Relationship between physical characteristics and results of hatching in chicken eggs

Objective: The objective was to investigate the relationship between egg physical parameters, which can be determined without breakage, and hatchability. The following egg parameters were chosen: egg weight (W), volume (V), shell surface area (S), specific gravity (D), breadth to length ratio (B/L), and the ratio of egg weight to shell surface area (W/S).

Methods: A sample of 505 eggs from the parent stocks of White Leghorn (WL, line 01), Rhode Island White (RIW, line 68) and Rhode Island Red (RIR, line 70) laying hens were investigated. To estimate the relationship between the hatchability and quantitative factors, a special ranking was performed. The three categories: “average”, “more than average” and “less than average”, were chosen. All parameters were divided into 3 groups: 1) those, which values were within the average ± standard deviation; 2) with values less than the 1st group; and 3) with the values more than the 1st group.

Results: The average hatchability for the fertile eggs over three investigated strains was 77.7%. There were no significant differences between the groups for the RIR eggs, except the hatchability of the eggs, for which D hit the 3rd group, was significantly higher (94.4.%) than for the other two groups (77.2 and 81.3%). For the WL and RIW the “big” eggs, which W, V, S, L and B hit the 3rd group, had the least hatchability (53.3% for the WL and 62.1% for the RIW). The highest hatchability for these strains had found for the “small” eggs (2nd group). The lowest hatchability (50%) was in the group of the WL eggs, which D values were in the 2nd group. However, the same group of the RIW eggs had the best result (85.2%) in comparison with the other ones (74.2% for the 1st group and 81.8% for the 2nd one). The more “round-shaped” eggs of the WL and RIW, which B/L ratio hit the 3rd group, were more successful at hatching (87.5% for the WL and 84.4% for the RIW) than “normal-shaped” (76.8% for the WL and 75.3% for the RIW) and “sharp-shaped” eggs (64.3% for the WL and 75.6% for the RIW). The only significant differed result for W/S values was observed in the RIW strain. The lowest hatchability (65.6%) had recorded for the eggs of the 3rd group.

Conclusions: The small eggs were more successful at hatching than the bigger ones. The hatchability of the “round-shaped” eggs was higher than for the others. The influence of egg specific gravity on the hatchability is differed among strains.