Application of natural aromatase blocker towards the level of testosterone in rooster layer gallus gallus gallus (Linn., 1758)

Aromatase blockers are agents that can inhibit the action of the aromatase enzyme so that testosterone will not be converted to estradiol. Thus, the level of testosterone in the blood is maintained high. The purpose of this study was to evaluate the effects of natural aromatase blocker (NAB) on the level of testosterone in serum and evaluate the effectiveness of chemical testosterone. This study used 100 days old chick (DOC) of Layer chicken that divided randomly into 4 treatment groups namely P0 (control), P1 (zinc sulfate 0.018 mg / 40 g BW), P2 (blood clamshell powder (Anadara granosa) 0.036 mg / 40 g BW as NAB), and P3 (testosterone 0.1 mL). Before doing the experiments, comb measurements were done, blood sampling was carried out through the brachial vein to analyze testosterone levels, and testicular weight was done after necropsy. The study design used the Completely Randomized Design (CRD) and the data were analyzed using analysis of variance (ANOVA) with SPSS software version 15. The results showed significant differences (P < 0.05) on the variable testosterone level, testicular weight, and the length and height of comb. It can conclude that NAB's administration during the initial growth period can increase testosterone levels, and the provision of chemical testosterone continuously can increase testosterone levels but significantly reduce the testicular weight. © 2021 Trans Tech Publications Ltd, Switzerland.