Abstract: Dietary cholesterol has elicited the most public
interest as it relates with coronary heart disease. Thus, humans have
been paying more attention to health, thereby reducing consumption
of cholesterol enriched food. Egg is considered as one of the major
sources of human dietary cholesterol. However, an alternative way to
reduce the potential cholesterolemic effect of eggs is to modify the
fatty acid composition of the yolk. The effect of palm oil (PO),
soybean oil (SO), sesame seed oil (SSO) and fish oil (FO)
supplementation in the diets of layers on egg yolk fatty acid,
cholesterol, egg production and egg quality parameters were
evaluated in a 42-day feeding trial. One hundred and five Isa Brown
laying hens of 34 weeks of age were randomly distributed into seven
groups of five replicates and three birds per replicate in a completely
randomized design. Seven corn-soybean basal diets (BD) were
formulated: BD+No oil (T1), BD+1.5% PO (T2), BD+1.5% SO (T3),
BD+1.5% SSO (T4), BD+1.5% FO (T5), BD+0.75% SO+0.75% FO
(T6) and BD+0.75% SSO+0.75% FO (T7). Five eggs were randomly
sampled at day 42 from each replicate to assay for the cholesterol,
fatty acid profile of egg yolk and egg quality assessment. Results
showed that there were no significant (P>0.05) differences observed
in production performance, egg cholesterol and egg quality
parameters except for yolk height, albumen height, yolk index, egg
shape index, haugh unit, and yolk colour. There were no significant
differences (P>0.05) observed in total cholesterol, high density
lipoprotein and low density lipoprotein levels of egg yolk across the
treatments. However, diets had effect (P
Abstract: A crossbreeding experiment was carried out between two Egyptian strains of chickens namely Mandarah (MM) and El-Salam (SS). The two purebred strains and their reciprocal crosses (MS and SM) were used to estimate the effect of crossing on egg laying and egg quality parameters, direct additive and maternal additive effects as well as heterosis and direct heterosis percentages for studied traits. Results revealed that SM cross recorded the highest significant averages for most of egg production traits including body weight at sexual maturity (BW1), egg numbers at first 90 days, 42 weeks and 65 weeks of age (EN1, EN2 and EN3; respectively), egg weight at 90 days, 42 weeks of age (EW1 and EW2), egg mass at 90 days, 42 weeks and 65 weeks of age (EM1, EM2 and EM3; respectively), feed conversion ratio to egg production at 90 days , 42 weeks and 65 weeks of age (FCR1, FCR2 and FCR3; respectively), fertility and commercial hatchability percentages. Moreover, SM line reached the age sexual maturity (ASM) and period to the first ten eggs (Pf10 egg) at earlier age than other lines. On the other hand, crossing did not well improve egg quality parameters. Estimates and percentages of direct additive effect (GI) were negative for most of the studied traits except for EN1, EN2, EN3, FCR3, fertility, scientific and commercial hatchability percentages that were positive. But Estimates and percentages of maternal heterosis (Gm) were positive for all the studied traits of egg production, except for BW2, BW3, ASM, Pf10, FCR1, FCR2, FCR3 and scientific hatchability that were negative. Also, positive estimates and percentages of heterosis were recorded for most of egg production and egg quality traits. It was concluded that using of SS strain as a sire line and MM strain as a dam line resulting in best new commercial egg line (SM) which is of great concern for poultry breeder in Egypt.