الفهرس 
Material and methodsOnly 14 pages are availabe for public view
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Abstract
~ 147
V. SUMMARY
This study was carried out at the Experimental Farm. Faculty
of Agriculture at Moshtohor. Za’J’azig University. Forty four
does from New Zealand White (NZW). CaljLfornian (Ca) and Giza
White (GW) rabbits were used in this study to investigate the
effects of breed. some other non-genetic factors in addition to
crude protein (CP) and crude fiber (CF) lev.~ls on some doe traits
during two consecutive production seasons (1986/87 and 1987/88).
Growth trails were performed on bunnies of each breed group produced
during each production Sf:~asonto studY the effect of the
forement ioned factors on growth p.erformance and carcass traits of
the growing rabbit. A digestibility trail was undertaken to
determine the effect of breed. d iet arv CP and CF levels on the
digest ibi 1itv of feed nutrients of the Elxperimenta1 diets. The
most important results obtained could be s\umnarized as follows:
Litter size:
1- NZW rabbits produced the l.argest litters at birth and Ca
ones gave the largest nt weaning·. Whereas. GW does produced
the smallest littens at both ages. The differences
in litter size due to b:l-eedeffects were not significant
at birth, but highly significant (P<O.Ol) at weaning.
2- Litter size at birth and at weaning differed according to
year of .production, month of kindling and parity, but the
differences were neither pronounced nor significant.
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3- Differences in litter size at birth and at weaning due to
effects of dietarY CP and CF levels were very small and
non-significant.
Litter weight:
1- NZW does recorded the heaviest weight at birth. while Ca
litters were the heaviest at weaning. GW litters recorded
the lightest weights at the two ages. Differences in litter
weight ~e to ~eed effects were not significant at
birth but highly significant (p<O.Ol) at weaning.
2- Changes in litter weight at birth and at weaning due to
year of production. month of kindling and parity effects
were very small and almost non-significant except for
those due to year of production which was significant
(p<O.05) at birth.
3- Protein and fiber level effects on litter weight at birth
or at weaning were alwayS non-significant.
Pre-weaning litter mortality:
1- Differences in pre-weanig litter mortality percent due to
breed effects were unsizable and non-significant.
2- Pre-weaning litter mortality percent varied slightly with
year of production. month of kindling and parity sequence.
but the differences failed to shOW anY significant effect
except for those due to month of kindling which were significant
(p<O.05).
- ---- - - - - - - -----_.--~.~---- - -------- - - ----~
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3- Dietary protein and fiber levels had no significant
effects on pre-~eaning litter mortality percent.
Weight of does at kindling:
1- AmoM the three breeds used. NZW does recorded the heaviest
~eight at kindling (3535.11 qm). ~hile GW ones
recorded the lightest ~eight (3201.93 qm). The differences
due to breed group effects ~ere significant (p<O.OI).
2- Weight at kindliM varied with year of production. month
of kindling and parity but the differences ~ere al~aYs
non-significant.
3- The differences in ~eight at kindling due to either CP or
CF level effects ~ere verY small and non-significant.
Growth performance traits:
1- NZW and Ca rabbits surpassed those of GW oneS in bodY
~eight and in daily gain at most ages studied. The differences
in body ~eight due to breed effects ~ere significant
(p<O.OI .p<O.OOI or P<O.OOOI) only from 9 to 16 ~eeks of
age. while the differences in daily gain ~ere almost
highly significant (p<O.Ol or P<O.OOOl).
2- Rabbits born in 1966/67 recorded heavier bOdy ~eights and
daily gains than those born in 1967/88. The differences in
body ~eight and daily gain due to year of production
effects ~ere almost significant (p<0.05. p<O.OI. p<O.OOl
or P<O.OOOl).
- - ------ - - - - - -------------------------------- -------~-------------------
3- Body weight and da·ly gain of rabbits at all ages studied
differed of birth. the differences due to month
of birth effects bodY weight and daily gain were always
significant (P(O. 5. p<O.Ol p<O.OOl or P<O.OOOl).
4- Body weight dailY gain of rabbits at different ages
improved with parity. The differences due to
parity effects were almost stgnificant (p<O.Ol or
P<O.OOOll .
5- Males recorded sightly heavier body weights than females.
but sex differe ces were not significant at all ages studied.
Daily differed with sex without any consistent
trend. but th differences were neither sizable nor significant.
6- Increasing the ietarY CP level from 16 to 18% almost
improved body weight and daily gain of rabbits. the differences
were most likely significant (p<O.05.P<O.Ol.
p<O.pOl. or P<O.OOOl).
7- Increasing the dietary CF level jfrom 10 to 16% relatively
decreased body weight and dailY gj~in of rabbits during the
different age’ intervals from 5 to 16 weekS. but the differences
were almost non-significant.
Feed utilization:
1- NZW rabbits recorded the b13S:tfel”d utilization (Fe and FE)
values. whereas GW ones shc)wed the poorest values through
all age intervals studied. The differences in FC and FE
values due to breed effects ~rere significant {p(O.05 or
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---------------------
~-_.-- ----
- 151 -
p<O.OOl) except during 12-16 weeks of age.
2- Increasing dietary CP level from 16 to 18% tended to
slightly improve the FC values. while FE values were
almost similar for rabbits receivin~1 either 16% or 1B% CP
level. The analysis of variance failed to detect any significant
differences in feed utilization values due to
protein level effect at all age intervals studied.
3- Increasing the CF level from 10% to 16% had no significant
effect on either FC or FE values du.ring the different age
intervals of this studY.
