Early Feeding Strategy Mitigates Major Physiological Dynamics Altered by Heat Stress in Broilers.

Heat stress is one of the stressors that negatively affect broiler chickens, leading to a reduction in production efficiency and profitability. This reduction affects the economy in general, especially in hot and semi-hot countries. Therefore, improving heat tolerance of broiler chicks is a key to sustained peak performance, especially under adverse environmental heat stress conditions. The present study investigated three early feed withdrawal regimes (FWD) as a potential mitigation for thermal stress exposure. A total of 240 unsexed one-day-old Cobb-500 chicks were randomly recruited to one of four experimental groups using a completely randomized design (10 birds × 6 replicates). The experimental groups included the control group with no feed withdrawal (control), while the other three groups were subjected to early feed withdrawal for either 24 h on the 5th day of age (FWD-24), 12 h on the 3rd and 5th day of age (FWD-12), or 8 h on the 3rd, 4th, and 5th day of age (FWD-8), respectively. Production performance was monitored throughout the experiment. Meanwhile, blood and liver samples were taken at the end of the experimental period to evaluate major physiological dynamic changes. Our findings demonstrated that under chronic heat stress conditions, FWD treatments significantly improved broilers' production performance and enhanced several physiological parameters compared with the control. Serum levels of thyroid hormones were elevated, whereas leptin hormone was decreased in FWD groups compared with the control. Moreover, serum total protein, globulin, and hemoglobin levels were higher, while total cholesterol and uric acid were lower in the FWD groups. Furthermore, FWD groups showed significantly higher antioxidant marker activity with a significantly lower lipid peroxidation level. Immunoglobulin levels, lysozyme, complement factor C3, and liver heat shock protein 70 (HSP70) concentration were also elevated in FWD compared with the control. Also, serum interleukin-1ß (IL-1ß) and interferon-gamma (IFN-γ) significantly increased with FWD. Based on our findings, early feed withdrawal can be applied as a promising non-invasive nutritional strategy for broilers reared under chronic heat stress conditions. Such a strategy promotes the alleviation of the deleterious effects of heat stress on broiler performance, immunity, and redox status, owing to the onset of physiological adaptation and the development of thermotolerance ability.

Dietary Corn Silk (Stigma maydis) Extract Supplementation Modulate Production Performance, Immune Response and Redox Balance in Corticosterone-Induced Oxidative Stress Broilers.

Immunosuppression is a serious consequence of oxidative stress exposure that negatively affects the productivity and profitability of birds, as well as their well-being. Thus, the present investigation was designed to evaluate the potential of corn silk extract (CSE) supplementation to overcome the negative impacts of oxidative stress induced by corticosterone administration (CORT) in broiler chickens. A total of 280 one day old Cobb 500 male chicks were divided into four groups in 2 × 2 factorial arrangements. The experimental groups included CSE supplementation (0 or 500 mg/kg diet, from 20 to 35 days of age) and CORT administration (0 or 25 mg/kg diet, from 22 to 35 days of age) as independent factors. At the end of week five of age, production performance parameters were measured. The humoral and cell-mediated immune response parameters, redox status, and stress markers were determined. Data revealed deleterious effects of CORT administration on the broilers' body weight, body weight gain, and feed conversion ratio. Moreover, an exponential increase in stress marker levels, in addition to immunosuppression and redox imbalance, were associated with CORT administration. However, CSE supplementation, with its high total phenols content, partially alleviated the negative impacts of CORT administration, as shown by a significant improvement in immune response parameters and antioxidant activity, as well as a reduction in stress marker levels. Furthermore, CSE supplementation to non-stressed birds even significantly improved total antioxidant activity, total white blood cells (TWBCs) count, T-lymphocyte stimulating index, and wattle thickness. It can be concluded that, under stress conditions in commercial broiler farms, dietary CSE supplementation can strongly be recommended to modulate the negative impacts of stress. Therefore, CSE can be used as an effective immunomodulator and antioxidant agent to increase commercial broiler farm productivity and profitability.

Effect of Dietary Blue-Green Microalgae Inclusion as a Replacement to Soybean Meal on Laying Hens' Performance, Egg Quality, Plasma Metabolites, and Hematology.

