الفهرس 
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Abstract
This study was carried out at Sakha Research Center, at
Kafrelsheikh, Agricultural Research Center, Ministry of Agriculture,
Egypt, during the period from June to August ٢٠١٢.
The study was aimed to investigate the effect of different omega-٣
fatty acids sources (fish oil, linseed oil and commercial omega-٣) on
body weight, growth rate, meat quality, meat lipid profile, serum lipid
peroxidation, antioxidative status and immune response in and New
Zealand White and Baladi Black rabbits. Eighty weaning rabbits, (٤٠
Baladi Black rabbits and ٤٠ New Zealand White rabbits) were
maintained from weaning to marketing age (٥ to ١٣ weeks of age).
Rabbits were randomly divided into five treatments (١٦ animals per
treatment of both sexes). Average body weight of rabbits at the
beginning of experiment was ٦٨٥±١٠ grams. Animals were healthy and
clinically free of external and internal parasites. Experimental diets
were formulated to have nearly similar digestible energy (DE) and
crude protein (١٧٪ crude protein, ٢٥٥٠ kcal DE per kg diet). The
experimental design consisted of five dietary treatments as fallows:-
The ١st group was fed the basal diet (control) while the ٢nd,٣rd, ٤thand
the ٥th groups were fed the basal diet supplemented with ٢٪ fish oil
(FO), ٢٪ linseed oil (LO), ١٪ fish oil plus ١٪ linseed oil and ١٪
Commercial Omega-٣ (CO), respectively. All diets were supplemented
with ٢٠٠mg vitamin E/kg as α-tocopherol acetate to protect dietary fatty
acid from oxidation. The rabbits were weighted at the start of the
experiment and then they were weighted weekly in each treatment. Live
body weight, body weight gain, feed intake, feed conversion ratio and
mortality rate were recorded.
At ١٠ weeks of age, four representative rabbits from each
treatment were intravenously injected with ٠٫٢ ml of ١٠٪ suspension of
packed Sheep Red Blood Cells (SRBC) to determine humoral immune response (antibody titer production against Sheep Red Blood Cells) and
at ١١, ١٢, ١٣ weeks of age blood samples were collected from marginal
ear vein of rabbits to determine humoral immune response.
At the end of the experimental period (١٣ weeks of age), eight
rabbits (٤ males and ٤ females) from each treatment were randomly
chosen and fasted approximately for ١٢ hours and weighed before
slaughter (pre-slaughtered weight) to study carcass traits. Blood
samples were collected after slaughtering to determine some blood
constituents, while meat samples were taken from slaughter rabbits for
analysis of meat lipid profile, total cholesterol and meat chemical and
physical characteristics.
The obtained results could be summarized as follows:
A. Productive performance traits:
١- Dietary supplementation with different Omega-٣ sources showed
insignificant changes in live body weight (LBW) of rabbits al all
growing periods.
٢- The heaviest LBW was obtained for rabbits fed fish oil plus linseed
oil supplemented diet followed by those fed commercial omega-٣ diet.
٣- Rabbit’s breed has a significant (P≤٠٫٠١) effect on LBW, where
Baladi Black rabbits (BB) was heavier than New Zealand White (NZW)
ones at ٩ and ١٣ weeks of age (WOA).
٤- No significant effect of dietary treatments on BWG, however, rabbits
fed commercial omega-٣ and FO+LO diets gained more weight than
then treatments.
٥- The BB rabbits gained significantly (P≤٠٫٠١) more weight than
NZW rabbits at the period from ٥-٩ WOA, only.
٦- There were significant decreases in feed consumption for rabbits fed
FO+LO – supplemented diets during the periods from ٥ to ٩ and ٥ to
١٣ WOA.
٧- No significant effect of both breed and sex of rabbits on feed intake
during all periods. ٨- There were significant decreases in FCR for rabbits that fed
commercial omega-٣ and those fed FO+LO diets than the control and
other treatments. Moreover, the effect of breed, sex and interaction
effect was not significant.
٩- Mortality rate significantly influenced by dietary treatments with the
lowest rate value recorded for the commercial omega-٣ and FO
treatment followed by those fed LO – supplemented diets.
١٠- There were insignificant effects of different dietary treatments on
carcass dressing weight and percentage; hot carcass weight, liver and
kidneys weight.
١١- Abdominal fat weight and percentage were significantly decreased
in rabbits that fed fish oil-supplemented diet compared with the other
treatments along with the control one.
١٢- Data depicted that breeds differ significantly in liver weight and
total giblets weight, regardless the effect of omega-٣ sources.
However, both hot carcass weight; abdominal fat weight and percent
and dressing weight were not significantly affected by rabbit’s breed.
١٣- There were insignificant effects of sex on different carcass traits,
except the abdominal fat weight and percentage. In this respect, females
had significantly higher values than males.
B. Chemical and physical characteristics of meat:
١- There were significant differences in moisture content between
different dietary sources of omega-٣, while no significant effect of
dietary treatments on protein, Ash, fat, cholesterol, LDL and HDL
contents of rabbits meat.
٢- Dietary effect on the physical characteristics of meat was not
significant but there were slight variation between treatments in the pH
value, tenderness and water holding capacity of meat.
٣- Fish oil, linseed oil and their mixture caused a significant decrease in
MDA level of stored meat after ٩٠ days, however, using the
commercial omega-٣ product gave the best results in this respect.٤- The effect of rabbit breed and sex on the chemical and physical
properties, MDA and vitamin E levels of meat was not significant.
C. The fatty acids profile of rabbits meat:
١- Dietary supplementation with FO; LO either singly or in combination,
resulted in the PUFAs concentration was significantly higher in the meat
of treated groups compared with the control one.
٢- Diets supplemented with LO or FO+LO led to a higher proportion of
α-linolenic acid in rabbit meat as compared with fish oil, commercial
omega-٣ and the control diet.
٣- The FO and commercial omega-٣ diets resulted in significantly higher
proportion of DHA n-٣ and EPA n-٣ fatty acids of rabbits meat.
٤- Baladi Black (BB) rabbits has significantly higher α-linolenic (n-٣)
fatty acid and saturated fatty acids (SFAs) than New Zealand White
rabbits (NZW).
٥- There were some slight increases in α-linolenic acid, EPA, DHA,
PUSFAs and total USFAs in meat samples from females compared with
males.
D. Blood plasma constituents:
١- Plasma total protein, albumin, globulin, total lipids, cholesterol, HDL
and transaminases activity (ALT and AST) were not significantly affected
by dietary oil supplements.
٢- Rabbit’s effect of breed and sex had insignificant effect on all plasma
parameters investigated.
٣- The effect of sex insignificant effect on all plasma parameters.
E. Immunological responses:
١- Dietary sources of omega-٣ PUFAs had a positive effect on humoral
immunity response of rabbits as measured by (antibody titer production
against Sheep Red Blood Cells) compared with control.
٢- Dietary fish oil supplementation significantly improved the humoral
immunity of rabbits at day ٧ post immunization with SRBC.٣- After ١٤ and ٢١ day post immunization, the highest values for
antibodies titer (Ab) were recorded for rabbits fed on commercial omega-
٣ fatty acid followed by those fed LO; FO+LO and then the FO
supplemented group, while the lowest Ab titer was recorded for the
control group..
٤- There was insignificant effect of breed and sex on immune responses
against SRBC at ٧ and ٢١ days post immunization, while at day ١٤ Baladi
Black rabbits recorded higher Ab titer than New Zealand White rabbits.