Materials and methods
This study was carried out at the Poultry Production Experimental Station, Faculty of Agriculture, Suez Canal University, Ismailia, Egypt. The experimental work was carried out within the period from October 1993 to December 1995. Two experiments were conducted, in the first one 3-way crosses were produced, while in the second 4-way crosses were produced. In both experiments the original pure breeds were produced along with the crosses.
Experiment 1:
Three-way crosses:
Two-way cross females, previously produced by diallel mating of three native and two exotic breeds of chickens ( Abd El-Gani, 1995 ) were crossed with males from a third breed to produce the three-way cross chicks. The two exotic used breeds were Rhode Island Red ( RR ) and Single Comb White Leghorn ( LL ) and the three native used breeds were Fayoumi ( FF ), Sinai (SS), and Dandarawi (DD ). The two-way cross pedigreed females were set in 21 pens (15 - 20 hens/ pen) with 2-3 cocks per pen. The cocks used to produce the three-way crosses were from RR, LL and SS breeds. The eggs were collected for 10 days and sorted before incubation. The eggs were incubated in November 1993 to produce 1500 one day-old chicks of five pure breeds and 16 different three-way crosses. Any cross was assigned a symbol with three letters, the first letter to explain its sire and the other two letters refer to its dam, for example the symbol (SRL) indicates the cross 0.5 Sinai, 0.25 Rhode Island Red and 0.25 Single Comb White Leghorn.
Experiment 2:
Four-way crosses:
On the second year the three-way cross females were mated to a pure male from the five pure breeds to produce the four-way-cross chicks. Ten days of egg production were collected and sorted before incubation. The chicks were hatched 13 th August 1994 to produce 1200 day-old chicks of five pure breeds and 16 different three-way crosses. The pedigreed females were distributed in 42 pens (5 - 8 hen/ pen) and one cock per pen. Any cross was assigned a symbol with four letters, the first letter to explain its sire and the other three letters refer to dam, for example the symbol (DSRL) indicates the cross 0.5 Dandarawi, 0.25 Sinai, 0.125 Rhode Island Red, and 0.125 Single Comb White Leghorn.
Management:
At hatch, all chicks were wing banded to keep their pedigree. The chicks were brooded and reared till 8 wk of age in 3 decks batteries (1 m2/deck). The chicks were vaccinated according to the following program:
1-14 day of age Furazolidone (feed 200g / ton)
at 7 th day Newcastle (Hitchner strain) in drinking water
at 14 th day For Gumboro in drinking water
at 18 th day Newcastle (Lasota strain) in drinking water
at 32 th day Newcastle (Lasota strain) in drinking water
at 8 wk till 18 wk Anti coccidiosis (feed 1kg / ton)
9 th wk of age Newcastle (lasota strain) in drinking water
at 12 wk Fowl Pox (scratching the wing)
16 th wk of age Newcastle oil vaccine (injection)
The birds were transferred at 12 wk of age to floor rearing pens till the end of the experiment. The pens were supplied with trap nest at 18 wk of age. Eggs were individually recorded till 43 wk of age. All chicks were fed ad - libitum using the rations in (Table A):
Table A: Ingredient and composition of rations used through the experimental periods.
|
Ingredient |
starter (0-2 wk) |
growing (1) (3-12 wk) |
growing (2) (13-19wk) |
laying (20-45wk) |
|
Yell Corn |
66 % |
70 % |
68 % |
65 % |
|
Soybean meal 44% |
24 % |
20 % |
8 % |
17.5 % |
|
Lime Stone |
- - |
- - |
2 % |
4.0 % |
|
Oyster Shell |
- - |
- - |
- - |
3.5 % |
|
Wheat Bran |
- - |
- - |
12 % |
- - |
|
Concentrate |
10 a % |
10 a % |
10 a % |
10 b % |
|
Total |
100 % |
100 % |
100 % |
100 % |
|
Calculated |
||||
|
Crud Protein % |
21.07 |
20 |
16 |
17.5 |
|
Calcium % |
1.05 |
0.85 |
1.75 |
2.72 |
|
Available Phosphorous |
0.53 |
0.47 |
0.53 |
0.52 |
|
Mehionine % |
0.43 |
0.43 |
0.35 |
0.39 |
|
Lysine % |
1.12 |
1.04 |
0.73 |
0.96 |
|
ME. ( kcal. / kg ) |
2940 |
3030 |
2825 |
2817 |
a, b : Broiler and layer concentrate respectively, Muvco Abu Soltan, Ismailia
Measurements of the studied traits:
a) Body weight:
Body weight was measured individually to the nearest gram every three weeks up to 21 wk of age. The measures were recorded at 3, 6, 9, 12, 15, 18 and 21 wk of age and at sexual maturity.
