الفهرس 
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Abstract
5A crossbreeding experiment was carried out during three consecutive
production years started in September, 1993 in fvfaryout Experimental Station
belonging to the Desert Research Center, Ministry of Agriculture and Land
Reclamation, Egypt. This station is located in a newly reclaimed area 35 km
to the south east of Alexandria. The experiment was conducted using Gabali
(Egyptian local) and Californian (exotic) breeds with the aim of investigating
and quantifying the effects of some non-genetic factors, mating or breed
group, crossbreeding and heterosis in addition to maternal additive and direct
additive effects on litter, doe reproductive, progeny and carcass traits.
Results could be summarized as follows:
5.1. Litter traits
Actual means of litter traits (LSB, LS21, LSW, LWB, LW21 , L’/WII,
MBWB, MBW21 , MBWW and PM) are within the ranges of the available
literature. The CV% of these traits ranged from 10.4 to 60.1 %.
Year of kindling, month of kindling and parity did not exert any
significant effect on most litter traits. Parity did not show any consistent
pattern of effect on these traits.
Most litter traits varied non-significantly with mating group.
Differences between Cal and Gab rabbits were not significant for most of
these traits and they were generally in favour of Cal rabbits. Crossbreeding
between these two breeds resulted in negative heterotic effect on most litter
traits.
/’ Maternal additive effect was mostly non-significant but their contrasts
were in favour of litters born by Cal does. AJso, direct additive effect was
mostly non-significant and in favour of litters sired by Cal breed.
5.2. Doe reproductive traits
Actual mean of NSC is relatively higher than those reported in the
available literature while those of DO, KI and GL are lower than those cited
from the previous research work. Estimates of CV% of NCS, DO and KI are
relatively high.
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Year-of-kindling effect was significant (P<O.01) on NSC and KI but not
so on Do and GL. Both months of kindling and parity did not contribute
significantly to doe reproductive traits of the study. Parity effect did not show
any definable trend on NSC and DO but caused the increase of KI and GL
with advance of parity order.
NSC, DO, KI and GL were found to be non-significantly influenced by
mating group. The differences between Cal and Gab for these traits were
also non-significant but in favour of Gab rabbits. Heterosis contrasts for NSC,
DO and KI were positive but non-significant, i.e. crossbreeding in this work
did not improve the performance of those three traits.
Maternal additive effect on doe reproductive traits was not significant
and in favour of litters produced by Cal does. Also, the direct additive effect
on these traits was not significant but in favour of litters sired by Gab bucks
for NSC, DO and KI.
5.3. Progeny traits.
Actual means of weaning and post-weaning body weights and daily
gain traits up to 16 weeks of age are within the ranges of the available
literature while those of post-weaning livability traits Lip to 16 weeks are lower
than their correspondings reported in the Egyptian research. Estimates of
CV% ranged from 4.15 to 22.27% for body weight and daily gain traits and
from 42.86 to 81.17% for livability traits.
Effect of year-of-birth was not significant on weaning and postweaning
body weight and daily gain but significant (P<O.01) on post-weaning
livability up to 12 and 16 weeks of age. Month-of-birth contributed
significantly (P<O.05, P<O.01 or P<O.001) to most body weight traits, postweaning
daily gain from eight to 12 weeks and to all post-weaning livability
traits. Parity effect was non-significant on most body weight traits, significant
(P<O.05, P<O.01 or P<O.001) on post-weaning daily gain from eight to 12
weeks and from four to 16 weeks of age and all post-weaning livability traits
studied. Most body weight traits, daily gain from eight to 12 and 16 weeks of
age and post-weaning livability up to 12 and 16 weeks of age were
significantly (Pdl05 or P<O.01) influenced by sex.
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Breed group constituted, in general, a significant (P<O.05, P<O.01 or
P<O.001) source of variation in body weight and daily gain traits but a nonsignificant
one in post-weaning livability traits. Linear contrasts showed the
superiority of Gab over Cal rabbits for body weight at most ages studied,
daily gain at all intervals of the study and post-weaning livabilities, all without
significant differences. Crossbreeding between the two breeds of the study
resulted in positive and significant (P<O.05,P<0.01 or P<O.001) heterotic
effect on most body weight and daily gain traits and positive non-significant
effect on post-weaning livability, i.e, crossbreeding has improved progeny
traits in general.
Maternal additive effect was significant (P<O.05 or P<O.001) on most
body weight and daily gain traits and non-significant on livability traits. Linear
contrasts were in favour of rabbits produced by Gab does for body weight at
most ages and daily gain at all intervals but in favour of those produced by
Cal does for post-weaning livability up to eight and 12 weeks of age. Direct
additive effect was significant (P<OO.05or P<O.001) on body weight and daily
gain at most ages and stages, but non-significant on post-weaning livability
up to eight, 12 and 16 weeks of age. . Linear contrasts were mostly in favour
of rabbits sired by Gab bucks.
