Influence of Dietary Chromium and Vitamin E Supplementation on Performance, Metabolism, and Physiology of Broilers Subjected to Cyclic Heat Stress

How heat stress (continuous or cyclical) interferes with nutrient digestibility, energy and nitrogen balances and performance in broilers

Bamboo leaf flavonoids ameliorate cyclic heat stress-induced oxidative damage in broiler liver through activation of Keap1-Nrf2 signaling pathway.

The dietary supplementation of trace minerals and probiotics has long been practiced to reduce the harmful effects of high environmental temperature in poultry. The study aimed to assess the effect of single or combined supplementation of ZnSO4•H2O and probiotic (Protexin®) on the growth performance, gut biometry and immune organs histomorphology in broilers reared under cyclic heat stress. For this purpose, 280 day-old broiler chicks were randomly divided into seven groups designated as control (basal diet), HS (heat stress + basal diet), HS-Zn30 (HS + 30 mg ZnSO 4 •H 2 O/kg feed), HS-Zn60 (HS + 60 mg ZnSO 4 •H 2 O/kg feed), HS-Pro (HS + 0.1 g Protexin®/kg feed), HS-Zn30-Pro (HS + 30 mg ZnSO 4 •H 2 O/kg feed + 0.1 g Protexin®/kg feed), and HS-Zn60-Pro (HS + 60 mg ZnSO 4 •H 2 O/kg feed + 0.1 g Protexin®/kg feed). Each group consisted of five replicates (8 birds per replicate). The birds were fed on starter (0 - 21days) and grower (22 - 42 days) diets. From day 22 onwards, the birds were exposed to cyclic heat stress (temperature and relative humidity at 35 ± 1 °C and 75 ± 5% respectively) for 8 hours. The results revealed that birds exposed to heat stress showed significant decrease in body weight (BW) and increase in feed conversion ratio (FCR) compared to the control group. The dietary supplementation of ZnSO 4 •H 2 O and probiotic either singly or in combination improved BW and FCR throughout the experimental period in heat-stressed broilers. Area of lymphatic nodule and lymphoid follicle in caecal tonsils and bursa of Fabricius increased in HS-Pro, HS-Zn30-Pro and HS-Zn60-Pro groups compared to HS group. In conclusion, zinc and probiotics combination partially improved performance and immune organs histomorphology in heat-stressed broilers. _ Keywords : Chicken, heat stress, immune organ, morphology, Protexin

This study aimed to examine whether dietary supplementation of broiler chickens with turmeric essential could mitigate the effects of cyclic heat stress conditions. Intestinal and immunological parameters and gene expression were evaluated during the grower phase. A total of 320 21-day-old male Cobb 500 broilers were distributed according to a completely randomized design with a 4 (diet) × 2 (environment) factorial arrangement and eight replications of five birds each. Dietary treatments consisted of a basal diet without essential oil (EO, negative control) and three diets containing low (100 mg kg-1), intermediate (200 mg kg-1), or high (300 mg kg-1) levels of turmeric EO. In the heat stress group, dietary supplementation with turmeric EO at 100 and 200 mg kg-1 improved body weight, feed conversion, breast yield, and relative liver weight. These supplementation levels reduced villus width, increased villus/crypt ratio, reduced the H/L ratio, and improved hepatic (HSP70 and SREBP1) and intestinal (OCLN) gene expression in birds under heat stress. These findings support the hypothesis that turmeric EO can be used to improve or restore intestinal integrity, modulate inflammation parameters, and, consequently, enhance the performance of broilers challenged by cyclic heat stress.

Effects of different levels of vitamin E on growth performance and immune responses of broilers under heat stress

Simple SummaryHigh ambient temperatures present challenging environmental factors in the poultry meat industry, causing heat stress. Heat stress impairs animal health and welfare, growth performance, and productivity, and deteriorates meat quality and its oxidative stability, resulting in economic losses. To mitigate the negative effects of heat stress, several nutritional strategies have been proposed, with vitamin and mineral supplementation being one of the most promising. Several studies reported that the addition of vitamins E and C, as well as selenium, to broiler diets improved the production performance and meat quality of broilers reared under heat stress. Due to the synergistic effects of these antioxidants against the oxidative damage to lipids, combined supplementation could be even more effective in alleviating the symptoms of heat stress on meat quality than supplementation alone, but this has not yet been studied. The results of the present study indicate positive effects of the supplementation with vitamin E on the oxidative stability of breast meat. However, no synergistic effects of the added antioxidants on the measured parameters were observed.The present study was conducted to investigate the effects of dietary supplementation with vitamin E, vitamin C, and Se, alone or in combination, on carcass characteristics, oxidative stability and meat quality parameters of breast meat from broilers exposed to cyclic heat stress (HS), and stored under different conditions. A total of 120 one-day-old male Ross 308 broilers were randomly assigned to six dietary treatments: NRC (minimal nutrition requirements), AVI (commercial nutritional recommendations for Ross 308 broilers), AVI + vitE (as AVI + 200 IU vitamin E/kg feed), AVI + vitC (as AVI + 250 mg vitamin C/kg feed), AVI + Se (as AVI + 0.2 mg Se/kg feed), and AVI + ECSe (as AVI + vitE + vitC + Se). From day 26 onwards, all birds were exposed to a high ambient temperature (31 °C) for 8 h per day. The results showed that dietary vitamin E alone or in combination with vitamin C and Se significantly increased the α-tocopherol content and decreased the malondialdehyde (MDA) content in breast meat. Although no obvious synergistic effects of the added antioxidants were observed, the addition of higher levels of vitamin E, vitamin C and Se to broiler diets had no adverse effects on carcass traits, oxidative stability and meat quality parameters when supplemented either alone or in combination.

