The secret to bigger, stronger eggs

New research suggests the right diet can help hens lay larger eggs with fewer cracks, right to the end of lay
Genetic advancements in layer hens means flocks are being kept on for longer than ever before. But there are well documented problems with older hens over 80 weeks laying weaker, larger eggs, leading to a greater proportion of seconds.
While the broiler sector has generally kept pace with genetic advancements by formulating feeds that get the most out of the birds, there has been less work in this area with layers. However, a new series of farm trials and scientific trials carried out with ForFarmers’ Sustain product has produced some promising results.
ForFarmers has a range of layer diets and Sustain, which contains the Shell Mix innovation, is the diet that is fed from mid-lay to the end of lay. “It was produced to support the requirement for the longer-living hen, which is what producers and packers are driving for at the minute,” says Dave Hilldrith, ForFarmers’ UK poultry director.
Traditionally, hens were fed on diets that were of a high specification early in lay, then were less nutrient-dense as the hens got older. But, says National Poultry Advisor Andrew Fothergill, the modern egg layer has the ability to produce far more eggs than in previous times. A diet that declines in nutrient density can affect egg numbers and shell quality.
So, the purpose of the farm trials was to establish whether a diet like Sustain, which has a high nutrient density, offered a financial benefit to the farmer and reduced the number of seconds. “We wanted to be able to give farmers the reassurance that if they were going to take their hens, which they would normally cull at 72 weeks, well into the 80+ weeks, that it was financially worthwhile,” says Iain Campbell, ForFarmers’ key account manager, poultry & pigs.
“Sometimes farmers are wary of doing that because if the rate of seconds is too high, then they are going to start to lose money. And there is a long lead in time to replace the flock, so the farmer needs to have confidence, generally, that when the flock is about 40 weeks of age about when to order his replacement pullets. He needs to know that if he goes to 85 weeks he is going to have a commercially viable flock and not a situation where he is losing money for the last 10 weeks or even that his packer may refuse to take his eggs.” 
The company arranged some farm trials with Robert Jackson & Son near Berwick. “We agreed to do a long-term trial on a flock and take them to 85 weeks,” says Campbell. “We put half of them on to the Sustain diet and we were able to get from that quite a successful result in terms of the commercial aspect and how much more money they made keeping them to 85 weeks.
“We were able to prove on that farm trial with Jacksons that there was a £6,000 benefit to keeping the hens longer, just on that particular flock. And if you are keeping hens longer and keeping all your flocks to 85 weeks then it means you are losing one flock every six flocks. You are getting five flocks to do the work of six flocks,” he adds.
Older hens 
Generally, when the hens drop below 80% production, it starts to become unviable. As the cycle continues, egg numbers go down, egg size goes up, and usually shell quality deteriorates, so there is a critical point when there is a disproportionate number of seconds.
“We have been involved in trials taking birds over 100 weeks, and the economics do begin to get a little marginal when you get up there but it shows it can potentially be done,” says Campbell.
Laying the foundations
Fothergill says it’s important to set the foundations for a long and productive life early on. “It may even start in the pullet,” he says. “The underlying principles that we built into the whole Vitafocus range, which is our overall layers feed brand, are things like fibre, particle size, the physical quality of the diet.
A lot of work that been done here in the UK and at our nutrition centre in the Netherlands looking at the type of fibre you use in the diet and the role that has in feather cover and controlling feather pecking and these type of problems. “Gut health is the other important thing, because a healthy gut leads to a healthy bird. If we get those things established early in lay, it is about maintaining that health and welfare later in the lay.”
The right nutrients
Shell Mix, the innovation within with Sustain diet, is a combination of specific vitamins, minerals and organic acids that help with the uptake of nutrients, says Fothergill. “What tends to happen as any animal ages is the efficiency of nutrient uptake from the gut diminishes, so the bird can’t take as much out of the feed as it ages. So, we use particular forms of vitamins and minerals that are particularly nutritionally available to the bird. According to Campbell, the financial benefits of a longer laying flock outweighs the additional feed cost.
“We have been weighing eggs and working out the percentage of the shell weight as total egg weight and also measuring total shell thickness,” he says. “In addition to the egg shell quality it’s also given improvement in egg weight, which is something that is very important to the farmer as well because they tend to on contracts where they get paid more for larger eggs. “In the Roslin Nutrition trial we have been able to show shell thickness is increased and average egg weight is numerically increased and that is a key aspect, it’s improving shell thickness, which is having a positive effect on egg weight.”
Scientific study on how to increase egg weight, by way of increased shell deposition, without increasing shell volume and associated stress on the bird, and reduce the percentage of second grade eggs
A fully independent study was carried out by Roslin Nutrition, involving 256 laying hens, randomly assigned to one of two treatments, with four birds per cage and 32 replicates of each. Over a 12-week study period, feeding the Sustain diet reduced the number of cracked eggs from 0.156% to 0% (@ Probability 0.0405) and significantly increased shell thickness from 0.363 mm to 0.396 mm (@ probability 0.0071) an increase of 0.033 mm Shell thickness was measured by Roslin Nutrition, using ultrasound to determine the shell thickness at the equatorial point of the egg.
In addition, eggs were submitted to SRUC for measurement by physical gauge at T1 (pointed end of the egg) and T2 (blunt end of the egg) The change in shell thickness from 0 weeks to 12 weeks was improved by feeding Shell Mix by T1 0.033 mm & T2 0.044 mm. Measurements were consistent with the statistically significant Roslin ultrasound trial data. Other notable numerical differences reported from this trial were an increase in egg number, egg mass and improved feed efficiency. 
Field trials
Catherine Armstrong, the owner of Detchant Farm in Belford, provided ForFarmers with an opportunity to feed two ends of an 8,000-bird flock – one on a conventional diet from the ForFarmers portfolio called ‘Original’ and one fed Sustain from mid-40 weeks, and committed to keeping the birds to as near 80 weeks as was practically possible.
In addition to an almost immediate visual improvement in egg appearance, the results of the trial demonstrated that the adoption of Sustain nutritional regime increased shell thickness by 0.05 mm (measured by SRUC), offsetting the anticipated age-related challenges as reported from British Free Range Egge Producers Association Belgian observation. “Our resultant improvement in margin is very welcome,” says Armstrong.
Another producer monitored cracks for a substantial colony cage unit. Over a period of time where there would be an expectation for cracks to increase with bird age, the introduction of Sustain actually reduced the percentage of cracked eggs.