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Influence of graded levels of brewers dried grains on pellet quality and performance in broiler chickens
Research Notes Influence of graded levels of brewers dried grains on pellet quality and performance in broiler chickens V. Denstadli,*1 S. Ballance,† S. H. Knutsen,† B. Westereng,‡ and B. Svihus* *Aquaculture Protein Centre, Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, PO Box 5003, N-1432 Aas, Norway; †Norwegian Institute of Food, Fisheries and Aquaculture Research, Oslovn. 1, N-1430 Aas, Norway; and ‡Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, PO Box 5003, N-1432 Aas, Norway ABSTRACT The aim of the current study was to evaluate the effect of a gradual substitution of wheat and soy with brewers dried grains (BDG) on pellet quality, performance, and organ weights in broiler chickens. Five diets were formulated in which 0, 10, 20, 30, or 40% BDG replaced wheat and soy, with a concomitant gradual reduction in the calculated AME level. Each of the 5 experimental diets was fed to 12-d-old broiler chickens (Ross 308) kept in 6 pens, with 12 birds/pen. The birds had ad libitum access to feed and water until termination of the experiment at d 33. Feed intake was not affected by BDG inclusion and compensatory feed intake did not occur, perhaps having been neutralized by a significant (P < 0.001) reduction in the pellet durability index. The pellet durability index was 85% in the control diet (0% BDG) and decreased significantly
(P < 0.001) to 68% in the diet with 40% BDG. Increased levels of BDG reduced BW gain significantly (P < 0.001) and led to a significant (P < 0.001) increase in the feed:gain ratio. The feed:gain ratio was significantly (P < 0.05) higher in birds fed 30 and 40% BDG compared with birds fed 0, 10, and 20% BDG. The apparent ileal digestibility values of protein and energy were significantly reduced by BDG inclusion (P < 0.01 and P < 0.001, respectively), whereas starch digestibility increased significantly (P < 0.001). The relative gizzard weight increased significantly (P < 0.001), whereas the relative cecal weights were not affected by BDG inclusion. To conclude, 10 to 20% inclusion of BDG supports acceptable growth and feed utilization, and favors the development of a well-functioning gizzard.
Key words: brewers dried grains, chicken, gizzard development, nutrient utilization, pellet quality 2010 Poultry Science 89:2640–2645 doi:10.3382/ps.2010-00724
INTRODUCTION Brewers spent grain (BSG) is the main waste product from beer production and accounts approximately 20 kg/100 L of beer produced (Mussatto et al., 2006). With a global production of 150 to 160 billion L of beer per year, the supply of BSG amounts to approximately 30 million metric tons. The fate of BSG is diverse, ranging from charcoal and brick production to animal feed (Mussatto et al., 2006). In the Nordic countries, it is often given away and used as feed for cattle, or, if there is a demand, it may be sold at prices of up to 20 euros/ metric ton. However, the storage stability of BSG represents a challenge. Not only is the DM content low (20 to 25%), but the microbial activity is also high; thus, it ©2010 Poultry Science Association Inc. Received February 23, 2010. Accepted August 29, 2010. 1 Corresponding author: [email protected]
may deteriorate quite rapidly if not conserved as silage or dried to obtain storage stability. Compared with distillers dried grains with solubles (DDGS), dry BSG or brewers dried grains (BDG) contain less protein and more fiber (NRC, 1994). During the last decade, interest has been growing in the functions and properties of the avian gizzard and how it is affected by feed structure and dietary fiber (DF). Trials have shown that dilution of concentrated diets with, for example, oat hulls has had positive effects on gizzard activity, which in turn may improve performance (Hetland et al., 2003). Studies have also shown that gizzard stimulation, and thus pH reduction, can prevent the entrance of pathogenic bacteria into the digestive tract (Bjerrum et al., 2005). The aim of this study was to evaluate the effects of a graded substitution of wheat and soy with BDG. Pellet quality, feed intake, growth performance, ileal digestibilities, and gizzard development were the main responses in the current trial.
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MATERIALS AND METHODS Diets Before feed production, fresh BSG was collected from Ringnes brewery (Gjellerudaasen, Norway) and subsequently air-dried to approximately 87% DM using a local hay barn dryer. Fresh BSG was placed on a sheet of open textile fiber with moving air from below at ambient temperature (15 to 20°C). The chemical composition of BDG is shown in Table 1. Five diets with graded levels of BDG (0, 10, 20, 30, and 40%; Table 2) were produced at the Centre for Feed Technology, Norwegian University of Life Sciences (Aas, Norway). The fish meal and soybean oil contents were kept constant, whereas BDG replaced wheat and soy. The diets had a constant AME:protein ratio, but with a gradual decrease in calculated AME as the inclusion of BDG increased. Amino acids were supplemented and balanced for each diet to exceed NRC (1994) requirements. The ingredients were ground through a 3-mm sieve in a Münch hammer mill (Münch, Wuppertal, Germany) and mixed before conditioning (77 to 78°C) and pelleting (84 to 86°C) in a Münch pellet press. The pellet diameter was 3 mm. Feed samples used for further analyses were collected at the beginning, middle, and end of each pelleting process.
Bird Management and Sampling Day-old male broiler chickens (Ross 308) were placed in litter-floored pens (75 × 150 cm) with wood shavings and fed a commercial starter diet until 12 d of age. The starter was a wheat- and soy-based diet with 23.5% CP and with ME of 2,910 kcal/kg. At 12 d of age, 360 birds with an average BW of 354 g (range: 328 to 380 g), were randomly assigned to 10 pens/room (12 birds/pen), in 3 windowless rooms, with 30 pens in total. Each experimental diet was fed to 2 pens/room by using of automatic feeders. Feed and water were provided ad libitum. From d 12, the temperature was
Table 1. Chemical composition of brewers dried grains1 Amount (g/100 g)
Item DM CP Crude fat Starch Nonstarch polysaccharides Rhamnose Fucose Arabinose Xylose Mannose Galactose Glucose Ash 1Two 2ND
replicates (n = 2) per analysis. = not detected (below the detection limit).
