Intestinal development and function of broiler chickens on diets supplemented with clinoptilolite

Zeolite and Neurodegenerative Diseases

Neurodegenerative diseases (NDs), characterized by progressive degeneration and death of neurons, are strongly related to aging, and the number of people with NDs will continue to rise. Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common NDs, and the current treatments offer no cure. A growing body of research shows that AD and especially PD are intricately related to intestinal health and the gut microbiome and that both diseases can spread retrogradely from the gut to the brain. Zeolites are a large family of minerals built by [SiO4]4- and [AlO4]5- tetrahedrons joined by shared oxygen atoms and forming a three-dimensional microporous structure holding water molecules and ions. The most widespread and used zeolite is clinoptilolite, and additionally, mechanically activated clinoptilolites offer further improved beneficial effects. The current review describes and discusses the numerous positive effects of clinoptilolite and its forms on gut health and the gut microbiome, as well as their detoxifying, antioxidative, immunostimulatory, and anti-inflammatory effects, relevant to the treatment of NDs and especially AD and PD. The direct effects of clinoptilolite and its activated forms on AD pathology in vitro and in vivo are also reviewed, as well as the use of zeolites as biosensors and delivery systems related to PD.

Using Natural Zeolite as a Feed Additive in Broilers' Diets for Enhancing Growth Performance, Carcass Characteristics, and Meat Quality Traits

BACKGROUND

Using natural zeolites as a food additive in poultry diets offers an intriguing perspective. The objective of this study was to investigate the effects of zeolite addition and particle size on broiler performance, carcass characteristics, meat quality, moisture of excreta and litter, and intestinal measurements during 35 days.

METHODS

A total of 560 1-day-old female Ross-308 broilers were divided into five treatment levels (0, 5, 10, 15, and 20 g zeolite/kg diet) (n = 16 replicates/treatment, n = 8 replicates /particle size of each treatment). Performance was calculated weekly. Carcass characteristics, meat quality, small intestine (SI) measurements, litter pH, and moisture content were determined on day 35.

RESULTS

Litter pH, breast redness, cooking loss, chewiness, total weight, and SI length were all affected by zeolite treatments (p < 0.05). Particle size had an impact on the gastric pH and texture analysis. Their interaction had an effect on color redness, litter pH, and cooking loss. Performance was unaffected by either the main or interaction effects.

CONCLUSION

Zeolite as a feed additive may be useful in broiler diets, particularly large particles. The performance and production efficiency factor improved numerically (p > 0.05) with increasing zeolite doses up to 10 g zeolite/kg diet.

A meta-analysis of the effects of clay mineral supplementation on alkaline phosphatase, broiler health, and performance

The crucial constraint in the broiler production sector is feed efficiency; many feed additives have been widely employed to increase broiler growth. Nonetheless, some of these substances exacerbate health and animal-based food product safety concerns. This meta-analysis examines the effect of clay minerals on alkaline phosphatase (ALP), broiler health, and performance. Metadata was constructed from 369 data items that were harvested from 86 studies. The addition of clay minerals was set as a fixed effect and the difference between experiments was established as a random effect. The metadata were fitted using a linear mixed model. Due to the presence of clay minerals, growth performance as assessed by body weight (BW), average daily gain (ADG), and performance efficiency index (PEI) increased significantly (P < 0.01). In the total period, the increases of BW, ADG, and PEI were 4.12 g, 0.0714 g/d, and 0.648, respectively, per unit of clay minerals added. Clay minerals did not affect blood serum parameters (e.g., ALP and calcium). The IgA and IgM concentrations in the jejunum and ileum were significantly greater (P < 0.01) in the starter phase. Among clay minerals, broilers fed diets with aluminosilicate, halloysite, kaolin, and zeolite consistently exhibited higher (P < 0.05) BW, ADG, PEI, and lower feed conversion ratio (P < 0.05) in the finisher phase. Aluminosilicate was the only clay that increased (P < 0.05) secretory IgA concentration in both jejunum and ileum. In conclusion, clay minerals could be used as a growth promoter, especially during the finisher phase, without adversely affecting feed intake, liver function, and mineral metabolism in broiler chickens. Aluminosilicate was superior in improving the mucosal immunity status of broiler chickens.