Spirulina platensisis (SP) is a blue-green microalgae with a high value for animal and poultry nutrition. The study employed 250 40-week-old, HY-Line W-36 commercial laying hens. The layers received one of five experimental diet substitutes in five groups for 10 consecutive weeks (five replicates of 10 hens each group); a soybean-corn basal diet formulation without SP (Control group) or the soybean partially substituted with 3% SP, 6% SP, 9% SP, and 12% SP (for the remaining four groups). The results showed that dietary SP treatment significantly (p < 0.05) improved the productive performance, egg quality, blood metabolites, and hematological parameters of laying hens. In addition, there were linear and quadratic effects for increasing the levels of SP inclusion into the layer diets; however, the highest values of most parameters were observed when using 9% SP (90 g/kg of the layer diets). Furthermore, the results showed that 4.7% of the soybean meal ingredient in the layer diet could be replaced by 1% of SP. In conclusion, the partial replacement of soybean meal by SP into layer diets could be used as a promising nutritional approach to optimize the performance of laying hens.

Citrullus colocynthis Seed Ameliorates Layer Performance and Immune Response under Acute Oxidative Stress Induced by Paraquat Injection.

Oxidative stress is a detrimental physiological state that threatens birds' productivity and general health. Colocynth is an herbal plant known for its bioactive properties, and it is mainly known for its antioxidant effects. This study's purpose was to investigate how effective colocynth seed is at lowering the detrimental impact of acute oxidative stress caused by paraquat (PQ) injection in laying hens. A total of 360 Hy-Line Brown chickens, aged 39 weeks, were gathered and divided into four equal groups (10 hens × 9 replicates) in a 2 × 2 factorial design. The experimental groups were given either a basal diet or the basal diet supplemented with colocynth seed (1% of diet). Starting from week 40 of age and for 7 successive days, the experimental groups were either injected daily with paraquat (5 mg/kg body weight) or with saline (0.5 mL, 0.9% NaCl). Egg production performance with selected stress biomarkers and immunological response parameters were investigated at the end of week 40 of age. Our data revealed a significant reduction in egg production with an increase in blood stress biomarkers (i.e., HSP-70, corticosterone, and H/L ratio) in PQ-injected groups compared with non-stressed groups. Furthermore, an unbalanced redox state was detected in acute oxidative stress groups, with a significant rise in lipid peroxidation level, a reduction in total antioxidant capacity (TAC), and a drop in superoxide dismutase (SOD) and catalase enzyme activity. Supplementing PQ-injected hens with colocynth seed reduced the deleterious effects of acute oxidative stress. There was a significant drop in stress biomarkers with a significant rise in antioxidant enzyme activity and TAC observed in the PQ-injected group provided with colocynth seed supplementation. Remarkably, supplementation of colocynth in the non-stressed group resulted in a significant 27% increase in TAC concentration and 17% higher SOD activity when compared with the non-stressed control group. Colocynth supplementation in the PQ-injected group elevated the total white blood cell count by 25% and improved the B-lymphocyte proliferation index (a 1.3-fold increase) compared with the PQ-injected group that did not receive supplementation. Moreover, the non-stressed colocynth-supplemented group had significantly higher cell-mediated and humoral immune responses than the non-stressed control group. This study demonstrated that colocynth seed supplementation in birds exposed to acute oxidative stress may effectively alleviate its negative impacts on production performance, immunological responses, and redox status. We also inferred that, under normal conditions, colocynth seed can be added to laying hens' diets to stimulate production and ameliorate immune responses.

Citrullus colocynthis Seeds: A Potential Natural Immune Modulator Source for Broiler Reared under Chronic Heat Stress.

There is an extensive search for natural products that can be introduced to broiler rations to improve performance, especially during the unfavorable breeding conditions. Under heat-stress conditions, the immune response seriously deteriorates, which consequently impairs broiler production performance. Thus, the present study aimed to investigate the potentials of Citrullus colocynthis seeds (CCs) supplementation to modulate the immune response of broilers subjected to chronic heat stress. A total of 300 Cobb-500 male broiler chickens aged 21 days were randomly divided into two equal groups and reared under either thermo-neutral condition (24 ± 1 °C) or subjected to cyclic heat stress (34 ± 1 °C for 8 h). Each group was further divided into two groups (5 replicate × 15 chicks) and was fed either the basal diet or the basal diet with 0.1% CCs supplementation. The results showed that heat stress impaired the production performance by lowering the final body weight and feed intake as well as impairing feed conversion. The levels of stress markers (i.e., malondialdehyde, tumor necrosis factor-α and corticosterone) increased (p < 0.05), whereas the activity of antioxidant enzymes decreased in broilers exposed to heat stress. Further, heat stress caused direct suppression of broiler humoral and cell-mediated immune responses. The stimulating index of T and B lymphocytes proliferation, as well as the antibody titer against sheep red blood cells, were significantly (p < 0.05) reduced by heat-stress exposure. However, CCs supplementation to broilers subjected to heat stress improved (p < 0.05) the final body weight, feed intake, and feed conversion ratio (FCR), compared to the non-supplemented stressed group. The cellular and cell-mediated immune response indicators significantly enhanced (p < 0.05) with CCs supplementation. Supplementation of CCs to broilers reared under similar environmental conditions elevated the total white blood cells (TWBCs) count and the broiler stimulating index of T and B lymphocytes. It can be concluded that CC seeds can be effectively used to stimulate the immune response and improve the production performance of broilers reared under heat-stress condition.

