الفهرس 
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Abstract
The present study was carried out at the Poultry Research Farm, An-imal and Poultry Production Dept., Faculty of Agriculture, Assiut Univer-sity during the period from December 2008 to May 2010.
This study aimed to evaluate the productive capability of two se-lected Fayoumi strains by Hossari (1970a). The first strain (PP) was se-lected for egg production. The second strain (GG) was selected for in-creased body weight. The third population (RR) was taken from the base population and considered as the control group. The selected srains PP and GG have been relaxed after ceasing selection by late 1960’s, and avoid-ance of inbreeding was practiced on the three strains since their derivation. These strains obtained from Fayoum poultry research station to be raised in Assuit Research Poultry Farm in order to evaluate these three genotypes for meat and egg production capability and some other related parameters under the environmental conditions prevailing in Assiut governorate to in-corporate these genotypes in the future breeding programme.
Eight hundreds and eighty unsexed day-old chicks represented the three genotypes were used in this study. Fayoumi chickens of GG strain were denoted as a heavy body weight genotype (HBW), PP strain chick-ens were recognized as light body weight genotype (LBW) and the RR strain chickens were designated as a control group.
The results obtained in this study could be summarized as follows:
1. Growth traits:
1.1. Body weight: The effect of genotype on chick’s body weight from hatch to 16 wks of age was highly significant. Heavy body weight chicks (HBW) had the highest body weight and light body weight chicks (LBW) had the lower body weight compared with the control group for all studied ages. It has been found that the differences in body weight between the HBW and LBW chicks increased by advancing age. The effect of sex on body weight was insignificant at hatch; however, it was highly significant (P≤0.01) from 4 to 16 weeks of age in favor of male chicks. Furthermore, there were no significant interaction between genotype and sex in all stud-ied ages.
A- Phenotypic correlations between body weights through growing period: It was noticed that there were positive and highly significant cor-relations between body weights from hatch to 16-weeks of age. It was ob-served that the final body weight during the growing period mainly de-pends on body weight at the early age. Therefore, the heavy chicks will continue to be heavier during all the growth periods.
1.2. Daily body weight gain: The effect of genotype and sex on absolute body weight gain (BWG) was highly significant (P≤0.01) from hatch to 16 wks old. where HBW genotype had the most high body weight gain (g/day) than LBW and control. However, LBW had the lowest body weight gain. In addition, males were superior in BWG compared with fe-males. The body weight gain (g/day) increased by advancing age in a gradual manner. Moreover, the interaction between genotype and sex was not significant.
1.3. Relative growth rate: It was noticed that R% decreased by the in-crease of chicks age at the first, second, third and fourth month of growth period. Moreover, the effect of genotype was highly significant (P≤0.01) in the first, second and third months of the same period. However, it was not significant in the fourth month. The HBW chicks had the highest rela-tive growth rate with a significant difference in the first month, thereafter; it decreased with increasing of chick’s age. Males were generally signifi-cantly heavier than females but relative growth rate decreased by the ad-vance of chick’s age. The interaction between genotype and sex was not significant.
1.4. Feed consumption: It was noticed that there was a significant in-crease in daily feed consumption (FC) correlated with the increase of body weight and chick’s age. The effect of genotype on weekly feed consump-tion (g/day) during the first and second months of age was in significant; whereas, it was significant (P≤0.05) during the third and fourth months of age. Heavy body weight genotype had significantly (P≤0.05) higher feed consumption (FC) in the third and fourth months than control and LBW groups.
1.5. Feed to gain ratio: The difference between HBW and LBW geno-types in feed to gain ratio (F: G Ratio) was not significant during the first three months of age, where a significant difference between the two geno-types was observed through the fourth month. This result indicated that the HBW chicks might be more efficient in feed utilization than the chicks of LBW genotype.
2. Egg production traits:
2.1. Body weight of laying hens for different genotypes: Differences be-tween genotypes were highly significant in body weight during egg laying season from 20 to 72 weeks of age. The HBW genotype had the heaviest weight than the other genotypes and vice versa for the LBW genotype.
A- Phenotypic correlations between body weights during egg laying season: The phenotypic correlations between body weights of genotypes at different ages were positive and highly significant. The HBW chickens were superior in body weight at the growing period and maintain this su-periority up to the end of egg laying season. The LBW chickens were the lightest during the growth period and the same manner was maintained un-til the end of egg laying season.