5.4. Carcass traits
Actual means of carcass traits of the study reveal that performance of
rabbits for carcass traits increased with the increase of slaughter age from 12
to 16 weeks of age. CV% for different carcass traits ranged from 0.3 to
12.4% at 12 weeks and from 3.1 to 19.4% at 16 weeks of age.
Effect of year of birth was non-significant on all carcass traits at 12
weeks of age and on most carcass traits of the study at 16 weeks of age.
Season of birth did not contribute significantly to the variance of all carcass
traits at 12 weeks but significantly (p<O.05 or 0.01) to the variance of 50% of
these traits at 16 weeks of age. Parity and sex did not show any significant
effect on all carcass traits either at 12 or 16 weeks of age.
Breed group differences were significant (P<O.05, P<O.01 or P<O.OO1)
on most carcass traits at either 12 or 16 weeks of age. Linear contrast
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showed that Cal and Gab rabbits were significantly (P<O.OS, P<O.01 or
P<O.001) different for most carcass traits at 12 and 16 weeks and most of
these differences were in favour of Gab rabbits. Crossing between Cal and
Gab resulted in positive significant (P<O.05, P<O.01 or P<O.001) heterotic
effect on most of these traits.
Maternal additive effect on most carcass traits at either 12 or 16
weeks of age was non-significant but in favour of rabbits darned by Gab
does. Direct additive effect was significant on 50 and 42% of carcass traits at
12 and 16 weeks of age, respectively and in favour of rabbits sired by Gab
bucks.
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The present study aims to elucidate the changes occurring
during cooking of fish by the two more common methods in
Egypt, which are the frying or grilling of whole and eviscerated
fish. Three species of fish were investigated, being Nile bolti
(Tilapia niloticai, morgan (Pagrus sp.) and sardine (Sardinella
sp.y; the first is a fresh water fish, while the other two species are
sea water fishes. The influence of dry salting with (35% or 50%
NaC!) and storage were studied using the sardine. Analysis
included the determination of physical weight, chemical
composition, total volatile nitrogen (T.V.N.), trimethylamine
(T.M.A.), ammonina (NH3), thiobarbituric acid value (T.B.A.),
total bacterial count (T.B.C.) and fatty acids (F.A.) composition.
The results arrived at revealed the following:
A. Weight composition:
1. The yield of meat was highest for sardine (61.80%), followed
by morgan (54.62%), being lower for bolti (47.92%), skin
proportions followed the levels of meat.
2. Total wastes levels showed a reverse trend as compared with
meat.
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B. Effect of frying and grilling on the quality attributes of fish:
a) Chemical composition:
1. Different studied species of fish could be arranged differently,
according to the level of chemical constituents. As for protein
on wet basis, sardine followed by morgan (19.40%) seems to
be the best source of protein (19.66%) followed by bolti
(18.52%) before cooking, after cooking the arrangement was
different being sardine (25-28%), bolti (24-26%) and morgan
(23-24%).
2. Cooking methods affected the chemical composition of fish.
On wet basis, the changes were influenced by the loss of
moisture and absorption of fat, while on dry basis the results
seems to be affected by the loss of protein in frying media and
the rate of fat increase. This was recorded of the species of
fish.
3. Cooking, decreased the moisture content while raised all
other, component as well as the energy value (W.W.) of the
cooked fish. In this concern, grilled fish, specially after
evisceration had highest level of protein.
4. On dry weight basis some loss of protein occurred, which
raised the ash and fat. Only for grilled eviscerated samples, the
fat decreased because of the escape of some oil from the open
fish; energy value, however increased only for the fried
sample.
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b) Some freshness tests:
1. Different species of fish could be arranged aescendingly
according to the level of (T.V.N.), (T.M.A.), (NH3) and
(T.B.A.) as follows, bolti, sardine and morgan, while
according to (T.B.C.) was sradine, morgan and bolti,
indicating the effect of species on the freshness tests values.