Blue-Green Algae (Spirulina platensis) Alleviates the Negative Impact of Heat Stress on Broiler Production Performance and Redox Status.

The modern broiler industry faces huge challenges to keep high production quality and quantity, especially under environmental heat stress conditions. The negative effect of heat stress on broiler productivity is mediated by oxidative stress induction. The blue-green alga (Spirulina platensis) has many applications in poultry nutrition with the high levels of bioactive antioxidant compounds, which can alleviate the oxidative stress damage induced by high ambient temperature. The current study was designed to investigate the effects of dietary Spirulina inclusion at different levels on growth performance, redox status, carcass traits, meat quality, blood hematology, and metabolites profile of broilers subjected to cyclic heat stress. A total of 300 one-day-old Cobb-500 broiler chicks were recruited. Starting from day 21 to 42 of age, birds were randomly divided into five treatment groups with 6 replicates × 10 birds per group, where the first one was provided with the basal diet and reared under normal thermal conditions (23 ± 1 °C) to serve as a negative control. Meanwhile, the other four groups were exposed to cyclic heat stress (34 ± 1 °C for 8 h per day) and were fed a basal diet supplemented with Spirulina at a concentration of 0, 0.5, 1 or 1.5%. Spirulina supplementation to heat-stressed broilers was able to alleviate the negative impacts of heat stress on the final average daily gain, body weight and feed conversion ratio, with the best impact observed among the chickens fed 1% Spirulina. Hematological results indicate increasing hemoglobin and hematocrit levels with Spirulina supplementation compared to the non-supplemented stressed group. Further, Spirulina supplementation significantly influenced blood lipid metabolites marked by reduced serum cholesterol and low-density lipoprotein (LDL), and increased high-density lipoprotein (HDL) levels. The lipid peroxidation level was reduced (p < 0.05), while the antioxidant enzyme activity was increased with Spirulina supplementation to the heat-stressed group. Spirulina supplementation at 0.5 or 1% improved carcass dressing, breast and leg percentages. It can be concluded that dietary Spirulina supplementation at 0.5 or 1% to broiler reared under heat stress conditions can effectively improve broiler production performance and balance the redox status.

Modulating Laying Hens Productivity and Immune Performance in Response to Oxidative Stress Induced by E. coli Challenge Using Dietary Propolis Supplementation.

Propolis (PR) is a resin product of bee colonies that has rich bioactive antioxidant and bactericidal compounds. Endotoxin, a byproduct of bacterial growth, is reported to cause progressive induction of endogenous oxidative stress and has negative impacts on individual health and wellbeing. Hereby, we investigated the ability of PR to alleviate the oxidative stress and immunosuppression imposed by avian pathogenic Escherichia coli using laying hen as a based model. In this study, PR was dietary supplemented to hens for 4 weeks at a concentration of 0.1%. At the beginning of the 4th week of the experiment, hens from control and PR treatment were injected with E. coli (O157:H7; 107 colonies/hen) or saline. The results showed significant (p < 0.05) negative impact of E. coli challenge on antioxidant status, immune response and productive performance. PR supplementation reduced (p < 0.05) inflammation markers levels (tumor necrosis factor α (TNFα) and interleukin 1ß (IL-1ß)) and plasma corticosterone concentration. The antioxidant status was ameliorated with dietary PR supplementation to challenged hens, showing significant (p < 0.05) reduction in malondialdehyde (MDA) levels and increasing total antioxidant capacity (TAC) concentrations. Cell mediated, as well as, humeral immune response improved significantly (p < 0.05) with dietary PR verified by the enhancement of T- and B-lymphocyte proliferation and the positive respond to phytohemagglutinin (PHA). Leucocyte cells viability increased significantly and the apoptotic factor forkhead box O3 (Foxo3) was reduced with PR supplementation. The current study revealed that dietary PR supplementation can effectively be used as an organic feed additive to overcome the endogenous oxidative stress induced by endotoxins challenge.

