This review examined the influence of environmental heat stress, a concern facing modern broiler producers, on protein metabolism and broiler performance, as well as the physiological mechanisms that activate and control or minimize the detrimental impacts of stress. In addition, available scientific papers that focused on amino acids (AA) digestibility under stress conditions were analyzed. Furthermore, AA supplementation, a good strategy to enhance broiler thermotolerance, amelioration, or stress control, by keeping stress at optimal levels rather than its elimination, plays an important role in the success of poultry breeding. Poultry maintain homeothermy, and their response to heat stress is mainly due to elevated ambient temperature and the failure of effective heat loss, which causes a considerable negative economic impact on the poultry industry worldwide. Reduced feed intake, typically observed during heat stress, was the primary driver for meat production loss. However, accumulating evidence indicates that heat stress influences poultry metabolism and endocrine profiles independently of reduced feed intake. In conclusion, high ambient temperatures significantly reduced dietary AA intake, which in turn reduced protein deposition and growth in broilers. Further studies are required to determine the quantity of the AA needed in warm and hot climates and to introduce genetic tools for animal breeding associated with the heat stress in chickens.

Ross 308 broiler chicks (n = 240) aged 1 day were assigned to five groups for eight replicates (six chicks for each) (3♂ and 3♀). Basal dietary groups were supplemented by 2000, 4000, and 6000 mg/kg cinnamon (CN) for 21 days. Basal diet alone was used as a negative control, and basal antibiotic diet (Colimox) was used as a positive control. At 10, 14, and 21 days of age, chicks that received 2000 mg CN and Colimox had a higher body weight, resulting in an increase in body weight gain. CN also resulted in the maximum improvement in the feed conversion ratio and feed efficiency over 1–21 days at the level of 2000 mg/kg. At days 10, the maximum relative breast weight was 2000 mg/kg of CN. Mean serum albumin concentrations, duodenal villus height, and goblet cell density increased (p < 0.05) by 2000 mg/kg of CN, and mean serum globulin and total protein concentrations and crypt depth increased (p < 0.05) by 6000 mg/kg of CN compared with control. Increased cecal Escherichia coli number was CN dose-dependent. In conclusion, dietary inclusion of 2000 mg/kg CN can be applied as an alternative to in-feed antibiotics for broiler starter diet.

A total of 192 one-day-old Ross 308 broiler chicks were assigned to 4 treatments with 8 replicate cages of 6 chicks (3♀ and 3♂) per cage according to a completely randomized block design. The dietary treatments were a basal diet (control) and a control diet supplemented with 1,000, 3,000, and 5,000 mg/kg Rumex nervosus leaves meal (RN). Gallic acid and some volatile compounds were detected in the RN extract. On day 10 of age, BW was improved (P = 0.016) with supplemental RN (1,000–5,000 mg/kg). On day 14 of age, dietary application of RN up to 3,000 mg/kg increased BWG (P = 0.003) compared with control, while a 1,000 mg/kg RN had the best feed conversion ratio (P = 0.016). On day 10 of age, samples were taken on a single female bird per replicate. The addition of RN (1,000–5,000 mg/kg) increased (P < 0.001) serum albumin and triiodothyronine levels and maximized the relative weight of breast meat (P = 0.003). Feeding a diet with 1,000 mg/kg RN resulted in greater duodenal villus height (P < 0.001) than control and the diet with 5,000 mg/kg RN. Broilers fed diet supplemented with 1,000 mg/kg RN had the best duodenal villus surface area (P < 0.001). Feeding a diet with 1,000 mg/kg RN decreased (P < 0.001) cecal Escherichia coli count compared with control and the diet with 5,000 mg/kg RN. Salmonella spp. count tended to increase with 5,000 mg/kg RN leaves meal (P = 0.069, linear P = 0.026). In conclusion, R. nervosus leaves meal could be considered as a phytogenic feed additive in broiler diets up to a 1,000-mg/kg inclusion rate because of its combined positive effects on BWG, feed conversion ratio, villus height, villus surface area, serum albumin and triiodothyronine hormone, and cecal E. coli during the starter period (day 10–14 of age). Further study is required to elucidate its molecular mechanism.

