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-Abstract
The reproductive performance of 181 female silver carps Hypopthalmichthys
molitrix (Valenciennes) was followed up during 8 months (March-October) in two
successive years. 2004 and 2005 under the Egyptian environmental conditions. To
study their reproductive performance. ovulation was stimulated in females with two
doses of a carp pituitary powder (Argent. Philippines. Manila): a preparatory dose (0.3
rngllrg) followed by a resolving dose of 4.0 mgfkg body weight after 9 h. whilst males
were stimulated with one single dose of 3 mg Ikg. Females were shipped
approximately 7-8 h after the second injection and eggs were immediately fertilized
"dry method“. Fertilized eggs were incubated in conical shaped fiberglass tanks
supplied with aerated fresh flow-through water. An attempt was also carried out to
outline the age at maturity in 214 females during 2005. The monthly trend of
spawning traits in terms of percentage of ovulated females. egg weight in grams and
as a percentage of female's body weight. number of seeds per kgflish. percentage of
fertilized eggs, larval survival rate and percentage of defomied larvae were estimated.
Highest female response to induced breeding and better larval quality were
obtainable from April to June. Females of silver carp attained sexual maturity at a
body weight of less than 2 kg and an age of two years old or less. The lowest
percentage of spawned fish was recorded in March (66.73nd 50.0% in 2004 and
2005, respectively). During other experimental months percentage of ovulated
females was in the range of 83.3 to 100%. The latency time was approximately 7.5 h
at a temperature of 255°C. Stripped eggs as a percentage of female body weight
(ES!) ranged from 6.87 to 15.75%. Relative fecundity of females was in the range of
51.070 and 156,440 eggsilrg. Hatching occurred after approximately 20 hours at 25.5
'0 water temperature. Fertilization and survival rates ranged from 85.91 to 97.86%
and 72.72 to 80.72%, respectively. The lowest percentages of deformed larvae (11-
12%) were observed during April-May compared with either that obtained during the
early season (March: 15-20%) or at the late spawning season (July-October: 16-
18%).
DOI
10.21608/jappmu.2006.235492
Keywords
silver carp. hypophysation, sexual maturity, induced breeding. fertilization rate. fecundity, 63! index, larval survival rate. percentage of deformed larvae
Authors
Affiliation
Fish Production Section, Department of Animal Production. Faculty of
Agrlculture, Aln Shams University. P.O. Box: 68 Hadayelr Shoubra,
11241, Cairo, Egypt.
Email
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Fish Production Section, Department of Animal Production. Faculty of
Agrlculture, Aln Shams University. P.O. Box: 68 Hadayelr Shoubra,
11241, Cairo, Egypt.
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https://jappmu.journals.ekb.eg/article_235492.html
Detail API
https://jappmu.journals.ekb.eg/service?article_code=235492
Publication Title
Journal of Animal and Poultry Production
Publication Link
https://jappmu.journals.ekb.eg/
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