Behavior of laying chicks fed diets containing sources and levels of dietary fiber in the starter phase

Abstract

This study evaluated the behavior and welfare conditions of laying chicks in the starter phase, fed with diets formulated with increasing levels of crude fiber (CF) and two feedstuffs with different fiber compositions. The experiment was developed at the Federal University of Goiás, in Goiânia - GO, Brazil. Three hundred Bovans White chicks were evaluated in a completely randomized design with a 2×2+1 factorial arrangement corresponding to two levels of CF in the diet (3.0 and 3.5%) and two fiber sources (wheat bran and sugarcane bagasse), plus a control treatment (maize- and soybean meal-based), totaling five treatments with six replicates of 10 birds each. Maintenance behavioral patterns and welfare were assessed at 21 and 42 days of age. There was no difference in behavior and classification by order of importance of the activities performed by the fiber-fed birds observed at 21 and 42 days, according to the Kruskal Wallis test (P>0.05). Medium and good welfare conditions were obtained with wheat bran at 3.5 and 3.0% CF, respectively, at 21 days of age. At 42 days, the use of sugarcane bagasse at the CF level of 3.5% and wheat bran at the level of 3.0%provided good behavior conditions. The use of crude fiber in the feeding of hens did not change their behavior.

INTRODUCTION:

The concern with animal welfare has culminated in changes in cage-based (battery) poultry farming systems. In this respect, identifying behavioral repertoires responsive to the rearing environment can validate welfare conditions (BATISTIOLI et al., 2016). By monitoring the behaviors expressed by the animal, it is possible to better assess its quality of life and production performance (GARCIA et al., 2015).

Natural behaviors of the species, such as running and scratching, have a positive implication for laying poultry. Chickens reared on bedding material, for example, have their wallowing and scratching behaviors stimulated (MOURA et al., 2017). However, in cage and/or high-density farming, scratching is naturally replaced by the act of biting the cage grids or feather-pecking, which vary in intensity between genetic lines and ages and are an indication of increased stress (PEREIRA et al., 2015). Under this situation, chickens may also display aggressive behaviors, including other stereotypies. Additionally, when reared in environments with limited space, they may tend to reduce their activities and remain idle or lying down for long periods (GARCIA et al., 2015).

However, laying hens raised in cages and fed with feedstuffs with insoluble and soluble fiber composition have shown controlled feather pecking and cannibalism in response to the increased gastrointestinal passage rate (GUZMÁN et al., 2015). It is believed that feedstuffs with a higher amount of insoluble fiber fractions are retained in the gizzard for grinding and soluble feedstuffs can increase the viscosity of intestinal mucosa due to the solvation capacity of some constituent sugars. In this way, the availability of nutrients for the bird is reduced, thereby extending feed intake time. As a result, idle time and the act of biting combs and feathers of neighboring birds are reduced (MANCABELLI et al., 2016).

In this scenario, this study aimed to assess the behavior and welfare characteristics of chicks in the starter phase (1^st to 6^th weeks of age) using diets with increasing levels of crude fiber obtained through the inclusion of sugarcane bagasse and wheat bran in the formulation.

MATERIALS AND METHODS:

The experiment was carried out in the experimental poultry farm of the School of Veterinary and Animal Science a tthe Federal University of Goiás, located in Goiânia - GO, Brazil.

A total of 300 Bovans White chicks was housed in batteries with galvanized wire cages (50 × 50 × 45 cm) and holding capacity of 10 birds per cage (25 cm²/bird). Birds were received at one day of age and raised from the 1st to the 6th week of age, following the recommendations provided in the manual of the genetic line (Bovans White - Mercoaves Product Guide). The chicks were distributed in a completely randomized design in a 2×2+1 factorial arrangement consisting of two levels of crude fiber (CF) in the diet (3.0 and 3.5%) and two feedstuffs with distinct fiber fraction compositions (wheat bran and sugarcane bagasse), plus a control treatment (2.5% CF, composed of maize and soybean meal), totaling five treatments with six replicates of 10 birds each, in the starter phase.

All experimental diets were nutritionally equivalent, except for the fiber levels, following the nutritional recommendations stated in the manual of the line. The CF levels were determined from the maize- and soybean meal-based diet, which was defined as the control treatment, considering the maximum inclusion of 2.5 to 3.0% CF in diets for monogastric animals (ROSTAGNO et al., 2017). The dietary CF inclusion levels of 3.0 and 3.5% were adopted for the other treatments, with sugarcane bagasse and wheat bran (Table 1). The composition of the fractions and sugars that make up the cell wall of fiber sources was determined (Table 2). For this step, representative samples of 1000 g of the feedstuffs were separated and analyzed at the Food Analysis Laboratory of AB Vista, a division of AB Agri Ltd. The formulation was made based on crude fiber, as it is described in the requirements tables, and can be considered usual in the formulation of diets for non-ruminant animals.

