Alternative Methods of Feeding Layers

I. INTRODUCTION

The current system of feeding laying hens with a fully mixed diet, that attempts to meet all the nutrient requirements of the birds, only really developed with the introduction of cage housing facilities after the Second World War. Research on confining laying hens to cages ramped up in the first half of the 20th Century in California but it was not until the late 1940s that the first commercial cage farms started to appear (American Egg Board, 2020). Nutrition research increased during the 1940s with development of the concept of metabolisable energy. Energy requirement and the concept of protein requirement for layers were more fully developed in the 1950s (Elwinger et al, 2016).

Feeding techniques, even for the small flocks of commercial hens, prior to confinement housing, largely involved the hens scavenging around the farmyard, with supplementary feeding comprising scattered grain and some shell grit (American Egg Board, 2020). In British egg farms, as flocks increased in size, hens were confined for the winter and were fed a warm wet mash in the mornings and grains in the afternoon (Henuk and Dingle, 2002). Up to the end of the first half of the 20th century most laying flocks experienced some form of choice feeding.

Once the cage system of feeding became established, fully formulated and processed feeds were the most convenient and consistent way of achieving high production. However, with the reemergence of alternative housing methods designed to improve bird welfare, attention has again been drawn to providing the hen with more efficient ways of feeding. A number of methods have been tested and all require birds to have some degree of choice over their diet. A further motivation has been to explore alternative methods of calcium delivery to extend the productive life of the flock (Molnar et al, 2017).

II. ALTERNATIVE FEEDING METHODS

Apart from fully formulated mixed diets there are three main options for varying the delivery of nutrients to laying hens. All methods need to consider the provision of a source of calcium (Ca) in the appropriate form at the required time of day.

Choice feeding involves offering the hens an energy source (typically whole or cracked grain), a protein concentrate and a source of Ca (typically coarse limestone or shell grit). Fine limestone may be included in the protein concentrate.
Loose mix feeding is a fully formulated diet where the grain portion of the feed is offered as whole grain. Fine and coarse Ca are supplied as part of the total mixed diet. It may be included in a sequential feeding program.
Sequential Feeding requires more than one feeding time for the hens - usually early morning and afternoon - such that different nutrients are supplied at different times of the day when the birds require it.

These methods will be considered in more detail with emphasis on their suitability for delivery by mechanised methods.

III. THE IMPORTANCE OF TRAINING THE HENS

A number of studies have reported on the importance of hens getting used to alternative methods of feed presentation. Forbes and Corvasa (1995) reviewed the literature on diet selection, including whole grain feeding, and emphasized that prior experience, training the flock during pullet rearing and social interactions all affect the outcomes of feed choices. Later workers picked up on this and included it in their experimental protocols (Umar-Faruk et al, 2010a).

Because whole grain is visibly different to meals, in mash feed it will be obvious (and attractive) to hens. Hens will naturally pick it out. Commercial experience has shown that naive hens will pick whole particles of grain or grain legume out of mash or pelleted feed to the detriment of production. The same is true for coarse limestone particles; hens pick them out of mash feeds. However, hens have been demonstrated to have a specific appetite for calcium which tends to regulate this feeding behaviour (Classen & Scott 1982; Taher et al, 1984). The essence of whole grain feeding is to get the hens to self-regulate their intake to meet their energy needs without over-consumption.

Broilers take about 10 days to learn to accurately select feeds during choice feeding (Cumming, 1984) so layers will take some time as well. The 2 week pre-lay period has been used for this purpose in some studies (Umar Faruk et al, 2010a).

IV. CHOICE FEEDING

Choice feeding implies offering the hens a choice between an energy source, a protein/mineral concentrate and a source of Ca. Because these have to be offered separately, it also implies the availability of a number of containers or troughs for feeding.

This method was discussed as a possibility for feeding layers before 1920, essentially because it reflected the natural feeding behaviour of chickens. Kempster (1916) published an experiment in which a variety of different feeds were offered to laying hens and the weights of those chosen were recorded. The author noted then the importance of offering the hens limestone or shell grit as a source of Ca. More recent work has shown the economic feasibility of choice feeding on a commercial scale (Leeson and Summers, 1979 Cumming, 1984; Henuk and Dingle, 2002).

