NUTRITIONAL NEEDS OF LONG LAYING HENS
The modern laying hen is distinctly different from old generation layers commercially farmed with in the early 1980s. This is due to competition between breeding companies for market share as well as the need to feed nine billion people around the world. The main rise in laying percentage is based on longer clutch length and improved uniformity of layer flocks.
The most popular aim of progressive layer geneticists is the 500-egg hen, in one cycle and without moulting. However, eggshell quality at the end of the production period deserves much more attention and support in comparison to a one-year production cycle (72 weeks of life). The so-called post-peak dip shows up as an additional challenge at the beginning of the production period. Both topics – a secured start of production and reaching peak performance and optimal egg shell quality up to 90 weeks of flock age (or more) are highly related to optimal nutrition of high prolific layer flocks.
Production records of the Hy-line Brown have been compared in Table 1 to serve as a practical example of the genetic improvement over the past 16 years. The modern laying hen is slightly lower in bodyweight (40 g) at 17 weeks, but is significantly more efficient during the rearing and production period with overall lower feed consumption. Other major improvements include a 50% production mark reached nine days earlier; the number of eggs at 80 weeks increased by 21 eggs; the number of weeks of egg production over 90% increased by five weeks; feed conversion improved by 18 points; and the hen is able to lay at least 500 eggs up to 110 weeks.
Higher productive hen for achallenging economic period
Even though the modern laying hen has improved, the economic climate has also changed dramatically. For example, Figure 1 illustrates the comparison in the production curves of the Hy-line brown, 1998 vs 2014. One can observe that the modern laying hen comes in to lay 1/2 weeks earlier and the production after 46 weeks of the 2014 hen is much more persistent. However, in 1998, the average feed price was R911/ton and the producer was Nutritional needs of modern long LAYING HENS
paid R3.72/dozen eggs, with an egg:feed price ratio of 2.04. In 2016, producers have paid, on average, R3700 for a ton of feed and were paid R11.50 for a dozen eggs, indicating a egg:feed price ratio of 1.56. The economic implication of this is that even though the modern hen is much more productive, the time required to reach the economic break-even of the hen has increased from 34 weeks in 1998 to 52 weeks in 2016. Producers therefore only start to make profit after 52 weeks, which indicates that the longer production cycles in the current economic client is imperative and a 'life-line' to survive the current economic challenges with record high feed cost, low egg price and depressed disposable income.
So how does the commercial nutritionist feed the modern, highly productive hen to ensure that producers extract the full financial benefit of the
Poor shell quality at any time not only results in financial loss, but also causes major contamination problems in highly mechanised egg packing and handling equipment. Poor shell quality at 72 weeks does not mean that all hens in an ageing flock produce eggs of
reduced quality; rather that the variability in egg quality within the flock increases. The long-term maintenance of the tissues and organs involved in producing eggs is therefore a prerequisite for extending the laying cycle of commercial flocks.
Some of the factors that need to be considered to
achieve 500 eggs in 100 weeks (via a persistence of lay) - and to increase the number of sellable eggs - include the rearing period, feed particle size during rear, gut health, calcium intake, egg weight control and the control of metabolic diseases.
Improve overall rearing weight of pullets
Optimal nutrition starts just after hatch to develop a pullet on an optimal bodyweight, uniformity and feed intake capacity. Growing and developing pullets correctly influences production, persistency of the production, and the persistency of shell quality from the early stages of the laying cycle.
Correct development of the skeleton, muscle and fat deposits are critical and highly influenced by nutrition. While early weight gain is important, achieving on, or above, target weights by six weeks and continuing to 13 weeks is critical, as this is when much of the bird’s muscle and frame development occurs. Small framed birds have lower bone mass and consequently a lower medullary bone mass and calcium reserve in the laying period, which will likely result in shell quality loss earlier in the laying cycle.
The use of crumbled feed as opposed to mash feed during the rearing period has proven to increase the bodyweight of hens at point of lay. Table 2 indicates that at 17 weeks of age, the hens were 131g heavier and had a 9-point improvement in FCR.
