Effect of Ground or Whole Wheat and Triticale on Productive Performance, Egg Quality, Gastrointestinal Tract Traits and Nutrient Digestibility of Laying Japanese Quails

Iranian Journal of Applied Animal Science

مقاله 19، دوره 10، شماره 2، شهریور 2020، صفحه 355-363   

نویسندگان

N. Bakhtiyary Moez؛ S. Mirzaie Goudarzi^* ؛ A.A. Saki؛ A. Ahmadi

Department of Animal Science, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran

چکیده

This study was conducted to investigate the effect of ground or whole wheat and triticale on productive performance, egg quality, gastrointestinal tract (GIT) traits and nutrient digestibility in laying Japanese quails. A total of 210 laying Japanese quails at 18 to 26 weeks of age were used. The experiment was designed as a 2 × 2 + 1 factorial arrangement with five treatments: a control diet was based on corn and soybean meal, two grain sources (wheat and triticale) and two physical forms of grain (ground and whole). Each treatment was replicated 6 times and the experimental unit was a cage with 7 birds each. Egg production, egg weight, egg mass, and feed conversion ratio were not affected by grain source, except for the average daily feed intake (ADFI), which was decreased by triticale but not wheat (P=0513). Average daily feed intake and egg production were higher in the group fed with whole grain versus the group fed with ground grain (p <0.05). Yolk color decreased by wheat or triticale compared with the control group (p <0.05). Relative weights of the liver, proventriculus, pancreas, gizzard and cecum were not affected by any of the treatments. The pH of the jejunum (P=0.0014), cecum (p <0.05), and intestinal viscosity increased (p <0.001) by feeding whole than ground grain. Dry matter digestibility (p <0.01), decreased by triticale but not wheat (p <0.05). In conclusion, ground triticale inclusion in the diet had a negative effect on ADFI, egg production and nutrient digestibility but feeding whole grain improved the productive performance and dry matter digestibility in laying quails.

کلیدواژه‌ها

grain source؛ laying quail؛ nutrient digestibility؛ performance؛ whole grain

اصل مقاله

INTRODUCTION

The important part of feed ingredients as a main source of energy is related to corn in the poultry diet. In Iran, corn production does not provide all feed requirements, so it must be imported. Corn price is increasing because of the limited world yield in covering the demands for both humans and livestock and using part of corn yield in the production of bio-ethanol. Due to limitation corn crop in Iran, approximately 50% of the corn required for poultry nutrition is supplied through the imports. Wheat is also a major feed ingredient in poultry diets and is available in almost all countries of the world. Triticale is more resistant to various diseases and dry weather. Thus, both wheat and triticale have been successfully grown under Iranian conditions (Chizari and Hajiheidary, 2010). The main non-starch polysaccharide (NSP) constituent in the endosperm cell walls of triticale is pentosan with some β-glucan, as in wheat and rye (Engberg et al. 2004). These compounds reduce the nutritive value by increasing gut viscosity and thus reducing the availability of nutrients for digestion and absorption. Ebrahimi et al. (2017) have reported that substitution corn with triticale in quail grower diets (zero, 50 and 100%) didn’t have any adverse effect on the final weight and daily body weight gain as well as improved feed conversion ratio. Whole grain feeding is also attractive as it meets the consumer demand for natural feeding in animal production systems and improved animal welfare (Gabriel et al. 2008). The primary aim of whole grain feeding is to lower feed costs by eliminating the grinding and transport steps. Whole wheat feeding is common in broilers in Europe, Australia, and Canada. In some parts of the world, whole wheat feeding is also used as part of a strategy for broiler breeders and egg layers. Although whole grain is more suited for feeding of adult birds, studies evaluating whole grain feeding in layers are limited (Singh et al. 2014). Whole grain feeding may influence the development and the gastrointestinal tract physiology and consequently nutrient utilization and bird performance. The most importantly interesting to use whole grain feeding is its effect on gizzard development, which is associated with a range of benefits in terms of digestive function (Svihus, 2011). Abdollahi et al. (2016) have shown that pre-pelleting inclusion of whole wheat (250 g/kg) in broilers' diet had greater relative gizzard weights and improved nutrient digestibility. Faruk et al. (2010) have noted that feeding whole wheat (350 g/kg) had no negative effect on performance and in laying hens and increased feed efficiency. Mixed feeding (MF) is also a commonly used method of whole grain feeding. In MF, whole grain is either substituted for a part of the ground grain in a complete diet or added to a complete diet in the same feeder at the same time in pellet or mash form. Mixed feeding allows for simple management without investment in additional feeders and manpower. In recent years, quail production is common in Iran because of its inexpensive rearing requirement, rapid maturation and adaptability to a wide range of environmental conditions (Ebrahimi et al. 2017). There are a lot of traditional quail breeding houses in Iran; hence, producers use whole grain in their diet to eliminate a grinding step. However, available information on the effects of MF on the performance of laying quail is quite limited. Therefore, the aim of this study was to evaluate the effect of ground or whole wheat or triticale inclusion in the diet on productive performance, egg quality, gastrointestinal tract traits and nutrient digestibility of laying Japanese quails from 18 to 26 weeks of age.