Curcumin (CUR) has been used since ancient times to treat several ailments as it possesses many pharmacological activities. This study intended to explore the mechanism underlying the protective effects of CUR in remodeling oxidative stress and apoptotic signals in cyclophosphamide (CP)-induced pulmonary injury in albino rats. CUR was administered at a dose of 300 mg/kg/day for 7 days and on the seventh day a single dose of CP (200 mg/kg) was given. Histopathological and ultrastructural examinations of CP-intoxicated rats showed complete alveolar obstruction, thickened inter-alveolar septa, enlarged blood vessels, severe inflammatory edema with pyknotic nuclei, and disappearance of cytoplasmic organelles. Significant increases in caspase-3, malondialdehyde (MDA), and protein carbonyl (PCO) and significant decreases in superoxide dismutase (SOD) and glutathione peroxidase (GPx) were observed. In contrast, rats that received CUR showed clear and empty lumina with single row of pneumocytes, disappearance of edema, and no interstitial electron dense bodies in rats’ lung tissues. Additionally, CUR significantly reduced caspase-3, MDA, and PCO and increased SOD and GPx. In conclusion, these findings revealed the protective effects of CUR against CP-induced pulmonary injury in rats through suppressing oxidative damage and apoptosis.

This research aimed to assess the influences of bentonite (BN) and zeolite (ZE) on reducing toxic influences of aflatoxin B1 (AFB1) in broilers by examining growth performance, carcase characteristics, serum indices, ileum morphology, apparent nutrient digestibility, and liver AFB1 residues. In total, 360 11-d-old straight-run broilers (Ross 308) were randomly allocated into 6 dietary treatments, with 10 replications of 6 birds each, in a 20-d experiment. The treatments were as follows: standard basal diet (negative control, NC); NC + 0.25 mg/kg AFB1 (positive control, PC); NC + 0.4% BN; NC + 0.4% ZE; PC + 0.4% BN; PC + 0.4% ZE. Compared to the NC diet, feeding the PC diet decreased daily feed intake (DFI) during the grower and overall periods (p < .01), reduced daily weight gain (DWG) and production efficiency factor (PEF) and increased feed conversion ratio (FCR) during grower, finisher, and overall periods (p < .001), lowered breast meat yield (p < .01), diminished dressing percentage, serum concentrations of total protein (TP), albumin (ALB), glucose (GLU), total antioxidant capacity (T-AOC), and total superoxide dismutase (T-SOD), villus height (VH), villus surface area (VSA), apparent digestibility of crude protein (CP) and ether extract (EE), apparent metabolisable energy (AME), and nitrogen-corrected AME (AMEn) (p < .001), and raised proportional liver weight, serum activities of glutamic oxaloacetic transaminase (GOT) and glutamate pyruvate transaminase (GPT), and residues of AFB1 in the liver (p < .001). Compared to the PC diet, feeding the PC + 0.4% BN or PC + 0.4% ZE diets increased DWG and PEF and decreased FCR during finisher and overall periods, raised dressing percentage, serum levels of TP, GLU, T-AOC, and T-SOD, apparent CP digestibility, and reduced proportional liver weight and AFB1 residues in the liver (p < .001). Moreover, feeding the PC + 0.4% BN diet increased VH, VSA, apparent EE digestibility, AME, and AMEn, and decreased serum GOT and GPT activities when compared to the PC diet (p < .001). Whereas, feeding the PC + 0.4% ZE diet increased DFI during all experimental periods (p < .05) and DWG and PEF during the grower period (p < .001) as compared to the PC diet. To conclude, our findings demonstrate that dietary addition of 4 g/kg BN can deliver a better safeguard against the adverse influences of AFB1 in broiler chickens.