Investigation of the use of phytase enzyme as a feed additive in poultry nutrition by meta analysis

This is study was conducted to investigate the effectiveness of phytase enzyme in poultry nutrition as feed additive by meta-analysis. In this context, 74 studies were selected from 441 studies published in 1999-2019. Since it was possible to input data of two groups (control and phytase group) and two parameters using Meta Essentials Excel Program, the studies performed according to the binary parameters supporting each other were grouped. Eigthy eight studies regarding binary parameters in broiler chicks (CA-YDO, YT-GCAA, bone Ca-P content), laying hens (YT-YDO, YV-YK, YA-SA, KK-KKD) and quail (YT-YDO) were subjected to meta-analysis, including some studies reused for different parameters. All of the studies, having a positive effect size showed that the effect of phytase enzyme was important and positive to the parameters studied. According to the results of the combined effect width and heterogeneity analysis, OR values of the studies were between 0,92-1,03, z values were less than 1 (P<0,01), the effect of phytase on these parameters was similar (I2 = 0,00%). When the studies examined for each data set were divided into two groups, there was no difference between the publications in terms of the effect of phytase enzyme. The effect width distribution on the Y axis in the funnel plots, the calculated I2 value was 0,00%, the tau-square (T2) value was 0,00 and the PQ value of Cochran Q statistic was 1,000 indicating that there was no bias between studies. In conclusion, it was determined by meta-analysis that the positive effects of phytase enzyme on body weight, body weight increase, feed consumption, feed conversion ratio, bone calcium and phosphorus contents, egg yield and mass, egg weight and yolk weight, shell thickness and breaking resistance were similar in investigated manuscripts.