Presentation forms, feeding systems and metabolizable energy levels in diets for semi-heavy laying hens in the laying phaseABSTRACT:
In this study the effects of the diets on semi-heavy laying hens regarding performance and egg quality were evaluated under different forms of presentation - PF (mash x pelleted), feeding systems - FS (ad libitum x controlled), and metabolizable energy levels - ME (2,800 x 2,550 kcal kg-1). The experiment included 400 laying hens, between 18 and 77 weeks of age, in a completely randomized distribution design following a factorial arrangement of 2x2x2 (with 5 replicates of 10 birds). The birds that had been fed pelleted feed, with ad libitum supply and 2,550 kcal kg-1 of EM demonstrated increased intake of feed and feed conversion; a higher uniformity, however, was identified in the controlled system. The best laying index was observed in birds fed ad libitum and 2,550 kcal kg-1; in the control system, birds fed with mash or pelleted diets revealed greater feed conversion, while higher uniformity was noted in the birds fed on and pelleted, ad libitum. The eggs were heavier in hens fed on the pelleted, ad libitum and 2,800 kcal kg-1 diet. The eggshells were thicker and the yield was higher when they were put on mash diets and 2,800 kcal kg-1. In terms of egg quality, hens given a pelleted diet ad libitum and 2,550 kcal kg-1 of ME produced heavier eggs; those provided with mash or pelleted diets in the control system displayed higher Haugh units. Therefore, for semi-heavy laying hens, the diet recommended is mash feed, ad libitum and 2,550 kcal kg-1 of metabolizable energy.
Key words:
egg quality; feeding management; feed restriction; hen; pelleted
RESUMO:
Avaliou-se o efeito de dietas com diferentes formas de apresentação - FA (farelada x peletizada), sistemas de alimentação - SA (à vontade x controlado) e níveis de energia metabolizável - EM (2.800 x 2.550 kcal kg-1) sobre o desempenho e qualidade de ovos de poedeiras semipesadas. Foram utilizadas 400 poedeiras de 18 a 77 semanas de idade, distribuídas em um delineamento inteiramente casualizado, em arranjo fatorial 2x2x2 (oito tratamentos, com cinco repetições de dez aves). As aves alimentadas com ração peletizada, fornecimento à vontade e 2.550 kcal kg-1 de EM apresentaram maior consumo de ração e conversão alimentar; maior uniformidade, entretanto, ocorreu no sistema controlado. Nas interações, no sistema à vontade e 2.550 kcal kg-1 o consumo foi maior comparado ao controlado e 2.800 kcal kg-1; melhor índice de postura ocorreu com fornecimento de ração à vontade e 2.550 kcal kg-1; com dietas fareladas ou peletizadas no sistema controlado, as aves apresentaram melhor conversão alimentar; melhor uniformidade foi observada nas aves arraçoadas à vontade e peletizada. Ovos mais pesados foram obtidos com dieta peletizada, à vontade e 2.800 kcal kg-1. A espessura e rendimento de casca foi maior com dietas fareladas e 2.800 kcal kg-1. Nas interações da qualidade de ovos, os mais pesados obtêm-se com dieta peletizada fornecida à vontade e 2.550 kcal kg-1 de EM, sendo que tanto com dieta farelada ou peletizada no sistema controlado apresentaram maior unidade Haugh. Recomenda-se ração farelada, sistema à vontade e 2.550 kcal kg-1 de energia metabolizável para poedeiras semipesadas.
Palavras-chave:
galinha; manejo alimentar; peletizada; qualidade de ovos; restrição alimentar
INTRODUCTION
Several sources in the literature concur with the advantages that pelleted feeds provide in broiler production (ANDRADE et al., 2016). Feed pelleting offers the following benefits namely - lowered microbiological load and the loss of antinutritional factors, higher net energy release, feed intake, and weight increase accompanied by improved intestinal integrity (WAN et al., 2021). However, one negative aspect evident in the carcass and viscera of the broilers was a rise in the abdominal and total fat (MASSUQUETTO et al., 2020).
Interestingly, the low-energy feeds reveal the higher benefits of pelleting because an increase in the energy levels of a diet boosts the feed efficiency and lowers the feed intake. However, this approach requires further investigation due to the paucity of literature on providing pelleted feed for laying hens (EGE et al., 2019).
Normally, commercial laying hens are fed ad libitum; however, in specific situations, the birds are incapable of proper regulation of their feed intake, sufficient to meet the nutrient consumption and satisfy the nutritional requirements (CLARK et al., 2019). During the laying phase, birds may become overweight because of consuming excess nutrients. Hence, to prevent obesity in laying hens, controlled feeding programs (SIMENEH, 2019) are required, as this will also decrease production expenditure.