87.4 20.9 9.0 8.1 34.3 ND2 ND 7.7 15.0 0.7 1.3 10.4 3.0
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kept constant at 23 to 24°C, and the birds were exposed to 6 h of darkness (0000 to 0600 h). At 33 d of age, the birds were killed by placing them in an air-proof container to which concentrated food-grade CO2 was added. The birds were killed within 1 min; this procedure was approved by the ethical committee at the Norwegian University of Life Sciences. Four birds per pen were dissected for collection of ileal contents, from Meckel’s diverticulum to the ileo-ceco-colonic junction. The samples from each pen were pooled and frozen immediately after collection (−20°C). In addition, the gizzard and ceca were dissected out, cleaned of visceral fat, and weighed without contents.
Pellet Durability Pellet durability was determined with a Holmen pellet tester (Borregaard LignoTech, Hull, UK). A 100-g sample of sieved, unbroken pellets was pneumatically conveyed through a cylinder loop for 1 min. The pellet durability index (PDI) was calculated as the percentage of unbroken pellets remaining after sieving the tested sample on a 2.5-mm sieve.
Chemical Analyses and Calculations Frozen ileal samples were freeze-dried and ground before analysis. The DM of feed was determined by drying at 105°C for 16 h, and dietary and ileal ash contents were determined by combustion at 550°C for 16 h. The constituent sugars of BDG were determined as alditol acetates after acid hydrolysis (Vestby et al., 2009). Starch content in feed and ileal contents were determined enzymatically following the procedure of McCleary et al. (1994), CP was determined as Kjeldahl-N × 6.25 (AOAC, 2003; method 981.10) on a Kjeltech 2300 instrument (Foss Tecator, Höganäs, Sweden), and crude fat was determined after extraction with petroleum ether and acetone (4:1 ratio) on an Accelerated Solvent Extractor (ASE200, Dionex, Sunnyvale, CA). Gross energy in diets and ileal samples was determined with a Parr 1281 Bomb Calorimeter (Parr Instrument Company, Moline, IL). The concentration of titanium dioxide in diets and ileal samples was determined as described by Short et al. (1996). Nonstarch polysaccharides in all diets were determined as described by Englyst et al. (1994). The apparent ileal digestibility was calculated as 100 − {100 × [(Dm × Im−1) × (In × Dn−1)]}, where Dm and Im represent the concentration of inert marker in diet and ileal contents, and Dn and In represent the concentration of nutrients in diet and ileal contents, respectively.
Statistical Analyses Orthogonal polynomial contrasts were used to test the linear and quadratic effects of a gradual substitution of BDG with wheat and soy in diets for broiler chickens (SAS Institute, 2002). After one-way ANOVA,
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Table 2. Diet formulation and chemical
composition1 BDG2 inclusion (%)
Item Ingredient (g/kg) Wheat Soybean meal3 BDG Fish meal Soybean oil Vitamin and mineral premix4 Choline chloride l-Lysine dl-Methionine l-Threonine NaCl Limestone Monocalcium phosphate Titanium dioxide5 Calculated AME6 (kcal/kg) Analyzed value DM (g/100 g) CP (g/100 g) Starch (g/100 g) Crude fat (g/100 g) Nonstarch polysaccharides7 (g/100 g) Rhamnose Fucose Arabinose Xylose Mannose Galactose Glucose Ash (g/100 g) Gross energy (kcal/kg)
0
10
631 210 0 60 41.6 3.1 1.3 3 3 1 3 20 17 5 2,920
576 167 100 60 41.3 3.1 1.3 3.15 2.65 1 3 20 17 5 2,860
88.8 22.6 36.1 5.88 10.4 (8.1) ND8 ND 2.6 (2.0) 3.4 (2.5) 0.3 (0.2) 1.3 (0.8) 2.9 (2.5) 6.6 4.01
88.9 22.0 33.9 6.68 13.4 (10.7) ND ND 3.2 (2.5) 4.7 (3.9) 0.3 (0.2) 1.4 (0.7) 3.8 (3.3) 6.7 4.08
20 520 123 200 60 41.2 3.1 1.3 3.3 2.3 1 3 20 17 5 2,800 88.9 21.6 31.2 7.10 15.3 (12.7) ND ND 3.5 (2.9) 5.3 (4.9) 0.4 (0.3) 1.4 (0.7) 4.7 (4.0) 6.6 4.13
30 465 78.3 300 60 41.1 3.1 1.3 3.45 1.95 1 3 20 17 5 2,750 89.7 21.1 28.7 7.70 18.1 (17.6) ND ND 4.2 (3.9) 6.8 (7.0) 0.4 (0.3) 1.3 (0.7) 5.3 (5.7) 6.7 4.23
40 404 39 400 60 41 3.1 1.3 3.6 1.6 1 3 20 17 5 2,680 89.8 19.6 29.0 8.71 20.8 (17.8) ND ND 4.3 (4.0) 8.3 (7.4) 0.4 (0.3) 1.1 (0.6) 6.8 (5.4) 6.3 4.23
1Two
replicates (n = 2) per analysis. dried grains. 3Solvent extracted. 4Provided the following per kilogram diet: Fe, 75 mg; Mn (MnSO ), 60 mg; Zn (ZnSO ), 105 mg; Cu (CuSO ), 15 mg; I, 0.75 mg; Se (NaSe), 0.3 4 4 4 mg; vitamin A, 2,700 IU; vitamin D3, 1,800 IU; dl-α-tocopheryl acetate, 123 IU; menadione (vitamin K3), 5.36 mg; pyridoxine (vitamin B6), 10.8 mg; riboflavin (vitamin B2), 13.5 mg; Ca-pantothenate (vitamin B5), 54 mg; biotin (vitamin B7), 0.36 mg; thiamine (vitamin B1), 3.6 mg; niacin (vitamin B3), 18 mg; vitamin B12, 0.02 mg; folic acid (vitamin B9), 2.7 mg. 5Titanium dioxide (Kronos Titan A/S, Fredrikstad, Norway). 6NRC (1994). 7Total nonstarch polysaccharides (values in parentheses are insoluble nonstarch polysaccharide values). 8ND = not detected (below the detection limit). 2Brewer’s
the mean values were ranked using Duncan’s multiple range test (SAS Institute, 2002), and the level of significance used was 0.05 for all tests.
