Commentry
Patra BC, Patra S and Bhatt
Abstract
Early fingerlings of Anabas testudineus were nurtured in the laboratory for six weeks under altered nutritional status (different dietary protein level and source) and feeding regimes (ad libitum, ‘limited’, and ‘starvation’ intervals). Their RNA/DNA, Ca/P ratios and protein biosynthesis were determined with highly sensitive fluorescence technique, spectrophotometer and liquid scintillation system respectively. Well-fed early fingerlings (4-6 weeks age group) having higher RNA/DNA (2.11), Ca/P (1.82) ratio and protein biosynthesis rates both in muscle and liver have significantly differs from fingerlings with ‘limited’ food supply and 'starvation' intervals. Rate of protein biosynthesis >244.33 & 603.24 in muscle & liver respectively (count per minute mg protein-1) when compared with well-fed fingerlings and reared under 'limited' food supply and 'starvation' intervals. At ‘starvation’ interval no significant differences were recorded due to different diet treatment. However, fingerlings showed higher mortalities, decreased growth, RNA/DNA, Ca/P ratio and protein biosynthesis rate that may be caused by malnutrition. Fingerlings (early) sampled after 42 days in nearby areas during late monsoon (September) showed RNA/DNA, Ca/P ratio and protein biosynthesis rate were surprisingly low almost as low as ‘starved’ fingerlings, when judged on the basis of mean body weight as compared to well fed fish. It was also observed under microscope that some of these fingerlings were seriously affected by an intestinal disease and this may be due to the ingestion of unsuitable copepods. The low RNA/DNA, Ca/P ratio and protein biosynthesis rate in field samples and ‘starved’ fish are, therefore, interpreted as a sub-lethal result of this disease and malnutrition respectively.