b) Sexual maturity:
Age at sexual maturity for each females was recorded, as well as, its body weight. At the same day, lengthes of shank (sh), keel (kl), comb (cl) and wattle (wa) and comb hight (ch), were measured to the nearest millimetre.
c) Egg production:
Egg production for 90 and 120 days were recorded for each individual hen. The eggs of three consecutive days for every other week were weighed till the end of experiment to estimate the average egg weight for each period. Egg production and average egg weight were used to calculate egg mass output g/day.
d) Heterosis :
Heterosis is the deviation of the cross mean from midparent means. Heterosis of body weight for both sexes and egg production for individual females were calculated applying the following equation.
Heterosis = cross record - mean of parental lines
E) Growth rate:
Relative growth rate (GR) was estimated according to the following equation (Lerner and Asmundson, 1932):
GR % = BW2 - BW1 * 100
BW1
Where: BW2 = current body weight
BW1= previous body weight
F) Heritability:
Heritability estimates were calculated using the variance component which calculated from ANOVA tables:
- From maternal half sibs = 4 s2 d
s2 p
- From paternal half sibs = 4 s2 s
s2 p
- From full sibs = 2 (s2 s + s2 d)
s2 p
Where: s2 s = sire variance component
s2 d = dam variance component
s2p = Phenotypic variance component
g) Correlations:
Genetic (rg) and phenotypic (rp) correlation coefficients among body weights and among egg production and sexual maturity were estimated according to Harvey, 1987 as follows:
a) Three-way crosses
cov d xy
rg = ____________
Ö s2 d x * s2 d y
cov dxy + cov wxy
rp = __________________________
Ö( s2 d x * s2 wx)Ö (s2 d y * s2 wy)
b) Four-way crosses
cov s xy + cov d xy
rg = __________________________
Ö(s2 s x + s2 d x)* Ö (s2 s y + s2 d y)
cov. s xy +cov. dxy + cov wxy
rp = ______________________________________
Ö s2 s x + s2 dx + s2 wx * Ö s2 s y + s2 d y + s2 w y
where: s2 s = sire variance component
s2 d = dam variance component
s2p = Phenotypic variance component
s2w= within variance component
cov d, cov s and cov w = dam, sire, and within covariance component respectively.
Methods of statistical analysis:
The data were analysed using the General Linear Model (GLM) Procedure of SAS (SAS institute, 1985). Least Square Means were estimated for all studied characteristics. Differences were tested by Least Square Difference method at level of (p £ 0.05). Heritabilities, genetic, and phenotypic correlations were estimated using Harvey’s Mixed Model Least Squares and Maximum Linklihood Computer Program LSMLMW, 1990.
The mathematical models used were:
a) Body weight:
1- three-way crosses
Yijkl= m + gi+ dj(i) +Sexk + Sex*g ik +eijkl
Where:
Yijkl = the observation lth from the kth sex from the jth dam from the ith genotype.
m = the over all mean.
gi = the effect of the ith genotype.
dj(i) = the effect of the jth dam from the ith genotype.
Sexk = the effect of the kth sex.
Sex*g ik = the interaction between kth sex and ith genotype
eijkl = the random error associated with the individual ijkl.
2- four-way crosses
Yijklm= m + gi+ Sj(i) +dk(ji) +sexl+ Sex*g il +eijklm
Where:
Yijklm = the observation mth from the lth sex from the kth dam mated to the jth sire from the ithgenotype.
m = the over all mean.
gi = the effect of the ith genotype.
Sj(i) = the effect of the jth sire from the ith genotype.
dk(ji) = the effect of kthdam mated to the jthsire from the ith genotype.
sexl = the effect of the lth sex.
Sex*g il = the interaction between lth sex and ith genotype
eijklm = the random error associated with the individual ijklm.
b) Egg production and sexual maturity:
1- three-way crosses
Yijk= m + gi+dj(i) +eijk
Where:
Yijk = the observation kth from jth dam from the ith genotype.
m = the over all mean.
gi = the effect of the ith genotype.
dj(i) = the effect of the jthdam from the ith genotype.
eijk = the random error associated with the individual ijkl.
2- four-way crosses
Yijkl= m + gi+sj(i) +dk(ji) +eijkl
Where:
Yijkl = the observation lth from the kth dam mated to the jth sire from the ith genotype.
m = the over all mean.
gi = the effect of the ith genotype.
sj(i) = the effect of the jthsire from the ith genotype.
dk(ji) = the effect of kth dam mated to the jth sire from the ith genotype.
eijkl = the random error associated with the individual ijkl.