Abstract
Studies were conducted on the effect of fertilization on the production
and quality of Artemia cysts in an integrated salt-Artemia production
system. Fertilization treatments were denoted as T, and T₂ in the first year
and T3 and T, in the second year. Treatment T; was the initial application of
inorganic fertilizer containing urea 50 kg and TSP 20 kg/ha while T₂ was
the application of organic manure at a rate of 250kg dried chicken
manure/ha. Dress up fertilization for T₁ was 25kg urea + 20kg TSP/ha,
while for T₂, it was 125kg chicken manure /ha/every 3-4 days. Treatment
T3 was the application of same rate of chicken manure as T₂ in the second
year and T, was double the rate of T3 both for initial and dress up manuring
in the second year. Production of cysts obtained from T₂ showed significant
variation with other treatments in the first and second year (P=0.0026 and
0.0015). The highest production (15.63kg/ha) of cysts (dry weight) was
obtained from the ponds under treatment T3 in the second year. Similarly,
the highest production of biomass (196.10 kg/ha, wet weight) was obtained
using single dose of organic manure in the second year (T3). Salt
production rate in the winter months remained unaffected due to Artemia
culture. Variation in the rate of production of salt obtained from the streets of different treatments during the same year was found insignificant, but
was highly significant among the treatments of different years.
Hatching trials with the cysts of different forms showed that hatching
percentage was maximum for the processed and decapsulated cysts
(86.0%±4.6) followed by the cysts of processed and preserved form:/
Hatching percentage of unprocessed and undecapsulated cysts was poor
under florescent light and in dark. The maximum percentage of hatching
was recorded in the salinity level of 20ppt followed by 10, 30 and 40ppt.
Above 20ppt the hatchability was decreased considerably. Hatching of
cysts under various light condition showed that the response was higher in
clear day light than artificial light. In the dark, hatching percentage was
reduced by about 50% for the same set of cysts that incubated in natural and
artificial light. Maximum hatching efficiency was found in the cysts of
treatment T₂. Viability test of the first produced cysts showed no change in
viability (87.30%) after twelve months of storage.
Proximate composition analysis of the cysts showed a higher content
of total crude protein (58.22-59.95%) and total lipid (22.65-23.08%).
Among the seventeen amino acids, cysts of treatments T₁, T2, T3 and T4
contained the highest percentage for 8,6,1 and 2 number acids, respectively.
Fatty acid analysis showed that the cysts were of fresh water type as they
contained higher amount of 18:3(n-3) acid and lower amount of marine type
EFA 20:3(n-3) in cysts from all sources.