The effects of free choice feeding have been reviewed again more recently (Molnar et al, 2018). These authors put together a table summarizing some of the earlier experiments with choice feeding. In all cases egg production was unaffected and feed conversion (FCR) was uniformly improved even though other parameters varied in their response.

The main drawback to commercial implementation is the requirement for multiple feed troughs or containers to keep the offerings separate and allow the hens to choose. A blending system for feeding into a single trough cannot, by definition, support choice feeding so this review will concentrate on those systems that can be delivered in a single trough or pan. Loose Mix feeding and Sequential Feeding satisfy this criterion.

Table 1 Effect of free-choice feeding on performance traits compared to conventional feeding.

V. LOOSE MIX FEEDING

As a result of the success of feeding whole grain to broilers in northern Europe, the possibility of including whole grain into layer feed was also considered. The reason for this wasto lower production costs because the grain did not have to be rolled or ground. Loose mix feeding was considered as an alternative to choice feeding because it could all be done in one feed trough and was adaptable to all conventional houses (Noiret et al, 1998).

Published examples on loose mix feeding are limited but one early study (Blair et al, 1973) showed that hens reduced energy and protein intake but maintained similar egg production and egg weight when a mixture of whole wheat, whole barley and kibble maize was fed. Later studies found contrary results. Bennett & Classen (2003) fed 2 strains of hens a mash diet with barley as the sole grain, either in ground or whole form and with or without insoluble grit. In the birds fed whole barley, egg production was reduced, feed intake was increased, egg specific gravity fell and body weight gain was increased. There was no difference in response to feeding insoluble grit and no difference between the 2 strains of hens. One reason for the decline in egg production is the absence of an appropriate beta glucanase enzyme to reduce the gut viscosity in the whole barely.

Oaurt et al (1986) fed various particle size wheat and corn to white leghorn hens and showed egg production was independent of grain type or particle size. However, in treatments with large particle size corn or with whole wheat, egg specific gravity was reduced. The authors speculated that this was due to the hens selecting the large grain particles in preference to the fine meal which contains the calcium source. The particle size of the limestone was not specified. One factor that could have impacted this experiment is that there was no mention of training the birds by exposing them to large particle size corn or whole wheat.

Figure 1 - Reduced egg specific gravity when fed whole wheat. Ouart et al (1986)

VI. BLEND FEEDING

Larger egg layer operations typically offer 2 to 3 diet regimes. Ideally the diets offered are an early layer, peak layer diet and a late lay diet (Hyline, 2018). The diets vary in energy (AME), essential amino acids and calcium/mineral content, depending on the birds age and feed intake, to meet the birds changing demands.

Each diet change is significant in the specifications and also raw material content, and can potentially disrupt feed intake and health health/microflora profiles. An experiment was designed to investigate the difference between the normal three diet program, changing at a specific time, compared with gradually blending in the diets to provide a more gradual change in dietary specifications and contents, which aimed to match the birds gradually changing metabolic and maintenance demands.

The study was conducted at the SCOLEXIA SCARF Attwood research centre (Melbourne Australia) in 2012, compromising 172 Hyline hens starting at 25 weeks of age with an average egg production of 97% (Scott, unpublished). Birds were housed in individual cages in an environmentally controlled shed. The control birds were offered an early layer diet for 8 weeks (change over at 33 weeks of age), mid or peak lay diet for 8 weeks and late lay diet until the study end with the birds at 55 weeks of age. The birds on the blended diets (conducted automatically by a Feedlogic Standard mixing and delivery unit) received a blending diet change every 10 days, blending two diets at the one time to more accurately match the birds’ requirements. As the birds on the blending diets aged, the blends of the different diets changed, to where for the last 10 days the birds received just the late lay diet.

Individual bird weight was unaffected by the treatment. There was no significant difference in egg production; however the birds on the blended diet exhibited numerically higher egg numbers of 6 eggs per bird. The number of cracked or damaged eggs was reduced from 572 in the control birds down to 222 egg for layers on the blending treatment (P< 0.001) and this correlated with an increase in egg shell thickness (P=0.024). There was also a significant reduction in egg weight of 2 grams per egg (P=0.041) for birds on the blending regime.

