar body size (Leghorn and Fayoumi) were characterized for phenotypic differences in response to heat. At 14 days of age, birds were exposed to 38°C with 50% humidity for 4 hours, then 35°C until the conclusion of the experiment. Non-treated individuals were kept at 29.4°C for the first week and then 25°C throughout the experiment. Birds in the heat-stress group were inoculated at day (d) 21 with Newcastle disease virus (NDV) La Sota strain to investigate the effects of heat stress and NDV infection. Thirteen blood parameters were measured using the iSTAT blood analyzer at three stages: 4 h, 6 d, and 9 d post heat-stress treatment, representing acute heat (AH) exposure, chronic heat (CH1) exposure, and chronic heat exposure after virus infection (CH2), respectively. Most blood parameters were significantly changed with heat stress in Leghorns at AH and in Fayoumis at CH1 and CH2. The Leghorn line had significant acute responses with disrupted acid-base balance and metabolic disorders. The heat-resilient Fayoumis maintained a relatively well-balanced acid-base balance. The current study provides the comprehensive profile of biomarker signatures in blood associated with heat tolerance and suggests that PO2, TCO2, HCO3, and base excess can be served as potential biomarkers that can be used to genetically improve heat tolerance in poultry.

Daily rhythms of cloacal temperature in broiler chickens of different age groups administered with zinc gluconate and probiotic during the hot-dry season

The aim of the experiment was to evaluate effects of zinc gluconate (ZnGlu) and probiotic administration on the daily rhythm of cloacal temperature (t_cloacal) in broiler chickens of different age groups during the hot-dry season. One-day-old broiler chicks (n = 60) were divided into groups I-IV of 15 chicks per group, and treated for 35 days: Group I (control) was given deionized water; Group II, ZnGlu (50 mg/kg); Group III, probiotic (4.125 × 10⁶ cfu/100 mL), and Group IV, ZnGlu (50 mg/kg) + probiotic (4.125 × 10⁶ cfu/100 mL). Air dry-bulb temperature (t_db), relative humidity (RH), and temperature-humidity index (THI) inside the pen, and t_cloacal of each broiler chick were obtained bihourly over a 24-h period; on days 21, 28, and 35 of the study. Values of t_db (32.10 ± 0.49°C), RH (49.94 ± 1.91%), and THI (38.85 ± 0.42) obtained were outside the thermoneutral zone for broiler chickens, and suggested that the birds were subjected to heat stress. Application of the periodic model showed disruption of daily rhythm of t_cloacal in broilers on day 21, which was synchronized by probiotic administration. The administration of probiotics or ZnGlu + probiotics to a greater extent decreased the mesor and amplitude, delayed the acrophases of t_cloacal in broilers, especially at day 35, as compared to the controls. Overall, the t_cloacal values in broiler chickens administered with probiotic alone (41.25 ± 0.05°C) and ZnGlu + probiotic (41.52 ± 0.05°C) were lower (P < 0.001) than that of the controls (41.94 ± 0.06°C). In conclusion, probiotic alone synchronized t_cloacal of the birds at day 21, and, in addition, decreased t_cloacal response most, followed by its coadministration with ZnGlu, the antioxidants may be beneficial in modulating daily rhythmicity of t_cloacal and alleviating adverse effects of heat stress on broiler chickens during the hot-dry season.

Behavioral and hematological responses of broiler chickens administered with betaine and ascorbic acid during hot-dry season

Heat stress is a major problem in poultry production in tropical regions. Assessing the impact of thermally stressful environmental conditions on the welfare of broiler chickens is of great importance. Behavioral responses in a novel environment and hematology of broiler chickens administered with betaine and/or ascorbic acid (AA) during the hot-dry season were evaluated. Broiler chickens were randomly divided into four groups: Group I (control) was given sterile water, Group II was given betaine, Group III was given AA, and Group IV received betaine + AA orally and daily for 42 days. An open-field test was used to assess behavior. Hematological parameters were obtained using a hematology auto-analyzer. The natural environmental conditions were predominantly outside the thermoneutral zone for broiler chickens. Results demonstrated that treated groups exhibited improved ability to adjust faster to a new environment and better hematological responses than controls, evidenced by enhanced behavioral responses, oxygen-carrying capacity, and immune responses of broiler chickens under unfavorable environmental conditions. Betaine and/or AA administration to broiler chickens improved some behavioral responses, hemoglobin concentrations, packed cell volume, and total leukocyte count during the hot-dry season.

