الفهرس 
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Abstract
SU!UIAlly
This work was carried out on Dokki-4 chickens (as a na~ive
breed) raised in the Poultry Research Farm at Inshas (Sharkia
Governora~e), Animal Production Research Institute, Ministry of
Agriculture, Egypt. A ~otal number of 4057 progeny produced by 3S
aires in three consecutive hatches were collected in the period
from March 1979 ~o June”1980. Data of individual body weight (DV)
at hatch and biweekly thereafter up to 12 weeks of age were analysed.
Other growth traits such as daily gain (DG), absolute gain
(AG) and relative growth rate (BS) between 0-4, 4-8, 8-12 and
0-12 weeks of age were analysed separa~ely. Kixed Kodel analyses
were performed in order to quantify the average genetic, phenotypic
and environmental variation and covariation of such growth
traits and to a••••• the direct and correlated re.pon.e. expected
from selection for these traits. The follOWing reSUlts were
obtained:
(1) DG and AS of Dokki-4 chickens increased wi~h the advancement
of age. KG was higher (137.45%) at the early s~age. (0-4
weeks), then decreased gradually with the advancement of age
at the interval of 8-12 weeks.
(2) Coefficient. of variation (CV) for growth ~ralt. are tended
generally ~o increase as the chick advaneeed in age. The AS
and KG during the period of 0-4 weeks were 19.83% and 7.2%
compared to 31.12% and 22.88% during the period of 8-12
weeks, respectively.
(3) Higbly .ignificant difference. (P(O.OS or P(O.Ol or P<O.001)
due to effects of hatch, .ex and ba~cb x sex interaction for
mo.t growth trait. were o~ined.
(4) The difference. due ~o sire. and daas for all growtb trait.
at diff.ren~ ages were highly .lgnlficant (P(O.01 or
P<O.001). Perc.n~ •• (~) of sire, daa .i~ln .ire and
error component. of variance are variable for different
growth trait. • S••11 proportiona of variation eft) due to
sire eff.c~s on B1J (2.4’) and.on bo’thD6 and M (2.7’) .ere
obtained. Ho.ever, large proportions of variation due to daIII
effect. were recorded at all ag.. coaparabl. to ~o.. of
sire. It ranged.froll 13.8. to 27.~ for _ (with an average
of 19.~) and 12._ ’to17._ for both D8 6. AS (1fi~ an
average of 14.5*).
” ”
(5) Bo con.i.~ent treDd for e.ti••t•• of b.ri~ility fra. paternal
half-sibs (b2s) was observed for growth trai~s. In
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general, low estimates of b2• for all growth traits were
obtained which ranged from-0.041 to 0.153 with an average
estimate equal to 0.097. The heritability estimates from
maternal half-sib. (b2D) ranged from 0.553 to 1.079 (with an
average equal to 0.760) for BW and from 0.511 to 0.717 (with
an average equal to 0.614) for both DG and AG. Estimat•• of
h2D for RG ranged from 0.343 to 0.602 (with an average equal
to 0.485). The estimates of heritability based on full-siba
(h2s+D) for growth traits at different age intervals were
moderate or high which ranged between 0.312 to 0.606 for aw
(averaged 0.429), 0.317 to 0.395 for both DG & AG (averaged
0.357) and between 0.227 to 0.360 for RG (averaged 0.289).
(6) All estimates of phenotypic correlation (rp) and both of
genetic (re) and environmental (rE) from paternal half-sib
(PHS), maternal half-sib (KHS) and full-sib (FS) components
among aw, DG and AG at different ages were positive and of
moderate or high magnitude, and tended to decrease in value
as the differences between the two ages get larger.
(7) Expected estimates of annual direct genetic progress based
on PHS for BY selected for hatch-, 2-, 4-, 6-, 8-, 10- and
12-week weight are 0.12, 0.75, 2.97, 1.74, 3.21, 2.71 ~nd
4.23 grams per chick per generation, respectively. The corresponding
estimates based on FS were 0.80, 3.41, 4.98, 7.66,
11.85, 16.42 and 22.62 grams in the same order. Selection for
4-we.1t body weigh1: and for both AG & R6 at In1:ervalof 0-4
weeks of age have been generally associated with a moderate
or high rate of expected correlated response in growth traits
a1:subsequent ages.