Phytosteron-incorporated diets as sexual stimulants: Role of dietary Tribulus terrestris extract to improve semen characteristics, sexual hormones, and reproductive indices of Nile tilapia (Oreochromis niloticus) broodstock.

The experiment examined the beneficial impact of a dietary Tribulus terrestris extract (TTE) on the reproductive performance of tilapia broodstock and the performance of their larvae. Broodstock were conditioning for 20 days by rearing females and males separately into four groups of each and fed with four levels of dietary TTE (0, 0.25, 0.5, and 1 g/kg). After that, a 100-day spawning experiment was conducted in 12 hapas (28 m3) with a stocking rate of 30 males to 90 females per hapa with an initial weight: 250 ± 20 g and 200 ± 25 g respectively. Males and females that received the same feed in the preparatory stage were mated and continued to be fed the same feed during this stage. After 30 days, a sample of 10 males and 30 females was taken from each treatment to evaluate semen quality, blood chemistry, gonadosomatic index GSI, and egg diameter. Also, every 10-12 days, hapas were checked to collect newly hatched or eggs which were transferred to incubators. At the end, a blood sample was collected from broodstocks of each group to assess serum biochemicals. A 28-day trial was done in triplicate to compare the extended effect of broodstock feeding of dietary TTE in each treatment on their larval performance, stocked at 20 000 larvae/hapa (8 m3) and fed a basal diet. Our Findings showed significant positive effects of dietary TTE in all parameters of physiological and reproductive performance such as semen quality, blood androgens (progesterone and testosterone), egg diameter, and GSI of broodstock. Furthermore, larvae were significantly affected by feeding their broodstock with dietary TTE. Generally, TTE at a dose of 1% had the highest No. of spawned females/hapa/period (399.10), the hatching rate (86.04%), fry production/hapa/period (151551 fry).