Exploring Multiple Impacts of Dietary Tea Supplements on Ruminants: A Meta-Analysis

Abstract

In many developing countries, small-scale ruminant farmers are often faced with health and productivity issues of livestock. Meanwhile, tea can act as a natural additive in ruminant diets. Different tea product supplementations (including leaf, extract, and waste) have the potential to improve the performance and health of ruminants. Both past and current studies regarding the effects of various dietary tea leaf products on ruminants do not show a comprehensive outcome. Therefore, this meta-analysis aimed to systematically examine the effects of different tea leaf product supplementations on ruminants. The PRISMA protocol was used to ensure the rigorous selection of suitable articles, and the OpenMEE approach was used to calculate effect sizes (Hedges’ g) across various output parameters. The results shows that tea leaf product supplementations had mostly no influence on the average weight gain in mass (AWG, Kg/head/day), body condition scores (BCS), DMI (g/day), dry matter digestibility (DMD, %), crude protein digestibility (CPD, %), acid detergent fiber digestibility (ADFD, %), neutral detergent fiber digestibility (NDFD, %), and blood urea levels. However, a significant reduction in blood glucose levels was observed (P = 0.002). A sub-group analysis showed that spent tea leaves supplementation affected the DMI (P=0.004) and ADFD (P = 0.032). In contrast, tea extract influenced blood glucose (mg/dl, P < 0.001) and blood urea (mg/dl, P < 0.001) levels. Based on the results, the tea can reduce glucose absorption in the intestines and further affect urea synthesis in the liver.