It was concluded that the more precise delivery of dietary energy, amino acid and mineral requirements enables the bird to produce a significantly better quality, smaller egg. The researchers suggested in non-blended diets (control), there was a over consumption of essential protein and energy, which produced a larger, potentially more fragile egg. The reduction in protein and energy consumption in the blended diets was evident due to a significant reduction in the amount of the early lay diet for birds on the blended diets, which also reduced the diet cost by 5% (19 cents per bird). Therefore, the blending of the different diets improved production measures and also reduced the cost of production of eggs.

VII. SEQUENTIAL FEEDING OR AM/PM FEEDING

Sequential feeding, Split feeding or AM/PM involves feeding a different diet in the morning to that fed in the afternoon. It was found that white leghorn hens fed a low (13%) protein corn/soy diet in the morning (0800-1400) and a high (16%) protein diet in the afternoon (1400-0800) had similar egg production and a similar egg size to hens fed the 16% protein diet alone (Penz and Jensen, 1991). This led to the conclusion that more protein is required when the birds are synthesizing albumen than at oviposition. Further, it provided an advantage over feeding a high protein diet for the whole day because the cost of the overall daily feed intake was lower. In other reports, energy, protein and Ca supply were varied during the day. De Los Mozos et al. (2012a) looked at the effect of feeding a diet high in ME (2900 kcal/kg) and protein (18.5%) and low in Ca (1.6%) in the morning from 2 hr before egg laying until 2hr, 4hr, 6hr, 8hr & 10hr after. From that time until 2hr before oviposition the next day, the hens were fed a diet low in ME and protein (2323 kcal; 13.3% CP) and high in Ca (4.5%). In hens fed the high Ca/low protein/low energy diet from 6 hr after oviposition compared to the control, hens on the split feeding regime consumed less energy (5%), less protein (13%) and less Ca (10%) but overall feed intake was similar. Further, despite consuming less Ca, eggshell quality parameters and egg weights were not affected. In a second experiment, this group looked at further reducing the crude protein of the afternoon diet (De Los Mozos et al., 2012b). Results showed that, while a smaller reduction of crude protein from 17% to 15.5% improved FCR, it had no effect on egg production. However, further reducing the crude protein of the afternoon feed to 14% protein made FCR significantly worse and numerically reduced egg weight.

Other approaches involved testing sequential feeding and feeding loose mix feed in the one experiment under different housing conditions (Umar Faruk et al., 2010a, 2010b). It is important to note that this experiment included a 2 wk feeding period before point of lay to allow the birds to get used to whole grain in their diet. During this period, the feed intake for the 3 feeding systems was about the same. In the first experiment, hens housed in groups of 5 birds per cage were fed either a complete mash feed or a protein/mineral/grain concentrate plus whole grain, either in a loose mix or sequentially as shown in Figure 2.

Figure 2 - Feeding and lighting regime from Umar Faruk et al (2010a). Whole wheat made up 50% of the grain portion of the loose-mix and sequentially fed diets

In the laying phase, which ran from 18 wk - 46 wk of age, the sequentially fed birds responded differently to the control group and to the birds fed the loose mix diet. The control diet (a complete mixed mash: 2,750 kcal of ME/kg and 17.5% CP) was offered in 2 equal portions of 60.5g per bird. What was not eaten was cleaned out of the feeders and weighed just before the afternoon feed and the same thing was done before the next morning feed. The loose mix feed, with whole wheat as 50% of the diet, was offered in a similar way to the control: 2 equal portions am and pm with feed remaining weighed each time. The sequential feeding was completely different: the whole wheat was offered in the morning and any remaining removed and weighed before the afternoon feed, which consisted entirely of Balancer (2,380 kcal of ME/kg, 23% CP, and 7.2% Ca). The results were analysed over 3 periods; Pre-Peak 19-26 wk; Peak 27-37 wk; Post-Peak 38-46 wk. The highlights were:

Total feed intake was significantly lower in the Sequential feeding treatment
Whole wheat intake was significantly lower in the Sequential compared with the Loose Mix treatment.
As a result, FCR was significantly improved in the Sequential treatment compared to Control and Loose Mix treatments.
There were no differences between treatments in Egg Production, Egg Weight or Egg Mass.
Birds were small group housed (5 birds per cage).

