Egg Size and Shell Damage

Everyone knows that eggs get larger and cracks increase as laying flocks age. These well known facts, however, are sometimes used to support the belief that most cracked egg problems in older flocks are caused by excessive egg size Egg Size and Shell Damage - Image 1

In Figure 1, you can see the percentage of cracks found in eggs of different sizes in a survey of 24 flocks in Saskatchewan. At both 55 and 66 weeks of age, the Extra Large and Jumbo sized eggs had 1% to 2% higher cracks than the Large sized eggs. The higher level of shell damage in the Extra Large and Jumbo sized eggs, however, had a limited effect on the total number of cracks in these older flocks. As an example, at 66 weeks of age, the flock with the biggest eggs had 71.5% Extra Large plus Jumbo sized eggs compared to 25.5% in the flock with the smallest eggs. While the difference in egg size was dramatic, it would only result in 0.5% to 1.0% higher cracks in the flock with the largest eggs. In the past, people have blamed egg size for problems where cracks were elevated by 3%, 4% and even 5%.

Excess cracks in the Extra Large and Jumbo sized eggs can occur in older flocks on farms where mechanical egg packers are used. At 66 weeks of age, the flocks using packers had 4% to 6% higher cracks in the Extra Large and Jumbo sized eggs than in the Large sized eggs (See Figure 2). With mechanical packers the effect of egg size on breakage is more significant. As an example, a 66 week old flock with 71% Extra Large plus Jumbo sized eggs would be expected to have 2% higher cracks than a flock with only 25% Extra large plus Jumbos. Comparing an old flock with very large eggs to one with average sized eggs, (say 71% versus 47% Extra Large plus Jumbos), you would expect the flock with the larger eggs to have 1% more total cracks. The increased breakage in Extra Large and Jumbo sized eggs is economically important but may not explain as many of the cracked egg problems as previously thought.

When investigating the cause of cracked eggs, it is important to estimate the effect of egg size on breakage by weighing the cracked and non-cracked eggs.

Egg Size and Shell Damage - Image 3