Growth, Survival and Haematological Responses of Heterobranchus bidorsalis Juveniles to Changes in Photoperiod

`

Abstract

Abstract

The effects of artificial photoperiods on growth and haematology of Heterobranchus bidorsalis 2 juveniles were assessed. Hetrobranchus bidorsalis (5.69±0.41g/100fish/m ) were randomly exposed to tanks representing different artificial photoperiods of 24L:0D (PD1), 18L:6D (PD2), 12L:12D (PD3), 6L:18D (PD4) and 0L: 24D (PD5) for 84 days. Feed intake, Mean weight gain (MWG), Feed Conversion Ratio (FCR), Specific Growth Rate (SGR) and Survival Rate were determined. Blood samples were analyzed for Packed cell volume (PCV), Red blood cells (RBC), Haemoglobin (Hb), White blood cells (WBC), platelets and white blood cell differentials. Data were subjected to one-way ANOVA and Fisher's LSD follow-up test was used to separate the means. Differences were considered significant at p <0.05 and correlation analysis was used to test relationship between variables. Feed intake showed no significant difference (p<0.05) in treatments, but was marginally higher in PD5. However, MWG was highest in PD4 and PD5 groups (22.30+ 4.48g and 20.40+5.63g respectively) while it was least in PD1 and PD2 (16.5+0.39sg and 15.0+3.77g). The FCR ranged between 1.2.±0.06 and 1.6±0.72, with the least values obtained in PD4 and PD5 while the highest value was in PD2. The PCV, RBC and WBC b ranged from 20.00±200 to 29.00±1.00, 1.30±0.14 to 2.10±0.22 and 15,000±200 and 27166.70±202 respectively. PD1 and PD2 had higher lymphocyte: neutrophil ratio, 68:24 and 67:27, respectively compared to the control (PD3) which recorded 71:21. The findings indicate that exposure of H. bidorsalis juvenile to continuous light for long duration could affect feed consumption and growth performance as well as haematological parameters while extended period of darkness achieves better performance.