In a second experiment (Umar Faruk et al., 2010b) these authors introduced a treatment where birds were offered (in Loose Mix or Sequential Fed) a diet designed to contain 25% whole wheat plus a balancer supplying the other 75% of the nutrients. Further variations were that the birds were housed in single bird cages and the diets fed ad libitum. In this experiment, the egg laying performance was recorded over a 23 wk period from 19-42 wk of age. In the 3 wk pre-lay period (16-18 wk) 2 groups of birds were habituated to whole wheat by sequential feeding of whole wheat (morning) and a concentrate balancer (afternoon) or ad libitum feeding of a Loose Mix of 35% whole wheat: 65% balancer. A control group was fed a conventional completely mixed mash diet (16% protein, 11.7 mj/kg ME, 1.2% Ca). All groups were fed ad libitum by increasing the time of daily access to feed to allow intake to increase.

From 19-42 wk the birds were assigned to 5 treatments:

1. Control: conventional layer diet ad libitum fed (17.5% protein, 11.5 mj/kg ME, 3.61% Ca).

2. Loose Mix 25 (25% whole wheat: 75% balancer concentrate).

3. Loose Mix 50 (50% whole wheat: 50% balancer concentrate).

4. Sequential 25 (25% whole wheat, fed morning: 75% balancer concentrate, fed afternoon).

5. Sequential 50 (50% whole wheat, fed morning: 50% balancer concentrate, fed afternoon).

In the habituation period feed intakes and body weight gains were about the same for all groups. The Sequential fed birds increased their daily whole wheat intake from 16g/d in wk 16 to 40 g/d in wk 18, demonstrating their acclimatization to whole wheat feeding. Balancer intake decreased across the same period from 51.6g/d to 40 g/d indicating the birds were able to balance their diet successfully.

In the experimental period significant effects were:

Feed intake was not different from Control (C) diet for Sequential fed (SF) birds.
Feed intake for Loose Mix fed birds was significantly lower that SF birds (P< 0.01).
Whole wheat intake was significantly higher in Loose Mix fed birds than SF birds (P< 0.01)
Egg production was significantly higher in Sequential fed birds than Loose Mix fed birds (P< 0.05) and not different from the control (94.8% SF: 94.6% C).
Egg weight was significantly higher by 2.3g in SF birds than Loose Mix fed birds (P< 0.05) and numerically higher but not different from the control (58.3g SF: 57.3g C).
There was no significant difference in body weight gain between Control and SF birds but both gained more weight than the Loose Mix fed birds (P< 0.01).
There was no difference in FCE (g egg/g/feed) between treatments.

The implication of these two experiments is that the birds fed in groups (albeit small groups) did better on Sequential feeding that birds housed singly. This would certainly suit non-cage housing systems but would equally work in cage systems with multiple birds per cage.

VIII. SEQUENTIAL FEEDING FOR OLDER HENS

A consequence of changing welfare regulations on commercial egg production is the likelihood that force molting will not be allowed in future. In response to this, the major breed suppliers have selected for birds that will produce in a single cycle to 100 wk of age (Hy-Line 2018). It is well established that feeding hens coarse limestone in conventional diets leads to better shell strength (Koreleski & Swiatkiewicz, 2004) and improved bone strength late in lay (Saunders-Blades et al, 2009).

The effect of sequential feeding of different ratios of fine and coarse limestone was tested on egg shell strength and bone integrity in old laying hens (Molnar et al, 2017). These authors fed Lohmann Brown hens, aged 72-83 wk and housed in cages (7 birds/cage). A 2 wk pre-experimental feeding period was also employed in this work when the hens were fed a corn/soy standard laying diet containing 4.25% Ca with ratio of 30:70 fine to coarse particles. Internal and external egg quality was recorded to provide a baseline for later treatments. Treatments with a range of limestone particle size ratios were offered to groups of hens.