Partial replacement of soybean meal with Chlorella vulgaris in broiler diets influences performance and improves breast meat quality and fatty acid composition

Alternative feed ingredients, such as microalgae, may be more sustainable in comparison to conventional feedstuffs that need large amounts of arable land and are often imported. This study evaluates the effects of Chlorella vulgaris various inclusion levels in the diet of broiler chickens on performance, carcass yield, organ measurements, breast meat quality, fatty acids profile, and antioxidant capacity. A total of two hundred forty 5 d old male Ross 308 broilers were randomly allotted to 4 groups (6 replicates of 10 birds each). Each group received either a control diet or a diet where soybean meal was replaced with 10% (CV10%), 15% (CV15%), or 20% C. vulgaris for 40 d. Performance parameters, carcass and meat traits were evaluated. Compared to the control group, birds supplemented with C. vulgaris (15% and 20%) had lower body weight, weight gain, and feed intake (P < 0.0001), whereas no differences were observed between the control and CV10% groups (P > 0.05). Feed conversion ratio did not differ between control and CV groups. Diets containing C. vulgaris significantly increased ileal digesta viscosity, weight and size of several gastrointestinal compartments, as well as breast muscle yield (P < 0.0001). Incorporation of C. vulgaris resulted in yellower breast muscle (P < 0.0001), with significantly increased chlorophyll a (P < 0.05), chlorophyll b, and total carotenoids contents (P < 0.0001). Inclusion of C. vulgaris decreased bacterial count in meat samples in comparison to controls (P < 0.0001). A 20% C. vulgaris inclusion resulted in higher water holding capacity (P < 0.05) and lower cooking loss (P < 0.05). As dietary C. vulgaris increased, concentrations of DHA + EPA (P < 0.05) and n-3 PUFA (P < 0.0001) increased in breast meat, while the n-6/n-3 PUFA ratio decreased (P < 0.0001). Sensory analysis showed that breast meat from the CV10% group had the highest acceptance score. Overall, dietary concentrations of C. vulgaris of up to 20% improve breast meat quality, whereas 10% of C. vulgaris inclusion is recommended.

Comprehensive Review on the Interactions of Clay Minerals With Animal Physiology and Production

Clay minerals are naturally occurring rock and soil materials primarily composed of fine-grained aluminosilicate minerals, characterized by high hygroscopicity. In animal production, clays are often mixed with feed and, due to their high binding capacity towards organic molecules, used to limit animal absorption of feed contaminants, such as mycotoxins and other toxicants. Binding capacity of clays is not specific and these minerals can form complexes with different compounds, such as nutrients and pharmaceuticals, thus possibly affecting the intestinal absorption of important substances. Indeed, clays cannot be considered a completely inert feed additive, as they can interfere with gastro-intestinal (GI) metabolism, with possible consequences on animal physiology. Moreover, clays may contain impurities, constituted of inorganic micronutrients and/or toxic trace elements, and their ingestion can affect animal health. Furthermore, clays may also have effects on the GI mucosa, possibly modifying nutrient digestibility and animal microbiome. Finally, clays may directly interact with GI cells and, depending on their mineral grain size, shape, superficial charge and hydrophilicity, can elicit an inflammatory response. As in the near future due to climate change the presence of mycotoxins in feedstuffs will probably become a major problem, the use of clays in feedstuff, given their physico-chemical properties, low cost, apparent low toxicity and eco-compatibility, is expected to increase. The present review focuses on the characteristics and properties of clays as feed additives, evidencing pros and cons. Aims of future studies are suggested, evidencing that, in particular, possible interferences of these minerals with animal microbiome, nutrient absorption and drug delivery should be assessed. Finally, the fate of clay particles during their transit within the GI system and their long-term administration/accumulation should be clarified.

Effects of the in ovo injection of vitamin D3 and 25-hydroxyvitamin D3 in Ross 708 broilers subsequently fed commercial or calcium and phosphorus-restricted diets. II. Immunity and small intestine morphology1,2,3

