الفهرس 
Introduction and Aim of the WorkOnly 14 pages are availabe for public view
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Abstract
In Egypt, aquaculture is an increasingly important option in
animal protein production. Recently, attention has been focused
on aquaculture systems, since it has a great potential for achieving
other sources of fish production. The Nile tilapia Oreochromis
nilolicus, is the most widely cultured tilapia in the world, in
particular is accepted to Egyptian consumers. While, the giant
freshwater prawn, Macrobrachium rosenbergii, its culture has
expanded rapidly not only within Asia but also in regions far
remote from the natural distribution of the species. Acidifiers
consist of organic acids and salts, they have been used for more
than 30 years to reduce bacterial growth and mould in feed stuffs
and thus preserve hygienic quality. Nowadays, it is adding to food
of human and many animals.
This study was undertaken to investigate were carried out
to investigate the effect of dietary sodium lactate, calcium lactate
and calcium propionate levels as acidifiers on growth, nutrient
digestibility, proximate body composition, feed utilization and
histological induces of Nile tilapia, Oreochromis niloticus and
freshwater prawn, Macrobrachium rosenbergii.
In the present study three experiments was conducted:
Experiment I, was carried out to investigate the effect of dietary
sodium lactate, calcium lactate and calcium propionate at a level of 0, 2, 3 and 4% of O. niloticus fingerlings for 124 days.
Experiment II, was carried out to investigate the effect of dietary
sodium lactate, calcium lactate and calcium propionate at a levels
of 0, 2, 3 and 4% of M. rosenbergii PL for 75 days. Experiment
III, was conducted to investigate the effect of dietary sodium
lactate at levels of 0, 1, 1.5, 2, 3 and 4% of M. rosenbergii PL for
102 days.
Nile tilapia fingerlings with an initial body weight of
10.98±2.63 g were obtained from Saft-Khalid hatchery, El-Behira
Governorate, while, freshwater prawn juveniles with an initial
body weight 1.54±1.11g and 0.30±0.18g for experiment I and II,
respectively from Fish Hatchery, Mariut Company, Alexandria
Governorate. Triplicate pens were randomly assigned to each
treatment. All pens were supplied with freshwater from the
Darawa Irrigation Branch, Kalubiya Governorate twice weekly.
After the end of the rearing period the following results
were obtained:
1. Experiment I:
- The fish fed on diet supplement with 4% sodium lactate
improved the growth performance, and the lowest one
observed with 2% calcium lactate.
- The highest value of the survival rate noticed for Nile
tilapia fed on diet supplement with 4% calcium lactate and
the lowest one was with 3% sodium lactate.
- The best value of FR and FCR were observed with Nile
tilapia fed on diet containing 3 and 4% calcium propionate
respectively, while PER and EU recorded with 4% calcium
lactate.
- The highest values of EE and GE observed with fish fed on
3% sodium lactate, while CP recorded with 3% calcium
lactate.
- The apparent protein digestibility (APD) and lipid
digestibility (ALD) improved with fish fed on all organic
acid salts comparison with control. Whereas, the best result
of APD was observed with diet containing 2% calcium
lactate and ALP with 4% sodium lactate.
- All treatments showed histological changes of the liver and
pancreas of O. niloticus, but the alternation of tissues
dilated with increase level gradually. Where, less
histopathological changes observed at 2% such as
cytoplasmatic vacuolation of hepatocytes, and some
congestion of the portal vein in the pancreatic tissue.
While, at 4% exhibited high histopathological lesions as
pyknosis nuclei and necrosis.
- No abnormalities were detected in the ovary tissue of Nile
tilapia. But, the histological changes of the testis exhibited
with all treatments, but the mild alternations observed for
fish fed diet with 2 and 3% calcium lactate and 2% calcium
propionate such as slight hemorrhage between seminiferous
tubules. But more lesions of testicular tissues noticed with
sodium lactate and calcium propionate especially at high
level (3 and 4%) such as malformation of seminiferous
tubules, degeneration of leydig cells and spermatogonia,
increase hemorrhage and necrosis of spermatocytes.
2. Experiment II:
- The growth performances improved for freshwater prawn
fed on diet containing 2% calcium lactate and 3% calcium
propionate.
- The survival rate increased for M. rosenbergii fed on diet
supplemented with 3% calcium propionate.
- The best values of FCR and PER were observed for diet
supplemented with 4% calcium lactate.
- Dietary 4% sodium lactate decreased all growth
performance, Survival rate and feed utilization.
- The highest values of CP, EE and GE were observed for
prawns fed diet supplemented with 4% calcium propionate.
- The histological studies of hepatopancreas showed mild
histological effect for prawn at 2 and 3% calcium
propionate such as slight increase of R-cell vacuoles, slight
decrease of B-cell numbers and mild shrinking of
connective tissue. While, more lesion with calcium lactate
was exhibited as malformation and swelling of B, R and Fcells.
While, No destructions were detected in gonads.
3. Experiment III:
- Dietary 1% sodium lactate improved all growth
performance and feed utilization of freshwater prawn.
- No clear trend was observed as the effects of different
dietary Na-lactate levels on proximate body composition of
prawn post-larvae, M. rosenbergii except for the higher
values recorded for CP and GE at 2% sodium lactate. Also,
the survival rate enhanced for prawns fed on 1.5% sodium
lactate.
- Dietary 4% sodium lactate improved the apparent protein
digestibility (APD) and lipid digestibility (ALD).
- A mild histopathological change of hepatopancreas for
M. rosenbergii at 1% sodium lactate has such as some
slough into the lumen, dense materials in vacuoles of Bcells
and reduced of lipid vacuoles of R-cells. Whereas, the
sections of the gonads exhibited intact at all treatments.
The present study recommended that, the best organic
acid salts used as acidifiers of O. niloticus is 2% calcium
propionate, and of M. rosenbergii is 2 , 3% calcium propionate
and 1% sodium lactate for the best biological results
associated with the best histological results exhibited with the
low levels.