RESULTS Pelleting diets with up to 40% BDG did not cause any problems during feed production, and the setup of the conditioner and pellet press was kept similar for all diets. The Holmen durability test showed that inclusion of BDG reduced the physical quality of the pellets significantly (P < 0.001). The PDI was acceptable for diets with 10 and 20% BDG, whereas the PDI decreased significantly when more than 20% BDG was incorporated into the diets (Table 3). The feed production was not repeated, but the durability test was performed on samples collected 3 times for each diet (beginning, middle, and end of production).
The mortality was 2.8, 5.6, 4.2, and 0% in birds fed diets with 0, 10, 20, 30, and 40% BDG, respectively. There was no significant effect of BDG inclusion on feed intake, whereas there was a significant linear (P < 0.001) reduction in BW gain as the dietary inclusion of BDG increased (Table 3). Thus, from these data, the feed:gain ratio increased significantly when increasing levels of BDG replaced wheat and soy. The feed:gain ratio was 1.45 in the control group (0% BDG), whereas it increased to 1.69 in the group of birds fed diets with 40% BDG. The feed:gain ratio was significantly higher in birds fed 30 and 40% BDG compared with groups fed 0, 10, and 20% BDG. The relative weight of the gizzards increased gradually as the inclusion of BDG increased, reaching a plateau at 30 and 40% BDG inclusion (Table 3). No significant effect of BDG on the relative weight of ceca was found (Table 3).
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The ileal digestibility of starch increased significantly with increased dietary BDG inclusion, from 94% in the control diet to 98% in the diet with 40% BDG. The ileal digestibility of protein and energy decreased significantly when BDG replaced wheat and soy. The apparent availability of ash decreased significantly from 33% in the control diet to 11% in birds fed the diet with 40% BSG.
in line with the report of Leeson et al. (1996), in which broilers fed grower diets diluted with oat hulls and sand displayed a significant compensatory feed intake. The control diet (0% BDG) and the diet with 40% BDG differed by only 8% for the calculated AME level in our study, whereas in the study by Leeson et al. (1996), the diets differed by 40% for AME level. In a study by Hetland and Svihus (2001), diets diluted with 10% oat hulls resulted in a significant increase in feed intake. Our data also disagree with the report by Onifade and Babatunde (1998) in which broilers fed 10 and 20% BDG increased their feed intake to compensate for differences in nutrient density. The reason for a lack of compensation in the present study could have been due to the reduction in pellet durability. Several reports have shown increased feed intake when birds have been offered diets with good pellet quality rather than poor pellet quality (McKinney and Teeter, 2004; Quentin et al., 2004; Lemme et al., 2006). Consequently, it may be that the dietary difference in nutrient density was more or less neutralized by the reduced pellet durability in the current trial. A general reduction in feed utilization was expected as the nutrient density declined with increasing levels of BDG, and our data support previous studies with BDG-fed chickens (Ademosun, 1973; Lopez and Carmona, 1981; Onifade and Babatunde, 1998). However, inclusion levels of 10 and 20% BDG increased the feed:gain ratio by only 2 and 4%, respectively, and did not give a feed:gain ratio that differed significantly (P < 0.05) from the control (0% BDG; Table 3). Similarly, Lumpkins et al. (2004) found that inclusion of 12 to 15% DDGS from corn did not reduce feed efficiency in broilers. It is well known that structural components and fibrous material stimulate the gizzard, and these may activate the secretion of pancreatic enzymes and bile acids (Hetland et al., 2003; Svihus et al., 2004),
DISCUSSION Insoluble fiber is generally assumed to reduce pellet durability because of its resilient and rigid properties (Thomas et al., 1998), which in turn allows less interaction with other feed-borne nutrients and water. The content of insoluble fiber increased gradually in the BDG diets, and the diet with 40% BDG contained approximately 100% more insoluble nonstarch polysaccharides than the control diet (0% BDG). Moreover, BDG contains more lignin and cellulose than wheat and soy (Serena and Knudsen, 2007); therefore, the total DF content would have been even higher in the BDG diets. Protein also influences pellet durability, and in a study by Briggs et al. (1999), the authors concluded that increased amounts of intact protein had a positive effect on pellet durability. Moreover, a study by Wood (1987) showed that raw proteins were preferable to denatured proteins in the formation of durable pellets. Processes such as malting and mashing induce protein denaturation (Jones, 2005), which in turn could have affected pellet durability negatively in the BDG diets. Consequently, the reduced pellet quality in the BDG diets was probably due to lower levels of intact protein as well as increased levels of insoluble fiber. As the inclusion of BDG increased, the birds did not compensate for the reduced dietary AME levels by adjusting their feed intake. This was unexpected and not
Table 3. Performance, organ weights, apparent ileal digestibility values, and pellet quality in broilers fed graded levels of brewers dried grains (BDG)1 P-value2