 

MATERIALS AND METHODS

Laboratory analysis

Representative samples of corn, wheat, and triticale were grounded using a 1 mm screen laboratory mill (Cyclotech Mill, Tecator, Sweden) followed by chemical analysis using standard methods (AOAC, 1990); for dry matter (method 967.03), total ash (method 942.05), crude protein (method 976.06), and ether extract (method 920.29). Crude fiber (CF) was measured sequentially using a filter bag system (Ankom Technology, Macedon, NY) (Van Soest et al, 1991). Amino acid profiles were estimated by near-infrared spectroscopy (NIRs; Evonik-Degussa, Hanau, Germany). Gross energy was determined using an adiabatic bomb calorimeter (model 1356, Parr Instrument Company, Moline, IL). The geometric mean diameter (GMD) of the experimental diets was determined in 100 g samples using a Retsch shaker (Retsch, Stuttgart, Germany) provided with eight sieves ranging in mesh from 40 to 5000 μm, as described by the American Society of Agricultural Engineers (1995). All analyses were conducted in triplicate. Table 1 shows the chemical composition of these experimental grains.

 

Husbandry and experimental diets

In total, 210 Japanese laying quail (18 weeks of age) with 86 percent egg production and 257.20 g body weight were randomly allocated to 30 cages (100×60 cm²) with nipple drinkers and a trough feeder each. The experiment was conducted as a completely randomized design with 5 treatments, 6 replicates and 7 quails in each. Treatments were as follows: control (basal diet based on ground corn and soybean meal), two grain sources (wheat and triticale) and two physical forms of grain (ground and whole). Wheat or triticale was added as a 20% ground or 10% whole + 10% ground grain. In the current experiment, whole grains were mixed with other ingredients in mash form by the MF method (Singh et al. 2014). The average temperature and relative humidity were maintained in 20-22 ˚C and 50-60%, respectively. The light program consisted of 16 hours of light: 8 hours of dark. Water and feed were offered ad libitum. The diets were formulated to meet the nutrient requirements of the quail as recommended by NRC (1994) (Table 2).

 

Productive performance and egg quality traits

Egg production and egg weight were recorded daily and feed intake was measured weekly. This information was used to calculate ADFI, egg mass and feed conversion ratio (FCR; feed intake/egg mass).

 

Table 1 Analyzed proximate and total amino acid content of the experimental grain sources (%, as fed basis)

 

¹ Estimated by NIR spectroscopy.

 

Table 2 Ingredient and chemical composition of the experimental diets (% as fed basis, unless otherwise indicated)

 

¹ Control: basal diet containing ground corn and soybean meal.

² Wheat was added to the basal diet as 20% ground grain wheat.

