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Published on March 18, 2022

Check out the MIAVIT Podcast : How to realize the genetic potential, focus on the potential of rearing

The aim of every egg producer is to achieve optimum, top quality eggs. But what do you need to consider in order to reach the genetic potential? The rearing period, in particular, is often underestimated. Learn which aspects are most important for good persistency. Why is it important to flatten the egg weight curve? What improvements in genetics have been developed over the last century?

In this MIAVIT Podcast, our colleague, Teun van de Braak, will give us deeper insights in the world of layer genetics.

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Podcast 1 : Egg production. How to realize the genetic potential – focus on genetic potential and the importance of rearing.

  1. Introduction

Thank you so much for the invitation to join this podcast. I am Teun van de Braak, and currently working as the product manager for Hendrix Genetics Layers. Maybe not everybody is familiar with Hendrix Genetics, but it is the breeding company behind many popular egg laying chicken breeds, think of the ISA Brown, the Dekalb White and the Bovans Brown. I obtained my master’s in Animal Breeding and Genetics from Wageningen University and Research 12 years ago, and since then I am working for Hendrix Genetics. The first 8 years I have been working as a geneticist, so I hope I can explain a lot about chicken breeding and genetics in the coming 20 minutes.

  1. Breeding companies are constantly working on improvement of the strains. What are the main developments in the last years? This question can be combined with question 3.

That’s correct! As a poultry breeding company we are continuously looking how to improve the general health and welfare of our chicken breeds.

By selecting for birds that stay fit and active for longer periods, we have also been able to select these chickens to lay more eggs. As a breeding company we are often being criticised that we are focusing only on output and efficiency, but let me be very clear on this, you need to have a vital laying hen as the basis for egg production. No matter where we go in the world, producers need a laying hen that is fit and active to stay productive, especially when we are talking about longer production cycles.

Next to this, nobody likes to see dead chickens, not the consumer, not us as animal breeders, and especially not egg producers, as they work day in day out with the chickens, and their income is obviously depending from the sales of the eggs that their hens are laying.

When we look at the last century, we can also clearly see differences in the way we are selecting our chickens, and the traits we are focusing on. But an overall objective has always been to improve the number of 1st quality eggs produced by every hen that got housed. By having that clear focus on all the hens that get initially housed, we clearly demonstrate that we focus on each individual hen. Every chicken matter to us.

Let’s take a look at the progress that has been made by animal breeders, nutritionists, animal health companies, egg producers, housing manufacturers and many others. We can clearly see that it is not a boring industry, and big progress has been made over all these years. Especially during the past decade.

The genetic potential of laying hens to stay fit, active, and productive, is definitely there, as clearly demonstrated by more and more flocks, from all around the globe. Overall mortalities are lower than ever before, while birds are getting older and older. Even here in Western Europe, where most countries have put a ban on the treatment of beaks, we see that when egg producers get more experienced, the better the results become. But we should not forget that we are working with living creatures. It is extremely hard to predict upfront how a specific flock will perform. Especially since most traits are the result of the interaction between genetics and the environment of the bird. In general, we can say, the lower the heritability, the bigger the impact of the birds’ environment on her performance. I know that when something is not going well, people first look at genetics, but unfortunately it is most of the time more complex, and multi-factorial in its origin.

One aspect that is very important to keep laying hens healthy and fit towards the end of their productive life is the egg size curve. We have “flattened the curve” where we could. When you look to the historical development of egg size during the lifetime of the bird, you can see that without selecting for flat egg curves, eggs that are produced today, tend to be slightly larger compared to the egg that was produced yesterday. This continuous increase in egg size negatively impacts eggshell quality. But also, the health of the laying hens. As too big eggs are related to the occurrence of prolapse, and we often observe more problems related to overall gut health in the field. We also observe that flocks that are really pushed for large eggs, are depleted at earlier ages. Yes, big eggs can really contribute to higher egg mass on the short term, but looking at longer cycles, hens that are more persistent in egg production, as they stay fit, healthy, and productive, show bigger overall egg mass but they are also more efficient in their feed conversion. It’s really, every egg counts! The benefit of the flattened egg size curves is that more 1st quality eggs can be collected, as you can grade your eggs for an extended time as well.

