J APPL POULT RES 2009. 18:487-493. doi:10.3382/japr.2008-00124
© 2009 Poultry Science Association
Dried cassava pulp as an alternative feedstuff for broilers: Effect on growth performance, carcass traits, digestive organs, and nutrient digestibility
S. Khempaka*,1,
W. Molee* and
M. Guillaume
* School of Animal Production Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; and Vitalac, Room 201, 2nd Floor, L11-L12 Mieu Noi, W3, Binh Thanh District, Ho Chi Minh City, Vietnam
1 Corresponding author: khampaka{at}sut.ac.th
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SUMMARY
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Dried cassava pulp (DCP), a by-product of cassava starch factory processing, contains a large quantity of starch. Therefore, it is certainly worthwhile to investigate its use as an energy source for poultry feed. Two experiments were conducted to examine the potential use of DCP for broilers. Growth, carcass traits, length and weight of digestive organs, and nutrient digestibility were determined in broilers fed diets containing 0 to 16% DCP. Seven-day-old mixed-sex chicks (n = 240) were randomly distributed to 5 dietary treatment groups through 42 d of age (experiment 1). In experiment 2, a total of 50 chicks were randomly allotted to individual cages at 15 d and fed 1 of 5 diets for 10 d to measure digestibility. Results showed that growth performance and nutrient digestibility decreased with increasing levels of DCP. In most cases, these parameters did not change significantly when DCP was at or below 8%. A significant increase in gizzard weight and a reduction in abdominal fat were also found in broilers fed DCP. In conclusion, it is suggested that DCP be used as an energy source at inclusion levels up to 8% in broiler diets.
Key Words: dried cassava pulp • growth performance • carcass • digestibility • broiler
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DESCRIPTION OF PROBLEM
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The feed industry in Thailand uses corn as the energy source for broiler diets. Recently, however, a large proportion of corn has been used for the production of ethanol, resulting in an inadequate supply of corn for use as an energy source in poultry diets. Studies involving the use of unconventional feedstuffs instead of corn are an important issue facing nutritionists, who must provide solutions to these problems.
Cassava (Manihot esculenta Crantz) is grown in tropical countries in Africa, Asia, and Latin America, with 70% of the world’s cassava production coming from Nigeria, Brazil, Thailand, Indonesia, and the Democratic Republic of the Congo [1]. Cassava root can be used to produce cassava chips, cassava pellets, and cassava starch, which are in high demand throughout the world. Thailand, Indonesia, and Brazil are the most prominent exporters of cassava starch, with their production accounting for 95% of the world’s supply [1]. Cassava pulp is the solid, moist by-product of cassava starch manufacture, and it represents approximately 10 to 15% of the original root weight. As cassava starch production increases, so does the large volume of waste by-product generated. In Thailand, at least 1 million tons of pulp is generated annually. After drying, some of the by-product is used to produce fertilizer or is included in diets for ruminants and swine. However, an abundance of byproduct still remains. According to composition values, cassava pulp contains 69.89% starch, 1.70% ash, 1.55% CP, 27.75% CF, and 0.12% EE on a DM basis [2]. The fiber content of dried cassava pulp (DCP) is reportedly in the form of insoluble fiber. Suksombat et al. [3] reported the fiber components of DCP as 36.7% NDF, 9.8% ADF, and 3.9% acid detergent lignin.
With respect to the practical use of DCP as a poultry feed, the high fiber content is an obvious concern. High levels of fiber, bulkiness, and dustiness in DCP are possible factors leading to decreased growth performance and digestibility. A strong negative correlation between the fiber fractions and nutrient digestibility has been reported in previous studies [4–6]. It has also been reported that poultry fed diets with high fiber levels have reduced performance and abdominal fat content and that the length and weight of the digestive organs is altered [5, 7, 8]. Even though the fiber level of DCP is problematic, its content is also composed of a high amount of starch. Therefore, it is certainly worthwhile to investigate the use of DCP as an energy source for poultry, and the literature is limited in this regard. Therefore, the purpose of this study was to evaluate the effect of DCP on BW gain, feed intake (FI), FCR, carcass traits, digestive organ weight and length, and nutrient digestibility in broilers.
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MATERIALS AND METHODS
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All experiments were conducted according to the principles and guidelines approved by the Animal Care and Use Committee of Suranaree University of Technology.
Preparation of DCP
We obtained fresh cassava pulp from a starch plant and it was sun-dried to a moisture content of approximately 10%. Dried pulp was ground to pass through a 1.0-mm mesh sieve. Prior to diet formulation, proximate and other analyses of DCP were determined (Table 1
). Metabolizable energy value was determined using the methodology established by Sibbald [9].