BDG inclusion (%) Item Beginning BW, 12 d (g) BW gain, d 12 to 33 (g) Feed intake (g) Feed:gain Relative gizzard weight3 (%) Relative cecal weight3 (%) Pellet durability index (%) Ileal digestibility (%) CP Starch Energy Ash availability (%) a–dMeans
0
10
358 1,917a 2,770 1.45b 1.01d 0.32 84.6a 66.9 93.9b 67.3a 33.2a
357 1,855a 2,736 1.48b 1.18c 0.40 80.0b 61.4 93.7b 59.1b 20.4b
20 355 1,815ab 2,736 1.51b 1.37b 0.33 79.2b 57.9 96.5a 56.1b 11.0c
30 347 1,709bc 2,812 1.65a 1.65a 0.40 70.9c 59.14 97.8a 55.7b,4 9.8c
40
Pooled SEM
L
Q
353 1,646c 2,768 1.69a 1.60a 0.37 67.5c 62.74 98.1a 57.8b 11.8c
4.5 44.1 38.3 0.03 0.05 0.02 0.54 2.14 0.66 1.36 1.90
0.15 <0.001 0.56 <0.001 <0.001 0.09 <0.001 0.13 <0.001 <0.001 <0.001
0.65 0.70 0.70 0.26 0.11 0.45 0.20 0.01 0.88 <0.001 <0.001
within the same row with different superscripts differ (P < 0.05). value represents the mean of 6 pens (n = 6). 2Orthogonal polynomial contrasts used to test the linear (L) and quadratic (Q) effects of increased levels of BDG. 3Relative weights are calculated as a percentage of BW: empty gizzard or ceca/BW × 100. 4n = 5 because of insufficient amounts of sample. 1Each
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which in turn is known to be positive for nutrient utilization (Hetland et al., 2003; Svihus et al., 2004). A positive effect on the feed:gain ratio by feeding whole BDG rather than ground BDG (1 mm) was also found in a recent trial with broiler chickens (Denstadli et al., 2010). However, insoluble fiber has a low nutritional value, and although gizzard stimulation may be favorable to some extent, it seemed evident from the present study that inclusion of more than 20% BDG reduced feed utilization drastically. To our knowledge, no reports exist on ileal or fecal digestibility values of the main nutrients in poultry diets containing BSG or BDG. The low protein digestibility in birds fed the control diet may have been due to digesta being collected from Meckel’s diverticulum to the ileo-ceco-colonic junction. Collection at the more distal end of this section could have increased this value. A significant (P < 0.01) reduction in the protein digestibility as BDG replaced the wheat- and soy-based control diet may have been due to the insoluble properties of the BDG protein. Hordein is the main storage protein in barley, and the protein insolubility in BDG may have been caused by the formation of protein aggregates during the mashing process (Moonen et al., 1987; Celus et al., 2006). Moreover, Crowe et al. (1985) suggested that protein-cellulosic aggregates formed during mashing would reduce the solubility of the protein. Reduced ileal energy digestibility was obviously caused by the increased presence of insoluble fiber, mainly derived from BDG. Our data are in line with those reported by Thacker and Widyaratne (2007), in which graded levels of wheat DDGS reduced the fecal digestibility of energy in broilers. The positive effect of BDG inclusion on starch digestibility is probably related to the coarse fiber particles in BDG because it has been shown repeatedly that inclusion of coarse fiber particles in wheat-based diets stimulates gizzard development and results in increased starch digestibility (Rogel et al., 1987). The drastic reduction in the apparent ash availability may have been due to the complexation between fibrous structures and minerals, and similar results have been reported previously in trials with monogastrics (Partridge, 1978; van der Aar et al., 1983; Aslaksen et al., 2007). More detailed studies are warranted to determine the effects of BDG on the mineral status of the bird. The increase in the relative gizzard weight is in line with numerous trials with chickens fed coarse fiber components in the diet (Banfield et al., 2002; Hetland et al., 2003; Gabriel et al., 2008). However, the size of the gizzard plateaued at 30 and 40% BDG inclusion. At these inclusion levels, the amounts of total DF were approximately 22 and 27%, respectively, compared with 11% in the control diet (0% BDG). These data agree with results of a study on the phenotypic development of the gizzard in adult Japanese quail (Starck, 1999), in which the size of the gizzard reached a plateau at a 30% inclusion level of nondigestible fiber. Starck (1999)
suggested that this could be due to physiological limitations in the capacity of the gizzard to grind fibers. No significant change was found in the relative cecal weights, and insoluble fiber seemed to have a less pronounced effect on cecal growth compared with soluble fiber, as reported earlier (Józefiak et al., 2004). Insoluble fiber thus primarily affects the development and functions of the upper digestive tract, and not the distal parts such as the ceca. We conclude that a gradual substitution of BDG with wheat- and soy-based diets reduced growth and feed utilization significantly. However, the performance in birds fed 10 to 20% BDG approached that of the control birds, and the gizzards in those groups were more developed compared with those of the control group. The hypothesized compensatory feed intake in birds fed more dilute BDG diets was not seen, and this was probably caused by a significant reduction in the pellet durability.
ACKNOWLEDGMENTS The work was a part of the project Added Value Products from Barley (ADDBAR NFR 167863) financed by the Norwegian Research Council (NFR, Oslo, Norway), Norwegian Agricultural Authority (SLF, Oslo, Norway), and Fund for Research Levy on Agricultural Products (FFL, Oslo, Norway).