2. On wet weight basis, T.V.N., T.M.A. and NH3 increased as a
result of moisture loss by cooking. On dry weight basis,
however all values decreased indicating the loss of
components (T.V.N., T.M.A., NH3, malonaldehyde) by
volatilization and due to the lethal effect of temperature on
bacteria.
c) Fatty acids composition (F.A.):
1. For the fresh sample, the major (F.A.) in the lipids of three
studied fish species was the C 16:0’ The major (F .A.) for bolti
were (CI6:O’ Cl7:0, CI8:2) for morgan (CI6:”0’ C18:1 C20:I) and for
sardine (CI6:O’ CI8:1’ C20:1) these acids formed 59, 74 and 72%
for bolti, morgan and sardine, respectively. Most of major
(F.A.) for boiti and morgan were saturated (6238%) and
(60.80%), respectively, while were unsaturated for sardine
(48.18%). The highest unsaturated (F.A.) in fresh bolti,
morgan and sardine were Cl8:2 (10.91 %) C18:l (17.88%) and
C16:1 (27.25%).
2. T. monoenoic F.A. were higher for fresh sardine, followed by
morgan and bolti. Nevertheless, T. dienoic F.A. (C18:2) T.
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trienoic F.A. (CI8:3) and total essential F.A. (T.E.F.A.), (CI8:2 +
C18:3) were higher for fresh bolti, followed by sardine and
morgan.
3. Ks value reflected the levels of T. unsaturated fatty acids,
while Du value, mostly reflected the T, polyenoic F.A..
4. Due to frying, T. unsaturated, T. dienoic F.A., total essential
F.A. (T.E.F.A.), Ks and Du values increased, while T.
saturated F.A. decreased. Also, T. monoenoic F.A. increased
in bolti, while decreased in morgan and sardine; total trienoic
F.A. (CI8:3) appeared in morgan and disappeared, in the total
lipids of bolti and sardine. By frying the nutritional value of
fish was increased pronouncedly, because (T.E.F.A.) increased
from 19 to 61% for boiti from a to 32.49 for morgan and from
11 to 35% for sardine and T. saturated F.A. decreased.
5. By grilling T. unsaturated F.A. and Ks values increased and T.
saturated F./A. decreased for bolti and morgan; the reverse,
however, was found for sardine. Unsaturation was higher for
fried then grilled fish. Moreover, unsaturated of grilled bolti
fish was higher for whole than eviscerated fish, while the
(reverse) was observed for morgan and sardine samples.
6. While (C18:2) was the dominant F.A. for all fried fish, for
grilled samples, the dominant F.A. in eviscerated fish was
C16:O, except for sardine (C12:o), and for whole fish the
dominant F.A. was (CI6:o), except for bolti (C16:1). The total
lipids of grilled samples (contrary to fried fish) were generally
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morgsa in Cd, Pb and Hg and sardine in Mg, Fe and Mn. By
grilling inside the fish the mentioned orders changed
indicating loss or gain (of minerals) for both viscera and liver).
3. By cooking all minerals increased in all 3 species of fish flesh,
except for minerals with bolti meat only.
4. The changes of minerals in viscera and liver due to grilling
reports abroad some migration of these minerals (Both toxic
morgan viscera and liver due to high Hg became none toxic by
grilling.
c- Effect of salting with different levels of sodium chloride on
the quality attributes of sardine:
a) Chemical composition:
1. Most of salt was observed by the tissues within the first
months of salting (26-27% NaCl). Afterwords, the NaCI
content of salted fish increased to 30-31% between 2 and 3
months, and increased only by 1% (31-32%) between 3 and 6
months of storage. This was observed for the two treatments
(35 and 50% NaCI).
2. Difference between treatment as regards the NaCI content
were slight. Nevertheless, NaCI content tended to show some
increase for 50% NaCI treatment when compared with that of
35% NaCI.
3. The moisture content followed the changes ofNaCl, showing a
rapid decreased at the first 15 days (from 77.35 to 56.57%).
Between 30 and 90 days, the moisture content fluctuated in
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the range 56-58% in many cases the moisture content tended
to show slight increase for 35% than 50% NaCI treatments,
which was confirmed by calculation of Naf’l concentration in
tissues that may reflect the osmotic pressure, being somewhat
lower (31.5-34.30%) for 35% NaCI treatment, than that of
50% NaCI samples (32.0-32.5%).
4. Due to moisture loss, the fat content was increased, showing
somafter 180 days of salting and storage, parallel to the
increase of water. At the end of storage, however, the fat
content, contrary to the protein, was still higher than that of
the unsalted fish. On dry weight basis a containuous decrease
of the fat was recorded.
5. In most of the cases, the salted fish with 50% NaCI had higher
fat content than that salted with 35% NaCl. This was found
when calculating on wet weight aswell as on dry weight basis.
6. The ash content of the wet sample increased prononuncedly
within the first 2 weeks (from 1.68 to 45% on dry weight
basis), mainly because of NaCI absorption from salting
medium.
7. At the end of experiment (after 180 days) the ash content on
wet weight decreased due to some increase of water.