³ Wheat was added to the basal diet as 10% whole + 10% ground grain.

⁴ Triticale was added to the basal diet as 20% ground grain triticale.

⁵ Triticale was added to the basal diet as 10% whole + 10% ground grain.

⁶ Mineral premix provided per kilogram of diet: Mn: 70 mg; Fe: 60 mg; Zn: 60 mg; Cu: 8 mg; I: 1.1 mg; Co: 0.15 mg and Se: 0.25 mg.

⁷ Vitamin premix provided per kilogram of diet: vitamin A: 10.000 IU; vitamin D₃: 2.500 IU; vitamin E: 20 mg; vitamin K₃: 2.5 mg; vitamin B₁: 2 mg; vitamin B₂: 5 mg; vitamin B₆: 3.5 mg; vitamin B₁₂: 0.015 mg; vitamin C: 50 mg; Niacin: 30 mg; Pantothenic acid (D-Ca pantothenate): 8 mg; Folic acid: 1 mg; D-biotin: 0.025 mg and Choline (choline chloride): 300 mg.

⁸ Geometric mean diameter ± geometric standard deviation.

 

Egg quality traits were measured using 3 eggs from each replicate at 20, 22, 24 and 26 wk of age. The eggs (3 eggs per replicate were taken after feeding the diets) were individually weighed and the egg external (egg weight, shape index, shell weight, and shell thickness) and internal quality (yolk index, yolk color, and Haugh unit) were measured. The shell was separated from the yolk and albumen, dried overnight at 60 ˚C and weighed (Grobas et al. 2001). Egg shell thickness was measured using a digital micrometer (Echometer 1061, Robotmation Company, Tokyo, Japan). Egg shell ratio was calculated by dividing shell weight to egg weight. The Haugh unit was calculated by using the egg weight (g) and albumen height (AH/mm) (Haugh, 1937).

 

Internal organ weights, pH of the GIT and intestinal viscosity

At 26 weeks of age, two birds per replicate were randomly selected, weighed individually, and euthanized using thiopental sodium (15 mg/kg of body weight, Sandoz GmbH, Kundl, Austria). The liver, proventriculus, pancreas, gizzard and cecum were weighed and expressed as the percentage of live body weight. The digesta pH of the gizzard, jejunum, ileum, and cecum was measured using a digital pH meter (Corning Glass Works, Medfield, MA), as described by Pang and Applegate (2007). For viscosity analysis, approximately 3 g (wet weight) of the fresh digesta were immediately placed in a microcentrifuge tube and centrifuged (12000×g) for 5 min. The viscosity of non-diluted supernatants was measured at 25 ˚C using a digital viscosimeter (Brookfield Engineering, Stoughton, MA, USA). Viscosity was expressed as centipoises (cP) (Khoramabadi et al. 2014).

 

Nutrient digestibility

At 26 weeks of age, chromium oxide was added at 5 g/kg to the experimental diets as an indigestible marker. The metabolism trial was composed of a 3 d preliminary adaptation period, followed by 2 d of excreta collection. Representative samples of excreta were dried (60 ˚C for 72 h), homogenized, and grounded (1 mm). Dry matter and crude protein digestibility and AMEn of the diets were determined as indicated by Garcia et al. (2008).

 

Statistical analysis

This experiment was conducted as a completely randomized design with 5 treatments in a 2 × 2 + 1 factorial arrangement and the main effects were analyzed by ANOVA using the GLM procedure of SAS (2004). The model included the control diet, two grain sources (wheat and triticale) and two physical forms of grains (ground and whole) as main effects. When the main effects were significant, the Duncan test was used to make pairwise comparisons among sample means. All differences were considered significant at P ≤ 0.05.