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Onifade, A. A., and G. M. Babatunde. 1998. Comparison of the utilisation of palm kernel meal, brewers’ dried grains and maize offal by broiler chicks. Br. Poult. Sci. 39:245–250. Partridge, I. G. 1978. Studies on digestion and absorption in intestines of growing pigs. 4. Effects of dietary cellulose and sodium levels on mineral absorption. Br. J. Nutr. 39:539–545. Quentin, M., I. Bouvarel, and M. Picard. 2004. Short- and long-term effects of feed form on fast- and slow-growing broilers. J. Appl. Poult. Res. 13:540–548. Rogel, A. M., D. Balnave, W. L. Bryden, and E. F. Annison. 1987. Improvement of raw potato starch digestion in chickens by feeding oat hulls and other fibrous feedstuffs. Aust. J. Agric. Res. 38:629–637. SAS Institute. 2002. SAS 9.1. SAS/STATS User’s Guide. Version 9.1. SAS Inst. Inc., Cary, NC. Serena, A., and K. E. B. Knudsen. 2007. Chemical and physicochemical characterisation of co-products from the vegetable food and agro industries. Anim. Feed Sci. Technol. 139:109–124. Short, F. J., P. Gorton, J. Wiseman, and K. N. Boorman. 1996. Determination of titanium dioxide added as an inert marker in chicken digestibility studies. Anim. Feed Sci. Technol. 59:215– 221. Starck, J. M. 1999. Phenotypic flexibility of the avian gizzard: Rapid, reversible and repeated changes of organ size in response to changes in dietary fibre content. J. Exp. Biol. 202:3171–3179. Svihus, B., E. Juvik, H. Hetland, and A. Krogdahl. 2004. Causes for improvement in nutritive value of broiler chicken diets with whole wheat instead of ground wheat. Br. Poult. Sci. 45:55–60. Thacker, P. A., and G. P. Widyaratne. 2007. Nutritional value of diets containing graded levels of wheat distillers grains with solubles fed to broiler chicks. J. Sci. Food Agric. 87:1386–1390. Thomas, M., T. van Vliet, and A. F. B. van der Poel. 1998. Physical quality of pelleted animal feed 3. Contribution of feedstuff components. Anim. Feed Sci. Technol. 70:59–78. van der Aar, P. J., G. C. Fahey, S. C. Ricke, S. E. Allen, and L. L. Berger. 1983. Effects of dietary fibers on mineral status of chicks. J. Nutr. 113:653–661. Vestby, L. K., T. Møretrø, S. Ballance, S. Langsrud, and L. L. Nesse. 2009. Survival potential of wild type cellulose deficient Salmonella from the feed industry. BMC Vet. Res. 5:43. Wood, J. F. 1987. The functional properties of feed raw materials and their effect on the production and quality of feed pellets. Anim. Feed Sci. Technol. 18:1–17.
(P < 0.001) to 68% in the diet with 40% BDG. Increased levels of BDG reduced BW gain significantly (P < 0.001) and led to a significant (P < 0.001) increase in the feed:gain ratio. The feed:gain ratio was significantly (P < 0.05) higher in birds fed 30 and 40% BDG compared with birds fed 0, 10, and 20% BDG. The apparent ileal digestibility values of protein and energy were significantly reduced by BDG inclusion (P < 0.01 and P < 0.001, respectively), whereas starch digestibility increased significantly (P < 0.001). The relative gizzard weight increased significantly (P < 0.001), whereas the relative cecal weights were not affected by BDG inclusion. To conclude, 10 to 20% inclusion of BDG supports acceptable growth and feed utilization, and favors the development of a well-functioning gizzard.
Key words: brewers dried grains, chicken, gizzard development, nutrient utilization, pellet quality 2010 Poultry Science 89:2640–2645 doi:10.3382/ps.2010-00724
INTRODUCTION Brewers spent grain (BSG) is the main waste product from beer production and accounts approximately 20 kg/100 L of beer produced (Mussatto et al., 2006). With a global production of 150 to 160 billion L of beer per year, the supply of BSG amounts to approximately 30 million metric tons. The fate of BSG is diverse, ranging from charcoal and brick production to animal feed (Mussatto et al., 2006). In the Nordic countries, it is often given away and used as feed for cattle, or, if there is a demand, it may be sold at prices of up to 20 euros/ metric ton. However, the storage stability of BSG represents a challenge. Not only is the DM content low (20 to 25%), but the microbial activity is also high; thus, it ©2010 Poultry Science Association Inc. Received February 23, 2010. Accepted August 29, 2010. 1 Corresponding author: [email protected]
may deteriorate quite rapidly if not conserved as silage or dried to obtain storage stability. Compared with distillers dried grains with solubles (DDGS), dry BSG or brewers dried grains (BDG) contain less protein and more fiber (NRC, 1994). During the last decade, interest has been growing in the functions and properties of the avian gizzard and how it is affected by feed structure and dietary fiber (DF). Trials have shown that dilution of concentrated diets with, for example, oat hulls has had positive effects on gizzard activity, which in turn may improve performance (Hetland et al., 2003). Studies have also shown that gizzard stimulation, and thus pH reduction, can prevent the entrance of pathogenic bacteria into the digestive tract (Bjerrum et al., 2005). The aim of this study was to evaluate the effects of a graded substitution of wheat and soy with BDG. Pellet quality, feed intake, growth performance, ileal digestibilities, and gizzard development were the main responses in the current trial.
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MATERIALS AND METHODS Diets Before feed production, fresh BSG was collected from Ringnes brewery (Gjellerudaasen, Norway) and subsequently air-dried to approximately 87% DM using a local hay barn dryer. Fresh BSG was placed on a sheet of open textile fiber with moving air from below at ambient temperature (15 to 20°C). The chemical composition of BDG is shown in Table 1. Five diets with graded levels of BDG (0, 10, 20, 30, and 40%; Table 2) were produced at the Centre for Feed Technology, Norwegian University of Life Sciences (Aas, Norway). The fish meal and soybean oil contents were kept constant, whereas BDG replaced wheat and soy. The diets had a constant AME:protein ratio, but with a gradual decrease in calculated AME as the inclusion of BDG increased. Amino acids were supplemented and balanced for each diet to exceed NRC (1994) requirements. The ingredients were ground through a 3-mm sieve in a Münch hammer mill (Münch, Wuppertal, Germany) and mixed before conditioning (77 to 78°C) and pelleting (84 to 86°C) in a Münch pellet press. The pellet diameter was 3 mm. Feed samples used for further analyses were collected at the beginning, middle, and end of each pelleting process.
