Response of juvenile abalone, Haliotis discus
hannai, to dietary calcium, phosphorus and calcium/phosphorus ratio
B.
Tan, K. Mai, Z. Liufu-2001
Aquaculture,
198 (1-2): 141-158
Abstract:
The
feeding experiment was conducted to determine the response of juvenile
abalone, Haliotis discus hannai, to dietary calcium, phosphorus and
the ratios of calcium to phosphorus. Fifteen isonitrogenous (approximately
30% CP) casein-gelatin-based diets containing five graded levels of
phosphorus (0%, 0.5%, 1.0%, 1.5% and 2.0%) for each of three levels of
calcium (0%, 1.0% and 2.0%) were fed to the animals previously fed a basal
diet (0.23% total P and 0.17% total Ca) for 14 days. After 16 weeks of
feeding, survival ranged from 94.7% to 100.0% with no significant difference
among dietary treatments. The weight gain rate (WGR), daily increment in
shell length (DISL), carcass concentrations of lipid and protein, soft-body
alkaline phosphatase activity and phosphorus, zinc, manganese contents were
significantly affected by dietary phosphorus levels. Supplementation of 1.0%
and 2.0% calcium to the basal diet reduced soft-body phosphorus deposition
and did not appear to increase the nutritive value of the diet, indicating
that a dietary calcium supplement is not required under the present
experimental conditions. The dietary phosphorus requirements were evaluated
from the pooled WGR and DISL, respectively, by using the second-order
polynomial regression analysis. On the basis of the pooled WGR and DISL, the
optimum ranges of dietary available phosphorus were 0.65-1.17%
(approximately 0.7-1.2% total P), and 0.64-1.14% (approximately 0.7-1.2%
total P), respectively. Based on these results, about 1.15% available
phosphorus (1.25% of total P) is recommended for the maximum growth of H.
discus hannai, and if dietary available phosphorus is reduced from 1.15%
to 0.65%, the growth of the abalone may be depressed with 5% likelihood. The
calcium/phosphorus ratio of the diets is not important within the range
assessed (approximately 0.1:1-9.0:1).
(Aquaculture Research Laboratory, College of Fisheries, Ocean University of Qingdao, Qingdao 266003, People's Republic of China, Tel.: +86-532-203-2282; fax: +86-532-203-2799), e-mail of K. Mai: kmai@mail.ouqd.edu.cn)