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Path to 100-week layer cage free hens
☛ from P14
that is almost as great as what happens during car- cass development.
This bone development is critical for good egg shell quality as the hens get older because it will provide up to 30 percent of the calcium of the egg shell when the supply of calcium in the diet is not sufficient.
At the start of produc- tion, the birds are chal- lenged as their needs are high and feed intake is far from the average feed in- take of a mature layer hen.
Therefore, it is impor- tant to produce a pullet with a high feed intake ca- pacity before production commences.
We need to develop the feed intake capacity using a certain amount of fibre in the pullet feeds, focus- ing on developer feed.
There is plenty of early literature in which the ad- dition of fibre has been shown to increase gut size.
However, fibre had a bad reputation for reducing performance and increas- ing the growth of patho- gens.
Recent research shows not all fibre is the same and that the type, level and source will have dif- ferent effects.
We need to understand that all fibre is not the same and we should prob- ably move from the crude fibre concept to neutro detergent fibre values in feed formulation, once we establish the require- ments.
The NDF values might give more accurate infor- mation about the expected effect we will get in the development of feed in- take.
However, so far, infor- mation is limited, so rec- ommendations are given in CF bases by the genetic companies.
The addition of fibre will reduce the time for the bird to achieve adult feed intake, and therefore it will be easier to achieve the right body weight dur- ing the start of lay. Energy and amino acids in production
Energy and amino acids are two major factors af- fecting the performance of the layer hen and are the most expensive part of the feed.
The energy needs of layers are driven mainly by the maintenance need and that is determined by body weight of the bird.
For layers with the same production of egg mass, body weight has a signifi- cant effect on daily energy needs (Table 2).
This body weight effect is not usually considered when formulation is con- ducted.
As there are differences among breeds and flocks in body weight, it is nec- essary to have informa- tion about body weight in order to adjust the feed formulation.
Historically we have not worried much about it, instead relying on the ca- pacity of the layer to self- regulate the feed intake based on its needs.
To a certain degree, this could be valid when the birds are in a closed house where the temperature can be controlled and the birds have no option but to eat what is in front of them in the feeder.
However, in cage free production, the birds may be exposed to high tem- peratures that will reduce feed intake, and what and where the bird eats is out of our control.
In cage free production, there will be an increase in maintenance needed due to the activity of the birds and temperature at the farm.
There will be a big impact on maintenance needs and energy intake because high tempera- tures reduce energy in- take.
Reported daily energy needs are very variable depending on the source of information; ranging from a 5-15 percent in- crease compared to cage housing.
The type of housing, barn or free range, and the temperature at the farm are some of the main rea- sons for this big variation in energy recommenda- tions.
Amino acid needs are driven mainly by egg mass production, which is about 80 percent of the total amino acid intake requirement.
If we review the egg mass produced by layer hens, we see egg mass starts dropping beyond 50 weeks of age.
The needs of these birds at 50 weeks are not de- creasing as they were in the old genetic stock.
The work on longevity conducted by geneticists has extended the high needs for amino acids be- cause egg mass produc- tion does not decrease as it used to.
However, it is a common practice to change to a more diluted feed after week 45.
In these situations, we hope the bird can obtain the necessary nutrients by increasing feed intake, but sometimes what we ask of the bird might not be possible.
The drop in amino acids, housing and feed intake capacity are some of the reasons birds do not ob- tain the amino acids they need.
The reaction of the mod- ern hen will be to sacri- fice feather covering, egg size and even health, as long as the egg is pro- duced.
In the field, we can see late mortality without specific symptoms that I think are related to insuf- ficient amino acids and effect of the oxidative stress.
Oxidative stress is a physiological challenge that occurs when the an- tioxidant system of the birds is overwhelmed by the production of free radicals.
The production of free radicals is increased in birds with a high metabol- ic rate, temperature stress, disease, oxidised fat and mineral and vitamin defi- ciencies.
In cage free produc- tion we have a high-per- forming bird exposed to temperature changes and more pathogens than be- fore, and therefore they might feel greater im- pacts.
The practice of chang- ing to a lower-density diet without considering the egg mass being produced could explain some of the issues when we try to achieve 100 weeks of production.
Calcium and phospho- rus nutrition
Calcium and phosphorus in layer diets are key to good egg shell quality as the hen gets older.
There must be a balance of the added levels and source of them.
Phosphorus has an im- portant role – its deficien- cy can decrease growth during the pullet phase and at the start of the pro- duction.
After the peak of pro- duction, its requirements progressively decrease.
In a meta-analysis con- ducted by Ahmadi et al., the needs for nonphytic phosphorus were shown to be 220mg/day after the peak of production.
An excess of phosphorus in the diet is a concern for sustainability and it has an impact on the absorp- tion of calcium by the hen.
It is well documented that excess phosphorus will impact calcium ab- sorption.
Calcium level is becom- ing as important as how it is provided in the diet.
Egg shell formation takes 20 hours, most of which happens during the night.
During the night, the source of calcium for the egg shell will come from whatever is left in the gut and bone reabsorption.
If we want to keep layer hens up to 100 weeks of production, we need to re- duce the calcium supplied from the bones, so we
need to provide calcium in the feed, with large par- ticle size (>3mm) for 70- 80 percent of the calcium supplied in the diet, and with delayed solubility so it will be longer in the gut, even during the night.
There will always be some calcium provided from bone reabsorption.
Therefore, it must be re- placed during the morning by bone mineralisation so there will be certain needs for calcium in the morn- ing that can be provided by fine limestone (1mm).
However, it should not be very fine because the layers will not eat fine particles due to selection of particles in the feed. Feed structure
Birds prefer to eat large particles before fines.
When birds are in cages, this selection capacity is reduced and with good management of the feed delivery we can minimise this activity, even if we do not have the correct feed structure.
When the birds are out of cages, we cannot con- trol this selection of parti- cle size, so it is important to make a feed as homog- enous as possible where the bird cannot select.
Making a homogenous feed is not easy – the layer feed raw materials are at the extremes with large particles such as the grains and calcium and very fine particles such as the synthetic amino acids, vitamins, minerals and trace minerals.
Therefore, there is an important job to do by the feed mill and the type of raw materials we select.
In the feed mill, it is important to have a pre- grinding facility where we can decide which raw material should or should not be ground as the first step.
At the grinding equip- ment, a roller mill will help us to have a more uniform cut of the grains and reduce the fines dur- ing milling.
In the selection of raw materials, we can make important decisions that might increase the feed cost but improve the per- formance of the birds be- cause they will eat what they need.
These decisions are about reducing the dusti- ness of the feed.
We can add as many liquids as possible in re- placement of the fine par- ticles and we can have a minimum of oil in the diet.
The oil will help to bind the fine particles, so we will reduce the fine parti- cles (<5mm) significantly.
However, despite the ad- ditional cost that might be involved, this practice can produce additional benefits (Table 3) as was shown in the study by Sa- faa et al.
Achieving 100 weeks of production will be a matter of improving the actual practices on egg production and, in cage free production, it will need additional manage- ment practices as we will no longer have as much control over the birds as they will be out of cages. X.A. Ugalde
H&N International
Extracted from the Aus- tralian Poultry Science Symposium 2019 pro- ceedings.
Effect of temperature on egg production.
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National Poultry Newspaper, July 2019 – Page 15