Bird Management and Sampling Day-old male broiler chickens (Ross 308) were placed in litter-floored pens (75 × 150 cm) with wood shavings and fed a commercial starter diet until 12 d of age. The starter was a wheat- and soy-based diet with 23.5% CP and with ME of 2,910 kcal/kg. At 12 d of age, 360 birds with an average BW of 354 g (range: 328 to 380 g), were randomly assigned to 10 pens/room (12 birds/pen), in 3 windowless rooms, with 30 pens in total. Each experimental diet was fed to 2 pens/room by using of automatic feeders. Feed and water were provided ad libitum. From d 12, the temperature was
Table 1. Chemical composition of brewers dried grains1 Amount (g/100 g)
Item DM CP Crude fat Starch Nonstarch polysaccharides Rhamnose Fucose Arabinose Xylose Mannose Galactose Glucose Ash 1Two 2ND
replicates (n = 2) per analysis. = not detected (below the detection limit).
87.4 20.9 9.0 8.1 34.3 ND2 ND 7.7 15.0 0.7 1.3 10.4 3.0
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kept constant at 23 to 24°C, and the birds were exposed to 6 h of darkness (0000 to 0600 h). At 33 d of age, the birds were killed by placing them in an air-proof container to which concentrated food-grade CO2 was added. The birds were killed within 1 min; this procedure was approved by the ethical committee at the Norwegian University of Life Sciences. Four birds per pen were dissected for collection of ileal contents, from Meckel’s diverticulum to the ileo-ceco-colonic junction. The samples from each pen were pooled and frozen immediately after collection (−20°C). In addition, the gizzard and ceca were dissected out, cleaned of visceral fat, and weighed without contents.
Pellet Durability Pellet durability was determined with a Holmen pellet tester (Borregaard LignoTech, Hull, UK). A 100-g sample of sieved, unbroken pellets was pneumatically conveyed through a cylinder loop for 1 min. The pellet durability index (PDI) was calculated as the percentage of unbroken pellets remaining after sieving the tested sample on a 2.5-mm sieve.
Chemical Analyses and Calculations Frozen ileal samples were freeze-dried and ground before analysis. The DM of feed was determined by drying at 105°C for 16 h, and dietary and ileal ash contents were determined by combustion at 550°C for 16 h. The constituent sugars of BDG were determined as alditol acetates after acid hydrolysis (Vestby et al., 2009). Starch content in feed and ileal contents were determined enzymatically following the procedure of McCleary et al. (1994), CP was determined as Kjeldahl-N × 6.25 (AOAC, 2003; method 981.10) on a Kjeltech 2300 instrument (Foss Tecator, Höganäs, Sweden), and crude fat was determined after extraction with petroleum ether and acetone (4:1 ratio) on an Accelerated Solvent Extractor (ASE200, Dionex, Sunnyvale, CA). Gross energy in diets and ileal samples was determined with a Parr 1281 Bomb Calorimeter (Parr Instrument Company, Moline, IL). The concentration of titanium dioxide in diets and ileal samples was determined as described by Short et al. (1996). Nonstarch polysaccharides in all diets were determined as described by Englyst et al. (1994). The apparent ileal digestibility was calculated as 100 − {100 × [(Dm × Im−1) × (In × Dn−1)]}, where Dm and Im represent the concentration of inert marker in diet and ileal contents, and Dn and In represent the concentration of nutrients in diet and ileal contents, respectively.
Statistical Analyses Orthogonal polynomial contrasts were used to test the linear and quadratic effects of a gradual substitution of BDG with wheat and soy in diets for broiler chickens (SAS Institute, 2002). After one-way ANOVA,
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Table 2. Diet formulation and chemical
composition1 BDG2 inclusion (%)
Item Ingredient (g/kg) Wheat Soybean meal3 BDG Fish meal Soybean oil Vitamin and mineral premix4 Choline chloride l-Lysine dl-Methionine l-Threonine NaCl Limestone Monocalcium phosphate Titanium dioxide5 Calculated AME6 (kcal/kg) Analyzed value DM (g/100 g) CP (g/100 g) Starch (g/100 g) Crude fat (g/100 g) Nonstarch polysaccharides7 (g/100 g) Rhamnose Fucose Arabinose Xylose Mannose Galactose Glucose Ash (g/100 g) Gross energy (kcal/kg)
0
10
631 210 0 60 41.6 3.1 1.3 3 3 1 3 20 17 5 2,920
576 167 100 60 41.3 3.1 1.3 3.15 2.65 1 3 20 17 5 2,860
88.8 22.6 36.1 5.88 10.4 (8.1) ND8 ND 2.6 (2.0) 3.4 (2.5) 0.3 (0.2) 1.3 (0.8) 2.9 (2.5) 6.6 4.01
88.9 22.0 33.9 6.68 13.4 (10.7) ND ND 3.2 (2.5) 4.7 (3.9) 0.3 (0.2) 1.4 (0.7) 3.8 (3.3) 6.7 4.08
20 520 123 200 60 41.2 3.1 1.3 3.3 2.3 1 3 20 17 5 2,800 88.9 21.6 31.2 7.10 15.3 (12.7) ND ND 3.5 (2.9) 5.3 (4.9) 0.4 (0.3) 1.4 (0.7) 4.7 (4.0) 6.6 4.13
30 465 78.3 300 60 41.1 3.1 1.3 3.45 1.95 1 3 20 17 5 2,750 89.7 21.1 28.7 7.70 18.1 (17.6) ND ND 4.2 (3.9) 6.8 (7.0) 0.4 (0.3) 1.3 (0.7) 5.3 (5.7) 6.7 4.23
40 404 39 400 60 41 3.1 1.3 3.6 1.6 1 3 20 17 5 2,680 89.8 19.6 29.0 8.71 20.8 (17.8) ND ND 4.3 (4.0) 8.3 (7.4) 0.4 (0.3) 1.1 (0.6) 6.8 (5.4) 6.3 4.23
1Two
replicates (n = 2) per analysis. dried grains. 3Solvent extracted. 4Provided the following per kilogram diet: Fe, 75 mg; Mn (MnSO ), 60 mg; Zn (ZnSO ), 105 mg; Cu (CuSO ), 15 mg; I, 0.75 mg; Se (NaSe), 0.3 4 4 4 mg; vitamin A, 2,700 IU; vitamin D3, 1,800 IU; dl-α-tocopheryl acetate, 123 IU; menadione (vitamin K3), 5.36 mg; pyridoxine (vitamin B6), 10.8 mg; riboflavin (vitamin B2), 13.5 mg; Ca-pantothenate (vitamin B5), 54 mg; biotin (vitamin B7), 0.36 mg; thiamine (vitamin B1), 3.6 mg; niacin (vitamin B3), 18 mg; vitamin B12, 0.02 mg; folic acid (vitamin B9), 2.7 mg. 5Titanium dioxide (Kronos Titan A/S, Fredrikstad, Norway). 6NRC (1994). 7Total nonstarch polysaccharides (values in parentheses are insoluble nonstarch polysaccharide values). 8ND = not detected (below the detection limit). 2Brewer’s
the mean values were ranked using Duncan’s multiple range test (SAS Institute, 2002), and the level of significance used was 0.05 for all tests.