This study investigated the protective effects of probiotic on heat stress-induced intestinal injury and inflammatory response in broilers. A total of 180 male broilers were randomly allocated to three treatments with four replicates each from 22 to 42days of age. The broilers were either raised under thermoneutral (TN) conditions (23±1°C) or subjected to cyclic heat stress (28-35-28°C for 12hr daily). The broilers kept at TN conditions were fed a basal diet, and those exposed to heat stress were fed basal diets supplemented with or without probiotic at a dose of 1.5×108 cfu/kg. Compared with the TN group, heat stress decreased (p<.05) the growth performance, reduced (p<.05) villus height and villus height: crypt depth ratio in intestinal mucosa, increased (p<.05) serum levels of D-lactic acid on day 28 and endotoxin, TNF-α and IL-6 on day 42, and decreased (p<.05) serum IL-10 content on day 42. Dietary supplementation of probiotic reversed (p<.05) all these changes except for the growth performance in heat-stressed broilers. In conclusion, dietary inclusion of probiotic could improve intestinal morphology and barrier function, alleviate inflammatory response, but exert no ameliorative effect on growth performance of broilers under cyclic heat stress.

Dietary vitamin A can improve immune function in heat-stressed broilers

Simple SummaryRecently, our laboratory published a heat stress model to induce gastrointestinal leakage in broiler chickens. Nevertheless, the model describes continuous heat stress (HS) conditions from day 21 until 42 days of age. The current brief report intends to present an alternative model (12 h/day), particularly more in accordance with real-world conditions, to evaluate nutraceuticals or products that can reduce the severity of HS under experimental conditions. Results of this study confirm what has been extensively reported by numerous scientists. Cyclic HS increased leaky gut, reduced performance, bone mineralization, and meat quality in broiler chickens.The goal of this research was to assess cyclic heat stress on gut permeability, bone mineralization, and meat quality in chickens. Two separate trials were directed. 320 day-of-hatch Cobb 500 male chicks were randomly assigned to four thermoneutral (TN) and four cyclic heat stress (HS) chambers with two pens each, providing eight replicates per treatment in each trial (n = 20 chicks/replicate). Environmental conditions in the TN group were established to simulate commercial production settings. Heat stress chickens were exposed to cyclic HS at 35 °C for 12 h/day from days 7–42. Performance parameters, intestinal permeability, bone parameters, meat quality, and leukocyte proportions were estimated. There was a significant (p < 0.05) reduction in body weight (BW), BW gain, and feed intake, but the feed conversion ratio increased in chickens under cyclic HS. Moreover, HS chickens had a significantly higher gut permeability, monocyte and basophil levels, but less bone mineralization than TN chickens. Nevertheless, the TN group had significant increases in breast yield, woody breast, and white striping in breast fillets compared to HS. These results present an alternative model to our previously published continuous HS model to better reflect commercial conditions to evaluate commercially available nutraceuticals or products with claims of reducing the severity of heat stress.

The objective of this experiment was to evaluate the effect of diet supplementation with vitamins C and E and organic minerals Zn and Se on the performance of 1 to 35 day-old broilers from, kept under cyclic heat stress (25 to 32ºC). Four levels of vitamin-mineral supplementation were used (T1-control diet (60/30 IU of vit E for starter and growing diet, respectively, zero vit. C, 80 ppm of inorganic Zn, 0.3 ppm of inorganic Se); T2-control diet + 100 UI vit E and 300 ppm vit C/kg; T3-control diet + 40 ppm Zn and 0,3 ppm Se/kg; T4-control diet + T2 and T3 levels) and two environments - thermoneutral and cyclic heat stress (TN and HS) from 14 to 35 days of age. In the period when part of the birds was submitted to HS, from 14 to 35 days, it was observed lower feed intake (FI) and better feed conversion (FC) for HS birds receiving supplementation compared to the group without supplementation. Evaluating the total period, all the types of supplementation provided lower FI and better FC than the control treatment, but not affected weight gain (WG). The supplementation of vitamins C and E and/or organic minerals Zn and Se improved the performance of birds due to a lower FI resulting in better FC, independently on the environment.

