The present study was carried out during winter months to estimate
response of two Dandarawi chicken phenotypes (crested (Cr) and non-crested (cr)) to
extra L-arginine (Arg) supplementation. Seventy two female from each of Cr and cr layer
Dandarawi hens were chosen when egg production(EP) reached 50 %. The Cr and cr layer
Dandarawi hens were distributed randomly into 3 experimental groups; each group
includes 24 layer hens divided randomly into 3 replicates with 8 hens each. The 1st group
from each phenotype fed control basal diet that satisfied recommendations of NRC.
Groups 2 and 3 from each type fed basal diet supplemented with 2% and 4% L- arginine
over NRC requirements respectively for three winter months. Arginine supplemented by
14gm/100kg diet and 28gm/100kg to perform levels 2% and 4% respectively.
The following results were obtained:-
Crested phenotype had higher significantly EP% and egg mass per hen per day than cr
during 2nd month and overall period moreover Cr laying hen consumed significantly
lower diets than cr during the first month of EP and improved significantly feed
conversion during the second month of EP. Significant decrease was observed in yolk
percent of egg laid by Cr hens but significant increase was observed in shell thickness.
Body temperature of Cr phenotype during chronic cold condition was lower by about
0.38°C than cr phenotype and had low significantly respiration rate.
Diets supplemented with excess Arg recorded significantly (P ≤ 0.05) higher EP% than
control diet during 2nd month, 3rd month and for overall period. Excess Arg
supplementation reduced significantly feed intake during the 1st month of EP, but
increased significantly feed intake during the 3rd month. Increasing Arg level to 4%
increased significantly (P ≤ 0.05) yolk percent and decreased significantly (P ≤ 0.05)
albumin percent.