RESULTS Pelleting diets with up to 40% BDG did not cause any problems during feed production, and the setup of the conditioner and pellet press was kept similar for all diets. The Holmen durability test showed that inclusion of BDG reduced the physical quality of the pellets significantly (P < 0.001). The PDI was acceptable for diets with 10 and 20% BDG, whereas the PDI decreased significantly when more than 20% BDG was incorporated into the diets (Table 3). The feed production was not repeated, but the durability test was performed on samples collected 3 times for each diet (beginning, middle, and end of production).
The mortality was 2.8, 5.6, 4.2, and 0% in birds fed diets with 0, 10, 20, 30, and 40% BDG, respectively. There was no significant effect of BDG inclusion on feed intake, whereas there was a significant linear (P < 0.001) reduction in BW gain as the dietary inclusion of BDG increased (Table 3). Thus, from these data, the feed:gain ratio increased significantly when increasing levels of BDG replaced wheat and soy. The feed:gain ratio was 1.45 in the control group (0% BDG), whereas it increased to 1.69 in the group of birds fed diets with 40% BDG. The feed:gain ratio was significantly higher in birds fed 30 and 40% BDG compared with groups fed 0, 10, and 20% BDG. The relative weight of the gizzards increased gradually as the inclusion of BDG increased, reaching a plateau at 30 and 40% BDG inclusion (Table 3). No significant effect of BDG on the relative weight of ceca was found (Table 3).
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The ileal digestibility of starch increased significantly with increased dietary BDG inclusion, from 94% in the control diet to 98% in the diet with 40% BDG. The ileal digestibility of protein and energy decreased significantly when BDG replaced wheat and soy. The apparent availability of ash decreased significantly from 33% in the control diet to 11% in birds fed the diet with 40% BSG.
in line with the report of Leeson et al. (1996), in which broilers fed grower diets diluted with oat hulls and sand displayed a significant compensatory feed intake. The control diet (0% BDG) and the diet with 40% BDG differed by only 8% for the calculated AME level in our study, whereas in the study by Leeson et al. (1996), the diets differed by 40% for AME level. In a study by Hetland and Svihus (2001), diets diluted with 10% oat hulls resulted in a significant increase in feed intake. Our data also disagree with the report by Onifade and Babatunde (1998) in which broilers fed 10 and 20% BDG increased their feed intake to compensate for differences in nutrient density. The reason for a lack of compensation in the present study could have been due to the reduction in pellet durability. Several reports have shown increased feed intake when birds have been offered diets with good pellet quality rather than poor pellet quality (McKinney and Teeter, 2004; Quentin et al., 2004; Lemme et al., 2006). Consequently, it may be that the dietary difference in nutrient density was more or less neutralized by the reduced pellet durability in the current trial. A general reduction in feed utilization was expected as the nutrient density declined with increasing levels of BDG, and our data support previous studies with BDG-fed chickens (Ademosun, 1973; Lopez and Carmona, 1981; Onifade and Babatunde, 1998). However, inclusion levels of 10 and 20% BDG increased the feed:gain ratio by only 2 and 4%, respectively, and did not give a feed:gain ratio that differed significantly (P < 0.05) from the control (0% BDG; Table 3). Similarly, Lumpkins et al. (2004) found that inclusion of 12 to 15% DDGS from corn did not reduce feed efficiency in broilers. It is well known that structural components and fibrous material stimulate the gizzard, and these may activate the secretion of pancreatic enzymes and bile acids (Hetland et al., 2003; Svihus et al., 2004),
DISCUSSION Insoluble fiber is generally assumed to reduce pellet durability because of its resilient and rigid properties (Thomas et al., 1998), which in turn allows less interaction with other feed-borne nutrients and water. The content of insoluble fiber increased gradually in the BDG diets, and the diet with 40% BDG contained approximately 100% more insoluble nonstarch polysaccharides than the control diet (0% BDG). Moreover, BDG contains more lignin and cellulose than wheat and soy (Serena and Knudsen, 2007); therefore, the total DF content would have been even higher in the BDG diets. Protein also influences pellet durability, and in a study by Briggs et al. (1999), the authors concluded that increased amounts of intact protein had a positive effect on pellet durability. Moreover, a study by Wood (1987) showed that raw proteins were preferable to denatured proteins in the formation of durable pellets. Processes such as malting and mashing induce protein denaturation (Jones, 2005), which in turn could have affected pellet durability negatively in the BDG diets. Consequently, the reduced pellet quality in the BDG diets was probably due to lower levels of intact protein as well as increased levels of insoluble fiber. As the inclusion of BDG increased, the birds did not compensate for the reduced dietary AME levels by adjusting their feed intake. This was unexpected and not
Table 3. Performance, organ weights, apparent ileal digestibility values, and pellet quality in broilers fed graded levels of brewers dried grains (BDG)1 P-value2