 

RESULTS AND DISCUSSION

Productive performance and egg quality traits

For the entire experimental period, egg production, egg weight, egg mass, and FCR were not affected by grain source, except for the ADFI which was decreased with triticale but not wheat (P=0.0513). Average daily feed intake and egg production were higher in whole grain versus ground grain (P<0.05). The birds that fed with ground triticale had the lowest ADFI (P<0.05) and egg production (P<0.001) compared to other birds (Table 3). Zarghi and Golian (2009) reported that the poorer FCR of the triticale-fed birds might be due to lower nutrient amounts, limited nutrient availability, or higher anti-nutritional factors such as soluble pentosans, trypsin inhibitor, and pectin content. Consistent with these results, Ebrahimi et al. (2017) reported that corn substitution by triticale in the quail grower diets reduced feed intake. Triticale-based diets contained higher amounts of soluble arabinoxylans as well as total NSP and crude fiber in comparison with wheat, which was also reflected in higher ileal chyme viscosities (Jozefiak et al. 2007). In addition, Ciftci et al. (2003) reported that there were no significant effects of grain type (triticale, wheat or corn) on egg weight, egg mass, or feed efficiency of laying hens. Abdel Wahed et al. (2010) reported that egg weight, egg mass, and FCR were not affected when corn was replaced with triticale in laying Japanese quail diets. Senkoylu et al. (2009) showed that the inclusion of whole grain wheat in the laying hen diets improved productive performance compared to the ground grain wheat. These researchers also observed that feed intake increased with whole grain, which could be due to selective feeding of birds, in agreement with the data reported herein. Egg quality was not affected by grain type or their physical form (Table 4), which is in agreement with results of Jamroz et al. (2001), who did not observe any effect of grain source on egg quality in hens fed diets based on wheat, barley, or triticale. The yolk color in birds, that consumed control diet was significantly higher than other groups (P<0.05), which might be due to the difference in levels of corn gluten meal used in corn than wheat and triticale diets (2.96 vs. 2.30 and 0.87%, respectively). The lower color of yolk can be due to the lack of carotenoids in wheat and triticale diets relative to corn, as reported by Roberts et al. (2007). In the current study, feeding quails with ground triticale decreased the Haugh unit.

 

Table 3 Influence of whole or ground wheat and triticale on productive performance of laying Japanese quails from 18 to 26 weeks of age

 

ADFI: Average daily feed intake and FCR: feed conversion ratio.

The means within the same column with at least one common letter, do not have significant difference (P>0.05).

SEM: standard error of the means.

 

Table 4 Influence of whole or ground wheat and triticale on egg quality from 18 to 26 weeks of age¹

 

¹ Data represent means based on 5 replicates per treatment, 3 eggs per replicate.

SEM: standard error of the means.

 

Abdel Wahed et al. (2010) have reported similar results that the substitution of corn by triticale decreased Haugh unit in laying Japanese quail. However, insignificant differences were detected in other egg quality characteristics as compared to the control diet. In the current study, the physical form of grain did not affect egg weight, shape index, yolk index, Haugh unit, shell weight, shell ratio and shell thickness. Haugh unit was increased with whole than ground triticale (P<0.05), which could be due to increased albumen height.

 

