Optimizing growth and shell pigmentation in Cherax quadricarinatus juveniles using purple sweet potato extract

The red claw crayfish (Cherax quadricarinatus) is a freshwater crustacean with promising
aquaculture potential due to its adaptability and economic value. This study investigated the effects of
purple sweet potato (Ipomoea batatas) extract as a natural feed additive on the growth and shell
colouration of juvenile Cherax quadricarinatus. The experiment employed four dietary treatments: a
control diet without extract (P1) and diets supplemented with 10% (P2), 20% (P3), and 30% (P4) purple
sweet potato extract over 30 days. Statistical analysis (p<0.05) revealed that P2 exhibited superior
growth performance, with the highest absolute weight (0.99±0.39 g), specific growth rate
(1.60±1.07%), and survival rate (80.00±8.16%). Additionally, colour intensity was optimized at 10%
extract concentration, achieving the highest values by Week 4. However, higher extract levels (20% and
30%) reduced carotenoid absorption and less efficient feed conversion ratios, indicating a dose
dependent effect. Carotenoid content decreased with increasing extract concentrations, with P1 and P4
showing the highest (71 µmol g-1) and lowest (36 µmol g-1) absorption, respectively. Water quality
parameters, including temperature, pH, and dissolved oxygen, remained within optimal ranges for C.
quadricarinatus, ensuring consistent results. The findings highlight the potential of purple sweet potato
extract as a sustainable alternative to synthetic additives, enhancing growth and colour intensity while
supporting environmentally friendly aquaculture practices. However, excessive supplementation may
hinder carotenoid absorption and feed efficiency. This research provides valuable insights into optimizing
natural additives for aquaculture feed to improve growth, pigmentation, and sustainability in crustacean
farming.