Comparative Studies on Physical and Chemical Property of Avian Eggs

Proportions of component parts, thickness and crushing strength of egg shells, and chemical compositions of eggs from ducks (Naki-a Japanese native breed, Khaki Campbell and Pekin), Muscovy ducks, chickens (Totenko-a Japanese native breed and Rhode Island Red), golden pheasant and silver pheasant were studied. Average egg weights of Naki, Khaki Campbell and Pekin ducks were 51g, 66g and 93g, respectively. Percentage of yolk weight of the total weight of duck eggs was 34-36% and no significant difference was found between 3 duck breeds studied. Average weight of Totenko and Rhode Island Red chicken eggs was 37g and 65g, and percentage of yolk weight of the total weight was 33% and 29%, respectively. Percentage of crude fat of the egg contents of Naki, Khaki Campbell and Pekin ducks was 14%, 16% and 13%, and that of Totenko and Rhode Island Red chickens was 13% and 11%, respectively. Decrease either in yolk percentage of the total weight or in fat percentage of the egg content with the increase of egg weight was observed in the chicken breeds, but not in the duck breeds. Percentage of egg shell of the total weight of Naki ducks and Totenko chickens was 11%, and that of Pekin and Khaki Campbell ducks and Rhode Island Red chickens was 9%. No significant difference was found in percentage of the egg contents in all the breeds of duck and chicken studied, being about 12%. Shell thickness of chicken eggs was 0.33mm and that of duck eggs was 0.34-0.36mm. Crushing strength of the shell of chicken and duck eggs was 2.5-2.8kg. In Muscovy ducks, percentage of crude protein of the egg contents (13%), percentage of shell weight of the total weight (11%), shell thickness (0.40mm) and shell strength (>4.6kg) were significantly higher (p<0.05) than those in the 3 breeds of duck eggs studied. In the golden phesant, percentage of yolk weight of the total weight was 39%, being higher than that in duck and chicken eggs. In the silver pheasant, percentage of yolk weight of the total weight (39%), percentage of crude fat (16%) and crude ash (1.2%) of the egg contents were significantly higher (p<0.05) than those in duck and chicken eggs. Percentage of shell weight of the total weight (13%), shell thickness (0.42mm) and shell strength (4.8kg) of silver pheasant eggs were the highest scores in all the eggs of the other species studied.