2.2. Sexual maturity:
A- Age at sexual maturity: The effect of genotype on age at sexual ma-turity was not significant which means that all genotypes reached sexual maturity at a similar age. The overall mean of age at sexual maturity was 150.7 days.
B- Body weight at sexual maturity: The overall mean of body weight at sexual maturity was 1280.9 g for all genotypes. The effect of genotype was highly significant. It was found that the HBW genotype was the heav-iest in body weight at sexual maturity and LBW genotype was the lightest one.
C- Weight of the first egg: There were no significant differences found between genotypes. It seemed that no effect of body weight (high or low) on the egg weight at sexual maturity, since all genotypes had similar first egg weight.
2.3. Egg number during the first 90 days of egg production: The over-all mean of egg number during the first 90 days of egg production was 40 eggs. The few egg number during the first 90 days of production was an early indicator for egg production through the laying season, which was lower than that recognized for Fayoumi. No significant differences were found between genotypes.
2.4. Egg number during the laying season: The overall mean of egg number during the laying season was 138.3 eggs/hen. The effect of geno-types on egg number were not significant.
2.5. Persistency: In general, the egg laying season was long for all geno-types (350.4 days). At the same time, the few eggs produced by each gen-otype indicated that the egg laying rate or intensity for Fayoumi chickens under Assiut conditions was low. There was no significant effect of geno-type on persistency.
2.6. Egg weight mean: The overall mean egg weight for the genotypes was 42.6 g. No significant effect of genotype on egg weight was found. It could be concluded that body weight (high or low) had no effect on egg weight in the present study.
2.7. Egg mass: The effect of genotype on egg mass was not significant. It was noticed that the egg mass followed the same trend as egg weight.
2.8. Phenotypic correlations:
A- Phenotypic correlations between the egg production traits: Pheno-typic correlations between age at sexual maturity and each of weight at sexual maturity, weight of first egg, egg weight and persistency were posi-tive and highly significant. However, there were negative and highly sig-nificant correlations between age at sexual maturity and each of egg num-ber and egg mass.
Phenotypic correlations between body weight at sexual maturity and egg weight or weight of first egg were positive and significant. Neverthe-less, the correlations between body weight at sexual maturity and each of egg number or persistency were negative and significant. Also, the corre-lation between body weight at sexual maturity and egg mass was negative but not significant.
Phenotypic correlations between egg number and each of weight of first egg, egg weight, persistency and egg mass were highly significant. Correlations between egg number and egg mass or persistency were posi-tive, while correlations were negative with egg weight or weight of first egg.
A negative highly significant phenotypic correlations were found between the length of laying season and weight of first egg, egg weight whereas, a positive correlation between length of laying season and egg mass.
Phenotypic correlation between weight of first egg and egg weight was positive and highly significant whereas it was positive and not signifi-cant with egg mass.
B- Phenotypic correlations between body weights during laying sea-son and egg production traits: The correlations between body weights in laying season and egg production traits (egg number, egg weight, egg mass and persistency) were not significant.
3. Egg components and shell quality:
3.1. Egg components:
A- Egg weight: The effect of age on egg weight was highly significant. The egg weight increased with advancing age from 32 up to 52 wks of age then decreased by the end of egg laying season at 74 wks of age. The in-teraction between genotype and age considering egg weight was not sig-nificant.
B- Yolk percentage: The overall mean of yolk percentage was 32.9%. The effect of genotype on yolk percentage was significant. It was found that HBW genotype had the highest percentage, where LBW genotype had the lowest percentage. The effect of age on the percentage of egg yolk was highly significant (P≤0.01). The yolk percentage increased with the ad-vanced age from 32 up to 52 of wks and then after the yolk percentages decline up to 74 wks of age. The interaction between genotype and age considering yolk percentage was not significant.
C- Albumen percentage: The overall mean of albumen percentage was 57.0%. The effect of genotype on albumen percentage was not significant. whereas, the effect of age was highly significant (P≤0.01). The interaction between the genotype and age was not significant.
D- Shell percentage: The shell percentage overall mean in our Fayoumi breed was 10.0%. The shell percentage was not influenced by the geno-type. However, the effect of age on shell percentage was highly signifi-cant. The effect of interaction between genotype and age on egg shell per-centage was not significant.
3.2. Shell quality:
A- Shell thickness: The overall mean shell thickness was 0.4 mm. The shell thickness was not significantly influenced by the genotype, but the effect of age was highly significant (P≤0.01). The effect of interaction was not significant.