In a trail that was conducted in the Netherlands, Lohman Classic hens were reared
Non the 3 different feeds, varying in protein and energy concentrations that produced birds with three different bodyweight profiles. It can be observed (table 3) that the heavier hens consumed more feed during the 18 to 24-week period, but the laying % and egg weight during the period were significantly higher. There was also a general trend that the feed conversion ratio improved with an increase in bodyweight.
Knowing flock feed intake is critical
utritionists can easily calculate the daily demand for optimal eggshell development based on standard scientific knowledge. Calculating the sufficient intake of daily calcium needs
Sto be based on the daily feed intake of an actual, specific flock. When targeting a 4,1g calcium intake per hen per day, the amount of calcium in the diet needs to be adjusted by up to 4,5% (90g effective ambient of daily feed intake), or to 3,41% calcium with 120g feed per hen per day. With a change in season, calcium and other critical nutrients need to be adjusted according to the intake of the birds.
4,10 g calcium needed x 100 120 g feed consumed = 3,41% calcium in the diet
Accepted practices to improve eggshell quality
witching lights on two hours earlier and introducing a midnight feeding has been shown to improve→
the synchronisation of dietary calcium intake with shell formation, and improved eggshell quality. To optimise eggshell quality, the calcium particle size should also be adjusted according to the density and solubility of the particulate calcium source (quarry or marine). Dietary lipid content and the active metabolite of Vitamin D3 have been shown to influence the efficiency of dietary calcium uptake in the gastro-intestinal tract. How this relates to the transfer of calcium in the shell gland remains to be determined. High levels of phosphorous, or too much or too little salt in the layer diet also have a deleterious effect on eggshell quality and should be avoided.
Synchronising calcium intake with egg formation
Protein, calcium and energy requirements of laying hens do not remain constant, but vary during the day depending on the hen’s physiological requirements for the various stages of egg formation. It is calculated that 90% of a hen’s eggs are laid early in the morning just after the lights come on.
Together with our international technical partners, the AFGRI Animal Feeds Research & Development division developed a feeding programme for laying hens according to the specific nutrient requirements for egg formation that varies throughout the day. Findings from years of research resulted in the formulation of South Africa’s first Split Feeding programme, where two diets (AM and PM) are used to meet
the dynamic requirements for egg formation.
The AM diet is designed to meet the requirements during the morning when the albumen is being formed, and when ovulation and oviposition occur. The PM diet is designed to meet requirements for eggshell formation that is highest during the afternoon period. New requirements for energy, amino acids, calcium and phosphorous were obtained for the AM and PM diets. Although the total intake of these nutrients was reduced, performance was at least as good as, if not better when compared to the single feed.
Economic benefits of the Split Feeding system
In a local experiment, the effect of the Split Feeding system was tested at Sondela Eggs near Eloff in Mpumalanga. House three with 13,091 Hy-line hens was fed the standard complete mixed ration, while House 4 housed 13,181 hens of the sister flock, and was fed the Split Feeding rations. Figures 1, 2 and 3 illustrate comparative graphs for the houses’ production, bodyweight and percentage of cracks. One can clearly observe the persistence of lay in the split fed house birds. Their bodyweight after 62 weeks was higher and percentage of cracks lower compared to the standard fed birds.
Table 4 indicates the production and financial performance of the trial conducted. It can be concluded that a split fed bird produced nine more sellable eggs/hen, which translated to R9,29/ hen, or alternatively stated, an improvement of R120,825
Tper house compared to the standard fed birds. The trial is still running and the profit per hen is likely to increase as the non-split house was depleted since the level of production was no longer economically viable to continue the cycle.