Enhancement of sperm motility and viability by turmeric by-product dietary supplementation in roosters

Improving sperm motility and viability are major goals to improve efficiency in the poultry industry. In this study, the effects of supplemental dietary turmeric by-product (TBP) from commercial turmeric production on sperm motility, viability, and antioxidative status were examined in domestic fowl. Mature Rhode Island Red roosters were divided into two groups - controls (groupC) without TBP administration and test subjects (groupT) fed a basal diet supplemented with 0.8g of TBP/day in a temperature-controlled rearing facility (Experiment 1) and 1.6g/day under heat stress (Experiment 2) for 4 weeks. In Experiment 1, TBP dietary supplementation increased the sperm motility variables straight-line velocity, curvilinear velocity, and linearity based on a computer-assisted semen analysis, 2 weeks following TBP supplementation. In Experiment 2, using flow cytometry, sperm viability at 3 and 4 weeks following TBP supplementation was greater in Group T than C, and this increase was consistent with a reduction in reactive oxygen species (ROS) production at 2 and 4 weeks. The results of both experiments clearly demonstrate that dietary supplementation with TBP enhanced sperm motility in the controlled-temperature conditions as well as sperm viability, and reduced ROS generation when heat stress prevailed. Considering its potential application in a range of environments, TBP may serve as an economical and potent antioxidant to improve rooster fertility.

Thermal manipulation during embryogenesis improves certain semen parameters in layer breeder chicken during hot climatic conditions

Thermal manipulation during incubation has been shown to improve post hatch performance in poultry. The aim of the present experiment was to evaluate thermal manipulation on semen quality of roosters during hot climatic conditions. Eggs obtained after artificial insemination from Dahlem Red layer breeders were randomly divided into two groups control (C) and heat exposed (HE). C group eggs were incubated at 37.5°C throughout the incubation period while the HE group eggs were exposed to higher temperature 40.5°C from 15th to 17th day of incubation for 3h each day. The relative humidity was maintained at 65% in both the groups throughout incubation. The chicks hatched were reared separately under standard husbandry conditions. During high ambient temperature semen from roosters (45 weeks of age) was collected and evaluated for different gross parameters, sperm chromatin integrity and sperm HSP27 and HSP70 gene expression by real-time PCR. The seminal plasma was evaluated for lipid peroxidation, ferric ion reducing antioxidant power (FRAP), triiodothyronine (T3) and matrix metalloproteinase-2 (MMP-2) activity. The shed average Temperature Humidity Index (THI) during the experiment period was 78.55. The percent live sperm and FRAP level were significantly (P<0.05) higher and sperm gene expressions were significantly (P<0.05) lower in the HE group. No differences in other parameters were observed between the groups. Thus from the results it could be concluded that thermal manipulation during incubation improves certain semen parameters of roosters at high ambient temperature.

Ameliorative effects of melatonin administration and photoperiods on diurnal fluctuations in cloacal temperature of Marshall broiler chickens during the hot dry season

Experiments were performed with the aim of determining the effect of melatonin administration on diurnal fluctuations in cloacal temperature (CT) of Marshall broiler chickens during the hot dry season. Birds in group I (12L:12D cycle) were raised under natural photoperiod of 12-h light and 12-h darkness, without melatonin supplementation, while those in group II (LL) were kept under 24-h continuous lighting, without melatonin administration. Broiler chickens in group III (LL + melatonin) were raised under 24-h continuous lighting, with melatonin supplementation at 0.5 mg/kg per os. The cloacal temperatures of 15 labeled broiler chickens from each group were measured at 6:00, 13:00, and 19:00 h, 7 days apart, from days 14-42. Temperature-humidity index was highest at day 14 of the study, with the value of 36.72 ± 0.82 °C but lowest at day 28 with the value of 30.91 ± 0.80 °C (P < 0.0001). The overall mean hourly cloacal temperature value of 41.51 ± 0.03 °C obtained in the 12L:12D cycle birds was significantly higher (P < 0.001) than the value of 41.16 ± 0.03 °C recorded in the melatonin-treated group but lower than that of 41.65 ± 0.03 °C obtained in the LL birds. Mortality due to hyperthermia commenced at day 28 in both 12L:12D cycle and LL broiler chickens but was delayed till day 42 in LL + MEL broiler chickens. In conclusion, melatonin administration alleviated the deleterious effects of heat stress on broiler chickens by maintaining their cloacal temperature at relatively low values.

