ABSTRACT
Postpartum blood calcium (Ca) concentration is related to the reproduction and health of cattle. Oral calcium supplements were given to dairy cows after calving to increase blood Ca concentration and reduce the risk of hypocalcemia. However, studies have shown that oral Ca has different effects in preventing disease. The purposes of this study were (i) to conduct a meta-analysis to evaluate the expected effect of oral Ca on incidence of calving-related diseases, pregnancy risk and milk yield in dairy cows, and (ii) to make a quality assessment of these related studies. In total, 22 eligible studies were included in this review. Meta-analysis showed that oral Ca could significantly reduce the incidence of hypocalcemia (clinical hypocalcemia: relative risk (RR) = 0.67, 95% confidence interval (CI) = [0.52, 0.87]; subclinical hypocalcemia: RR = 0.81, CI = [0.72, 0.91]), and incidence of retained placenta (RR = 0.77, CI = [0.62, 0.95]), improved blood Ca concentrations: mean difference (MD) = 0.08; 95% CI = [0.04, 0.11]. For other results, the meta-analysis revealed a lack of evidence of the correlation between oral Ca and serum magnesium (Mg) / phosphorus (P) concentration (Mg: MD = -0.04; 95% CI = [-0.10, 0.02]; P: MD = 0.05; 95% CI = [-0.10, 0.21]) or incidence of other calving-related disorders (metritis: RR = 1.06, CI = [0.94, 1.19]; ketosis: RR = 1.04, CI = [0.91, 1.18]; mastitis: RR = 1.02, CI = [0.86, 1.21]; displacement of the abomasum: RR = 0.81, CI = [0.57, 1.16]) or pregnancy risk (pregnancy risk at first service: RR = 0.99, CI = [0.94, 1.05]; overall pregnancy rate: RR = 1.03, CI = [0.98, 1.08]) or milk yield (MD = 0.44; 95% CI = [-0.24, 1.13]). The distribution of the funnel plot formed by the included studies was symmetrical, and the Egger's test had a p > 0.05, indicating that there was no significant publication bias. Sensitivity analyses results suggested that the results of meta-analysis are robust. Quality assessment of the included studies revealed that the risk of bias was focused on selection bias, performance bias, detection bias and other sources of bias, and the future research should focus on these aspects.
ABSTRACT
ETHNOPHARMACOLOGICAL RELEVANCE: The antitumor effects of Grifola frondosa/maitake polysaccharide (GFP) have been reported in many preclinical studies, especially in vivo experiments. The present meta-analysis aimed to provide an in vivo evidence and theoretical basis for future clinical trials by assessing the efficacy and underlying mechanisms of GFP in tumor treatment. MATERIALS AND METHODS: English and Chinese databases were examined to include animal experiments to study the antitumor activity of GFP. Literature screening, data extraction, and meta-analysis were conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. In addition, the Systematic Review Center for Laboratory animal Experimentation (SYRCLE) risk of bias (RoB) tool was used to assess the risk of bias of the included animal studies. RESULTS: Potentially relevant studies (442) were identified, and finally 24 eligible studies (all in English) were included. The meta-analysis revealed that GFP has significant effects in inhibiting tumor growth (high dose: mean difference (MD) = -1.34, 95% confidence interval (CI) = [-1.73, -0.95]; low dose: MD = -5.68, 95% CI = [-7.27, -4.09]), improving tumor remission rate (odds ratio = 25.59, 95% CI = [9.08, 72.11]), and enhancing immune function in both cellular (CD4+ T cell percentage: MD = 3.03, 95% CI = [1.16, 4.90]; CD8+ T cell percentage: MD = 1.10, 95% CI = [-0.29, 2.49]) and humoral immunity (MD and [95% CI] of interleukin (IL)-2, IL-12 and tumor necrosis factor-α were 7.86 [6.29, 9.44], 35.95 [5.18, 66.72], and 10.03 [8.71, 11.36], respectively), and the differences between the two groups of the above indicators were statistically significant (all P < 0.01) except CD8+ T cell percentage. Additionally, the quality of the included studies was not high, and the risk of bias mainly concentrated on selection, detection, and reporting biases. CONCLUSION: GFP is a potential candidate for tumor treatment and clinical trials. TRIAL REGISTRATION: The review protocol for this study was registered with the PROSPERO database before beginning the review process (CRD42018108897).