Internal organ weights, pH of the GIT and intestinal viscosity

Relative weights of the liver, proventriculus, pancreas, gizzard, and cecum were not affected by grain type, physical form of grain or dietary treatments (Table 5). Ebrahimi et al. (2017) reported that triticale inclusion in the quail s’ grower diets decreased the relative weight of crop and proventriculus at 21 days of age. This decrease can be associated with reduced feed intake. The relative weight of the small intestine increased with increasing levels of triticale in the diet that might be influenced by an increase in the activity of this organ in response to higher levels of dietary NSP. There is mounting evidence that gizzard responds rapidly to changes in the diet, particularly to changes in insoluble fiber and particle size (Svihus, 2011). The extent to which gizzard weight may increase in different experiments is probably due to different degrees of grain hardness, bird genotypes, and nutritive values of feeds used in the control group. The lack of the effect on gizzard size and gut-segments might probably be related to the age (18 to 26 weeks of age) of quails used in the current study, as they were already mature in terms of their body development. It is clear that gastrointestinal development occurs during the early stages of life (Uni et al. 1998). These results are similar to those of Konca and Beyzi (2013) who reported that feeding of quails with triticale or wheat had no effect on the weight of total GIT, liver, small intestine and heart. Ciftci et al. (2003) also reported that relative weights of pancreas, crop, proventriculus, gizzard, and cecum were not affected by grain type (triticale, wheat and corn) in laying hens. Senkoylu et al. (2009) observed that whole wheat supplemented with or without xylanase had no significant effect on gizzard weight in laying hens. Wu and Ravindran (2004b) and Ravindran et al. (2006) did not observe any change in relative weights of gizzard with the inclusion of whole wheat, consistent with the results reported herein. The pH of different segments of the GIT was not affected by the grain source. However, the pH of the jejunum (P<0.01) and cecum (P<0.05) significantly increased by whole grain than with ground grain )Table 6). In the current experiment, increased intestinal pH might be related to a higher intake of whole grain than ground grain (Svihus, 2014). Also, the feeding of coarse particle size seemed to stimulate pancreatic secretions. An increased pancreatic bicarbonate secretion may therefore partly explain the higher intestinal pH values observed in this diet (Engberg et al. 2002). In agreement with our study, Mirzaie et al. (2012) reported that digesta pH of different organs of the GIT was not affected by wheat inclusion in laying hens. Frikha et al. (2011) did not find any effect of wheat inclusion in substitution of corn on gizzard pH in 120-d-old pullets. The effect of whole wheat feeding on the pH of intestinal contents is also contradictory (Singh et al. 2014). Senkoylu et al. (2009) reported that the inclusion of whole wheat into the diets of laying hens decreased gizzard pH from 4.68 (control) to 4.35 (whole wheat), that disagreed with our findings. Intestinal viscosity was not affected by grain source, but it was increased with whole than ground grain (P<0.01). Also, intestinal viscosity was lower for control than other treatments (P<0.01; Table 6). Ciftci et al. (2003) reported that intestinal viscosity was significantly affected by grain type (triticale, wheat and corn) in laying hens. Soluble NSP content of grains increases digesta viscosity, which reduces intestinal passage time and availability of nutrients. In agreement with the data reported herein, Wu et al. (2004a) showed that whole wheat increased digesta viscosity in the duodenum and jejunum of broilers fed diets containing 20% whole wheat. Whole wheat feeding may also influence the feed passage rate and digesta viscosity but published data on these aspects are limited. Engberg et al. (2004) also reported that whole wheat feeding increased digesta viscosity.

 

Table 5 Influence of whole or ground wheat and triticale on relative weight (% BW) of internal organs of laying Japanese quails at 26 weeks of age

 

SEM: standard error of the means.

 

Table 6 Influence of whole or ground wheat and triticale on the pH of the organs of the gastrointestinal tract and intestinal viscosity of laying Japanese quails at 26 weeks of age

 

The means within the same column with at least one common letter, do not have significant difference (P>0.05).

SEM: standard error of the means.

 

Table 7 Influence of whole or ground wheat and triticale on nutrient digestibility and AMEn content of the experimental diets

 

AMEn: apparent metabolizable energy corrected by nitrogen.

The means within the same column with at least one common letter, do not have significant difference (P>0.05).

SEM: standard error of the means.

 

In contrast, Konca and Beyzi (2013) reported that choice feeding with triticale and wheat to quail had no effect on intestinal viscosity. The degree of digesta viscosity is dependent upon the amount of NSP, which varies among grains (Amerah et al. 2007).