B- Shell strength: The overall mean of shell strength was 3.9 kg/cm2. The effect of genotype on egg shell strength was not significant. It seemed that the egg of LBW genotype had the highest shell strength whereas, the low-est shell strength was found in HBW genotype. Shell strength in Fayoumi chicken increased regularly from 32 up to 52 wks of age. Then after de-creased down to the end of egg laying season. There was no significant effect of age or interaction between genotype and age on egg shell strength.
3.3. Phenotypic correlations between egg weight, egg components traits and shell quality traits: There were no significant correlations be-tween egg weight and the other traits. However, all these correlations were positive except the correlation between egg weight and shell percentage was negative. The correlations between yolk percentage and each of shell percentage, shell thickness and shell strength were not significant. More-over, the correlation between yolk and albumen percentages was negative and highly significant. Correlations between albumen percentage with shell percentage and thickness were negative and highly significant, while it was negative and significant with shell strength. There were positive and highly significant correlations between shell percentage and each of shell thickness and strength. The correlation between shell thickness and strength was positive and highly significant.
4. Reproductive traits:
4.1. Fertility percentage: The overall mean of fertility percentage for Fayoumi chickens was 96.4%. In general, it was higher than that con-cluded in previous studies. The effect of genotype on fertility percentage was not significant.
4.2. Hatchability percentage: The effect of genotype on embryonic mor-tality during the incubation period and both of hatchability percentages (based on fertile and total eggs) was not significant. These values were 77.1 and 74.3%, respectively. Both were less than that reported previously in literatures about Fayoumi chickens.
4.3. Female reproductive system: In general, the effect of genotype on anatomical reproductive system traits was not significant. The insignifi-cant differences in reproductive system anatomy traits between genotypes consequently reflected on the insignificant results in egg laying season traits. The effect of age on ovary component was significant. These char-acteristics increased as the pullets advanced in age from 32 to 52 wks, then decreased up to 74 wks of age. Generally, the effect of age on the ov-iduct parts weight and length was not significant as well as the effect of interaction between genotype and age was not significant.
5. Physiological and anatomical traits:
5.1. Hemoglobin concentration (mg/ dl): The overall mean of blood he-moglobin concentration was 11.92 mg/dl. The effect of genotype on blood hemoglobin levels was highly significant (P≤0.01). The HBW genotype had the highest value of hemoglobin concentration. The effect of ages on the same trait was highly significant. The highly hemoglobin concentra-tion in blood was at 52 wks of age. Moreover, there were highly signifi-cant interaction of genotype and age on blood hemoglobin concentration.
5.2. Dressing percentage and carcass traits: The overall mean of evis-cerated carcass and dressing percentages were 63.3% and 66.3%, respec-tively. The effect of genotype on these traits was significant (P≤0.05), where the HBW genotype recorded the highest values, while the effect of age and the interaction between genotype and age were not significant on the same traits.
5.3. Phenotypic correlations between slaughtering traits: Phenotypic correlations were positive and highly significant between pre-slaughter body weight and New York dressed carcass percentage. It was positive and not significant with giblet, eviscerated carcass and dressing percent-age. Phenotypic correlations were negative and highly significant between New York dressed carcass percentage and each of blood, feather, giblet, shank percentages. It was positive with head, eviscerated carcass and dressing percentages and highly significant for the last two traits.
5.4. Digestive system: The effect of genotype on esophagus, proventricu-lus and large intestine length was significant. HBW genotype hens re-corded the longest measurements, while the effect of genotype on the total digestive tract length, crop, duodenum, small intestine, caeca length was not significant. The effect of age on total digestive tract length, crop, proventriculus, duodenum and caeca length was significant.
The longest value of the digestive system organs were recorded at 52 wks of age. In general, the interaction between genotype and age on the total length of digestive tract and its parts was not significant. The geno-type had highly significant influence on total digestive tract weight, giz-zard, duodenum, and large intestine weight. The HBW genotype recoded the greatest values for these parts of digestive tract. The effect of age on digestive tract weight and its parts weight except proventriculus were sig-nificant. The effect of interaction between genotype and age on proven-triculus, large intestine and liver weight was significant, while it was not significant on weight of other digestive tract parts and its accessory or-gans.
Finally, our results clearly suggested using selection programme to improve body weight during growth period in the HBW chicks in Assiut governorate. However, LBW chicken did not express the potentiality of this genotype for egg production under the prevailing environmental con-ditions in Assiut. It is recommended to use selection programme for sev-eral generations for LBW genotype aiming at increasing egg production for useing this genotype in crossing programme in the future.