For decades, antibiotics were routinely incorporated into the diets of poultry and rabbits to enhance growth and productivity. Mounting concerns about antimicrobial resistance and food safety have driven the search for natural and safe alternatives. Lysozyme, an endogenous enzyme most abundantly found in egg white, has emerged as a promising candidate due to its antimicrobial and immunomodulatory activities. This review synthesizes current evidence on the dietary inclusion of lysozyme in poultry (broilers, layers, and quail) and rabbit production systems. Reported benefits include improved weight gain, feed efficiency, egg production, and carcass traits, alongside enhanced immune responses and healthier gut microbial profiles. Effective supplementation levels range from 50 to 200 mg/kg, depending on species and production goals. Beyond growth promotion, lysozyme contributes to gut integrity, supports the regulation of immune-related gene expression, and reduces reliance on antibiotics. Importantly, lysozyme modulates immunity by regulating cytokines, enhancing mucosal defenses, and promoting a balanced gut microbiota by suppressing pathogenic bacteria while supporting beneficial populations. Despite its potential, knowledge gaps persist regarding long-term safety, cost-effectiveness under commercial conditions, optimal species-specific dosing, and interactions with other natural feed additives. Collectively, the available data highlight lysozyme as a safe, environmentally friendly, and sustainable tool to improve health and performance in poultry and rabbit farming.

This study investigated the effects of supplementing broiler drinking water with Egyptian clover honey on growth performance, carcass characteristics, and blood biochemical parameters. A total of 525 one-day-old male Hubbard broilers were assigned to seven treatment groups to evaluate two concentrations of honey (13 and 26 mLL-1) administered at three different frequencies (daily, every other day, and every 3 d), along with a control group receiving no honey. Supplementing drinking water with honey significantly enhanced overall broiler performance. Birds receiving honey, particularly at the higher concentration and at intermittent intervals, showed improved body weight gain and feed efficiency compared to the control group. The highest relative weights of key lymphoid organs - such as the spleen, bursa of Fabricius, and thymus - were observed in supplemented groups, indicating a positive impact on immune system development. Hematological analysis revealed increased red and white blood cell counts, hemoglobin, and packed cell volume in honey-fed birds, reflecting improved oxygen transport and immune competence. Serum biochemical profiles demonstrated a favorable shift, with significant reductions in markers of metabolic stress and liver function (uric acid, creatinine, cholesterol, triglycerides, and alanine aminotransferase (ALT)) and notable increases in total protein, albumin, and globulin levels. Additionally, honey supplementation significantly enhanced humoral immune response, as evidenced by higher hemagglutination inhibition titers against Newcastle disease virus. The results indicate that honey supplementation via drinking water, especially at 26 mLL-1, administered intermittently, can effectively improve growth performance, physiological health, and immune function in broiler chickens. These findings support the potential of honey as a natural antibiotic-free additive to promote sustainable poultry production.

This study examined the influences of dietary lemongrass oil (LEO), geranium oil (GEO), and their mixture on growth, physiological status, immunity, antioxidant activity, nutrient utilization, mineral profile, and gut microbiome of growing quails. 315 Japanese quail chicks that were one week old were split into seven treatment groups at random, each consisting of 45 chicks (3 replicates/15 chicks). As a control, the first group was given the basal diet excluding any supplements; the second and third groups were given the basal diet plus 200 and 400 mg LEO/kg feed, respectively. The basal diet was supplemented with 200 and 400 mg GEO/kg feed for the fourth and fifth groups, respectively. The basal diet was supplemented with 200 and 400 mg of LEO+GEO/kg (1:1), respectively, for the sixth and seventh groups. Supplementation with either oil, especially the 400 mg/kg mixture, significantly enhanced body weight, daily gain, feed conversion ratio, and performance index. Improvement in digestive enzyme activities and nutrient digestibility supported higher carcass yield and reduced muscle fat content. The oil treatments also increased total protein, albumin, globulins, and positive lipid indices and reduced cholesterol, triglycerides, Low-Density Lipoprotein (LDL), and liver and kidney stress markers. Hematological indices were increased, pointing to improved physiological resilience. Immune responses were enhanced, as reflected in higher levels of complement C3, IgY, IgM, and lysozyme activity. At the same time, antioxidant defense mechanisms developed more favorably superoxide dismutase (SOD), glutathione peroxidase (GPx), total antioxidant capacity (TAC), and catalase (CAT) with a reduced MDA value, showing reduced oxidative stress. Fe, Ca, and Zn mineral concentrations in serum were markedly enhanced. Besides, oil supplementation considerably reduced pathogenic intestinal bacteria, coliforms, E. coli, Salmonella, and Enterococcus, and the total microbial load. Generally, however, the combined LEO-GEO mixture at 400 mg/kg provided the most consistent and marked benefits. From the above, it becomes apparent that lemongrass and geranium oils are two valid natural growth-promoting additives that can be used to improve performance, health, and gut ecology in quail production systems.

