112 A Meta-Analysis on the Effect of Guanidinoacetic Acid Supplementation on Growth Performance of Growing Pigs

Abstract

Abstract Guanidinoacetic acid (GAA) is produced in the kidney from arginine and glycine and transported to the liver for the synthesis of creatine. Dietary GAA supplementation can have arginine and energy-sparing effects. The objective of this meta-analysis was to assess the effect size of GAA in growing pigs based on available literature. Using internet search (until October 31, 2021), we identified 7 scientific publications. Only studies that 1) reported growth performance of growing pigs (7 to 107 kg BW), 2) had control without GAA supplementation, and 3) did not aim to demonstrate GAA sparing effects of energy or arginine were selected. From the 7 publications, 4 publications met the criteria, and 2 of the publications contained 2 studies, therefore, a total of 6 studies were included in the meta-analysis. The statistical analysis utilized a random effect model to estimate the mean effect size (MES) of the difference between control and GAA-supplemented pigs, the 95% confidence interval of MES, the probability of MES being different from zero, the probability of the studies to share a common effect size (heterogeneity), and no publication bias. The data were analyzed using SAS 9.4 using a SAS macro created by Rendina-Gobioff and Kromrey (2006). Summary statistics and average change in percentage are reported in Table 1. Pigs fed GAA-supplemented diets had greater (P < 0.001) final BW, ADG, and G:F, and the magnitude of the effect is considered to be large (>|0.8|). GAA did not influence (P = 0.976) ADFI. The presence of heterogeneity was observed in all the responses, suggesting that the effect size varies among studies. Publication bias was not found for any of the responses. Overall, supplementation of GAA increased BW, ADG, and G:F by 1.68, 3.95 and 7.01%, respectively, and the effect size varies, potentially due to the inclusion rate and duration of supplementation.