The effect of dietary L-carntine [i.e. carnitine] supplementation on production performance parameters of Mozambique tilapia, Oreochromis mossambicus, at sub-optimal water temperature

[摘要] ENGLISH ABSTRACT:60-day growth experiment was conducted to investigate the effect of dietary Lcarnitinesupplementation on the production performance parameters of Mozambiquetilapia, Oreochromis mosambicus. A number of approximately 140 tilapia fry withaverage weight of l.4g ± 0.71g were stocked in each of 40 fine-meshed hapas(I mx 1mx 1.5m) submerged within a complete recirculation pond system. During the first30 days of the experiment water temperatures ranged from 19 to 23°C where after itdecreased to 16-20°C for the consecutive 30-day period. Dietary treatments consisted of 8replicates of 5 levels of L-carnitine supplementation labelled as Co, C250,C500, C750 andC 1000represented Omg, 250mg, 500mg, 750mg and 1000mg L-carnitine supplementationper kg feed respectively. Results were analyzed for significant differences using one-wayanalysis of variance (ANOVA) and Tukey's pairwise comparison test for growth rate,feed intake (FI) and feed conversion efficiency. After completion of the trial 8 fish fromeach hapa were sacrificed and analyzed for cephalosomatic index (CSI), dress outpercentage (viscera, gills and head excluded), viscerosomatic index (VSI) andhepatosomatic index (HSl).Poor production performance results were generally observed as water temperatures weresub-optimal, especially during the second 30-days period. Results from the trial indicateno significant differences (P>0.05) between treatments for weight gain, FCR, FI and VS!.A negative trend was observed for FCR with increasing level of L-carnitinesupplementation for both the first 30-day period (1.50±0.07, 1.53±0.08, 1.58±0.09 and1.61±0.17 for C250,C50Q,C750and C 1000)as well as for the consecutive lower temperature30-day period (2.22±0.10, 2.25±0.ll, 2.27±0.28 and 2.29±0.2l for C250, C500, C750 andC 10(0)'Although statistically not significant, fish fed the C250showed better performancein dress out percentage weight either than the control or the higher levels. The increasingtrend for head weight with increasing level of L-carnitine supplementation weresignificant (P<0.05) from Co and C250with and above C500.The decreasing trend for liverweight with increasing level of L-carnitine supplementation became significant (P<0.05)with and above C750.The results of the current study showed a trend in the improvementof L-carnitine on the production performance parameters. However, the natural content ofL-carnitine in the basal diet impaired with the inclusion levels, thus further research atlower inclusion levels is recommended.

[发布机构] Stellenbosch University