Many nutritional requirement tables which list diets with the recommended ME levels for commercial laying hens are available. In their study, PÉREZ-BONILLA et al. (2012), reported the direct influences that ME exerts on food intake; they found on feeding the hens a diet with a level lower than the recommended one, the intake was higher but performance and egg quality remained unaffected. Earlier studies suggested the likelihood of this happening during the growth (SALDAÑA et al., 2015) and laying phases (SALDAÑA et al., 2016; EGE et al., 2019).
In the present research, the aim was to determine the effects of feeding semi-heavy laying hens in the age range of 18 to 77 weeks with either a mash or pellet form of diet, adopting the ad libitum and controlled feeding systems, while maintaining an ME level of 2,800 and 2,550 kcal kg-1 on their performance and egg quality.
MATERIALS AND METHODS
The Poultry Sector of the Center for Agro-Veterinary Sciences (CAV) of the State Universidade do Estado de Santa Catarina (UDESC), with the geographic coordinates 27°48’11.9” S and 50°18’17.9” W, southern Brazil, was the site of the experiments.
The experiments were performed using 400 Hy-Line Brown birds in the 18- to 77-week age range, in 15 periods of 28 days each. The birds were placed in an open aviary, enclosed on all sides with screens and plastic curtains. The average minimum and maximum temperatures (16.9 ºC and 24.6 ºC, respectively) were recorded on a daily basis. At the commencement of the experiment, the initial weight of the birds was recorded as 1,548 ± 148 g. The birds were distributed in 40 cages (100 x 45 x 40 cm) adopting the random design. Each cage (experimental unit) had two nipple drinkers and a front trough feeder. Lighting was kept constant at 16 h of light/8 h of dark for the duration of the experiments. Using the completely randomized design, in a 2 x 2 x 2 factorial arrangement, the treatments involved presenting the feed in two forms (mash x pelleted), using two feed supply systems (ad libitum x controlled) and two ME levels (2,800 x 2,550 kcal kg-1). Altogether eight treatments were done, with five replicates of ten birds. For birds fed on an ad libitum diet (AL), the feeders were filled several times throughout the day, while for those fed on the controlled feed (CONT), the quantity of feed was provided based on the weekly recommendations cited in the manual of the lineage used and the feeders were refilled daily only once every morning.
The isonutritive diets given were corn and soybean meal prepared following the nutritional requirements listed in the study by ROSTAGNO et al. (2017), with variations only in the EM levels (Table 1). The granulometry of the mash (MAS) and pelleted (PEL) diets was maintained, adopting the method recommended by ZANOTTO & BELLALER (1996), keeping to the mean geometric diameter of 517 µm in the mash diet and 5,638 µm in the pelleted diet.
To determine bird performance, the feed intake was evaluated by giving a predetermined quantity, and at the end of each week the leftovers were weighed and expressed as g/bird/day. Egg collection was done twice daily, at 11 am and 4 pm, and the number of cracked, broken and deformed eggs was recorded. Egg production was given as the percentage of the number of birds in each repetition. Feed conversion was determined using the relationship between feed intake and egg weight (g/g). Uniformity (%) was assessed when the experiments were completed by weighing all the birds in each cage to calculate the average weight and finally, by noting the number of birds which fell within the range of +/- 10%, proportionate to the average cage weight. On the final two days of each period, the eggs that remained intact in each repetition were utilized to evaluate the weight, Haugh units (HU), shell thickness and shell yield. Egg weight was determined using a precision scale (0.01 g) and average egg weight (g) was calculated. Post weighing, three eggs were randomly selected, broken on a flat, level surface and the albumen height (mm) was measured using digital calipers. Applying the formula UH = 100 log (h + 7.57 - 1.7W0.37) the Haugh unit was calculated, where h represents the height of the albumen (mm) and W represents the weight of the egg (g). After drying the eggshells for 48 hours at room temperature, the shell thickness (mm) was measured at the equatorial region of the egg with a digital micrometer. The yield of these shells was calculated as the percentage ratio between the dry shell weight (g) and egg weight (g).
Data collected were analyzed by GLM procedure of SAS software (SAS Institute Inc., 2002). The statistical model included the influence exerted by the type of feed presentation (MAS or PEL), feeding systems (AL or CONT) and ME levels (2,800 or 2,550 kcal kg-1) and their interactions. For all the variables, each cage was regarded as an experimental unit. Using Tukey’s test, the means were compared at 5% probability. The outliers were recognized through the Interquartile Range and deleted from the database.
