| Summary: | 碩士 === 國立臺灣海洋大學 === 水產養殖學系 === 96 === This experiment was designed to investigate the effects of temperature, photoperiod and dietary β-carotene level on somatic growth and gonad development of sea urchin? Tripneustes gratilla.
A 2x3x3 factorial feeding experiment was conducted with the two levels for temperatures at 25℃ and 29℃? three levels for photoperiods：10L/14D? 12L/12D, 14L/10D and the three dietary β-carotene levels：0mg/kg, 60mg/kg, 120mg/kg with duplicated treatment. Prepared diets were fed to the urchins once daily at a ration of 0.5% body wet weight for 120 days.
Temperature effect was observed on the sea urchins all with higher values held at 25℃：PWTG(38.16%)? survival rate(95%)? FCR(2.25)? PER(1.98)? SGR(0.27) than those held at 29℃(PWTG, 25.41%., survival rate, 86.67%., FCR, 3.26., PER, 1.40., SGR, 0.19). However, no temperature effect on the gonad color? GSI(Gonad index) and GDS(Gonad development stage) between urchins held in the two temperatures.
Photoperiod with light exposure shorter than 12hrs, 10L/14D(GSI, 18.78) exhibited significant lower GSI values than those groups exposed to longer day light conditions, 12L/12D(GSI, 24.03) and 14L/10D(GSI, 23.50). The 12L/12D urchin group had the highest GDS(2.45) than the two photoperiod groups, 10L/14D(GDS, 1.82) and 14L/10D(GDS, 2.00). However? there were no significant differences on PWTG, survival rate, FCR, PER, SGR, and gonad color among the urchins confined in the three levels of photoperiods.
Concentrations of dietary β-carotene also significantly affected the urchin’s PWTG, FCR, SGR and gonad color. Dietary β-carotene level at 60ppm resulted in values for the highest PWTG(37.44)? FCR(2.12)?and SGR(0.26)? than those urchins fed at 0ppm(PWTG, 25.64%., FCR, 3.47., SGR, 0.19) and 120ppm(PWTG, 32.28., FCR, 2.68., SGR, 0.23). Dietary β-carotene level had no effect on the survival rate, PER, GSI and GDS of urchins. Urchins received β-carotene level exceeded 60ppm exhibited significantly higher gonad color values, 120ppm(Gonad color, 3.49), 60ppm(Gonad color, 3.39) than those fed 0ppm(Gonad color, 2.48).
The interaction between temperature and photoperiod was well reflected on the WTG of urchins. Higher WTG value was observed on the urchins held at 25℃ then 29℃, and shorter day light exposure less then 12L exhibited better growth rate. However, the enhanced effect on the growth when urchins held at 25℃ and 10L/14D was observed. The other confliction of the two factors was 14L/10D exhibited better growth performance than the 12L/12D photoperiod group.
Interaction of the three factors occurred on the GDS of urchins which resulted in a best combination of 25℃, 12L/12D and 60ppm β-carotene treatment.
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