annual report - Central Institute of Brackishwater Aquaculture

41.5696, fat 8.13% carbohydrate 21.9746,
moisture 53%, crude fibre 4.46% and ash
1854%) was supplied in 4 grades namely
Pre-starter (0.5 mm), Starter (1.0 mm),
Grower and Finisher (3 mm). At a stocking
density of 70,000 noha, P. monodon (PL20)
attained an average size of 22 g in 112 days,
the growth being comparable to that achieved
with imported mmmercial feeds.
Production and testing of shrimp feeds in
interaction with industry
In order to promote interaction with
the shrimp industry for on-farm research,
steps have been initiated to collaborate with
the commercial feed manufacturers for
large-scale production of feeds wing the feed
formulations developed by the Institute.
'Testing of these feeds under field conditions
in association with the industry will be subsequently
taken up.
Development of standards for quality
control of shrimp feeds
To develop quality standards for
shrimp feeds, fifteen commercial feeds (both
indigenous and imported) were ana1yst.d for
their proximate composition. Indigenous
feeds generally showed higher percentag ol
acid insoluble ash compared to imp~rted
feeds. Moisture content of some of the feeds
analy.sed was high (17%). Water stability of
pellets determined at different time intervals
indicated that loss in weight of pellets occurred
in the first half-hour and almost remained
constant upto seven hours. Studies
are in progress using standard AOAC methods
to estimate the total volatile nitrogen
which determines the rancidity of fat for
stored feed samples.
Diagnosis, prophylaxis and control of die
eases of commexcially impottant brackish
water shrimp/fish (TIDPISP)
Madras : S. V. Alavandi (PL), T.C.
Santiago, K. K. Vijayan, S. S. Mishra, K. V.
Rajendran, M.Shashi Shekhar and K.O.
Joseph.
Shrimp farms in the coastal districts of
Orissa vu., Bhadrak and Balasnre and Andhra
Pradesh vu., East Godavari, West Godavari,
Krishna and Prakasam were surveyed
to investigate the shrimpdisease outbreaksin
those areas. Detalled microbiological and
histopathological investigations revealed
that the white spot disease was the major
cause of mortality of shrimpP. monodon and
1'. indrcus in most of the farms. Analysis of P.
rnonodon samples from shrimp farms near
Kannur (Kerala) revealed that the disease
had also struck the coastal districts along the
west coast. Further, the incidence of white
spot disease was also ~hserved in the brtx>dstock
ol IJ. rnutzdon in shrimp hatchcries at
Madras and Nellore. 'The causative agent of
this disease was idcntificd to hc a virus, the
Systemic Eetodermal and Mesodermal Uaculovirus
(SEMRV). Ihe major clinical ymptoms
included circumscrikd white spots on
the carapace and other parts of the cuticle,
broken antennae and discolourntion of the
hody. Experimental induction of the disease
to study the host range of the virus revealed
that in addition to shrimp, crabsof the genus
SryUu were also affected by the disease.
Studies on the mode of transmission of the
virus lo the host indicated that SliMDV infection
can k elicited in healthy animals by
feeding on the carcass of infected animals as
well as by intra-muscular injection with extracts
of gills from the same.
Apart from the while spot disease,
Monodon Bnculovirus (MBV) was also
prevnlent in the farms in Andhra I'radesh and
Tamil Nadu. The shrimp larvae were affected
by this diwasc in some or the hatcheries
'n Nellorc and Ongole (A.P) and
Kovllam and Chinglepei ireas (T.N.). In
addition lo these two major diseases, Vibriosis
and protozoan infection cauwd by
Zoothrrmnium sp, were also common in both
hatcheries and farms.