Today, it is not the productivity of the flock that is the deciding factor when an egg producer is ordering a new flock, but the egg quality. The packing station has the biggest vote when it comes to accepting eggs from older flocks. Overall, we can say that with the current breeding program, we can add almost 1 week of longevity for every new flock that enters the laying farm when you compare it to your previous flock.

  1. Are these developments the same for white and brown strains?

We have aligned the breeding programs for our brown and white egg laying chicken breeds as much as possible. There are of course differences between the breeds, and in the way they respond to the breeding program. This is no surprise to us, as the breeds come from different origins, and they are genetically separated from each other for more than 2 centuries. You can imagine that’s a whole lot of generations!

Big difference between the breeds can be seen in the way they behave, especially in cage-free housing systems. The brown egg layers are more curious, they are more distracted about what’s happening in their environment, and by each other compared to the whites. This comes along with benefits, as they are calmer, but sometimes they can be too calm (or lazy), it can be harder to get them make use of an aviary system for example. We also observe in the field that the production of floor and system eggs, feather pecking, and smothering are more frequent in brown egg layers compared to white egg layers. In persistency they are a bit behind compared to white egg layers when we look at egg numbers, when looking at total egg mass the differences become smaller.

But we all know that the overall chance of success with a flock producing white eggs is higher, especially with intact beaks in cage-free housing systems. This is clearly demonstrated in the field, and also the main reason that countries like Germany, Denmark and the Netherlands have increased their share of White egg layers significant during the past 10 years. In all these countries the White egg layers are the most dominant chicken breeds currently present. When looking at the more Nordic European countries, that are working with birds with intact beaks for a long, long time already, the white egg layers have been the preferred breed for decades.

Although we believe it is the free choice of each consumer which colour of an egg he/she wants to buy, the White egg layers, and several of the benefits they bring along did also not get unnoticed by the retailers. The Lidl retailers in the Netherlands decided to only sell white eggs 2 years ago, as white eggs have a lower carbon footprint compared to brown eggs. By making the shift from brown to white they contribute towards more sustainable egg production. As a breeding company we foresee, that in the coming years, the share of white egg layers will continue to grow.

  1. What topics are the main factors for a good persistency?

Good persistency is the result of many factors. Of course, as I am working for a poultry breeding company, the right choice of genetics plays an important role. There is no doubt about that, it should be in their DNA!

What is extremely important to share with you all today, is the importance of the rearing period. The journey to become a productive laying hen really starts as soon as the chick is hatched. The impact of the rearing period should not be underestimated. You can really “make or break” the bird during the rearing.

It is key that the rearing period is seen as an investment, that lays the basis to become a productive laying hen later on. And not seen as solely a cost! Yes, it is expensive to grow a pullet, and yes there is no money coming in during this growing period, but it is the rearing period that really creates the fundament for a productive laying hen.

During the rearing period, clear focus should be on body weight development, uniformity, and feed intake. Always steer and adjust the management of your flock based on these traits, not just on age.

During the 1st 5 weeks, the only goal should be to get them growing, you cannot ruin the birds during this period by making them to fat, you can if they don’t grow well enough!

There are loads of practical advices available in our management guides, not just on management, but also on nutrition, as the impact of nutrition should not be underestimated, especially in cage free housing systems.

It is not just the right feed at the right development-phase, but also feed structure, and feed management play essential roles when growing chicks into high quality pullets. Feed presentation, particle size and fiber content play a crucial role in feed structure. In return feed structure is essential in developing the digestive system, a good crop, and overall gut health. And we know from research that gut health is so important in relation to bird behavior, but unfortunately this podcast is too short to go into too much detail I am afraid. When looking to feed management, we strongly advice to apply the empty feeder technique in the later phases of the rearing period. With the empty feeder technique, you can train and stimulate the birds to eat, so they can develop a good appetite and a good crop. Pullets that have a good appetite will grow more easily in general, and that’s what you need, a well-developed pullet, with a good frame! This will benefit the overall average egg size profile, the peak of production, and the hen’s persistency. The empty feeder technique also safeguards that the birds are ingesting all essential nutrients. Birds with intact beaks can be more selective in their eating preferences, which could result in an insufficient intake of important trace elements, vitamins, and minerals. As these are often the finer particles, they have a higher chance to accumulate in the feeders when no use is being made of the empty feeder technique. While they are essential elements of the diet of a healthy pullet.

