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Objective: This study performed a meta-analysis of published trials to determine the effects of zinc on the immune response and production performance of broilers.Methods: A database was built from published literature regarding the addition of zinc forms or doses and their relation to the immune response and production performance of broilers. Different doses or forms of zinc were identified in the database. The recorded parameters were related to the immune response and production performance. The database contained a total of 323 data points from 41 studies that met the criteria. Then, the data were processed for a meta-analysis using a mixed model methodology. The doses or different forms of zinc were considered fixed effects, different studies were treated as random effects, and p-values were used as the model statistics.Results: An increase in zinc dose increased (p<0.05) pancreas metallothionein (MT) and zinc concentrations in the plasma, tibia and meat, all in quadratic patterns, but linearly decreased (p<0.05) the heterophil/lymphocyte (H/L) ratio. Regarding the different zinc forms, both inorganic and organic zinc increased (p<0.05) the zinc concentrations in the plasma and tibia, the calcium and phosphorus contents in the tibia, and the antioxidant activity of superoxide dismutase in meat as compared to control. An increase in zinc dose increased average daily gain (ADG) and decreased feed conversion ratio (FCR) following a quadratic pattern (p<0.05). Inorganic and organic zinc decreased (p<0.05) FCR and H/L ratio than that of control, but these two forms were similar for these parameters.Conclusion: Zinc addition has a positive impact on immunity and broiler production. Zinc can suppress stress and inhibit the occurrence of lipid peroxidation in broilers, and it can also improve ADG, FCR, and the quality of broiler carcasses.

Objective: The purpose of this meta-analysis was to evaluate the effect of dietary essential oils (EOs) on productive performance, nutrient digestibility, and serum metabolite profiles of broiler chickens and to compare their effectiveness as growth-promoting additives against antibiotics.Methods: Peer-reviewed articles were retrieved from Web of Science, Science Direct, PubMed, and Google scholar and selected based on pre-determined criteria. A total of 41 articles containing 55 experiments with 163 treatment units were eligible for analyses. Data were subjected to a meta-analysis based on mixed model methodology considering the doses of EOs as fixed effects and the different studies as random effects.Results: Results showed a linear increase (p<0.001) on body weight gain (BWG) where Antibiotics (FCR) and average daily feed intake decreased (p<0.001) linearly with an increasing dose of EOs. Positive effects were observed on the increased (p<0.01) digestibility of dry matter, crude protein, ether extract, and cecal Lactobacillus while Escherichia coli (E. coli) population in the cecum decreased (p<0.001) linearly. There was a quadratic effect on the weight of gizzard (p<0.01), spleen (p<0.05), bursa of fabricius (p<0.001), and liver (p< 0.10) while carcass, abdominal fat, and pancreas increased (p<0.01) linearly. The dose of EOs linearly increased high density lipoprotein, glucose, protein, and globulin concentrations (p<0.01). In comparison to control and antibiotics, all type of EOs significantly reduced (p<0.001) FCR and tended to increase (p<0.1) BWG and final body weight. Cinnamaldehyde-compound was the only EOs type showing a tendency to increase (p<0.1) carcass weight, albumin, and protein of serum metabolites while this EOs together with EOs-Blend 1 decreased (p<0.01) E. coli population. Low density lipoprotein concentration decreased (p<0.05) with antibiotics and carvacrol-based compound when compared to the control group.Conclusion: This evidence confirms that EOs are suitable to be used as growth promoters and their economical benefit appears to be promising.

Background and Aim: Tannins are functional secondary metabolites that may provide benefits to ruminants. However, to date, their effects on broiler chickens remain inconclusive. This study aimed to evaluate the effectiveness of dietary tannin levels on the performance, body organs, and amino acid (AA) digestibility of broiler chickens using a meta-analysis. Materials and Methods: After verification and evaluation, a total of 22 articles were included in the present study. All data regarding dietary tannin dosages, performance, digestibility, and gastrointestinal physiology of broiler chickens were tabulated into a database. The database data were then statistically analyzed using mixed models, with tannin dose as a fixed effect and study as a random effect. Results: High levels of dietary tannins negatively affected the average daily gain and average daily feed intake of broiler chickens according to linear patterns (p<0.001). In addition, dietary tannins decreased drumstick and liver weights, as well as bursa of Fabricius and spleen weight (p<0.05). Meanwhile, other carcass traits (i.e., thigh, wings, and body fat) were not influenced by dietary tannins. Regarding AA digestibility, high dietary tannin concentrations induced negative responses on isoleucine, leucine, and methionine digestibility (p<0.05). Conclusion: Dietary tannins appear to have a negative effect on broiler performance, lymphoid organ weight, and AA ileal digestibility. Hence, the addition of tannins to broiler diets is not recommended.

Zinc is one of the essential minerals that are important for poultry. The disadvantage of Zn in the conventional form is its low bioavailability. One of the efforts to increase the bioavailability of Zn is to make it in a nano form. Nano Zn-Phytogenic (NZP), is a combination of Zn and phytogenic compounds of plants in nanoparticle size. The NZP was self-produced utilizing the green synthesis process of inorganic Zn and guava leave extract (Psidium guajava). The objective of this study was to evaluate the effects of supplementation NZP in diet on the performance, antioxidant status, and population of pathogenic intestinal bacteria (Escherichia coli and Salmonella sp) of broilers chicken. This study used 180 males and 180 females of Lohman broilers day old chick (DOC). The experiment was subjected to a completely randomized design with 6 (six) treatments and 5 (five) replications, and each experimental unit consisted of 12 DOCs (6 males and 6 females). The treatment given in this study were; R1= basal diet; R2= R1 + Zn Sulfate (90 mg Zn/kg) + 5.32 mg/kg guava leaf meal (added as a source of phytogenic compounds); R3= R1 + NZP (45 mg Zn/kg); R4= R1 + NZP (90 mg Zn/kg); R5= R1 + NZP (135 mg Zn/kg); R6= R1 + NZP (180 mg Zn/kg). The variables observed were performance, antioxidant activity in meat, and population of pathogenic intestinal bacteria (E. coli and Salmonella sp) of broiler chicken. The results showed that the addition of NZP up to a dose of 90 mg Zn/kg in the diet improved (p<0.05) body weight gain compared to the basal diet. The addition of NZP had no significant effect on the FCR. The addition of NZP increased (p<0.05) SOD activity in meat when compared with the dietary treatment without NZP. Groups of chicken fed NZP (R3, R4, R5, R6) had significantly (p<0.05) lower E. coli and Salmonella sp population. It could be concluded that the addition of NZP up to a dose of 90 mg Zn/kg in the diet of broiler chicken had positive benefits in improving performance, increasing antioxidant activity, and reducing pathogenic intestinal bacteria (E. coli and Salmonella sp).