RESULTS AND DISCUSSION
Notable differences (P < 0.05) were evident in the feed intake between the presentation forms, feeding systems and energy levels; interactions were observed between the factors, presentation forms x feeding systems, presentation forms x ME levels and between the feeding systems x ME levels (Table 2).
Birds given the PEL diet had higher feed intake than the ones provided with the MAS, a finding reported earlier as well (SALDAÑA et al., 2016). This greater intake occurs because of the higher feed density, homogeneity of particle size, decreased food selectivity, and diet palatability (BOZKURT et al., 2019). Birds given the MAS and AL diets revealed increased consumption (P < 0.05) than those given MAS and CONT. The same observation was made for the PEL feed, where AL provision induced higher intake than CONT. Concerning AL consumption, greater PEL consumption was noted compared to those on MAS, result similar to WAN et al. (2021) and EGE et al. (2019); these authors attributed to the improved texture of the feed due steam and mechanical pressure applied to the mash, besides the fact that chickens require less time on feed intake and show preferences for larger particles (MASSUQUETTO et al., 2020). The interaction also suggested that in the birds given the AL diet, the consumption increased (P < 0.05) in the 2,550 kcal kg-1 diets compared to the 2,800 kcal kg-1 diets. The birds fed on the AL feed showed higher intake (P < 0.05) than those given CONT. This was an anticipated outcome, concurring with previous reports (PÉREZ-BONILLA et al., 2012; ANENE et al., 2023), wherein the ME level present in the diet exerted a direct effect on the quantity of daily feed intake, and the birds consumed to satisfy their energy demands. Therefore, voluntary feed consumption decreases proportionate to the increase in the energy content of the diet. However, MURUGESAN & PERSIA (2013) reported no such interaction between the feeding system (AL and CONT) and ME levels (2,880 kcal kg-1 x 2,790 kcal kg-1) in laying hens of the Hy-Line W36 line, (where there was only a 90 kcal kg-1 difference between the ME levels), while in the current research it was 250 kcal kg-1. Egg production showed no change (P > 0.05) between the presentation forms, feeding systems, and ME levels (Table 2). However, an interaction (P < 0.05) was observed between the feeding systems and ME levels (Table 2). Irrespective of the ME level, a decrease exceeding 10% in egg production was evident with the CONT feeding (79.5%), compared to AL (90.2%). ANENE et al. (2023), also recorded similar results. As it is well known that the hens mainly utilize energy and nutrients for maintenance, and egg production is only a secondary obligation, controlled feeding may limit the energy and nutrients needed to produce eggs, thus exerting a negative impact on the laying index. Therefore, from the findings drawn in the present study, the ME level can be decreased to 2,550 kcal kg-1 in the diet of laying hens without affecting egg production at all. Concurring with this deduction, MURUGESAN & PERSIA (2013) also reported no differences in the laying index when the ME levels were 2,790 or 2,880 kcal kg-1. In their comparison of the levels of 2,750 to 3,050 kcal kg-1, KANG et al. (2018) found no change in the laying index (P = 0.10), as did JALAL et al. (2006) in their study comparing 2,800, 2,850 and 2,900 kcal kg-1 of ME.
Considering feed conversion, a difference (P < 0.05) was observed between the presentation forms, feeding systems and ME levels, and interactions (P < 0.05) between the presentation forms x feeding systems, as well as presentation forms x ME levels and between feeding systems x ME levels (Table 2). Birds given the CONT feed revealed the best conversion values (P < 0.05) when they were fed on both MAS and PEL feeds. The CONT system was found to improve the feed conversion by around 7%. In their research, MEINERZ et al. (2001) indicated an interaction between the types of feed presentation and AL and CONT feeding systems, as studies showed that the PEL diets give better feed conversion outcomes (MOUSAVI et al., 2016; WAN et al., 2021) and that feed restriction raises feed usage (SU et al., 1999).