When the pullets can grow well, they are able to develop a good frame as well. Skeletal health is key for the long-life layer. Only birds with healthy bones, sufficient calcium-reserves, and well-functioning calcium absorption /calcium release mechanisms are able to maintain the production of 1st quality eggs. The benefit of cage-free housing systems is more activity for the birds, resulting in stronger bones. The challenge is of course the interaction of the birds with more complex housing systems, which can result in an higher occurrence of fractures in the keel bones. House design, both in production and in rearing, can play an important role to steer the behavior of birds in more complex housing systems. Training the birds in rearing to get used to explore the surroundings in a three-dimensional world and installing ramps for example will greatly help the birds to go from A to B without the need to jump and fly. Laying hens are not designed to fly, that is why we focus a lot on robust birds that have good skeletal frames. By also applying the right lighting program, and defining the goal of your flock upfront, you can steer your flock much better.

But next to feed, it is also the vaccination strategy that’s is part of growing fit and healthy pullets. We already see big differences between vaccination strategies between European countries. Imagine the difference that we observe all around the globe. What is really clear is that there is not just 1 program that fits all. It just doesn’t exist, not only because of differences in legislation, allowance and the availability of the different vaccines, but also related to the local disease pressure, and overall chicken densities. It is no surprise that the Scandinavian countries can make use of less vaccinations as the overall chicken density is much lower compared to for example the Netherlands. We strongly advice to sit around the table and design with your poultry veterinarian and pullet rearer the vaccination scheme that is appropriate for your flock.

Vaccinations do impact the growth and development of your pullets, this is because the vaccines activate the birds defence system, and this comes at an energy cost and the birds might show signs of reduced appetite, or their body really needs the energy as an immune challenge has been activated. Fortunately, the developments for poultry vaccines are still ongoing.

We often get questions about the effectiveness of vaccines as our laying hens are getting older and older. Unfortunately, not a lot of research has been done by animal health companies, so you won’t find a lot of vaccine inserts that claim protection all the way up to 100 weeks of age. Research studies are indeed much more costly for laying hens when compared to broilers, and less easy to do repeats. We know all about this as we have extended our own breeding stock laying cycles already 15 years ago! What we have seen in our own trials in collaboration with a vaccine-supplier is that hens at older ages still have an active immune system which is able to respond to disease challenges, and vaccination-titres last beyond 90 weeks of age, even when the vaccination occurred only in the early rearing period. Hopefully more knowledge becomes available in the coming years, we actively seek the cooperation and collaboration with animal health companies.

When we talk about the rearing period, we should really mention the importance of the housing system itself. We have seen huge disasters with flocks reared in cages, that went into laying houses with aviary systems. The poor birds had no idea how to make use of those systems. You can imagine the problems that will occur in these cases: a lot of stress, high mortalities because bird were not able to find water and feed, massive amounts of floor eggs as they could not find the nests, and much more troubles occurred. We, as the egg sector should work and aim for to prevent these situations and make sure the rearing environment matches the ultimate production environment.

Fortunately, today there is a lot of knowledge available with pullet rearers, and poultry housing equipment manufacturers. And this knowledge is only becoming better and better. We could talk about this topic the entire day, but I am afraid time will not allow me to do so. I just want to mention once again, that it is important to align the housing system in the rearing period with that of the productive life. There are many different aviary systems available on the market, in the ideal situation each of them is aligned to a specific rearing system as well. That is of course mission impossible, but we clearly notice that more and more research has been done on the systems used in the rearing period, and that this knowledge is more and more implemented in practice.

In today’s egg sector, you really need to be on top of your flock to achieve good results. Management is key, and data collection is really a useful tool that gives producers insight in key parameters of your flock, and also helps you in raising the early warnings. Don’t underestimate the value of data for your daily management, not just when you are a poultry breeding company (data obviously is essential), but also as a parent stock farmer, a hatchery, pullet grower, or an egg producer, data tells you so much. And todays automated data management systems will help you, but also your vet, your pullet supplier and the nutritionist in getting your flock to the next level. Don’t be afraid of this data but try to see the opportunities and the added value that it brings along for your farm.

I have not mentioned it yet in this podcast, but when we talk about today’s laying hens, we talk about top performing athletes. The rearing period is the key period to develop, prepare and train the chicks to become successful during the productive life. Better rearing today, for a more vital and productive layer tomorrow!

Discover more practical tips and tricks on the management during the rearing period

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