Effects of the in ovo injection of vitamin D₃ (D₃) and 25-hydroxyvitamin D₃ (25OHD₃) on the immunity and small intestine morphology of broilers fed calcium and phosphorus-restricted diets were investigated. At 18 d of incubation (doi), live embryonated Ross 708 broiler hatching eggs were in ovo-injected with a 50 μL solution of one of the following treatments using an Inovoject multiegg injector: 1) diluent (control); diluent containing either 2) 2.4 μg D₃; 3) 2.4 μg 25OHD₃; or 4) 2.4 μg D₃ + 2.4 μg 25OHD₃. At hatch, 18 randomly selected male broilers belonging to one of the 4 in ovo injection treatments were placed in each of 12 floor pens and were fed either a commercial diet or a diet restricted by 20% in calcium and available phosphorus (ReCaP) content for the starter, grower and finisher dietary phases. Concentrations of plasma IgG and IgM at 14 d of age (doa) and α-1-acid glycoprotein at 40 doa were determined. Bursa, liver, spleen, duodenum, jejunum, and ileum weights were recorded at 7, 14, and 40 doa and small intestine histology was evaluated at 14 and 40 doa. Blood and organ samples were randomly collected from 1 bird in each of the 6 replicate pens within each of the 8 (4 in ovo x 2 dietary) treatment groups. Plasma IgG levels were higher in 25OHD₃ than in diluent or D₃ in ovo-injected birds. At 14 doa, a higher jejunal villus length (VL) to crypt depth (CD) ratio (RVC) was observed in birds that were in ovo-injected with 25OHD₃ alone as compared to all other in ovo injection treatments. At 40 doa, ileal VL increased and jejunal CD decreased in commercial diet-fed birds compared to ReCaP diet-fed birds. In conclusion, the in ovo injection of 25OHD₃ alone increased the immune response and improved the small intestine morphology and subsequent nutrient uptake of Ross 708 broilers. However, a ReCaP diet was observed to be detrimental to their small intestine morphology.

Ducks' Growth, Meat Quality, Bone Strength, and Jejunum Strength Depend on Zeolite in Feed and Long-Term Factors

Simple Summary

Natural agents ensuring the biosecurity of poultry production and the high quality of meat have again gained increasing interest. Natural zeolites absorb toxic gases and can also stimulate digestion and improve the physicochemical parameters of meat, which is important from the consumer’s point of view. The aim of the study was to assess the effect of a diet with a 4% inclusion of zeolite on the growth, the meat quality, and the strength of the bones and jejunum of Orvia and Cherry Valley ducks of different age and sex. The addition of zeolite was associated with reduced body weight gains and an increased feed conversion ratio, but with a higher water-holding capacity of breast muscles in seven-week-old ducks, and with a higher yellowness and water-holding capacity of leg muscles in six-week-old ducks. Interactions were found between long-term factors (age, sex, and origin) and the addition of zeolite. The results are inconclusive and indicate a need for further research, testing different doses of zeolite in different forms. Studies on the use of zeolite may help reduce the negative impact of poultry production on the environment, and ensure its safety and profitability.

Abstract

The safety of production and the high quality of meat are important aspects of rearing poultry, especially when natural solutions are used. Because of the increasing popularity of duck meat, the aim of the present study was to assess the effect of a diet with an inclusion of zeolite on the growth performance, meat quality, and strength of the bones and jejunum in ducks of different origin, sex, and age at slaughter. The study was conducted on 320 Orvia and Cherry Valley ducks. Birds were allocated to eight groups, according to their sex and origin. Half of the birds received feed with a 4% inclusion of zeolite. Body weight gain, feed intake, and feed conversion ratio per kilogram of gain were calculated. After six or seven weeks, five birds from each group were selected and slaughtered. After dissection, meat quality (pH, water-holding capacity, colour) and the strength of the bones and gut were analysed. The analysis revealed that zeolite was associated with reduced body weight gains and increased feed conversion ratio, but with a higher water-holding capacity of breast muscles in seven-week-old ducks, and with a higher yellowness and water-holding capacity of leg muscles in six-week-old ducks. A positive effect of long-term factors (age, sex, origin) and the interaction with zeolite was found for most of the analysed traits. Findings on the effect of 4% inclusion of zeolite in duck diet were inconclusive. The study implies the need for further research, since zeolite has potential as a natural sanitizing agent and can improve the quality of produced duck meat.

Effects of Dietary Inclusion of Bilberry and Walnut Leaves Powder on the Digestive Performances and Health of Tetra SL Laying Hens

Simple Summary

In poultry, diet composition influences growth performance, egg production, as well as digestion. In this study, the effects of dietary additives obtained from bilberry and walnut leaves powder on the digestive performances of Tetra SL hens were evaluated by histologic and morphometric analyses of the intestinal mucosa as well as by the enzymatic activity measurements of alpha-amylase, invertase, maltase, and trypsin correlated with cecum microbiota.

