Highly productive breeds are available nearly all over the world and we know very detailed recommendations for feeding different layer hybrids bred by each primary breeding company. Some practical challenges, However, still need to be overcome, says Robert Pottgüter.
challenge for all nutritionists is energy evaluation of all available raw
materials and complete feed. The majority of the energy in the feed for our
birds is based on crude protein, crude fat, crude starch, and sugar. Which
measurement should we use: metabolisable energy (ME) expressed as kilocalories
(kcal) or as mega-joules (MJ)? Which metabolisable energy system should we use?
Should we use the tables from the WPSA (World Poultry Science Association) or
should we work with a kilocalorie formula based on the main nutrients mentioned
above when we use the well-known kilocalorie unit system? The same question is
evident when we work with a ME system expressed as mega-joules. Every energy
evaluation system we use must be easy to handle for raw materials and complete
feed. It should also be possible to use this system with currently used
optimisation programmes to create and optimise practical diets. When nutrient
values of raw materials change, it is better to use systems with slight
inaccuracies rather than not adjusting matrix data at all. This has to be done,
for example, by variation of starch content in grains or protein and fat content
in oil seed meal or cakes.
Robert Pottgüter received his Diplom- Ingenieur-
Agrar at the Georg August Universität Göttingen in Germany. He has spent 24
years working as poultry feed product manager for deuka Deutsche Tiernahrung
GmbH & Co. KG in Düsseldorf, Germany and, since 2006, as a nutritionist
expert at Lohmann Tierzucht GmbH. Feeding modern layers starts with the day-old
chick, because during this first period the performance of the layer hen is
With all systems or formulas, energy is the most expensive restriction in feed
optimisation. The energy content of the feed also has a major influence on feed
conversion ratio (FCR) and overall productivity. As a consequence, everybody
should check complete feed regularly for its energy content, especially if the
complete feed paid for. In order to accomplish these tasks, it is obvious that a
system is needed, which is based on easily analysed nutrients. This requirement
is the opposite of a ‘scientific only’ approach to conduct digestive trials with
animals to determine the ME-content of every raw material. This easy-to-use
energy evaluation system is needed for raw materials and complete feed as well.
The mega-joule formula from WPSA expressed as ME in mega-joules
per kilogramme represents such a system. The formula
includes the main nutrients, namely crude protein, crude fat, crude starch and
sugar, and is regression-based on animal trials.
Calculating from mega-joules to kilocalories and vice versa is done using the
factor 4,187. Which energy evaluation system should we use when enzymes are
included in the feed formulation and how will we work with the so-called energy
uplift? The energy uplift of NSP enzymes has been determined first with
broilers, and depends mainly on improved fat digestibility. However, layer diets
are completely different from broiler diets because layer diets, for instance,
very often show low levels of added fat and oil. Should the energy uplift
be based on single raw materials and the adjustment of matrix data, or should it
be based on a percentage addition to the complete mixture? The uplift depends on
the inclusion level of raw materials with higher NSP content, if in fact this
uplift really exists. When using energy uplift to calculate the ME value of the
diet, the NSP content of the main raw materials needs to be analysed. Although
many questions in terms of using enzymes are not yet answered, it is recommended
to use NSP enzymes to promote healthier digestion. The enzymes must be used in
liquid form and “end-of-line” dosage if the feed has to be heat
Egg weight and quality
Egg weight and quality An important further challenge in
feeding layers is the short-term influence on egg weight. The optimal egg weight
depends on market demands in different countries, and is impossible to influence
very quickly by means of genetic changes. Nevertheless, while every breed is
bred for a certain egg weight, it is much easier to adjust egg weight by management and feeding. As we know, the main limiting
nutrients for egg weight are methionine, protein and linoleic acid. The content
of crude fat and the energy density of the feed also have a big influence on egg
weight during the laying period. One of the most common ways to adjust the egg
weight is to use a phase-feeding programme. Egg producers in most world markets
want to achieve a rapid increase in early egg weight followed by a very gradual
increase after peak production. Controlled feeding with the goal of reduced feed
intake and adjustment of house temperature are other means by which to influence
egg weight. In terms of egg quality, it is important to keep water quality in
mind. Egg producers should always ask: “Would I drink this water myself?” The
drinking water should be analysed regularly to avoid egg quality problems.
Mineral content is an example because it can certainly influence the eggshell
strength and overall egg quality. Water is also a carrier of vaccines,
medications and sometimes additional vitamins. The water system has to be
cleaned regularly to ensure healthy birds and optimal egg quality. In hot
climatic conditions, water is also necessary for cooling the birds.
Protein and amino acids
talking about protein and amino acids, there is much more common knowledge in
most countries concerning raw materials. Every breeding company has (to some
extent) different recommendations in feeding, especially regarding amino acids
for the different breeds. Also, since only the total amino acid content can be
analysed easily, the feed has to be formulated based on available amino acids.
The better the feed is adjusted in available amino acids, the lower the crude
protein content may be. In many situations, this is an easy way to save money on
feed formulation. Therefore, all nutritionists should use internationally
recognised methods to build the best amino acid matrix for each raw material.
For example, a well-known data tool is aminodat by Degussa or similar
information from Adisseo and Novus. For all who are involved in feeding layers,
it is a general recommendation to create an ideal amino acid profile for layers.
This should be the approach used by all scientists working in poultry
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