Supplementation of Commercial Probiotic Lactobacillus casei in Rearing Early Stage Silver Therapon (Leiopotherapon plumbeus) Larvae: Effects on Growth, Body Composition and Stress Tolerance
Frolan A. Aya, Reylan C. Gutierrez, Mark Joseph Reyes, and Luis Maria B. Garcia
Received: September 26, 2023; Revised: June 07, 2024; Accepted: September 02, 2024
Supplementation of probiotics in live feeds and rearing water may improve the growth, survival, and resistance of fish larvae. This study examined the beneficial effect of a commercial probiotic bacteria Lactobacillus casei on the growth, body composition, and stress resistance in early-stage silver therapon (Leiopotherapon plumbeus) larvae. Larvae at 12 d post-hatch (DPH) (9.76 ± 1.32 mm total length [TL] and 13.48 ± 4.80 mg body weight [BW]) were reared in triplicate groups of 15 larvae per tank from 12 – 40 DPH (Phase 1) and 41 – 96 DPH (Phase 2). From 12 – 40 DPH, larvae were fed (I) unenriched Artemia nauplii (no-PB or control group); (II) probiotic-enriched Artemia nauplii (PB); and on (III) probiotic-enriched Artemia nauplii and rearing water (PB + W). The same feeding regime was used from 41 – 96 DPH except that the larvae were co-fed Artemia nauplii and microparticulate diet (MPD). Mean survival rates at 40 (97.78% – 100%) and 96 DPH (86.67% – 91.11%) did not show significant differences among treatments. However, except for body depth (BD) and Fulton’s condition factor (K), mean TL, BW, length increment (LI), and length- (SGRL) and weight-specific growth rates (SGRW) of PB + W-fed larvae were significantly higher than PB-fed and no-PB-fed larvae at 40 DPH. While these parameters were similar among treatment groups at 96 DPH, slightly higher values for BW and SGRW were noted for the PB + W group, as supported by the higher proportion of L. casei to total microbiota in the intestines of early-stage larvae. Whole body protein and lipid contents were highest in the PB + W and PB groups, respectively, but did not differ from the no-PB group. Survival rates (93.33% – 100%) after 18 h exposure to 30 ppt did not show significant differences. However, recovery rates after 15 min of air exposure of early juveniles in the PB and PB + W groups (93.33%) were significantly higher than those fed unenriched Artemia (66.67%). These results indicate that supplementation of probiotic bacteria L. casei in live feed and rearing water may support growth of early-stage larvae of silver therapon and its resistance to stress conditions during culture.