الفهرس 
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Abstract
SUMMARY
Egypt
r e co r ds (1653, 1075 and 683 records, respectively) ’:.ott a i fled
ttr~ugh the period from 1960 t,~ 1986 wer2 used to investlgat~ :he
lM305’
yi~ld (TMY) ,
ated by best 1ineal’ unbiased prediction procedure .(BLUP). i’!i>:ed
model pr oc edur-e s wer e followed for analysing- such d a ta .
s2C’ond a.r:d
t n i r-d la.ctations, respectively were 2149.”3, 2466.4 a nd 2669.2 Kg
f’JY M305; 2460.7.2747.2 and 2922.6 Kg f,y,- TMY; 341.:. 342.9
332.4 days fe.r LP; end 135.1. 112.::’; and 99.:: days £’:’1’ DP. The
average length for first, second and third gestation was 278.3,
277.8 and 277.6 days. respect i ve 1y. The C’cITesponding aver-ages
for CI were 433.6 and 413.9 days, whlle for DO were 19C.l.
170.7 and 149.7 days.
(2) Year ·:·f calving affected significantly (P<O.Ol) M305.and TMY
in the first three lactations. Length of LP varied significantly
(P<O.Ol or P<O.05) with year of calving only for the first and
the third lactation. Year of calving did not sonstitute a signif-
tiOlJ3. The contritl..lti,:)n ,:,f yeal’ o:.:’f ’:.’oS.L!ing in the variance of
0.05) foy DO 0~ the first and thjrd lactation.
either GL. CI or DO WdS small’although it proved significance (P<
tations of the study. These effects proved to be highly signifi-
(in b:,th the fil’St and third lactati;AJ) en(~ elf; GL of the first
ea n t (2< 0.01) ’Xl LP (in the first and sl:;c,)nd lactations on ly ) DF
C1
~h~ seco~d lactation varied significa~tly (P~
detected.
0.05) with SEaSOD of celving. Nc significant effects fOl” season
(4) Tne partial 1-eg1’es3ion c,.)efficients c;f M305, TMY and LF on
age
were highly significant 0.01)
lactation only, while LP. DP, 8t, C1 and DO were not signifi-
Most estimates of partial linear and quadratic regression coefcantly
linearly dependent on age at calVing at all lactations.
ficients of CI and DO on age at ,:-alving were negative (P>0.05) in
the first three lactations. while GL and DP showed positive
tively.
significant (P<O.Ol) in the second and t h ir-d lactations,
dependent quadr.atic relationship on age at calVing which proved
l:~espt9c-
M30~. TMY, LP and DP on DO were highly significant
(5) Most estimates of partial linear and quadratic regressions of
all lactations studied. Linear and quadratic regression coeffi-
(P<O.Ol) f.:)r
0_ 01), whi 1e those of GL en PO we:re nori-Signi ficant in the first
cients for CIon DO were positive and highly significant (p<
~ for milk Yield. L2. GL. CI ’~d DO. respectively.
:.5.between 0.01 to 4.0 b~tween
.:t O.~J6~ O.2C:.:: t”, ,”, ,-1 ~.. i. -r
0.16 + o .07,
O.W.± 0.12 f·:·rDP, O.OC. 0.10.± 0.09 .,Cd 0.05 T 0.79 i c.r GL,
r~ .-.n
-’ . ’-’ ’,-’
and 0.16 ~ 0.12 for DO.
0.07.± 0.08 and 0.00 for cr and 0.08 + 0.06. 0.00
LP. and between TMY Md LP. COn-elations we”e negative between
always Positive and me,suy high between M305 and each of TMY and
(8) Genetic cor”elations in the first thr.. lactations Were
M305 and DP. betwee n TMY and DP. between LP and DP and between GL
between milk yield and .ach of cr and DO. LP.
DO. P0sitiw estimates of ger.etic cOn-elations lJ•.•-J W•••• obtained
and cr. It was mostly low b.t~en GL find DO ’nd b.twe.n cr and
each of GL. CI and DO.
POSitive •.••With GL. cr .nd DO. DP ~s POSitively correlated with
in general, had
DO and betwe~n cr and DO were obtained. PhenotYPic correlations
(9) Positive PhenotYPic COrrelati-ons among M305, TMY, LP, GL and
between lactation tl-aits fM305. TMY and LP) and DP and among GL
and each of CI and DO were negative.
(10) Environmenta] GO’Te] ations r” between M3Q5. TMY. LP. DP and
obtained between DP and each of CI and DO. POsitive envlro~~nta]
each ot GL and DO ~re POsitive. POSitive ostimates of. (r”J were
had POsitive YE With CI and DO.
Cone] ations (”,,)amcCor,g M305. TMY. LP. GL and DO. DP. in genera I .
ttehrisr. d lactations were obtained for sires haVing 5 or more daugh-
(11) BLUP est incates for M305. DP and CI in first. second and
SlreE with BL~ estimates of > +200 Kg in
both M305 and TMY ranged beti,.e.n12.2 and 14.3
thr.::e
lactations. in the first
,-’-, .o.f•.....Q. _’),.
98 and 112 days
third l’ctatlons. r.sp.ctiv.ly.~. dlfferenc •• betw ••n top Sir ••
days foY the first
and b”t torn ,Ones [(”,DP and cr . respecti VB ly , Were 154 and 199
lect.tjon. 106 and 245 days for the seoond