الفهرس 
Introduction
Effect of dietary energyOnly 14 pages are availabe for public view
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Abstract
Summary
The current work was conducted to test the effect of
different dietary energy and protein levels on growth
performance, carcass traits, blood parameters, cecal contents,
digestion coefficient of nutrients, nitrogen balance and
economical efficiency of growing rabbits. Sixty male (45 days
old) New Zealand White rabbits were obtained from a local
commercial source and divided randomly to five groups, twelve
rabbits in each. Rabbits were housed individually in batteries
(galvanized wire cages that allowed separation of feces and
urine) provided with feeders to provide free access to feed and
automatic drinkers (nipple waterers), fresh and clean water ad
libitum. The experiment lasted for 10 week. Control diet was
designed according to NRC (1977) to meet the nutritional
requirements of growing rabbits, and had a classical energy and
protein content (16% CP and 2500 kcal DE / kg diet).
High and low energy diets (3007&2059 kcal DE / kg diet)
were formulated to contain about 500 kcal DE / kg diet higher
and lower, respectively than control. While high and low protein
diets (20&12.15 % CP) were formulated to contain 4% CP
higher and lower, respectively than control.
Growth performance including body weight, weight gain,
feed intake and feed conversion indices was calculated.
Mortality rate was recorded during the experiment. Three
randomly selected rabbits from each group were slaughtered at
the end of the experimental period for measurement of carcass
traits, blood parameters, cecal parameters and for chemical
composition of meat.
At the end of the experiment, three rabbits from each
group were kept to be used in the digestibility experiment. The
feed intake was recorded individually and total faecal excretion
was collected daily in the same individual bag and stored at -
18°C or less. For each rabbit, the apparent digestibility
coefficient of different nutrients was calculated. Urine was
collected daily from each rabbit during the digestibility trial and
nitrogen concentration was determined using Kjeldahl apparatus
for determination of nitrogen balance.
Monetary value was calculated and experimental crude
data were subjected to statistical analysis.
The following results were obtained:
1. The group of rabbits fed high protein diet recorded the best
body weight and weight gain.
2. The highest feed intake values were recorded by group of
rabbits fed high protein diet followed by rabbits fed high
energy diet then control one.
3. The best feed conversion was recorded by high protein diet
and the worst feed conversion was recorded by low protein
one. Groups of rabbits fed control diet and high energy one
recorded nearly equal feed conversion ratio.
4. The highest dressing % was recorded by high protein
group followed by high energy one, while the lowest
dressing% was recorded by low protein group followed by
low energy one.
5. Regarding chemical composition of meat, no significant
differences were detected among groups of rabbits in DM
content of either the breast or the thigh meat. While there
were significant differences in CP, EE and ash in the
breast and thigh of meat between the different groups.
6. There were significant differences in the cecal parameters
between the different groups. Regarding pH value, the
highest value was recorded by high protein diet. While the
highest value of total volatile fatty acids and highest
number of total bacterial count were recorded by high
energy diet.
7. No significant differences were detected in serum total
protein, albumin, globulin, cholesterol and glucose. While
there were significant differences only in the serum urea
and serum triglycerides between the different groups.
8. There were significant differences in digestion coefficients
of DM, OM, CP, CF, EE, NFE and Ash between different
groups due to different levels of dietary energy and
protein.
9. There were significant differences between different
groups in nitrogen intake, faecal nitrogen, urinary nitrogen,
total excreted nitrogen, absorbed nitrogen, absorbed
nitrogen percentage, retained nitrogen, nitrogen retention
of intake % and nitrogen retention of absorbed %.
10. Rabbits fed diets containing high energy and low protein
levels, respectively had no mortality during the whole
experimental period, while control, low energy and high
protein diets were accompanied by 8.33, 16.67 and 16.67
% of mortality, respectively.
11. The best economical value was recorded by the group fed
high protein diet followed by the group fed high energy
diet.