ADDITION OF COMMERCIAL PROBIOTIC (LACTOBACILLUS DELBRUEKII AND L. FERMENTUM) IN RED TILAPIA BROODSTOCK DIET IN DIFFERENT REARING SYSTEMS. I- EFFECTS ON REPRODUCTIVE PERFORMANCE AND LARVAL QUALITY

This experiment was carried-out to evaluate the combined effects of dietary commercial probiotic Lactéol Fort^® supplementation and different rearing systems on reproductive performance of red tilapia broodstock. In completely randomized, 2X2 factorial design, 2 different tank systems, clear water (CW) and biofloc combined with two different levels (0 and 1 g kg^-1) of dietary probiotic Lactéol Fort^® attaining 4 experimental treatments; T1: CW without probiotic), T2: CW + probiotic, T3: biofloc without probiotic) and T4: biofloc + probiotic with three replicates for each treatment compromising twelve tanks (each 2 m³). Red tilapia broodstock reproductive performance was compared during the reproductive period. The probiotic Lactéol Fort^® containing Lactobacillus delbruekii (10¹³ CFU: colony forming unit) g^-1 and L. fermentum (10¹³ CFU) g^-1 was administered as a feed additive to broodstock diet. For the reproductive performance assay, 216 females and 72 males of red tilapia Oreochromis mossambicus × O. niloticus at density of 24 (18 females: 6 males) tank^-1 equivalent to stocking density of 9: females: 3 males m^-3 with a sex ratio of 3 females to 1 male. Average body weight of female and male tilapia broodstock were 127.5 and 148 g, respectively). Reproductive variables (spawned female %, absolute and relative fecundity) were estimated in four subsequent seed clutches. No mortalities were found in male and female tilapia broodstock as affected by biofloc and probiotic levels. The results revealed that broodstock fed the commercial probiotic in biofloc tanks (T4: biofloc + probiotic), had the highest values for reproductive performance followed by T3 (biofloc without probiotic addition), T2 (CW + probiotic), and finally T1 (CW without probiotic).  The results recommend continuous intake of probiotic (Lactéol Fort^® containing Lactobacillus delbruekii (10¹³) CFU g^-1 and L. fermentum, 10¹³ CFU (colony forming unit) g^-1 at a dose of 1 g kg^-1 of broodstock feed in biofloc tanks during the spawning season of red tilapia, due to the higher reproductive performance and fry survival.