Rosmarinic acid (RA), a bioactive polyphenol found in Salvia officinalis and other Lamiaceae herbs, has attracted attention for its functional feed application in animal nutrition. RA supplementation positively influences growth efficiency, liver antioxidant status, and serum biochemical indices in broilers. Its antimicrobial and immunomodulatory effects promote health and productivity. Studies suggest benefits for gut health and meat quality; however, epigenetic regulation of RA in poultry is considered a minor future perspective, being mostly based on mammalian studies. Hypothesized impacts of RA on chronic disease prevention and as a microbiome-engineering agent require further investigation. This review explores the regulatory effects of RA on DNA methylation, non-coding RNAs (ncRNAs), and histone modifications, which influence gut microbiome structure, nutrient absorption, and immune function in poultry. It emphasizes RA's potential as a functional food for gastrointestinal health, metabolic regulation, and chronic disease prevention, alongside its use in antibiotic-free poultry feed for microbiome engineering. The review also discusses RA’s effects on lipid metabolism and oxidative stress, highlighting its role in maintaining intestinal barrier health. Nevertheless, certain limitations must be acknowledged, as successful nutritional interventions depend on understanding individual variability, including genetics, metabolism, age, and health status. Tailored methodologies, such as micronutrition and genomic nutrition, can improve diet quality, promote nutrient absorption, and enhance overall animal health. A tailored feeding regimen focuses on selecting nutrients with proven benefits for key health outcomes, such as omega-3 fatty acids, which scientific evidence shows promote brain and heart health while reducing inflammation.

This study evaluated the efficacy of Barnouf (Pluchea indica Less) extract (BE) as a natural antioxidant and immune-modulating supplement in broiler chickens. A total of 210 chicks were assigned to three treatments in a completely randomized design, with each treatment consisting of seven replicates of ten unsexed chicks. The control group received water without additives, whereas the other treatments received Barnouf extract (BE) at 3 or 6 mL/L. Supplementation with BE at both inclusion levels improved growth performance (P <= 0.05). Birds receiving 6 mL/L exhibited greater body weight gain (BWG) from days 5 to 20 and days 21 to 33 compared with the control. Feed intake (FI) decreased (P <= 0.05) in both supplemented groups, accompanied by improved feed conversion ratio (FCR); additionally, the 3 mL/L group demonstrated a higher performance index (PI) (P <= 0.05) on day 33. Broilers receiving 3 or 6 mL/L of the extract showed increased water consumption (WC) and higher water-to-feed ratios between days 5 and 20 (P <= 0.05), with the 6 mL/L group showing the greatest values, while still exhibiting reduced FI. Supplementation with BE increased abdominal fat percentage, live body weight, and relative weights of the gizzard and liver, whereas carcass percentage varied among treatments. Heart and spleen weights showed numerical reductions (P >= 0.05) with increasing extract levels. Health-related biochemical indices were favorably altered by BE supplementation. Levels of aspartate aminotransferase (AST), urea, total lipids, and malondialdehyde (MDA) were reduced (P <= 0.05), whereas concentrations of high-density lipoprotein (HDL), antioxidant enzymes-glutathione peroxidase (GPX), glutathione S-transferase (GST), and reduced glutathione (GSH)-and immunoglobulins G (IgG) and M (IgM) increased (P <= 0.05). Meat quality also improved, as reflected by more stable pH values, lower microbial loads, and reduced storage-related water loss, with significant effects observed for color parameters (P <= 0.05). Additionally, both supplementation levels increased lactobacilli count while reducing total bacterial count (TBC), bacilli, Escherichia coli, coliforms, and Salmonella (P <= 0.05). In conclusion, dietary inclusion of BE at 3 or 6 mL/L enhanced growth performance, immune competence, antioxidant status, meat quality, and gut microbial balance in broiler chickens without adverse effects, supporting its potential as a safe natural feed additive.

This study examined the effects of dietary sage and thyme leaves, fed individually or in combination, on broiler growth performance, carcass characteristics, and hematological and biochemical profiles. A total of 480 one-day-old Hubbard broiler chicks were randomly allocated to four dietary treatments: a basal diet (D1), a basal diet with 0.5% sage (D2), 0.5% thyme (D3), or a combination of 0.25% sage and 0.25% thyme (D4). Birds received the diets for six weeks. The combined treatment (D4) produced the greatest improvements in live body weight and body weight gain (P < 0.01), along with reduced feed intake from the second week onward and better feed conversion ratio during the first and sixth weeks. Carcass yield and most organ relative weights increased in all supplemented groups compared with the control. Thyme supplementation (D3) yielded the highest packed cell volume (PCV), hemoglobin concentration, and red blood cell (RBC) count, whereas sage (D2) increased heterophil numbers, total protein, and globulin concentrations. Birds fed the combined diet (D4) showed the highest white blood cell (WBC) and lymphocyte counts. Chicks on the basal diet (D1) exhibited the highest hemagglutination inhibition (HI) titer, heterophil-to-lymphocyte (H/L) ratio, albumin, uric acid, creatinine, triglycerides, cholesterol, aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Overall, adding sage and thyme to broiler diets can significantly enhance broiler growth performance, carcass traits, and physiological status, and enhanced economic efficiency.

