Optimum Production and Nutrition of Layers

The potential of the modern layer strains for egg production is very high, and continues to increase with every new generation, due to the selection programs of the major breeders. It is important to understand what this potential is, and to strive to achieve it.

This article discusses the potential of current layer strains, with examples given of actual flock performance, the nutrient requirements needed to achieve that potential, and factors to work on to achieve this potential under Asian conditions.

Production Standards
The place to look for standards of production are the management manuals provided by the breeding companies. Here we will find numbers, which represent the potential of the layer under conditions of good management, good quality pullets, good quality feed, absence of disease and a suitable environment. These standards are high, but are achievable. Since all countries in Southeast Asia are using the international strains, these are the standards we must compare against. The standards are not very different between strains, with the exception that white egg strains, as used in the Philippines for example, are smaller in bodysize and feed consumption. However egg production numbers are not very different between all strains. Table 1 gives the standards for the Hy-Line Brown strain. These figures would largely apply to all the major brown egg laying strains.

Achieving Levels Of Production For Commercial Use
Experience has shown that it is quite possible to achieve the standards set by the breeding companies on a consistent basis. Cumulative eggs per Hen Housed (HH) is perhaps the single most important production parameter, and this can be achieved and exceeded by as much as 10 eggs with some flocks.

Examples of production from two commercial flocks are given in Table 2, compared against the Hy-Line Brown standards. These are from two different layer farms in Australia, during the year 2002. Housing is environmentally controlled, with temperatures held in the range 23-25°C at all times. The feed contains wheat, wheat pollard/bran, meat and bone meal, lupins, canola meal, tallow, lysine, liquid hydroxy methionine, threonine, limestone grit, sodium bicarbonate, salt, yolk pigment, phytase, xylanase, and vitamins/trace minerals.

Both these flocks have performed well, and have met the standards for cumulative eggs. Note there are some differences in egg size, feed consumption and mortality between the flocks. These differences are not necessarily strain related, but are more related to bodyweight at 16 weeks, and feed specifications.

Using Production To Determine Nutrient Requirements
Estimates of nutrient requirements of layers are available from several sources, including NRC, breeding companies and published research. These estimates vary greatly, particularly those provided by the layer breeding companies. As a general rule, breeding companies do not conduct much research on nutritional requirements, and more likely obtain their recommendations from external sources.

In addition, most nutrient requirements figures are quite limited as to the number of essential amino acids they cover (often only lysine, sulfur amino acids, and tryptophan) and are usually expressed on a total basis, whereas I formulate on a digestible amino acid basis.

I developed my estimates on requirements initially from published research, particularly from the work of Dr Craig Coon (59th Minnesota Nutrition conference, 1998, pages 263-278), and have modified them over the years from experience with numerous flocks. I have had good access to records of many layer flocks over a 10 year period from my Australian clients. I assume that when flocks perform close to their genetic potential, their consumption of nutrients at that time is close to their requirements.

An example of this is shown in Table 3. Six flocks were selected whose total cycle production data indicated they have performed close to potential. For these flocks I have indicated in the table the minimum nutrient specs of the diet fed. The average daily consumption throughout lay (18- 74 weeks) for these flocks was 110 grams. I then calculated the daily consumption of nutrients in the last column, by multiplying the minimum specs by the feed consumption. I then take this to be the nutrient requirements.

In Table 4, these requirements have been translated into minimum nutrient specs for flocks with different feed intakes. Several points should be made about this approach. Firstly the nutrients are based on my ingredient matrix, and will be somewhat different if the matrix of another nutritionist is used. Secondly it is noted that I use the minimum specs as formulated for these calculations. In a number of cases the actual levels of some nutrients will be above the minimums. Thirdly the method is only valid with “normal” feed intakes, and would be in error in a situation of high feed intake due to low house temperatures or low feed intake due to high house temperatures.

Note that no protein requirement figure is used, as this is unnecessary when the 8 limiting digestible amino acids are covered. It may be argued that there is no need to specify amino acids beyond lysine, the sulfur amino acids and tryptophan, particularly with corn-soybean meal diets. However when using a greater range of ingredients there is the possibility that threonine, arginine, isoleucine or valine can be limiting. For example threonine can be limiting in high wheat diets, and isoleucine in diets with meat and bone meal and blood meal.

For those who still formulate with total amino acids, these requirements can still be used. Total lysine requirement may be calculated by dividing digestible lysine requirement by 0.85, then other amino acids calculated in proportion.

Achieving The Potential Production In Southeast Asia
Can the genetic potential of the modern layer be achieved on a consistent basis under the conditions of Southeast Asia? Here the same international layer strains are used, and there are no reasons why management and feed quality should limit performance. However, the high temperatures and humidity of most Southeast Asian climates definitely impose a constraint on the ability of the layer to achieve its potential. This is particularly seen in egg size, which will be 2-3 grams lower than in a temperate situation. Otherwise it should be possible to achieve the egg number standards. Factors which need to be worked on to achieve the standards are as follows:

Pullet weights. It is most important to meet the bodyweight standards during rearing. For brown egg layers these are 380 grams at 5 weeks and 1550 grams at 18 weeks of age (Hy-Line Brown standards), and around 1280 grams at 18 weeks for white egg strains. Failure to achieve these will negatively influence early egg size and peak egg production. In Southeast Asia, the climate tends to restrict growth and pullets are commonly underweight going into the laying house. Higher starter and grower feed specs should be used to achieve the target weights.

Feed specs and quality. Feed specs which are suitable for the strain and the feed intake as suggested above must be used. Using lower feed specs for the purpose of giving a lower feed cost per tonne will not allow maximum performance and will be counter productive.

Ventilation. High temperature and humidity are a limitation to egg production and any measures to assist, such as improved ventilation through house design, use of fans, cool drinking water etc. are all helpful.
Environmentally controlled, closed housing offers the possibility for a better environment, but high humidity severely limits the gains from this system. It is usually not possible to bring house temperature below 28°C. with such housing. If well designed, this housing does offer benefits, but they are more in the consistency of egg production and savings in labour than any large increases in egg production. When not designed well, they can be worse than open housing, with poor airflow and inadequate removal of ammonia.

Linoleic acid. High levels of linoleic acid in the grower and early lay periods is one way to increase early egg size, at a time when the return for small eggs is usually low. This is not so easy as the oils necessary to achieve a level of 1.3-1.5 % linoleic are usually not readily available in Asia. The best oils for this purpose are safflower or sunflower oil (60-70% linoleic), but canola and soy oil (50% linoleic) may also be used. Fullfat soy is one way of achieving these high levels. The cost of doing this should be judged against the low returns for eggs below 50 grams in size.

Delaying the onset of lay by 2 weeks with light control (in closed housing) or feed restriction is another way to increase early egg size, but the cost of doing this is a reduced egg number at 74 weeks of age.

by David Creswell

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