Genetics, nutrition, feeding regimen all play a role in boosting eggshell quality in older hens
A split feeding regimen can play a role in maintaining the eggshell strength in the later stage of lay, compared to conventional feeding, according to the US study.
But split feeding alone is not sufficient to tackle the challenges linked to the later stage of laying, a period prone to a decrease in eggshell strength and an increase in soft-shelled and cracked eggs, say the authors of the paper, published in Animal Feed Science and Technology.
“Future research should focus on a combined strategy of improved genetics, nutrition, feeding regimen, and management strategy to maintain the eggshell quality in the late production phase.”
White laying hens are currently kept in egg production up to 80 weeks of age or longer, reads the paper.
However, in the later stage of laying, there is a decline in the bird's ability to utilize calcium (Ca) from the diet (Wistedt et al., 2019). This leads to decreased eggshell strength, with an increased number of deformed eggs such as soft-shelled and cracked eggs.
Indeed, they noted that the incidence of cracked eggshells can reach as high as 20%. Even for hens at mid-lay (45 week), the egg breakage can be as high as 6–11% at the point of lay, said the team, which included researchers based at Mississippi State University.
Those specialists also outlined how the majority of eggs by commercial laying hens are laid in the cooler hours of the day, usually in early morning to early afternoon hours.
"For the first five to six hours after ovulation, albumen and eggshell membranes are deposited in the reproductive tract, and it is only after the eggs enter the uterus that eggshell formation occurs, which usually takes 19 hours. The estimated time an egg stays in the uterus for eggshell formation is from late afternoon to the next morning."
A potential solution to compensate for the decreased ability for the older birds to utilize Ca and provide adequate Ca during the eggshell formation is to feed the majority of Ca in the afternoon as a split (S) feeding regimen, pointed out the team.
However, they noted a lack of consistency in results published in relation to such an approach (Keshavarz, 1998, Waldroup and Hellwig, 2000, Molnár et al., 2017, Molnár et al., 2018a, Molnár et al., 2018b).
They therefore decided to run a 20-week study to determine the effect of conventional (C) and split (S) feeding regimens on performance parameters such as feed consumption, egg production, egg quality, and eggshell quality.
They also wanted to check out the effect of limestone particle size ratios on egg quality, eggshell strength, and bone strength in the late production phase.
Their experiment comprised two feeding strategies, which included conventional feeding (C) and split feeding (S) and four limestone ratios of 35:65, 25:75,15:85, and 0:100 FL:CL, respectively.
There were 4 conventional diets for the C regimen, while the S regimen involved 4 afternoon diets and 1 morning diet. Thus, eight feeding regimens were tested.
For the S regimen, one standard morning diet was fed without any added limestone. The morning diet for the S regimen was fed at 7:30, and the afternoon diet for the S regimen that included limestone was provided at 15:30.
In the C group, all diets were available for the hens the entire time the lights were on from 5:30 in the morning until 21:30.
The basal diet (78.76%) without added limestone was formulated for all diet types.
In the S regimen, 21.24% of corn was added in the morning diet, and 21.24% limestone was added to the afternoon diet. Similarly, in the C regimen, 10.62% limestone and 10.62% corn were added in morning and afternoon diets.
Feed intake (FI) per bird was measured twice a day.
Eggs were collected once daily at 15:00. The daily number of eggs produced and the quality of the eggs, such as intact, cracked, dirty, and soft-shelled eggs, were recorded.
The team reported an interaction between feeding regimens and age of birds for average eggshell breaking strength (EBS), indicating, they said, that the split (S) feeding regimen maintains EBS compared to conventional (C) feeding regimen.
They observed that feeding the majority of the Ca in the afternoon helps the EBS and lowers the percentage of soft-shelled or damaged eggs.
However, the researchers also saw an increase in egg size, which they said might be due to an increase in the size of oviduct in these older hens, and this could undermine the split feeding approach.
“Even though the split feeding regimen has shown promising results in reducing the number of soft-shelled eggs in the late production phase, increasing egg size due to age may lessen its impact. Therefore, a split feeding regimen alone is not sufficient to maintain eggshell quality in the late production phase.”
The authors said there was also interaction between limestone particle ratio and age for feed intake indicating that a higher amount of feed is consumed when fine limestone is not added to the diet.
The main effect of limestone ratio was observed for tibial breaking strength (TBS) where the birds fed 35FL:65CL or 25FL:75CL ratio diets had a greater TBS than 15FL:85CL and 0FL:100CL, they added.
“Increasing the proportion of coarse limestone in the diet leads to a continuous supply of Ca in the bloodstream, which alters cancellous bone resorption and medullary bone formation (Fleming et al., 1998).
“In our study, higher tibial breaking strength (TBS) was observed in diets with 35FL:65CL and 25FL:75CL and increasing the coarse limestone beyond this did not improve the TBS."
Source: Animal Feed Science and Technology
Title: Role of conventional and split feeding of various limestone particle size ratios on the performance and egg quality of Hy-Line® W-36 hens in the late production phase
Authors: I Poudel, CD McDaniel, MW Schilling, D Pflugrath, PA Adhikari