This study investigated the effects of synbiotics supplementation on growth performance, antioxidant status, immune function, and intestinal barrier function in broilers subjected to cyclic heat stress. One hundred and forty-four 22-day-old male broilers were randomly assigned to one of three treatment groups of six replicates each for a 21-day study, with eight birds per replicate. Broilers in the control group were reared at a thermoneutral temperature and received a basal diet. Broilers in the other two heat-stressed groups were fed a basal diet supplemented without (heat-stressed group) and with 1.5g/kg synbiotic (synbiotic group). One and a half gram of the synbiotic consisted with 3 × 109 colony forming units (CFU) Clostridium butyricum, 1.5 × 109CFU Bacillus licheniformis, 4.5 × 1010CFU Bacillus subtilis, 600mg yeast cell wall, and 150mg xylooligosaccharide. Compared with the control group, heat stress increased rectal temperatures at 28, 35, and 42days of age, respectively (P < 0.05). Birds subjected to heat stress had reduced weight gain, feed intake, and feed efficiency during 22 to 42days (P < 0.05). In contrast, supplementation with the synbiotic decreased rectal temperature at 42days of age and elevated weight gain of heat stress-challenged broilers (P < 0.05). Heat-stressed broilers exhibited a lower superoxide dismutase (SOD) activity in jejunal mucosa and a higher malondialdehyde accumulation in serum, liver and jejunal mucosa (P < 0.05), and the regressive SOD activity was normalized to control level when supplementing synbiotic (P < 0.05). Heat stress increased interleukin-1β (IL-1β) and interferon-γ (IFN-γ) levels in serum and IL-1β content in jejunal mucosa of broilers (P < 0.05). Synbiotic reduced IL-1β level in serum of broilers subjected to heat stress (P < 0.05). Compared with the control group, elevated serum diamine oxidase activity and reduced jejunal villus height were observed in broilers of the heat-stressed group (P < 0.05), and the values of these two parameters in the synbiotic group were intermediate (P > 0.05). Heat stress upregulated mRNA abundance of IL-1β and IFN-γ and downregulated gene expression levels of occluding and zonula occluden-1 (ZO-1) in jejunal mucosa of broilers (P < 0.05). The alterations in the mRNA expression levels of jejunal IL-1β and ZO-1 were reversed by the synbiotic (P > 0.05). In conclusion, dietary synbiotics could improve growth performance, antioxidant capacity, immune function, and intestinal barrier function in heat-stressed broilers.

An experiment on Cobb-500 male broilers was conducted to evaluate the effects of vitamin E (alfa-tocopherol-acetate), vitamin A (retinol), and their combination on broiler performance and serum concentrations of triiodothyronine (T3), thyroxine (T4), adrenocorticotropine hormone (ACTH) and some metabolite and mineral concentrations in broilers reared under heat stress (32&amp;deg;C). One day-old 120 broilers were randomly assigned to 4 treatment groups, 3 replications of 10 birds each. The birds were fed either a control diet or a control diet supplemented with either vitamin A (15 000 IU retinol/kg diet), vitamin E (250 mg alfa-tocopherol-acetate/kg diet), or a combination of vitamin A and E (15 000 IU retinol plus 250 mg of alfa-tocopherol-acetate/kg diet). Considered separately or as a combination, supplemental vitamin A and vitamin E increased feed intake (P&amp;nbsp;= 0.01) and live weight gain (P&amp;nbsp;= 0.03). However, feed efficiency remained similar in all treatments (P= 0.18). Serum T3&amp;nbsp;and T4&amp;nbsp;concentrations were also higher (P&amp;nbsp;&amp;le; 0.001) with vitamin A, vitamin E, and vitamin A plus vitamin E groups than those of the control. However, ACTH concentration in serum was lower (P&amp;nbsp;&amp;le; 0.001) in supplemental dietary vitamin groups compared with control. Serum glucose, uric acid, triglyceride, and cholesterol concentrations decreased (P&amp;nbsp;&amp;le; 0.001) while protein and albumin concentrations increased (P&amp;nbsp;&amp;le; 0.001) when both dietary vitamin E and vitamin A were supplemented. Serum activities of serum glutamic oxalate transaminase (SGOT) and serum glutamic pyruvate transaminase (SGPT) were not influenced by dietary vitamin E, vitamin A nor by a combination of vitamin A and vitamin E (P&amp;nbsp;&amp;gt; 0.72). However, serum activity of alkaline phosphatase (AP) increased (P&amp;nbsp;&amp;le; 0.001) with supplemental dietary vitamin E, vitamin A, or a combination of vitamin A and vitamin E. In addition, supplemental dietary vitamin E and vitamin A resulted in an increase in serum concentrations of both Ca and P (P &amp;le; 0.001). In general, when a significant effect was found for a parameter, the magnitude of responses to vitamin supplements was greatest with the combination of vitamin A and vitamin E, rather than that of each vitamin supplement separately. The results of the present study show that supplementing a combination of dietary vitamin E and vitamin A offers a good management practice to reduce heat stress-related decreases in broiler performance. &amp;nbsp;