Abstract

The purpose of this study was to examine the effects of dietary inclusion of two additives at the final concentration of 0.5% bilberry (E1) and 1% walnut (E2) leaves powder in the basal diet on digestive health of hens. A total number of 90 Tetra SL hens were divided into two experimental groups (E1 and E2) and one control group (C) consisting of 30 hens each. After four weeks, 10 hens of each group were sacrificed and tissue samples and intestinal content were taken from the duodenum, jejunum, and cecum in order to perform histological, enzymatic, and microbiota analyses. In groups E1 and E2, the histological analysis showed a significant increase of villus height, resulting probably in increased absorption of nutrients in duodenum and jejunum. A decrease in the specific activity of alpha-amylase and trypsin in E1 and E2 for both duodenum and jejunum compared to the control one was also recorded. In addition, the maltase and invertase specific activity in duodenum increased, a tendency that was kept for maltase but not for invertase in jejunum. The cecal microbiota of E1 and E2 individuals was characterized by an increase of Firmicutes and Lactobacilli and a decrease of Enterobacteriaceae. In conclusion, our results indicate that bilberry and walnut leaves additives in feed may improve the health status of the poultry gastrointestinal tract.

The effect of feed supplementation with Transcarpathian zeolite (clinoptilolite) on the concentrations of acute phase proteins and cytokines in the serum and hepatic tissue of chickens

The aim of the this study was to determine the effect of different levels of Transcarpathian zeolite (clinoptilolite) on selected indicators of the immune response in chickens by assessing the concentrations of the acute phase proteins haptoglobin, C-reactive protein (CRP), serum amyloid A, transferrin, and alpha-1-acid glycoprotein and the cytokines tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), IL-2, and IL-10 in the serum and hepatic tissues of chickens. The study was conducted on 450 one-day-old male Ross 308 chickens. The total rearing period was 42 D. The samples of blood and liver were collected before the start of the study (day 0) and on day 42, after rearing was completed. ELISA kits specific for chicken CRP, haptoglobin, alpha-1-acid glycoprotein, serum amyloid A, transferrin, TNF-α, IFN-γ, IL-2, and IL-10 were used to determine the levels of acute phase proteins and cytokines in the serum and liver homogenates. The results of immunological tests suggest that for long-term maintenance of homeostasis in chickens, the addition of 2% zeolite as a feed additive is most beneficial. The results indicate that 3% clinoptilolite induce production of Th1 pro-inflammatory cytokines, increasing the synthesis of IL-2, IFN-γ, and TNF-α. The high concentration of IL-10 after the use of zeolite in conjunction with the high concentration of IL-2, TNF-α, and IFN-γ indicates a reduction in the intensity of inflammatory processes, the enhancement of the humoral immune response, and the simultaneous inhibition of the production of Th1-type cytokines. The increase of CRP concentration in conjunction with high concentrations of pro- and anti-inflammatory cytokines in the birds from the group receiving 3% clinoptilolite demonstrates indicates that it can influence the development of local inflammatory processes and enhance immune regulation in birds. Our research has shown that clinoptilolite influences on an increase in birds' resistance to infection, as confirmed by clinical observations and anatomopathological examination and by the increase in the synthesis of acute phase proteins with immunoregulatory properties.

Effects of Dietary Zeolite Supplementation as an Antibiotic Alternative on Growth Performance, Intestinal Integrity, and Cecal Antibiotic Resistance Genes Abundances of Broilers

The study investigated the effects of dietary zeolite supplementation as an antibiotic alternative on growth performance, intestinal integrity, and cecal antibiotic resistance genes abundances of broilers. One-day-old chicks were assigned into three groups and fed a basal diet or a basal diet supplemented with antibiotics (50 mg/kg) or zeolite (10 g/kg). Antibiotic or zeolite increased (p < 0.05) average daily gain (ADG) from 1 to 42 days and duodenal villus height to crypt depth ratio (VH:CD) at 21 days. Zeolite increased (p < 0.05) ADG and average daily feed intake from 1 to 21 days, jejunal VH:CD at 21 and 42 days, ileal VH and VH:CD at 42 days, zonula occludens-1 mRNA abundance at 21 days, and duodenal occludin mRNA abundance at 42 days, whereas reduced (p < 0.05) jejunal CD and malondialdehyde levels in ileum at 21 days and duodenum at 42 days, serum D-lactic acid and diamine oxidase levels at 42 days, and plasma lipopolysaccharide content at 21 and 42 days. Antibiotics reduced (p < 0.05) duodenal claudin-2 mRNA abundance at 21 days, whereas increased (p < 0.05) cecal tetB abundance at 42 days. These findings suggested that the beneficial effects of zeolite in broilers were more pronounced than that of antibiotics.