The light period was from 04:30 to 20:30 and the morning feed was distributed at 07:30 and the afternoon feed at 14:30. All birds were left with the afternoon feed until the morning distribution was made at 07:30. The ‘C’ treatments were offered all their feed in the morning (126g/bird) with the ratios of fine to coarse limestone shown in Table 2. The ’S’ treatments were offered 58 g/bird at the morning feed of a basal diet supplemented with 20% whole wheat. In the afternoon, each diet fed had a different ratio of fine to coarse limestone as shown in Table 2. It is important to note the morning diet for the ’S’ treatment was a low Ca diet (0.73%) so these birds are taking in the bulk of their Ca in the afternoon feed.

Calcium intake in this experiment is very interesting and different between the birds fed the conventional ‘C’ diets and the sequential fed ’S’ treatments (Table 2).

Table 2 - Daily Ca and P intake of laying hens (73 to 83 wk) per treatment. Adapted from Molnar et al, (2017).

In conventionally fed birds, Ca intake increased with the inclusion rate of coarse limestone. In the birds fed sequentially, Ca intake was maximized at 50% coarse limestone but was also significantly higher than the Ca intake of the conventionally fed birds. The ’S’ 70% coarse lime treatment had the lowest cracked egg percentage over the experimental period but the crack percentage of groups before the trial started was not reported. Cracked egg percentages were variable and not consistent between treatments. The treatments with the lowest cracked egg percentages over the whole trial were ‘C’ 50CL and ‘S’ 70CL. Why this was the case was not apparent and was not commented on by the authors. Importantly, over the whole experimental period, birds from the ’S’ groups ate significantly less feed than the conventionally fed birds (Figure 3).

Figure 3 - Daily feed intake (Adapted from Molnar et al, 2017).

Morning and afternoon feed intakes were not reported directly but it was mentioned that ‘S’ treatment hens consumed about half their feed in each feeding period whereas the ‘C’ treatment hens consumed more feed in the morning.

Rate of lay declined in all treatments and, although there were some significant differences within each time period, when looked at over the whole period of the experiment, it was hard to see any trends that may have favoured any treatment or feeding system (Figure 4). The one treatment that seemed to come out worst was ‘S’ CL100. This treatment also had the highest overall incidence of cracked eggs and was significantly worse in all 3 periods than most other treatments. The coarse limestone was uniformly coarse with only about 6% of particles less than 1mm.

Figure 4 - Rate of lay (Adapted from Molnar et al, 2017).

In a series of studies by Trouw Nutrition in Belgium between 2015 and 2018 that involved 2,800 broiler breeders (https://www.feedstuffs.com/nutrition-health/split-feeding-scheme-broiler), researchers compared the reproductive and physical performance breeders receiving a split-feeding program in the morning and afternoon to a group of commercial hens fed a regular broiler breeder diet to hens. The split-feeding or AM/PM program was designed to provide a more accurate nutrient supply, according to the egg formation need of breeders. This dietary strategy is similar to that tested in the previous mentioned studies in egg layers, which provided less crude protein (CP), apparent metabolizable energy (AME) poultry, calcium and digestible phosphorous compared to the control diet. The key findings of the research by the Trouw Nutrition group studies include:

Increased egg production in birds fed a split-feeding regimen compared to the control group, resulting in higher total and hatching eggs, as well as higher chick quality and subsequent growth.
A significantly lower feed cost for birds fed the sequential or split-feeding system compared to birds receiving the control diet, and
Birds receiving the split-feeding program demonstrated improved feathering, reduced pecking and showed fewer behaviors indicative of hunger.

This research was further supported by three large commercial evaluations involving 122,600 breeders, using both Ross and Cobb genetics. This demonstrates the advantages of sequential or split feeding across all layer and broiler breeders as well as commercial egg laying flocks.

IX. COMMERCIAL IMPLICATIONS AND SOLUTIONS

Of the 3 systems that involve some form of choice feeding, only Loose Mix and Sequential feeding make sense if applying them to existing sheds. They could both be adapted to all current Australian housing systems: cage, barn and free range, aviary or flat floor. Both should work with trough or pan feeding. Although feeding whole grain was considered in most of the experiments reported, it is not a pre-requisite. However, if it significantly contributed to the economics of production, there is ample evidence that current laying strains can be readily adapted to it.