Low protein with high amino acid diets improves the growth performance of yellow feather broilers by improving intestinal health under cyclic heat stress

A study was conducted to evaluate the effect of cyclic or chronic heat stress (HS) on the incidence and severity of white striping (WS) and histopathological changes in breast muscle of broiler chickens. One hundred eighty 1-day-old male chickens were randomly assigned to three research groups: control (standard temperature throughout the experiment), cyclic HS (32 ºC between 0800 and 2000h from day 21 until the end of the experiment), and chronic HS (32 ºC from day 21 onwards). Cyclic and chronic HS groups showed a significant (P < 0.05) decrease in body weight gain and feed intake and poor feed conversion ratio in grower, finisher, and overall period. Serum biochemical profile was not different among the groups except globulin and P which were significantly higher (P < 0.05 and P < 0.001, respectively), in cyclic and chronic HS groups. Overall, WS incidence was numerically higher in control birds followed by chronic HS and cyclic HS birds, respectively. The chronic HS group had a lower incidence of mild (score 1) and a higher incidence of severe (score 2) WS lesions compared to control and cyclic HS groups. Histopathological analysis revealed that broilers subjected to chronic HS showed increased severity of myodegenerative changes, perivenular CD3 + cell infiltration, and lipidosis compared to control group. However, control and cyclic HS groups were not different in terms of histopathological lesions. In conclusion, this study confirms that cyclic or chronic HS may adversely affect the growth performance and that chronic HS may increase the severity of WS in broiler chickens.

Simple SummaryThermal stress is a critical issue for poultry during the summertime. It is imperative to overcome this problem by controlling the environment inside poultry houses or by water additives. This experiment evaluated the effects of two supplements for broilers in water. Nano-emulsified vegetable oil or betaine was used in two groups of broilers. One group was kept under a thermo-neutral temperature (24 °C) while the other was kept under a high temperature (35 °C). The high temperature lasted from 21 to 35 days old. The high-temperature group consumed less feed and suffered significantly from lower daily gain. Moreover, the thermo-neutral group had good meat attributes when compared to the high-temperature group. The two supplements improved the ability of broilers to use feed more efficiently and convert it to body gain compared to the un-supplemented birds. In addition, betaine enhanced carcass characteristics such as breast temperature and pH compared to the control. In summary, the heat challenge caused significant disadvantageous impacts on growth efficiency and meat qualities, while the two supplements used herein improved the performance. Therefore, it is recommended to use these supplements in the case of high temperatures inside broiler houses.The effects of nano-emulsified vegetable oil (NEVO) and betaine (BET) supplements on growth performance and meat qualities of broilers reared under cyclic heat stress (HS) were investigated. Two hundred and eighty-eight mixed-sex broilers at 21 d were randomly distributed to a 2 × 3 factorial arrangement of treatments formed by two environmental temperatures (thermoneutral (TN; 24 ± 1 °C) and cyclic high-temperature (HT; 35 ± 1 °C)) and three dietary treatments (control (CON), NEVO, and BET). The cumulative performance (21–35 d) revealed a reduction in average daily gain (ADG) (p < 0.05) in the CON compared to NEVO. NEVO and BET groups had a better feed conversion ratio (FCR) and performance efficiency factor (PEF) compared with the CON (p < 0.001, p < 0.01, respectively). The environmental temperature affected daily feed intake (DFI), ADG, FCR, and PEF. The addition of BET improved breast fillets yield, temperature, pH15min, and pH24hr (p < 0.05) in comparison with the CON. Moreover, the TN group had lower fillet temperature and higher pH15min compared to the HT. Moreover, HT increased shear force (SF), hardness, springiness, cohesiveness, and chewiness of the fillets compared to TN. In conclusion, dietary supplementation with BET and NEVO could effectively improve performance parameters and meat characteristics under HS conditions.