 

Nutrient digestibility

Dry matter digestibility (P<0.01) and AMEn of the diet (P<0.05) were higher for birds fed with wheat than for triticale. Nutrient digestibility and AMEn were not affected by the physical form of grain. Dry matter digestibility significantly decreased by ground triticale than with other treatments (P<0.05). Also, AMEn of the diet was higher for control than for other treatments (P<0.01). The use of high viscosity grains such as rye, barley, oat, triticale, and wheat in the diet increases the viscosity of the digestive tract content of birds. These conditions reduce nutrient release, digestibility and absorption capacity and, consequently, loss of yield. Low nutrient digestibility of triticale may be more related to NSP as it has been reported, the use of triticale in feeding poultry is limited due to the presence of NSP, especially those of xylane and arabinoxylan. These compounds reduce the nutritional value of triticale by increasing the viscosity of the digestive system and consequently reducing the availability of nutrients for digestion and absorption. Several authors have suggested that the improvement in nutrient utilization with diets containing whole wheat was partially due to an increase in starch digestibility. Consistent with the current results about the improvement of DM digestibility by whole than ground grain, Svihus et al. (2004) reported that the inclusion of 375 g/kg whole wheat significantly increased starch digestibility. Preston et al. (2000) also reported an increase in AME when ground wheat was replaced by whole wheat in broiler diet, whereas Uddin et al. (1996) found no differences when two wheat cultivars were fed ground or whole at different levels (100-400 g/kg) to broiler chickens from 19 to 27 days. An improvement of AMEn and amino acid digestibility with whole wheat may be due to a slower passage rate of large feed particles through the gizzard (Nir et al. 1994) and increased exposure to hydrolytic digestion in the gizzard. Amerah et al. (2012) observed that inclusion of whole wheat (100 and 200 g/kg) increased ileal protein digestibility, but had no effect on apparent ileal digestible energy. Biggs and Parsons (2009) reported that birds fed whole wheat had increased AMEn at 4, 7, 14 and 21 days of age and amino acid digestibility also increased at 21 days. No improvement with whole grain on AMEn might be caused by the low level of whole grain used in the quail s' diet in the current research.

 

CONCLUSION

The results of this study have indicated that triticale inclusion in the diet had a negative effect on feed intake, egg production, nutrient digestibility and AMEn of the diet compared to wheat which was pronounced for ground form. The feeding of whole grain in mixed feeding, improved feed intake, egg production and dry matter digestibility compared with ground form. The yolk color in birds, that consumed wheat and triticale was lower than the control group. Haugh unit increased by the inclusion of whole triticale in the diet.

 

ACKNOWLEDGEMENT

Our special thanks to Bu Ali Sina University for providing facilities and financial support for this study.

مراجع

Abdel Wahed H.M., Namra M.M.M. and Ragab M.S. (2010). Triticale grains as substitute for yellow corn in laying Japanese quail diets. Egyptian J. Nutr. Feeds. 13, 563-576.

Abdollahi M.R., Ravindran V. and Amerah A.M. (2016). Influence of partial replacement of ground wheat with whole wheat and exogenous enzyme supplementation on growth performance, nutrient digestibility and energy utilization in young broilers. J. Anim. Physiol. Anim. Nutr. 100, 929-937.

Amerah A.M., Peron A., Zaefarian F. and Ravindran V. (2012). Influence of whole wheat inclusion and a blend of essential oils on the performance, nutrient utilization, digestive tract development and ileal microbiota profile of broiler chickens. British Poult. Sci. 52, 124-132.

Amerah A.M., Ravindran V., Lentle R.G. and Thomas D.G. (2007). Feed particle size: Implications on the digestion and performance of poultry. World's Poult. Sci. J. 63, 439-455.

American Society of Agricultural Engineers. (1995). ASAE Standard: ASAE S319. Method of Determining and Expressing Fineness of Feed Materials by Sieving. Agricultural Engineers Yearbook. St. Joseph, Michigan.

AOAC. (1990). Official Methods of Analysis. Vol. I. 15^th Ed. Association of Official Analytical Chemists, Arlington, VA, USA.

Biggs P. and Parsons C.M. (2009). The effects whole grains on nutrient digestibilities, growth performance, and cecal short chained fatty acid concentrations in young chicks fed ground corn soybean meal diets. Poult. Sci. 88, 1893-1905.