BDG inclusion (%) Item Beginning BW, 12 d (g) BW gain, d 12 to 33 (g) Feed intake (g) Feed:gain Relative gizzard weight3 (%) Relative cecal weight3 (%) Pellet durability index (%) Ileal digestibility (%) CP Starch Energy Ash availability (%) a–dMeans
0
10
358 1,917a 2,770 1.45b 1.01d 0.32 84.6a 66.9 93.9b 67.3a 33.2a
357 1,855a 2,736 1.48b 1.18c 0.40 80.0b 61.4 93.7b 59.1b 20.4b
20 355 1,815ab 2,736 1.51b 1.37b 0.33 79.2b 57.9 96.5a 56.1b 11.0c
30 347 1,709bc 2,812 1.65a 1.65a 0.40 70.9c 59.14 97.8a 55.7b,4 9.8c
40
Pooled SEM
L
Q
353 1,646c 2,768 1.69a 1.60a 0.37 67.5c 62.74 98.1a 57.8b 11.8c
4.5 44.1 38.3 0.03 0.05 0.02 0.54 2.14 0.66 1.36 1.90
0.15 <0.001 0.56 <0.001 <0.001 0.09 <0.001 0.13 <0.001 <0.001 <0.001
0.65 0.70 0.70 0.26 0.11 0.45 0.20 0.01 0.88 <0.001 <0.001
within the same row with different superscripts differ (P < 0.05). value represents the mean of 6 pens (n = 6). 2Orthogonal polynomial contrasts used to test the linear (L) and quadratic (Q) effects of increased levels of BDG. 3Relative weights are calculated as a percentage of BW: empty gizzard or ceca/BW × 100. 4n = 5 because of insufficient amounts of sample. 1Each
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which in turn is known to be positive for nutrient utilization (Hetland et al., 2003; Svihus et al., 2004). A positive effect on the feed:gain ratio by feeding whole BDG rather than ground BDG (1 mm) was also found in a recent trial with broiler chickens (Denstadli et al., 2010). However, insoluble fiber has a low nutritional value, and although gizzard stimulation may be favorable to some extent, it seemed evident from the present study that inclusion of more than 20% BDG reduced feed utilization drastically. To our knowledge, no reports exist on ileal or fecal digestibility values of the main nutrients in poultry diets containing BSG or BDG. The low protein digestibility in birds fed the control diet may have been due to digesta being collected from Meckel’s diverticulum to the ileo-ceco-colonic junction. Collection at the more distal end of this section could have increased this value. A significant (P < 0.01) reduction in the protein digestibility as BDG replaced the wheat- and soy-based control diet may have been due to the insoluble properties of the BDG protein. Hordein is the main storage protein in barley, and the protein insolubility in BDG may have been caused by the formation of protein aggregates during the mashing process (Moonen et al., 1987; Celus et al., 2006). Moreover, Crowe et al. (1985) suggested that protein-cellulosic aggregates formed during mashing would reduce the solubility of the protein. Reduced ileal energy digestibility was obviously caused by the increased presence of insoluble fiber, mainly derived from BDG. Our data are in line with those reported by Thacker and Widyaratne (2007), in which graded levels of wheat DDGS reduced the fecal digestibility of energy in broilers. The positive effect of BDG inclusion on starch digestibility is probably related to the coarse fiber particles in BDG because it has been shown repeatedly that inclusion of coarse fiber particles in wheat-based diets stimulates gizzard development and results in increased starch digestibility (Rogel et al., 1987). The drastic reduction in the apparent ash availability may have been due to the complexation between fibrous structures and minerals, and similar results have been reported previously in trials with monogastrics (Partridge, 1978; van der Aar et al., 1983; Aslaksen et al., 2007). More detailed studies are warranted to determine the effects of BDG on the mineral status of the bird. The increase in the relative gizzard weight is in line with numerous trials with chickens fed coarse fiber components in the diet (Banfield et al., 2002; Hetland et al., 2003; Gabriel et al., 2008). However, the size of the gizzard plateaued at 30 and 40% BDG inclusion. At these inclusion levels, the amounts of total DF were approximately 22 and 27%, respectively, compared with 11% in the control diet (0% BDG). These data agree with results of a study on the phenotypic development of the gizzard in adult Japanese quail (Starck, 1999), in which the size of the gizzard reached a plateau at a 30% inclusion level of nondigestible fiber. Starck (1999)
suggested that this could be due to physiological limitations in the capacity of the gizzard to grind fibers. No significant change was found in the relative cecal weights, and insoluble fiber seemed to have a less pronounced effect on cecal growth compared with soluble fiber, as reported earlier (Józefiak et al., 2004). Insoluble fiber thus primarily affects the development and functions of the upper digestive tract, and not the distal parts such as the ceca. We conclude that a gradual substitution of BDG with wheat- and soy-based diets reduced growth and feed utilization significantly. However, the performance in birds fed 10 to 20% BDG approached that of the control birds, and the gizzards in those groups were more developed compared with those of the control group. The hypothesized compensatory feed intake in birds fed more dilute BDG diets was not seen, and this was probably caused by a significant reduction in the pellet durability.
ACKNOWLEDGMENTS The work was a part of the project Added Value Products from Barley (ADDBAR NFR 167863) financed by the Norwegian Research Council (NFR, Oslo, Norway), Norwegian Agricultural Authority (SLF, Oslo, Norway), and Fund for Research Levy on Agricultural Products (FFL, Oslo, Norway).
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