The birds’ behavior was determined initially by all-occurrence sampling to qualify the behavioral activities (Table 3) and develop the ethogram (PEREIRA et al., 2015). Natural behaviors of birds such as scratching and biting the litter, even in the absence of bedding material, were noticed in the sampling. In this case, the animal would bite and scratch on the cage floor, similarly to activities described on the litter. Therefore, they were considered in the ethogram, because, if constantly performed, they could represent discomfort of the bird. Subsequently, at the end of the 3rd and 6th weeks of the starter phase (21 and 42 days of age, respectively), the animals were recorded by video cameras on two consecutive days (20 and 21; and 41 and 42 days of age), in two periods of the day (08h00 and 13h00) (PEREIRA et al., 2015).Group representative of each replicate of the treatments were chosen, in a total of six 5-min recordings per period per treatment (ROYER et al., 2015). The birds’ behaviors were evaluated by the focal and indirect animal observation method, whereby five randomly chosen birds were evaluated per replicate (HETLAND et al., 2005). The frequency of individual behaviors was obtained by simultaneously observing the animals. One-minute sessions of evaluation of activities were applied per bird, in a total of five evaluations per video of each replicate, per recording period, and then the average occurrence of each activity in the recorded videos was calculated (CASTRO et al., 2017). Subsequently, the five-minute recording was considered as representative of the activities in a day (100%), in percentage terms, and the sum of the activities recorded in the evaluation session was considered the total number of activities developed in a day of life, per bird (PEREIRA et al., 2015).

The frequency of each activity predetermined in the ethogram (PEREIRA et al., 2015) was expressed by the following formula:

% of activity = Number of times the animal performed the activity ^* 100/Total number of activities performed.

This formula indicated the percentage of time spent by the animal on a given activity during the day (representative time of 5 min) (ROYER et al., 2015). After the percentage of each activity was obtained, the behaviors were classified based on the values proposed for maintenance behaviors essential for the life (feeding and drinking), health and comfort (sleeping, lying down, scratching, preening, spreading wings, walking and others) of the animal (Table 4).The intervals proposed for the evaluation of representative behaviors to meet the essential needs of life and comfort were also defined (Table 5), as described by HURNIK (1995) and adapted by ALVES et al. (2007) and ROYER et al. (2015).

The mean values obtained in the two days of evaluation of each rearing period (third and sixth weeks) were evaluated per period. Data were analyzed by the Kruskal-Wallis non-parametric test (5% probability), using R Software version 2.15. 1 (R CORE TEAM, 2013).

RESULTS AND DISCUSSION:

There was no difference in behavior (Table 6) or in the classification by order of importance of the activities performed (Table 7, Figure 1A and 1B) by laying hens fed diets containing sugarcane bagasse (fiber with a higher amount of insoluble fractions, ADF) and wheat bran (fiber with a higher amount of soluble fractions, NDF), at 21 and 42 days, according to the Kruskal Wallis test (P > 0.05). However, in other studies evaluating the effects of increasing dietary fiber contents intake decreased due to the volume occupied in the digestive tract; the slower passage of the digesta; and the high-water absorption capacity of the soluble fractions that make up some feedstuffs (ASSUNçAtilde;O et al., 2018). This change in frequency of visits to the feeder may be due not only to the fiber content of the diet, but also to the bedding material, which expands the behavioral repertoire and substitutes water and feed consumption (MOURA et al., 2017) for dust bathing and foraging activities.

The replacement of activities in birds raised in cages when subjected to environmental changes, such as replacing feed consumption and the acts of biting neighboring birds and preening(GARCIA et al., 2015) with pecking and scratching the litter, is common and corresponds to exploration of the environment (PEREIRA et al., 2015). Nevertheless, even in cage farming, increases in the CF content and the use of feedstuffs with a higher amount of ADF and NDF in the diet can change behavioral patterns. VAN KRIMPEN et al. (2009) increased the ADF content (fractions with less metabolizable sugar constituents of the cell wall, such as some celluloses and lignin) in the diet of layers and noticed a lower incidence of feather pecking and cannibalism in laying birds reared in cages. This behavior is responsive to the birds’ natural appetite for fiber sources, which improve the motility of the gizzard and intestines. BRAZ et al. (2011) increased the amount of fiber in chicken diets by increasing the inclusion of wheat bran (which increased the content of NDF, a soluble fraction) and observed that up to the limit at which it provided 18.50% of NDF in the composition, the ingredient did not promote changes in the characteristics of the diet enough to compromise feed intake by the hens.