8. Energy value increased due to moisture loss by salting,
tending to be relatively higher for 50% than 35% NaCl
samples. Differences however, between treatments were so
small to be used for preference of either of the two drying
methods.
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b) Freshness tests:
1. After 15 days of salting a decrease in (T.V.N.) occurred
(D.W.) indicating the slow rate of its formation compared to
loss with separated fluids. On wet weight basis an increase
was observed, being affected by the loss of moisture Fartherly
(T.V.N.) was gradually increased, showing a sharp increase at
120 and 180 days of salting and storage, which may indicate a
tangible loss of salted sardine quality at 120-180 days.
2. The development of T.M.A. during salting seems to be less
prononunced than that of T.V.N., because after 15 days,
T.M.A. decreased when calculating results on wet weight and
loss of moisture, failed to show anyrise in T.M.A. furtherly
T.M.A. increased gradually, with a sharp increase at 120 and
180 days. The lower levels ofT.M.A., recorded for 50% NaCI
treatment, indicated the efficiency of this treatment for
maintaining the quality of salted sardine as compared with
35% NaCI treatment.
3. The ammonia level was always higher for 35% then 50% NaCI
treatment, showing that the last treatment was the best for the
shelf-life of salted sardine. On dry weight a loss of NH3
occurred after 15 days of salting, while a continuous increase
took place thereafter until the end of storage, while a sharp
increase was recorded. This indicated a possible considerable
loss of quality after 180 days.
4. After 15 of salting some loss of malonaldehyde took place, but
at 30, 45 and 60 days. Lipids oxidation was indicated by the
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continuous Increase of malonaldehyde content. After 90 and
120 days the T.B.A. value decreased, possibly because of
malonaldehyde reaction with other components of fish. After
180 days of salting and storage T.B.A. value was 2.5-3.1 folds
higher than that of unsalted sardine which were 1.42-1.77
folds on dry weight. Samples of 50% NaCI treatment showed
higher T.B.A. values as compared with that of 350/0NaCI.
5. Total bacterial counts (I.B.C.) were higher than the halophilic
bacteria count (H.B.C.)~both counts decreased after 15 days of
salting showing continuous increase after 30, 45 and 60 days,
then decreased after 120 and 180 days.
6. At any giver time of salting and storage, bacterial counts were
higher for 350/0 than 500/0 NaCI samples, indicating the
importance of the last treatment for keeping quality of salted
sardine fish.
c) Fatty acids composition:
1. The dominant F.A. of all studied sardine samples (unsalted
and salted) was CI6:O which composed 34-42% of F.A.,
Nevertheless the nomber of major F.A. ranged 3-5 F.A. which
were CI6:0, CI6:1, CI8:0, C18:1 and C18:2. The major F.A. in
unsalted and salted sardine for 1 month were unsaturated,
nevertheless after 4 and 6 months of salting and storage most
of major F.A. were saturated.
2. Parallel to these changes Ks and Du values decreased. Such
changes indicated the lipids oxidation which increased with
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advancement of the salting and storage time. It seems that this
oxidation occurred via the decrease OfC16:1 and the increase of
C16:0 in this concern NaCI, particularly the higher
concentration (50% in composition with 35%) enhanced the
lipids oxidation.
3. With progression of salting and storage period the balance
between T. unsaturated F.A. and T. saturated F.A. was
disturbed for; example in the case of unsalted sardine T.
unsaturated F.A. and T. saturated F.A. were 48 and 62%,
respectively, being 38 and 62%, respectively after 6 months of
salting and storage with 35% NaCI, while for 50% NaCl
samples values were 29 and 71%, respectively.
4. T. dienoic and T. trienoic F.A. and accordingly T.E.F.A.
increased some what with progression of salting and storage
period. This indicated some imporvernent in the nutritional
value. After 6 months of salting and storahe with 35% NaCI
T.E.F.A. were higher (18%) then for 50% NaCI samples
(13%) indicatins that the nutritional value of the former
product was much better than that of the latter treatment.
d) Minerals:
1. By salting for 1 month either with 35% or 50% NaCI the
minerals (Mg, Fe, Cu, Mn, Zn, Cd, Pb and Hg) were increased
in tissues with few exceptions. After 6 months the minerals
decreased; but still were higher then in the raw fish.
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2. Salted fish with 350/0 NaCI had somewhat higher minerals
(with few exceptions) than the fish salted with 50%, possibly
due to slight difference in moisture content.
3. No danger of toxicity might be observed in any of salted
sardine samples due to presence ofPb or Hg. e) pH values:
The pH value was progressively decreased during salting,
showing some increase after 6 months.