Chizari A. and Hajiheidary M. (2010). The effects of market factors and government policies on maize marketing in Iran. African J. Agric. Res. 5(12), 1351-1359.

Ciftci I., Yenice E. and Eleroglu H. (2003). Use of triticale alone and combination with wheat or maize: Effects of diet type and enzyme supplementation on hen performance, egg quality, organ weights, intestinal viscosity and digestive system characteristics. Anim. Feed Sci. Technol. 105, 149-161.

Ebrahimi E., Sobhani Rad S. and Zarghi H. (2017). Effect of triticale level and exogenous enzyme in the grower diet on performance, gastrointestinal tract relative weight, jejunal morphology and blood lipids of Japanese quail (Coturnix coturnix Japonica). J. Agric. Sci. Technol. 19, 569-580.

Engberg R.M., Hedemann M.S. and Jensen B.B. (2002). The inf uence of grinding and pelleting of feed on the microbial composition and activity in the digestive tract of broiler chickens. British Poult. Sci. 44, 569-579.

Engberg R.M., Hedemann M.S., Steenfeldt S. and Jensen B.B. (2004). Influence of whole wheat and xylanase on broiler performance and microbial compositionand activity in the digestive tract. Poult. Sci. 83, 925-938.

Faruk M.U., Bouvarel I., Même N., Rideau N., Roffidal L., Tukur H.M., Bastianelli D., Nys Y. and Lescoat P. (2010). Sequential feeding using whole wheat and a separate protein-mineral concentrate improved feed efficiency in laying hens. Poult. Sci. 89, 785-796.

Frikha M., Safaa H.M., Serrano M.P., Jimenez-Moreno E., Lazaro R. and Mateos G.G. (2011). Influence of the main cereal in the diet and particle size of the cereal on productive performance and digestive traits of brown-egg laying pullets. Anim. Feed Sci. Technol. 164, 106-115.

Gabriel I., Mallet S., Leconte M., Travel A. and Lalles J.P. (2008). Effects of whole wheat feeding on the development of the digestive tract of broiler chickens. Anim. Feed Sci. Technol. 142, 144-162.

Garcia M., Lazaro R., Latorre M., Gracia M. and Mateos G.G. (2008). Influence of enzyme supplementation and heat processing of barley on digestive traits and productive performance of broilers. Poult. Sci. 87, 940-948.

Grobas S., Mendez J., Lazaro R., de Blas C. and Mateos G.G. (2001). Influence of source and percentage of fat added to diet on performance and fatty acid composition of egg yolks of two strains of laying hens. Poult. Sci. 80, 1171-1179.

Haugh R.R. (1937). The Haugh unit for measuring egg quality. US Egg Poult. Mag. 43, 522-555.

Jamroz D., Skorupinska J., Orda J., Wiliczkiewicz A. and Klunter A.M. (2001). Use of wheat, barley or triticale in feed for laying hens supplemented with carbohydrases derived from trichoderma longibrachiaturn. J. Appl. Anim. Res. 19, 107-116.

Jozefiak D., Rutkowski A., Jensen B.B. and Engberg R.M. (2007). Effects of dietary inclusion of triticale, rye and wheat and xylanase supplementation and xylanase supplementation on growth performance of broiler chickens and fermentation in the gastrointestinal tract. Anim. Feed Sci. Technol. 132, 79-93.

Khoramabadi V., Akbari M.R., Khajali F., Noorani H. and Rahmatnejad E. (2014). Influence of xylanase and vitamin A in wheat-based diet on performance, nutrients digestibility, small intestinal morphology and digesta viscosity in broiler chickens. Acta Sci. Anim. Sci. 36, 379-384.

Konca Y. and Beyzi S.B. (2013). Effect of free choice feediong based on emmer, triticale and wheat to Japanese quail (Coturnix coturnix japonica) on performance, inner organs and intestinal viscosity. Anim. Sci. 56, 113-119.

