Weight and Various Interior Qualities of Eggs from Leghorn and Meat-Type Breeds and the Correlations among These Characteristics

Abstract

Mature eggs produced from White Leghorns consisting of two lines (WL, WL-D), White Rocks (WR) and White Cornishes (WC) were used for measuring the various qualities. The experiment was done during five months from April to August of 1967. The eggs were placed under the natural temperature until the evening after laying and then those were stored at approximately 23°C for 16 hours. Mean values for 12 traits of eggs, i.e., weight, length, breadth, shell weight, shell thickness, albumen weight, albumen height, Haugh unit, yolk weight, yolk color, blood and meat spots, and correlations among these measurements were estimated.1. Average egg weights in various breeds are arranged in order of WR (66.6g), WL-D (62.0g), WC (60.8g) and WL (58.5g). Albumen weight ranged from 34.9g (WL) to 39.4g (WR), and ratios of the albumen weight to the egg weight averaged about 59% in most breeds, being the lowest in WC (57.9%). The yolk weight ranged from 18.1g (WL) to 21.2g (WR), and ratio of the yolk weight to the egg weight was around 31% in all the breeds. The ratios of the yolk weight to the albumen weight were higher in the meat-type breeds of WR and WC (54-55%) than in the Leghorns (52%). Albumen height averaged 6.0mm, but there existed considerable variations owing to the individual difference among eggs. Haugh units were computed to be 74.9 (WL) to 76.7 (WL-D).Average shell weights ranged from 5.6g (WL) to 6.2g (WC), and those are equivalent to 9.6 to 10.2% of the egg weight. Average shell thickness in three parts of the waist, broad and narrow poles of the egg fell into the range from 0.337mm (WL) to 0.378mm (WC). There appeared a higher intensity of yolk color in the egg from the meat-type breed as compared with that in the Leghorns.The incidence of the blood spot averaged 2.9%, ranging from 1.6% (WC) to 3.9% (WR). The incidence of the meat spot averaged 7.2%, and it is noticeable that the WR represented the highest value of 14.4%.2. Significant correlation coefficients above 0.8 were found between egg weight and albumen weight, and between egg weight and egg breadth in all the breeds. Correlations between egg weight and yolk weight were the lowest in the WR (r=0.52) and the highest in the WL (r=0.80). The correlations of the albumen height and the Haugh unit to the egg weight were not so high, showing only r=0.26 even in the highest estimation. The high correlation coefficients above 0.94 were observed between albumen height and Haugh unit in all the breeds.Correlation coefficients above 0.8, except the WL-D line, were estimated between albumen weight and egg breadth, and those above 0.3, except the WR, were observed between albumen weight and albumen height. The high correlation coefficients of 0.7-0.8 were estimated between shell weight and shell thickenss.3. The repeatabilities comupted from the analysis of variance were estimated to be above 0.8 for egg weight, egg breadth and albumen weight, and to be 0.6 to 0.8 for shell weight, shell thickness and albumen height.