Taken together, the experiments above indicate that SF is certainly feasible but its major drawback remains the accurate distribution of feed in the morning and afternoon. That is where an automated feeding system capable of accurately weighing feed is essential to make it work. Industry experience indicates that a number of egg producers have been interested in it over the years but did not have the means to make SF work. As the data presented by Molnar et al. (2017) indicated that sequential fed birds ate about 50% of their feed in the morning and 50% in the afternoon, it is relatively easy to allocate feed, given that the producer has good flock feed intake data for the sheds. Most of the bigger players have those data. The setting of the feeding times is also important and 07:30 to 08:00 for distribution of the morning feed and 14:30 to 15:00 for the afternoon feed would fit in with the work practices on most farms.

Any investment must return a profit, so quantifying the advantages of SF is necessary to convince producers to invest in new equipment. The improvement in feed intake is likely to be the best way to demonstrate a payback. In the experiment reported by Umar Faruk et al. (2010a), feed intake was reduced by 7g/bid per day over the course of the experiment for the same egg production, egg weight and mortality. The advantage of SF over conventional feeding is that, with the latter, the birds need to over-consume feed to match the metabolic needs of albumen formation and shell formation which occur at different times of the day.

To make it easy to visualize the economic advantage, an average feed cost of $510/t was assumed. The savings over laying periods of 62 wk (18-80 wk) and 82 wk (18-100 wk) are shown in Table 3.

Table 3 - Feed cost savings for flocks of various sizes for a weighted average feed cost of AUD$510/t.

Feed savings per flock are potentially substantial depending on the reduction in feed intake actually achieved in practice. However, the projections shown should be attractive to farmers with rapid paybacks available, depending on the price of the blending equipment.

The other important element of this discussion is how to best formulate and implement a feeding program that will reproduce the feed savings shown in the research situations. It is clear that two bins with different feeds that can be delivered to the birds in the morning and afternoon will be necessary. The normal situation is one feed bin per house. However, if houses are close together, it may be possible to place 2 bins, each holding a different feed, between 2 houses, meaning that extra bins may not be required but some will have to be moved. Of course, if houses are spread out this might not be possible. Many older farms have houses relatively close together so extra bins might not be a major disincentive on these farms.

Formulation approaches can be flexible. As most diets currently have a mix of grains, due to the price structure of the current market, a whole grain morning: concentrate afternoon approach might not be the best way to go. It is not clear how the birds would take to a mix of whole grains and whether one would be preferred and the other rejected. However, a mix of coarse cracked grains in the morning with a concentrate in the afternoon might work. The research reviewed above supports using a mix of coarse and fine limestone and this is compatible with all mash feeding systems.

The other complication that needs to be addressed is the variation in the nutrient requirements of hens over the production cycle. Young birds with low feed intake will require a feed with a higher concentration of energy and amino acids than birds at the end of the program. With a 2 bin feeding system it may possible to run the afternoon feed with high calcium as a constant formulation whilst varying the nutrient density of the morning feed.

On balance, it is suggested that the approach of De Los Mozos (2012a) is worth considering. In this experiment the morning feed was high in ME and protein and low in Ca compared to the afternoon feed. Because it will be required to start this program at 16 wk of age with newly placed pullets, making the morning feed as a high nutrient density diet with Pre-Layer levels of Ca and available phosphorus would work well until first egg. In the Pre-lay period (16-18) wk of age the same diet can be fed morning and afternoon to both to train the birds and meet their nutrient needs. Equal portions of feed can be offered morning and afternoon and this period can also be used to learn the flock’s consumption pattern. At first egg the afternoon feed can be changed to the high Ca balance with lower ME and amino acids.

XI. CONCLUSIONS

There are significant advantages of SF, choice feeding or blending of current mash diets compared to the current strategy of providing one specific diet to the bird at time. While commercial diets in mash form do offer some choice to pick out individual components, the alternative feeding methods mentioned in this paper, SF and feed blending in particular, have been shown to reduce the overconsumption of protein and energy and producing more ideal Ca intake through the layers life. This, in turn, improves feed efficiency and increases egg quality.

Choice feeding will be difficult to implement into the commercial shed designs; however, SF or the blending of diets can be incorporated into new buildings or retro-fitted using the current feeding lines and pans. The performance benefits potentially create a rapid rate of return on the installation of alternative automatic feeding systems.

Presented at the 32th Annual Australian Poultry Science Symposium 2021. For information on the next edition, click here.