Influence of acidified drinking water on growth performance and gastrointestinal function of broilers

The ban on the use of antibiotic feed additives as growth promoters compelled the researchers for exploring the future utility of other alternatives. This experiment was designed to evaluate the effect of acidified drinking water on growth performance, gastrointestinal pH, digestive enzymes, intestinal histomorphology, and cecum microbial counting of the broiler chicken. A total of 540 one-day-old male broilers (Arbor Acre) were randomly assigned to 5 treatments, with 6 replicates of 18 chicks per replicate. Broilers received diets and water as follows: NC (negative control, basal diet, normal water), PC (positive control, basal diet + 8 ppm colistin sulfate + 8 ppm enduracidin, normal water), A1 (basal diet, continuous supply of acidified water during whole experiment period), A2 (basal diet, intermittent acidification of water during 0 to 14 d, 22 to 28 d, and 36 to 42 d), and A3 [basal diet, intermittent acidification of water (24 h/d from 0 to 14 d and from 10:00 am to 4:00 pm on d 15 to 42)]. During the entire period, the acidified groups (A1, A2, and A3) and PC group showed improve on weight gain, average daily gain and feed conversion ratio compared to NC group (P < 0.05). The pH in crop, proventriculus and ileum at 43 d declined by 0.04, 1.03, 1.23; 0.55, 0.69, 0.70; and 0.63, 0.74, 1.21 in A1, A2, and A3 group, respectively. There was a significant decline of lipase activity in the PC and acidified groups compared to NC group. The A2 group had higher villus height in jejunum than NC group. The PC and acidified groups reduced (P < 0.05) the total aerobic bacteria count of cecum when contrasted to NC group. Therefore, we conclude that acidified drinking water can improve growth performance, compensate for gastric acidity, and control pathogenic bacteria in broilers and may be considered as a potential alternative to improve production parameters. Discontinuous supply of acidified water had the same or even better influence on broilers compared to continuous supply.

The Effects of Natural Clinoptilolite and Nano-Sized Clinoptilolite Supplementation on Lipid Profile, Food Intakes and Body Weight in Rats with Streptozotocin-Induced Diabetes

Purpose: To determine the effect of natural clinoptilolite (CLN) and nano-sized clinoptilolite (NCLN) on lipid profile, food intakes (FI) and weight changes in streptozotocin (STZ) induced diabetic rats. Methods: In this experimental study, 36 rats were randomly divided into two groups: diabetic group which was injected STZ (60 mg/kg BW), and a non-diabetic group. Three days after diabetes induction, each of these groups was randomly divided into 3 subgroups of 6 animals ((1) control, (2) 1%/food CLN, (3) 1%/food NCLN). The animals were supplemented for 28 days, starting three days after STZ administration. At the end of the study, blood was drawn for biochemical assays. The weights and FIs of the rats were measured at the beginning and end of each week. Results: Our findings revealed that there was no significant change in lipid profile, 28 days after administration of STZ in diabetic rats. Low density lipoprotein (LDL) was increased slightly in diabetic rats treated with NCLN without any significant changes in other lipid profile parameters in the other groups. Weight was reduced significantly in diabetic rats. Administration of CLN and NCLN prevented further weight loss in diabetic rats. All groups treated with STZ had higher food intake during the study. Conclusion: Lack of beneficial changes in lipid profile may be attributed to short study duration, insufficient for appearance of lipid abnormalities. Given the partial improvement in weight status and lack of undesirable effects of clinoptilolite supplementation, further research is recommended in subjects with typ1 diabetes mellitus.