Mirzaie S., Zaghari M., Aminzadeh S., Shivazad M. and Mateos G.G. (2012). Effects of wheat inclusion and xylanase supplementation of the diet on productive performance, nutrient retention, and endogenous intestinal enzyme activity of laying hens. Poult. Sci. 91, 413-425.

Nir I., Hillel R., Shefet G. and Nitsan Z. (1994). Effect of grain particle size on performance. 2. Grain texture interactions. Poult. Sci. 73, 781-791.

NRC. (1994). Nutrient Requirements of Poultry, 9^th Rev. Ed. National Academy Press, Washington, DC., USA.

Pang Y. and Applegate T. (2007). Effects of dietary copper supplementation and copper source on digesta pH, calcium, zinc, and copper complex size in the gastrointestinal tract of the broiler chicken. Poult. Sci. 86, 531-537.

Preston C.M., McCracken K.J. and McAllister A. (2000). Effect of diet form and enzyme supplementation on growth, efficiency and energy utilisation of wheat-based diets for broilers. British Poult. Sci. 41, 324-331.

Ravindran V., Wu Y.B., Thomas D.G. and Morel P.C.H. (2006). Influence of whole wheat feeding on the development of digestive organs and performance of broiler chickens. Australian J. Agric. Res. 57, 16-21.

Roberts S.A., Xin H., Kerr B.J., Russell J.R. and Bregendahl K. (2007). Effect of dietary fiber and reduced crude protein on nitrogen balance and egg production in laying hens. Poult. Sci. 86, 1716-1725.

SAS Institute. (2004). SAS^®/STAT Software, Release 9.4. SAS Institute, Inc., Cary, NC. USA.

Senkoylu N., Samli H.E., Akyurek H., Okur A.A. and Kanter M. (2009). Effects of whole wheat with or without ylanase supplementation on performance of layers and digestive organ development. Italian J. Anim. Sci. 8, 155-163.

Singh Y., Amerah A.M. and Ravindran V. (2014). Whole grain feeding: Methodologies and effects on performance, digestive tract development and nutrient utilization of poultry. Anim. Feed Sci. Technol. 190, 1-18.

Svihus B. (2011). The gizzard: Function, influence of diet structure and effects on nutrient availability. World's Poult. Sci. J. 67, 207-224.

Svihus B. (2014). Function of the digestive system. J. Appl. Poult. Res. 23, 306-314.

Svihus B., Juvik E., Hetland H. and Krogdahl A. (2004). Causes for improvement in nutritive value of broiler chicken diets with whole wheat instead of ground wheat. British Poult. Sci. 45, 55-60.

Uddin M., Rose S.P., Hiscock T.A. and Bonnet S. (1996). A comparison of the energy availability for chickens of ground and whole grain samples of two wheat varieties. British Poult. Sci. 37, 347-357.

Uni Z., Ganot S. and Sklan D. (1998). Posthatch development of mucosal function in the broiler small intestine. Poult. Sci. 77, 75-82.

Van Soest P.J., Robertson J.B. and Lewis A. (1991). Methods for dietary fiber, neutral detergent fiber, and non-starch polysaccharides in relation to animal nutrition. J. Dairy Sci. 74, 3583-3597.

Wu Y.B., Ravindran V., Thomas D.G., Birtles M.J. and Hendriks W.H. (2004a). Influence of method of whole wheat inclusion and xylanase supplementation on the performance, apparent metabolisable energy, digestive tract measurements and gut morphology of broilers. British Poult. Sci. 45, 385-394.

Wu Y.B. and Ravindran V. (2004b). Influence of whole wheat inclusion and xylanase supplementation on the performance, digestive tract measurements and carcass characteristics of broiler chickens. Anim. Feed Sci. Technol. 116, 129-139.

Zarghi H. and Golian A. (2009). Effect of triticale replacement and enzyme supplementation on performance and blood chemistry of broiler chickes. J. Anim. Vet. Adv. 8(7), 1316-1321.