Egg weight control in ageing flocks
o ensure optimal eggshell quality in extended production cycles, you need to consider the egg weight/ size. Due to the aging calcium metabolism, there is a decreased percentage of eggshell in relation to the total egg weight in larger eggs. Breeding programmes are providing flatter egg weight curves with higher weights in early lay and lower weights in later lay compared to previous generations. Lighting programmes, applied at both the beginning and end of the rearing period, also influence egg weight.
Appropriate rearing programmes are an important first step, because nutritional intervention to control egg weight often has a secondary, detrimental effect on production. Individually and in combination, dietary amino acid concentration has been demonstrated to impact egg weight as well as productivity, whilst sulphur amino acid concentration is most associated with egg weight, and methionine and cysteine concentrations are often adjusted to obtain the desired egg weight profile. There may also be an influence from other nutrients related to sulphur amino acid metabolism. Through involvement in the methylation pathway, choline/betaine and even vitamins B12, B6 and folic acid may be relevant. Field responses indicated that egg weight can be controlled by reducing methionine + cysteine concentration whilst increasing the ratio of methionine:cysteine to minimise the impact on production.
Feeding for persistency in lay
During the laying period, the first challenge is to adjust the energy and protein requirements to optimise egg output and to carefully control bodyweight. Growth requirement is only present for the first few weeks at the onset of egg production. Energy required for maintenance thereafter depends on bodyweight and feather coverage, and increases with hen age.
Studies show a strong negative correlation between feed intake and dietary energy concentration. This adaptation is only partial and high energy diets can be used during the first part of the laying period to satisfy the continued requirement for growth and to promote heavier, early egg weight without the risk of overfeeding and producing ‘fat hens’. The hen’s energy requirement decreases as egg production becomes established. To minimise fat deposition, a lower energy diet can be used at this time, as the birds will be able to partially compensate by increasing their feed intake. Laying hens also adjust their feed intake according to the relative size of the particles in relation to beak size. Varying particle size allows further balancing of energy intake.
Crude protein concentration and amino acids in the layer diet are also important; methionine is the main limiting amino acid. Consumption of an extra 1g of protein per day, for example, results in an average increase in egg weight of 1,4g. The amount of protein consumed is dependent on the dietary energy concentration and the form of the ration. Ideally, the protein and amino acid concentration in the diet should be estimated relative to the egg weight (mg/g of egg for amino acids) and adjusted to optimise egg production throughout the laying cycle. An additional difficulty is that the heterogeneity of the flock increases with age. The best strategy is to focus on maintaining the production of the higher producing hens and to adjust the supply of proteins and amino acids accordingly, provided the cost is not prohibitive.
Liver health to support egg production
Feeding for liver health is not only a veterinarian issue, but also an important nutritional topic. The liver provides nearly all the basic nutrients for yolk and albumen development, and even supports the development of the eggshell, providing the protein in the eggshell, which is mainly responsible for a certain elasticity of the shell. Feeding layer birds with a certain amount of added fat and oil serve as a well-known tool to reduce the incidence of so-called fatty liver syndrome. A certain amount of added choline chloride in layer diets to support the liver metabolism should be a non-questionable standard practice. Every socalled fatty liver supplement will be based on choline chloride alongside important vitamins (K3, E, B12, B1 and folic acid).
Both disease and environmental stress can induce changes in egg formation at any time during the laying year. Diseases like infectious bronchitis, egg drop syndrome and Newcastle Disease influence egg quality, either directly by altering oviduct structure or indirectly by lowering the general health status of the individual bird. Remedial action in such cases often involves medicating or vaccinating the entire flock with variable success.
Benefits of genetic selection for improved persistency in lay and stability in egg quality can only be realised if they are matched by improvements in hen nutrition. It is however up to commercial nutritionist, producers and veterinarians to form partnerships to ensure that the genetic advances packaged in the modern laying hen is released by applying the latest knowledge and technology.
Figure 1: Economic breakeven point 1998 vs 2014
Figure 2: Bodyweight comparison of standard versus split fed birds
Figure 3: Cracks (%) comparison of standard versus split fed birds
Figure 1: Production comparison of standard versus split fed birds