Rising global temperatures, compounded by diminishing water resources, have escalated the incidence and severity of heat stress in poultry production, posing a critical threat to animal welfare, productivity, and food security. Heat stress represents a multifactorial physiological challenge, disrupting the thermo-immuno-endocrine axis and thereby impairing hypothalamic thermoregulation, suppressing immune responses, and altering endocrine signaling pathways. Such imbalances contribute to reduced feed intake, compromised growth and reproductive performance, elevated mortality rates, and heightened disease susceptibility. Central to this response is the hypothalamus, particularly the preoptic area and the hypothalamic-pituitary-adrenal axis, which integrates environmental and internal stress cues to regulate corticosterone release, thyroid hormone activity, and immunological cascades. This review consolidates current evidence on the pathophysiological impacts of heat stress on poultry, with emphasis on oxidative stress, cytokine imbalance, and lymphoid tissue degeneration. It also explores pharmacological strategies for heat stress mitigation e.g., nonsteroidal anti-inflammatory drugs (NSAIDs), antioxidant supplementation (vitamins C, E, selenium), and bioactive plant-derived compounds (e.g., ashwagandha, betaine, resveratrol, curcumin). These interventions demonstrate potential in restoring cellular homeostasis, modulating endocrine activity, and enhancing immune resilience; however, their efficacy is contingent upon dosage, duration, and production context. Moreover, concerns remain regarding drug residues, side effects, and variability in responses across poultry strains. In parallel, the integration of precision livestock and poultry farming tools-such as sensor-based monitoring, automated ventilation, and real-time climate control-emerges as a complementary approach, enabling proactive management of thermal loads. Collectively, the convergence of pharmacological, nutritional, and technological strategies provides a multifaceted framework to mitigate heat stress and improve poultry resilience under climate change. Nevertheless, further longitudinal and field-based studies are required to elucidate mechanistic interactions, validate interventions under commercial conditions, and align practices with sustainability and food safety goals.

Ziziphus spina-christi (ZS-C) is gaining attention as a natural feed supplement for livestock production in arid and semi-arid regions. Its leaves contain relatively high crude protein, metabolizable energy, essential minerals, and bioactive compounds with antioxidant properties, suggesting potential nutritional and functional benefits. Studies have shown that dietary supplementation with ZS-C may improve growth performance, feed efficiency, milk and egg production, immune response, and oxidative status in different livestock species. Positive effects on meat, milk, and egg quality have also been reported. In addition, ZS-C may represent a sustainable and costeffective alternative feed resource under conditions of feed scarcity and climatic stress. However, information on optimal inclusion levels, mechanisms of action, and long-term effects remains limited. The aim of this review is to summarize and critically discuss the current knowledge on the botanical characteristics, nutritional composition, and potential applications of ZS-C in livestock nutrition, with emphasis on animal productivity, physiological responses, product quality, and sustainability aspects.

The present study evaluated the feasibility of rearing fast-growing broiler chickens in an open-sided house for 42 days in Bangladesh using different feed withdrawal strategies, with particular emphasis on growth performance, meat quality, survivability, and economic returns. A total of 480 Indian River meat-type day-old chicks (DOCs) were reared up to 42 days and randomly allocated into four treatment groups. The first group was a control that provided ad libitum feeding throughout the production cycle (AdLF). The remaining groups received ad libitum feeding for the first 7 days, followed by daily feed withdrawal for 8 h. Accordingly, the second group was subjected to feed withdrawal from 8 to 28 days (3-WksFW), the third group from 8 to 35 days (4-WksFW), and the fourth group from 8 to 42 days (5-WksFW). Each treatment consisted of six replicates with 20 birds per replicate. Key performance indicators, including body weight (BW), body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR), survivability, carcass yield, meat quality, and benefit-cost ratio (BCR), were evaluated. As expected, the overall BWG was significantly higher in the AdLF group (3170.52 g/bird; P = 0.000), followed by the 3-WksFW (3040.43 g/bird) and 4-WksFW (2878.86 g/bird) groups, with the lowest value observed in the 5-WksFW group (2510.85 g/bird). Similar trends were observed for final BW and FI. Despite the higher BW, BWG, and FI in the AdLF group, feed withdrawal strategies improved survivability, meat quality, and, notably, economic efficiency. The highest BCR was recorded in the 4-WksFW group (1.14), followed by the 3-WksFW (1.07), 5-WksFW (1.07), and AdLF (1.05) groups. FCR was not significantly affected by treatment; however, abdominal fat deposition was reduced in birds subjected to feed withdrawal. Overall, feed withdrawal improved water holding capacity with a significant decreased of cooking loss, although the meat color was unaffected. In conclusion, the 4-WksFW strategy is recommended for rearing broilers up to 42 days in open-sided housing under local conditions, as it optimizes meat quality, survivability, and profitability in small-scale production systems.