In terms of the interaction between the forms of presentation and ME levels on feed conversion, in both forms of feed presentation (MAS or PEL) the birds demonstrated improved conversion with 2,800 kcal kg-1 of ME. However, in their research, SALDAÑA et al. (2016) reported no such interactions between the presentation forms (MAS and PEL) and ME levels (2,750 and 2,650 kcal kg-1); although, conversion was more efficient in diets with higher ME. When the level of 2,800 kcal kg-1 alone was considered, the birds fed on MAS were observed to show improved conversion (1.61) than those on the PEL diet (1.65). On analyzing the interaction between the feeding systems and ME levels, birds fed on the CONT form and 2,800 kcal kg-1 had the best feed conversion (1.60). In contrast, birds given AL access and 2,550 kcal/kg revealed the worst conversion (1.84). In terms of uniformity, a difference (P < 0.05) was observed for the feeding systems (Table 2), with interaction (P < 0.05) between presentation forms and feeding systems. The laying hens fed on the PEL and AL feeds displayed the highest uniformity. Previous studies reported that hens given the PEL feed, besides revealing an increase in intake (McKINNEY & TEETER, 2004; WAN et al., 2021), also showed a boost in their efficiency of retention of apparent ME. Feed pelleting lowers the energy expenditure of birds for consumption, thus favoring reduced maintenance energy and heightened net production energy (NIR et al., 1994), thus culminating in improved uniformity.
Depending on the presentation form feeding systems and ME levels, differences (P < 0.05) were observed in egg weight (Table 3), with interactions between presentation forms and feeding systems, as well as between presentation forms and ME levels. The appearance of such interactions suggested that the hens that received the PEL and AL diets produced eggs that were heavier than those produced by hens given the PEL and CONT diets. Concerning ME, intake of the 2,800 kcal kg-1 feed induced the production of heavier eggs, irrespective of the form of feed presentation (MAS or PEL). However, SALDAÑA et al. (2016) reported no interactions between presentation forms and ME levels in a comparative study of the levels of 2,750 and 2,650 kcal kg-1; but this implies that the PEL feed raises the body weight of the hens which in turn results in heavier eggs. The findings of such a difference in egg weight can also be attributed to the physical and chemical changes triggered by the PEL process, which causes the net energy levels in the diet to escalate, via starch gelatinization and better digestibility of the nutrients (LARA et al., 2013).
Regarding the Haugh unit, a difference (P < 0.05) was noted in the feeding systems and ME levels, with interactions between the presentation forms and feeding systems (Table 3). The MAS and PEL forms, both induced an increase in the Haugh unit for the CONT system. A few authors, during their use of the different ME levels in the diet of laying hens, reported differing results. In their respective studies, GRANGHELLI et al. (2019) and SALDAÑA et al. (2016) found no difference in the HU after using different ME levels; WU et al. (2005) and PÉREZ-BONILLA et al. (2012) on the contrary, observed a drop in the Haugh unit as a response to the increase in ME.
Birds fed on the MAS diet than on the PEL diet revealed higher eggshell thickness and shell yield (Table 3) (P < 0.05). With the 2,550 kcal/kg of ME, higher (P < 0.05) shell yield and thickness were seen when compared to the 2,800 kcal kg-1 diet. However, neither the AL nor the CONT feeding system affected these variables (P > 0.05). No interactions were reported between the factors (P > 0.05) either. SALDAÑA et al. (2016) and KANG et al. (2018) reported no difference in shell thickness when they utilized different ME levels; however, PÉREZ-BONILLA et al. (2012), detected a drop in the eggshell weight when the ME level of the diets was increased. It was JUNQUEIRA et al. (2006) who perceived similar outcomes on raising the ME from 2,850 to 3,050 kcal kg-1. It is noteworthy that as the energy content of a diet was increased the dietary fat level showed a corresponding rise and the fat could form soaps with the calcium salts in the diet, causing the calcium retention to reduce, thus affecting the relative weight of the shell (ATTEH & LEESON, 1984).
CONCLUSION
The recommendations derived from the outcomes of this study are to provide semi-heavy laying hens in the laying phase a mashed feed, ad libitum, with 2,550 kcal kg-1 of metabolizable energy.
ACKNOWLEDGEMENTS
The authors would like to thank the Universidade do Estado de Santa Catarina (UDESC) for granting research scholarship, Fundação Instituto de Apoio ao Ensino, Pesquisa e Extensão do Centro de Ciências Agroveterinárias da UDESC for assistance and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Brasil - Finance code 001 to finance in part this project.
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BIOETHICS AND BIOSECURITY COMMITTEE APPROVAL
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CR-2024-0499.R1
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The experiment was submitted to and approved by the Animal Experimentation Ethics Committee - CETEA, from UDESC-CAV University (protocol number 01.56.14).
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DECLARATION OF USE OF ARTIFICIAL INTELLIGENCE
This manuscript has been written without aid of any kind of artificial intelligence.
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DATA AVAILABILITY STATEMENT
Not applicable.
Edited by
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Editor
Rudi Weiblen (0000-0002-1737-9817)Charles Keifer (0000-0001-9622-2844)
Not applicable.