Diurnal and seasonal fluctuations in rectal temperature, respiration and heart rate of pack donkeys in a tropical savannah zone

The study was designed to determine diurnal and seasonal changes in basic physiologic responses of donkeys adapted to the tropical Savannah. The rectal temperature (RT), respiratory rate (RR) and heart rate (HR) of six male Nubian pack donkeys, and the dry-bulb temperature (DBT), relative humidity and heat index of the experimental site were concurrently recorded hourly, from 06:00 h to 18:00 h (GMT +1), for three days, spread 1 week apart, during the cold-dry (harmattan), hot-dry and humid (rainy) seasons, in an open grazing field. Values of the physiologic parameters recorded during the morning (06:00 h–11:00 h) were lower (P<0.001) than those obtained in the afternoon (12:00 h–15:00 h) and evening (16:00 h–18:00 h) hours in all seasons, but the robustness of the diurnal rhythm differed (P<0.05) between seasons. Many diurnal hourly DBT mean values recorded during the harmattan and hot-dry seasons fell outside the established thermoneutral zone for tropically-adapted donkeys, while those obtained during the rainy season were within the zone, indicating that the dry seasons were more thermally stressful to the donkeys than the humid season. Overall mean RT dropped (P<0.05) during the harmattan season. The RR rose, while HR dropped (P<0.001) during the hot-dry season. In conclusion, daytime and season had profound influence on RT, RR and HR of the donkeys, therefore, diurnal and seasonal variations should be taken into account during clinical evaluation before reaching conclusion on health status and fitness for work in donkeys.

Morphometric Identification, Gross and Histopathological Lesions of Eimeria Species in Japanese Quails (Coturnix coturnix japonica) in Zaria, Nigeria

The objective of the study was to identify the species, gross and histopathological lesions of Eimeria in Japanese quails in Zaria. A total of 400 fresh faecal samples were collected and 10 quail birds were purchased from a quail farm. The faecal samples were processed using simple floatation technique. Oocysts shape indices of sporulated oocysts were determined. The intestines were observed for gross lesions and segments were analyzed using Giemsa stain and Haematoxylin and Eosin stain and then observed microscopically for the developmental stages of the parasite. Four species of Eimeria were identified in the study. Eimeria bateri of shape index of 1.36 conformed to the guidelines used while the other three Eimeria species with shape indices of 1.48, 1.03, and 1.40 were not confirmed. The main gross lesion seen was nonhaemorrhagic ballooning of the caeca. Intestinal scrapping smear revealed a developmental stage of the parasite (merozoites) in the jejunum. Histopathology also revealed a developmental stage (schizont) of the parasite in the caecum and desquamation of the epithelial lining with areas of necrosis. Further study is required using molecular techniques to properly identify the unknown species of Eimeria that were detected in the study.

Rectal temperature responses of donkeys administered with ascorbic acid and subjected to load carrying (packing) during the harmattan season in Nigeria

The aim of the experiment was to evaluate the effect of 4-h load carrying (packing) on donkeys administered with ascorbic acid (AA) during the harmattan season. Six donkeys administered orally with ascorbic acid (200 mg/kg) and subjected to packing served as experimental animals, while six others given only distilled water served as control animals. The rectal temperature (RT) of each donkey and dry-bulb temperature (DBT) and relative humidity (RH) of the research pen were recorded at 0600 hours pre-packing; while post-packing, the values were obtained at 1430, 1600 and 1800 hours. The DBT values (ranges) recorded before, during and after packing were 13.7 ± 1.3 °C (11-15 °C), 28.4 ± 1.0 °C (22.7-30.3 °C) and 30.6 ± 3.0 °C (19.8-45 °C), respectively. The highest temperature-humidity index (THI) of 83.4 ± 6.9 was obtained at 1430 hours after packing, and the value decreased to 64.2 ± 5.8 at 1800 hours. The thermal environmental conditions were outside the thermoneutral zone for the donkeys. The RT values recorded immediately after packing did not differ (P > 0.05) in experimental and control donkeys; but at 1600 and 1800 hours, values obtained in control donkeys (38.48 ± 0.12 and 38.12 ± 0.12 °C, respectively) were significantly higher (P < 0.05) than those recorded in experimental donkeys (38.16 ± 0.14 and 37.85 ± 0.14 °C, respectively). In conclusion, administration of ascorbic acid reduced the rise in RT due to packing and may be of value in the amelioration of adverse effects of heat stress associated with work in donkeys.