Shell strength is more than calcium

Chickens face many challenges throughout their lives. Incidentally, the first day is one of the most stressful and has the highest impact on long-term animal health, welfare, performance, sustainability, and food safety. Even before the egg is laid, the hen’s nutrition is key to developing resilient and vital day-old chicks.

Focus on quality: Hatcheries are crossroads where day-old chicks from different origins are in contact with each other, increasing the risk of cross-contamination. Even with the most stringent biosecurity program, the performance of hatcheries strongly depends on the quality of the hatching eggs. Since chicks are the potential of the farms, it is the goal of any broiler breeder and hatchery manager to efficiently produce as many healthy and active day-old chicks as possible.

Hairline cracks are open doors for contamination: An effort is being made to prevent microbial-contaminated eggs from entering the hatchery. One way to do this is to ensure there are no hairline cracks or star cracks. A study by Khabisi et al. (2011) shows that even minimal defects of the eggshell significantly influence hatchability and day-old chick quality in broiler breeders. When cracks are present, there is an increased risk of eggs becoming contaminated with E. coli or Salmonella. One study found that the rate of contamination with hairline cracks can be at least 5 times higher than in normal eggs, Simset et al. (2009).

The impact of contamination lasts longer than a day: In a large field trial under commercial conditions when hairline cracked eggs were compared to normal eggs, the effect on hatchability and day-old chick quality found that hairline cracks decreased broiler performance in a significant way. One study found hairline cracks negatively affected mortality, feed intake, weight gain, and feed conversion Adnan Jabar et al. (2019). Other studies have seen decreased effects on performance, directly affecting profitability and detrimentally impacting food safety.

More calcium is not the solution: As the hen ages, due to a reduction of shell thickness and shell breaking strength, the incidence of these types of eggshell defects increases. However, in contrast to what many people believe, adding additional calcium to the diet to maintain shell strength is not the solution. Under normal circumstances, the calcium uptake rate is not affected by the hen’s age or the quantity of calcium available in the diet. In fact, increasing calcium levels above recommended intake can even have negative effects on shell quality Negoita et al. (2017). Also, it is clear when given a certain calcium rate, shell weight becomes constant after reaching maximum egg output; indicating that calcium deposition is constant in time (Figure 1).

Evolution of shell weight in relation to flock age
Figure 1: Evolution of shell weight in relation to flock age (commercial layers, 4 different feed formulations) Negoita et al. (2017).

There is strength in supporting shell deposition: Given the shorter intervals between ovulation and oviposition (as performance improves year by year), facilitating and improving the process of shell calcification results in the best possible improvements. To guarantee success as hens age, it is evident that the strategy to maintain egg quality needs to be built on improving not only calcium but shell deposition.

Protecting protein is the key: When a hen is not stressed, more protein can be attributed to production as well as the quality of the eggs; especially the albumen. Medium chain fatty acids have been shown to improve the shell strength and the nutrients available to young chicks through the albumen, which results in higher hatchability and better chicks quality.

In this regard, Agrimprove conducted several trials using Shellbiotic on broiler breeders close to 60 weeks old. Shellbiotic was found to be helpful in improving egg production and quality as well as reducing hairline cracks to improve hatchability. These results indicate less microbial contamination, maintained albumen quality, and better liveability in day-old chicks (Table 1).

Table1: Economic values in broiler breeders

Economic values in broiler breeders

The trial results in the table above show what happens to embryos in the hatchery matters not just for their immediate welfare, but also for later growth in the first week. This suggests Shellbiotic has a positive effect on poultry production.

The impact is evident: In conclusion, day-old chicks face tremendous stress in the first 24–72 hours after hatching. In addition to these stressors, they are bombarded with potential contaminants. Studies have shown improving shell strength reduces hairline fractures, supports chick vitality, and improves later-life efficacy. Most broiler breeder diets provide adequate calcium, meaning the shell strength solution is not in adding calcium to the diet but in supporting albumen quality and shell disposition. On average, broiler breeder managers and hatchery managers using Shellbiotic notice improvements in the number of hatching eggs (1.5 to 2.5 ) and hatchability (1 to 1.5%); resulting in 2.5 to 3 more first-grade day old chicks. By looking to shell disposition and albumen quality, producers achieve fewer hairline cracks indicating more vital and sustainable day-old chick production.

Your Agrimprove expert

Jan Vervloesem
Category manager poultry

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