DIETARY PHOSPHORUS REQUIREMENT OF CULTER ALBURNUS FINGERLING

A feeding trial was conducted with water flow-through fiberglass tank systems to evaluate the dietary phosphorus requirement ofCulter alburnus fingerling. Seven sem-ipurified diets containing phosphorus levels ranging from 0.53% to 1.61% were formulated by including graded levels of monobasic sodium phosphate. Test diets were fed to triplicate groups of 30 fingerlings initially weighing 3.79?.20g/fish. Water temperature during the feeding trial was controlled at 27?癈. The fish were hand-fed to approaching satiation three times a day for 8 weeks. The results show that fish fed the two diets with low levels of phosphorus( diet 1 and diet 2) have significantly lower weight gain and feed efficiency(pp> 0.05) between treatments of diet 1 and diet 2 and among treatments of diet 3, diet 4, diet 5, diet 6 and diet 7; the survival rate of fish is not affected by the levels of dietary phosphorus. It was also observed that, at the end of feeding trial, the whole body lipid has a tendency to decrease with the increment of dietary phosphorus levels, even though there is no significant difference among treatments (p> 0.05); the whole body ash is affected significantly(pp> 0.05) among fish groups fed diets of 1 to 4, of 3 to 6 and of 5 to 7, respectively; whole body phosphorus is significantly lower (p> 0.05) when the fish fed two diets with phosphorus levels of less than 0.88%, and reaches to a plateau when the fish fed diets with phosphorus levels of 0.88% and more; vertebrae ash appears to have similar responses to the levels of dietary phosphorus as whole body phosphorus; there is no significant difference (p> 0.05) of whole body moisture, whole body protein, scale ash, scale phosphorus and vertebrae phosphorus among test groups. It can be concluded that the dietary phosphorus requirement for C. alburnus fingerling is approximately 0.88% of dry diet, which was important for this species to maintain the normal growth and vertebrae mineralisation as well as a stable level of whole body phosphorus.