Propolis supplementation attenuates the negative effects of oxidative stress induced by paraquat injection on productive performance and immune function in turkey poults.

Paraquat (PQ) is used as a herbicide in agriculture and causes oxidative and inflammatory damage to animal tissues. The current study was conducted to investigate the positive effects of dietary propolis (PR), as a potent naturally produced antioxidant, on growth performance and immune function of turkey poults exposed to oxidative stress induced by PQ injection. Native male turkey poults (n = 120, 49-d-old) were randomly assigned into 4 groups: poults received a basal diet with a daily subcutaneous PQ injection of 5 mg/kg BW for 7 consecutive days (PQ group), an experimental diet containing 1 g/kg PR with a daily subcutaneous PQ injection for 7 days (PR+PQ group), or received the experimental PR diet with a daily subcutaneous injection of 0.5 mL sterile saline for 7 days (PR group); while the control poults received a basal diet with a daily subcutaneous saline injection for 7 consecutive days (C group). The productive performance in the PQ group showed a significant (P < 0.05) reduction in the weight gain (WG) and feed intake (FI), and impaired feed conversion ratio (FCR). Propolis supplementation in the PR+PQ group significantly ameliorated the PQ effects on WG and FCR. Turkey poults of the PQ and PR+PQ groups had a significant augmentation in the blood malondialdehyde (MDA), tumor necrosis factor-α (TNFα), and corticosterone levels, and in contrast, a significant reduction in the triiodothyronine (T3), when compared to the C group. While propolis significantly reduced the MDA and corticosterone, and increased the T3 levels in the PR+PQ group compared to the PQ group. Furthermore, the dietary PR supplementation significantly limited the PQ-suppressive effects on cell- and humoral-mediated immunity and lymphocyte proliferation of turkey poults. In addition, propolis supplementation in the PR and PR+PQ groups markedly reversed the PQ-induced DNA fragmentation and heat shock protein 70 (Hsp70) over-expression in blood cells. It can be concluded that PR could improve turkey immunity and performance, particularly under inflammation and oxidative stress induced by PQ exposure.

Depression of leukocyte protein synthesis, immune function and growth performance induced by high environmental temperature in broiler chickens.

In tropical and semitropical regions, raising broiler chickens out of their thermal comfort zone can cause an added economic loss in the poultry industry. The cause for the deleterious effects on immunity and growth performance of broilers under high environmental temperatures is still poorly understood. Therefore, the aim of the current investigation was to evaluate the effect of heat stress on leukocytes protein synthesis and immune function as a possible direct cause of low performance in broiler chickens under such condition. In this study, 300 one-day-old male broiler chicks (Cobb500™) were randomly assigned into 2 groups with 5 replicates of 30 chicks each. From 21 to 42 days of age, one group was exposed to non-stressed condition at 24 °C and 50% relative humidity (control group), while the other group was exposed to heat stress at 35 °C and 50% relative humidity (HS group). At 42 days of age, blood samples were collected from each group to evaluate stress indicators, immune function, and leukocytes protein synthesis. Production performance was also recorded. Noteworthy, protein synthesis in leukocytes was significantly (P < 0.05) inhibited in HS group by 38% compared to control group. In contrast, the phosphorylation level on threonine 56 site (Thr56) of eukaryotic elongation factor (eEF2), which indicates the suppression of protein translation process through altering the protein elongation phase, was significantly threefold higher in HS group than in control (P < 0.05). In addition, an increase in stress indicators was markedly (P < 0.05) presented in the HS birds by twofold increase in heterophil/lymphocyte (H/L) ratio and threefold increase in plasma corticosterone level compared to control. Furthermore, the immune function was significantly (P < 0.05) suppressed in HS birds than control (0.99 vs. 1.88 mg/mL plasma IgG, 89.2 vs. 148.0 µg/mL plasma IgM, 4.80 vs. 7.20 antibody titer against SRBC, and 1.38 vs. 3.39 stimulation index of lymphocyte proliferation in HS vs. control group, respectively). Moreover, results on the broiler performance indicate that HS birds had a significant (P < 0.05) lower body weight gain by 58%, lower feed consumption by 39%, higher conversion ratio by 27%, and higher mortality by more than three times, compared to control birds. In conclusion, our results demonstrate that the inhibition of leukocyte protein synthesis through increasing the level of eEF2 Thr56 phosphorylation may play a key role in the observed decrease in immune function and growth performance with the high mortality rate encountered in broiler chickens under heat stress environment.