Considering inferences of the activities and intervals proposed by ALVES et al. (2007), medium and good welfare conditions were obtained with the use of wheat bran at the CF levels of 3.5 and 3.0%, respectively, at 21 days of age. At 42 days, the use of sugarcane bagasse at the CF level of 3.5% and wheat bran at 3.0% CF improved welfare conditions (Table 7).

The early age of birds for the research with nutrition and inclusion of fibers was chosen in response to the behavior of feather, back and cloaca pecking, which chicks may already present in the second week of life (VAN HIERDEN et al., 2002; FREITAS et al., 2014). Therefore, beak trimming is conventionally performed with industrial machine and burning of the tip of the beak of birds, to avoid cannibalism inside the cages. In the first weeks of life , chicks sleep and play more, reducing food consumption, constantly stimulated to visit the feeder (MATEOS et al., 2012; FREITAS et al., 2014). In this period, some authors also describe the development of digestive organs that may interfere in the utilization of nutrients and consequent reproductive development. The hypothesis questioned in this study was the possibility of including fiber in the diet with two sources and levels: sugarcane bagasse and wheat bran, which may alter the consumption behavior. Responsive to the higher speed of passage through the digestive tract, causing the birds to return to the feeder more often, reducing the time of sleep and play, as well as the reduction of cannibalism behavior, since they are busy eating and do not peck the neighboring birds. This consumption of food, consequently, stimulate the functioning of the digestive organs and the presence of fiber, could stimulate the activity of the gizzard, causing its muscle development and increase in size. In a research carried out by GONZÁLEZ-ALVARADO et al. (2007) it was noticed that with the increase of the oat hulls and soy hulls, the size of the gizzard and digestive organs, including pancreas, was also increased, indicating its greater activity in the production of digestive secretion. This can interfere in the digestibility of the nutrients in the diet, with its greater utilization and consequent greater development of the bird, especially of the reproductive tract. VAN KRIMPEN et al. (2009) described a natural appetite for the consumption of fiber sources by birds to improve the motility of and intestine, which in turn, may lead to birds consume litter, pecking and plucking the feathers of the neighboring birds. As the pecking of feathers and cannibalism occurs already in the first weeks and is indicative of low conditions of well-being, and as the stage of offspring, especially the first four weeks of age are important for the quality of the chicken, the study was considered already in the stage of offspring.

Diet formulation with increasing levels of fiber has been studied in laying hens diets. The composition of the cell wall of vegetables varies among foods, some sugars that make up the fractions of the cell wall may have different behaviors with regard to solubility and may present greater or better metabolization (de VRIES, 2013). Important reviews were published by AKINOLA & ONUNKWO (2009); MATEOS et al. (2012) and recently by SINGH and KIM (2021). Ingredients with a higher amount of acid detergent fiber (ADF) fractions, for example, can impair diet metabolization and increase the rate of passage through the digestive tract or cause damages in intestinal villi. This reduces the absorption of nutrients and can increase the frequency to the eating of birds. However, this content in ADF, can supply the natural need of the bird by fibrous materials, because it alters the motility of the intestine, reducing depraved behaviors, such as pecking of the feathers and of other birds.

The rations for non-ruminant animals are commonly not formulated in the composition of neutral detergent fiber (NDF) and ADF, but in CF (FREITAS et al., 2014). Therefore, in this experiment, the recommended levels of fiber were used, evaluating diets with the same level of CF, but with feedstuffs that have distinct fractions of sugars that are constituents of the cell wall. According to MATEOS et al. (2013), it is important to understand the way in which the constituents behave metabolically, and how they interfere in animal behavior. Since low nutrient absorption, possible reduction or increase in gastric motility and the supply of natural bird needs can alter natural behaviors, increase or reduce stereotypes. With these results, we could also increase the number of ingredients used in the feeding of non- ruminant animals, with residues such as sugarcane bagasse or other co-products, reducing the use of corn and soybeans and consequent competition with human consumption and feed costs of the activity.

CONCLUSION:

The use of diets with increasing levels of crude fiber did not change the behavior of laying hens’ chicks at 21 and pullets at 42 days of age.

ACKNOWLEDGEMENTS

To Fundação de Amparo à Pesquisa do Estado de Goiás (FAPEG), Mercoaves Comércio de Aves LTDA, Nutrial Alimentos, Tectron and Escola de Veterinária e Zootecnia da Universidade Federal de Goiás (UFG).

The authors thank CNPq - National Council for Scientific and Technological Development for the undergraduate scientific fellowship granted to the first author and senior researcher fellowship granted to the seventh author.

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