In recent years, the swine industry has witnessed the withdrawal of antibiotics and continuous regulation of zinc and copper oxides in the early-life nutrition of piglets. Due to this development, alternative additives from plant sources have been extensively explored. Therefore, this study’s objective was to evaluate the effect of dietary supplementation with tannins on weaned piglets’ growth performance, serum antioxidant capacity, and serum immune status using a systematic review and meta-analysis approach. A total of 16 studies with parameters of interest were deemed eligible after a two-step screening process following a comprehensive literature search in the scientific databases of Web of Science, Scopus, ScienceDirect, PubMed, and Google Scholar. The inclusion criteria were mainly (1) studies involving basal diet supplemented with tannins and (2) studies with the quantification of tannin doses, while the exclusion criteria were (1) studies with pre- and post-weaning pigs and (2) challenged studies. Applying the random-effects models, Hedges’ g effect size of supplementation with tannins was calculated using R software to determine the standardized mean difference (SMD) at a 95% confidence interval. Sub-group analysis and meta-regression further explored heterogeneity (P_SMD < 0.05, I² > 50%, n ≥ 10). Supplementation with tannins reduced the feed conversion ratio (p < 0.01) but increased the final body weight (p < 0.01) of weaned piglets. Chestnut and grape seed proanthocyanidin tannin sources yielded higher effects on growth performance. In addition, meta-regression models indicated that tannin dosage and supplementation duration were directly associated with tannins’ effectiveness on productive performance. In the serum, the concentration of glutathione peroxidase, superoxide dismutase, and total antioxidant capacity were elevated (p < 0.01) in response to tannin supplementation, whereas malondialdehydes was reduced (p < 0.01). Likewise, increased immunoglobin M and G levels (p < 0.01) were detected. In conclusion, dietary supplementation with tannins, particularly with chestnut and grape seed proanthocyanidins, increases the productivity of weaned piglets. At the same time, it is a possible nutritional strategy to mitigate oxidative stress and stimulate gut health. Thus, supplementing chestnut and grape seed proanthocyanidin tannins in the early phase of swine production could be used to alleviate the incidence of diarrhea.

Multiple studies have yielded conflicting findings regarding the impact of incorporating triticale as a feed ingredient on laying hens’ production parameters. This article used a meta-analysis to assess the factors influencing its effects on layers’ performance. According to the PRISMA guidelines, articles examining the influence of triticale on layers’ egg production (EP), egg weight (EW), egg yolk color (EYC), feed intake (FI), and feed conversion ratio (FCR) were identified across Google Scholar, PubMed, and Science Direct. As a result, six articles were selected and categorized into 16 experiments for inclusion in our meta-analysis. Overall, the trim-and-fill method indicated that triticale had comparable effects to conventional cereals on the performance of laying hens. However, the meta-ANOVA emphasized that the Hy-Line Brown hen strain and Joesong and Juanilo triticale strains induced the best laying hen performance. Moreover, the meta-regression emphasized a positive correlation between the triticale inclusion percentage and the EW in Juanilo triticale diets and a negative correlation between the triticale inclusion percentages and the EYC in the triticale and laying hens strains studied. Therefore, this meta-analysis makes a valuable contribution to comprehending the factors that may influence the effects of triticale on the performance of layers.

Triticale is known for being an alternative energy source to usual cereals such as maize and wheat in poultry nutrition. Several studies suggested opposite results regarding its incorporation as a feed ingredient on laying hens’ production parameters. This article used a meta-analysis to assess the factors influencing the effects of triticale on layers’ performance. In July 2022, papers studying the effect of triticale on layers’ egg production (EP), egg weight (EW), egg yolk color (EYC), feed intake (FI), and feed conversion ratio (FCR) were identified on Google Scholar, PubMed, and Science Direct. According to the eligibility criteria of PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, 6 articles were registered and segmented into 16 experiments for our meta-analysis. Overall, the trim and fill method revealed that triticale had similar impacts to conventional cereals on laying hens' performance. However, the meta-ANOVA and the meta-regression emphasized that triticale percentage, triticale strains and laying hens strains could significantly influence the effect of triticale on layers' performance. Indeed, the meta-Anova highlighted that the Hy-Line Brown strain and Joesong and Juanilo triticale strains in-duced the best laying hens’ performance. Moreover, the meta-regression emphasized a positive correlation between the triticale inclusion percentage and the EW in Juanilo triticale diets and a negative correlation between the triticale inclusion percentages and the EYC in the triticale and laying hens strains studied. Even though the funnel plot and the Egger linear test suggested sig-nificant publication bias, the present meta-analysis remains consistent research to understand how certain factors could influence the impact of triticale on layers' performance.

Numerous studies have suggested controversial findings regarding the impact of microalgae on dairy cows’ production parameters. This meta-analysis aimed to investigate the overall effects of microalgae on dairy cows’ performance and milk fatty acids and to highlight variation factors inducing opposite findings in the impact of microalgae on dairy cow nutrition. Following the PRISMA guidelines, articles examining the influence of microalgae on dairy cows’ performance and milk fatty acids were searched through Google Scholar, Web of Science, Science Direct, and Scopus. As a result, 10 articles were selected and categorized into 18 experiments for inclusion in our meta-analysis. The results suggested significant increasing effects (p < 0.05) of microalgae on milk yield and rumenic acid, while decreasing effects (p < 0.05) were observed in caproic acid, caprylic acid, capric acid, lauric acid, pentadecanoic acid, and myristic acid. The sub-group analysis suggested that the Aurantiochytrium limacinum microalgae strain showed more consistent effects compared with other evaluated strains. Thus, the present meta-analysis makes a valuable contribution to comprehending the beneficial effect of microalgae in dairy cow nutrition and the factors that may influence the impact of this sustainable feed additive on milk production and quality.