Nutrients Digestibility:
1- Digestibility of most nutrients for NZW rabbits were some
what higher than those for Ca ones. Whereas. GW rabbits
recorded. almost. the lowest digestibility values. The
differences due to breed on digestibility of OM. EE and
NFE were significant {p<O.05 or P<O.OOOU. while digestibility
of CP and CF were not affected by breed group.
2- Increasing the dietary CP level from 16% to 18% significantly
(P<O.OOOl) improved CP digestibility. whereas it
decreased (P<O.Ol) EE digestibilit,y. Protein level had no
s igf\if icant ef feet on the digest i:bi1ity of OM. CF and NFE.
3- Increasing the dietary CF level from 10 to 16% significantlY
(P<O.OOOl) increased OM and CF digestibilities.
whereas CF level did not sOow any significant effect on
the digestibility of CPo EE and ~rPE.
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Carcass tr~its:
1- At 8 weeks of age, GW rabbits ree rded the heaviest fasted
slaughtered and carcass weights, while NZW rabbits showed
was observed,. as NZW rabbits s owed. the heaviest weights
for the three traits and GW rabb ts recorded the lightest
a reverse trend
the lightest ones. At 12 weeks
ones. Differences due to breed ffects on fasted slaughtered
and carcass weights were no significant at 8 weeks
of age and highly significant (p(o.Ol or p<O.OOl) at 12
weeks of age. No significant differences were detected due
to breed group effects on dress”ng percentages at 8 and 12
weeks of age. Weights of car ass cuts (fore-qUarters.
hind-quarters. chest and loin and different organs differed
slightly with breed group but without anY consistent
trend. The differences
small and almost nonsignificant
at both slaughter
,
2- Carcass traits (fasted. slaugh~ered. and carcass weights as
well as dressing percentage. weights of carcass cuts and
different organs) for rabbits ~orn in the first year of
I
production (1986/1987) were alrost superior than those for
rabbits born in the second of production (1987/1988)
attain the best carcass
The differences in carcass
at 8 and 12 weeks of
traits due to year of product”on effects were unsizable
and most likely non-signifiea
at~both slaughter ages.
3- Carcass traits changed wi
IBonth of birth. Rabbits
kindled in January and
tepded in general to
aita. Differences in carcass
- - ._ - __ - __ 0. _
______ --- ------- -----r---
I
traits due to mont st. failed to show significant
effects a both 8 and weeks of age.
4- The absolute we ght of most cass traits studied were
heavier in the fir t parity than in the second one at both
slaughter ages c nsidered.while the reverse was observed
for dressing percentage. Parity effects were non-significant
at 8 and 12 weeks of ge for all carcass traits
except liver and kidney weights t 12 weeks of age.
5- Carcass traits differed slightly with Sex. the differences
were. in general. infavour of males et 8 weeks of age. but
the reverse was true at 12 weeks of e.ge. The differences
were in most cases non-significa t.
6- Increasing dietary CP% from 16% to 18% significantly
(P<O.05) increased fasted ereCland carcass weights
at 12 weeks of age. while CP level had no significant
influence on all other carc 5S traits studied either
at 8 or 12 weeks of age.
7- Fasted and slaughtered weights a 12 weeks of age. significantIy
(P<0 .05) decreased as di tanr CF IeveI increased
from 10% to 16%. All other carca s t)~aits differed according
to dietary CF level. but differences were neither
pronounced nor statistically ificant at both slaughter
ages. except for he~d.kidney. lu 9S and coat weights at
12 weeks of age which attai ed significance (P<O.05.
P<O.OOl or P<O.OOOl).
- 153 -
ity effectS. and the
I yaried very slightly with par-
I d~ffe:rences were alwaYS nonis
of age.
- 154 -
Meat composition:
1- Breed effects. at B weeks of age. were highly significant
(p<O.011 on percentage of EE. Ibut non significant on DM.
I
CP and ash contentS. At 12 week
of’ age. breed effects
were highly significant (P<o.o 1 on percentages of CP and
EE. but non-significant on DM a d aan contents.
2- Rabbits born in the second yearl of production had significantly
(p<o.o11 higher EE con~ents than those born in the
first year of production at ~ weeks of age. but the
reverse was true at 12 weeks ~f age. Whereas. the differenceS
in DM. CP and ash conten~s due to year of production
I
effects were non significant ~t both slaughter ages.
3- Differences in meat comp;~ition due to month of birth
effects were significant (P<oj011 for EE content at B
I
weeks of age and for CP I and EE at 12 weekS of age.
I
WhereaS. these differences were non-significant for DM. CP
and ash contents at 8 wee~s of age. and DM and ash contents
at 12 weeks of age.
4- DM. CPo EE and ash contents
significant at 8 and 12 wee
5- Differences in meat composi ion due to sex effects were
significant (P(o.0011 for EE content and non-significant
for DM. CP and ash contents at ])oth slaughter ages.
6- DietarY CP level had no sig ificant effect on the chemical
composition of rabbits m at at neither B nor 12 weeks of
age. except for EE content. Which decreased (p(o.o11 with
___~---- . .__ -------------- _.- --r-
I
- 155 -
increasing CP level from 16% tp 18~t at 8 weeks of age.
whereas it increased (P<0.01) with! increas ing di etary protein
from 16 to 18% at 12 weeks ofi age.
7- Increasing CF level from 10~ to 16% significantlY
!
(P<O.Ol orP<O.OOl) increased EE cqntent in rabbits meat at
8 and 12 weeks of age. whereas. lit d.ecreased (P<0.01) CP
content in rabbits meat at 12 wee~s of age. Dietary CF
level had no significant effeqt on DM content at both
slaughter ages. CP content at 8w~eks of age and ash content
at 12 weeks of age.