Zeólitas naturais na dieta de frangos de corte

RESUMO O objetivo deste trabalho foi avaliar o efeito da inclusão de 0,5% da zeólita natural clinoptilolita na dieta de frangos de corte sobre o consumo de água, ração e características das excretas. Foi conduzido um ensaio em gaiolas metabólicas, com frangos de corte de linhagem comercial, no período de 14 a 23 dias de idade. O experimento foi constituído de dois grupos de aves, sendo que um recebeu dieta sem inclusão de zeólitas (controle) e outro dieta com inclusão de 0,5% de zeólita (clinoptilolita) em rações isonutritivas, em um delineamento inteiramente ao acaso, com 10 repetições de 10 aves. Avaliou-se o consumo de água e de ração, nas excretas, pH, teor de nitrogênio total e umidade. A inclusão de 0,5% de zeólitas naturais na dieta não alterou (P>0,05) o consumo de água e de ração e o teor de nitrogênio das excretas, entretanto, reduziu (P<0,05) o pH e a umidade das excretas. Conclui-se que a inclusão de 0,5% de zeólitas naturais na dieta de frangos de corte reduz o pH e a umidade das excretas e pode ser utilizada como aditivo alimentar sem prejudicar o consumo de água e de ração.

Influence of Butyrate Loaded Clinoptilolite Dietary Supplementation on Growth Performance, Development of Intestine and Antioxidant Capacity in Broiler Chickens

The study was conducted to evaluate the effects of dietary butyrate loaded clinoptilolite (CLI-B) on growth performance, pancreatic digestive enzymes, intestinal development and histomorphology, as well as antioxidant capacity of serum and intestinal mucosal in chickens. Two hundred forty 1-day-old commercial Arbor Acres broilers were randomly assigned to 4 groups: CON group (fed basal diets), SB group (fed basal diet with 0.05% sodium butyrate), CLI group (fed basal diet with 1% clinoptilolite), and CLI-B group (fed basal diet with 1% CLI-B). The results showed that supplementation of CLI-B significantly decreased (P < 0.05) feed conservation ratio at both 21 and 42 days of age, improved the pancreatic digestive enzymes activities (P < 0.05), increased the villus length and villus/crypt ratio (P < 0.05), and decreased the crypt depth of intestine (P < 0.05) as compared to the other experimental groups. Furthermore, the CLI-B environment improved the antioxidant capacity by increasing the antioxidant enzyme activities (P < 0.05) in intestine mucosal, and decreasing the NO content and iNOS activity (P < 0.05) in serum. In addition, CLI-B supplementation had improved the development of intestine and antioxidant capacity of broilers than supplementation with either clinoptilolite or butyrate sodium alone. In conclusion, 1% CLI-B supplementation improved the health status, intestine development and antioxidant capacity in broiler chickens, thus appearing as an important feed additive for the poultry industry.

Effects of dietary supplementation with the combination of zeolite and attapulgite on growth performance, nutrient digestibility, secretion of digestive enzymes and intestinal health in broiler chickens

This study was designed to investigate the effects of basal diets supplemented with a clay product consisting of zeolite and attapulgite (ZA) at 1:1 ratio on growth performance, digestibility of feed nutrients, activities of digestive enzymes in small intestine and intestinal health in broiler chickens. In experiment 1, 112 one-day-old male chickens were randomly divided into 2 groups with 8 replicates of 7 chickens each. In experiment 2, 84 one-day-old male chickens were randomly allocated into 2 groups consisting 6 replicates of 7 chickens each. The experimental diets both consisted of a maize-soybean basal control diet supplemented with 0% or 2% ZA. The diets were fed from 1 to 42 days of age. The results showed that ZA supplementation could increase body weight gain (BWG) and feed intake (FI), but had no significant effect on feed conversion ratio. The apparent digestibility values of crude protein and gross energy were significantly increased (p<0.05) by ZA from 14 to 16 d and 35 to 37 d. Dietary ZA treatment significantly increased (p<0.05) the activities of amylase, lipase and trypsin in jejunal digesta and the activities of maltase and sucrase in jejunal mucosa on days 21 and 42. The ZA supplementation also significantly increased (p<0.05) the catalase activity, reduced (p<0.05) the malondialdehyde concentration in the jejunal mucosa. In addition, a decrease of serum diamine oxidase activity and an increase (p<0.05) in concentration of secretory immunoglobulin A in jejunal mucosa were observed in birds treated with ZA on 21 and 42 days. It is concluded that ZA supplementation (2%) could partially improve the growth performance by increasing BWG and FI. This improvement was achieved through increasing the secretion of digestive enzymes, enhancing the digestibilites of nutrients, promoting intestinal health of broiler chickens.