Experiment 1
Five experimental diets (1 control and 4 DCP diets) were formulated to similar levels of calculated ME (approximately 3,102 kcal/kg) and CP (approximately 20 and 17% in the starter and finisher diets, respectively; Table 2). All other nutrients were calculated to meet the NRC requirements [10]. Dried cassava pulp was included in the broiler diets at the levels of 4, 8, 12, and 16%. Seven-day-old mixed-sex broiler chicks (n = 240; Arbor Acres [11]) were randomly allotted to 15 pens. Each pen (n = 16) was fed 1 of 5 diets and there were 3 replicate pens per diet. All birds received starter and finisher diets in mash form from 7 to 21 d and 22 to 42 d, respectively. Diet and water were provided ad libitum throughout the experimental period. Body weight, FI, and FCR were determined for each pen at 14, 21, 28, 35, and 42 d of age. At the end of the experiment, 2 birds (male and female) from each pen were fasted overnight with access to water and sacrificed by exsanguination. Carcass traits and the length and weight of different segments of the intestine emptied of residual digesta were measured.
Experiment 2
Fifty 11-d-old male broiler chicks (Arbor Acres [11]) were placed in individual cages. After a 4-d adaptation period, all chicks were randomly allotted to an experimental diet (10 birds per diet) for 10 d. All birds were fed starter diets in mash form (nutrient composition identical to starter experimental diets in experiment 1). Feed and water were provided ad libitum throughout the experimental period. Body weight and FI of individual chicks were recorded daily (15 to 25 d of age). Excreta were collected on experimental d 7 to 10 (22 to 25 d of age), sprayed with 5% HCl, and dried at 55°C. Dried excreta were stored at –20°C until analyses. Dry matter, organic matter (OM), and N in diets and excreta were measured to assess their digestibilities and retention according to standard methods [12].
Statistical Analysis
Data were analyzed by ANOVA and by using SPSS version 13.0 [13]. Significant differences among treatment were assessed by LSD. The effect of increasing DCP was partitioned into linear, quadratic, cubic, and quartic components by using polynomial trend analysis. A significant level of P 
0.05 was used.
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RESULTS
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Inclusion of DCP in diets at various levels resulted in significant decreases (linear, P = 0.0001) in BW at 42 d of age (Table 3). Compared with the values in the control group, BW did not change significantly in the 4 and 8% groups, but decreased significantly in the 12 and 16% groups. The significant differences in FI and FCR among treatments (P 0.05) were observed from 14 to 35 d and 14 to 21 d, respectively. The dietary effects on FI and FCR were similar to that of BW. Even though the BW of broilers fed 16% DCP showed a greater result than the 12% DCP at 21 d of age, no significant differences between these 2 groups were observed at the end of the experiment.
The effects of DCP on carcass traits are presented in Table 4. The percentages of eviscerated carcasses and giblets found in broilers fed DCP were not significantly different from those of the control. The test results for breast, fillet, drumstick, thigh meat, and drumstick meat percentages were similar to those of eviscerated carcasses and giblets. The percentage of abdominal fat decreased linearly (P = 0.0002) with increasing levels of DCP.
The results for digestive organ measurements are presented in Table 5. There were no significant differences (P > 0.05) in lengths of the duodenum and ceca per 100 g of BW among the treatments, whereas lengths of the jejunum and ileum found in broilers fed DCP were significantly increased (P 0.05) in the 16% and the 12 to 16% groups, respectively, compared with the control group. The weights of the heart, liver, pancreas, spleen, proventriculus, jejunum, ileum, and ceca did not change significantly among treatments (P > 0.05). Gizzard weight per 100 g of BW increased linearly (P = 0.0118) with increasing levels of DCP. Compared with the value in the control group, gizzard weight did not change significantly in the 4, 8, and 12% groups but did increase significantly in the 16% DCP group.
Nutrient digestibility and retention are presented in Table 6. Overall, DM and OM digestibility decreased linearly (P = 0.0001 and P = 0.0001, respectively) with increasing levels of DCP, but the greatest decline was observed in the 12 and 16% DCP groups. Retention of N was 63.68% in the control group. Retention of N decreased linearly (P = 0.0027) with increasing levels of DCP. Compared with the value in the control group, N retention did not change significantly in the 4 and 8% groups, but did decrease significantly in the 12 and 16% groups.
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DISCUSSION
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Dried cassava pulp contains starch that can be used as an energy source in poultry diets. In our experiments, increasing DCP up to 8% did not significantly influence BW when compared with the control treatment, which contained no DCP. The decline in BW was most likely due to the high fiber content of DCP (13.59%). Many previous studies have reported that a high-fiber-content diet can depress FI, and consequently can cause growth depression [5, 6]. The depression in FI in the 14- to 35-d period by inclusion of 12 and 16% DCP could be due to the increased bulkiness of the diet and limited digestive tract capacity in broilers. In addition, the increase in bulk has also been reported to reduce palatability [14] and thus may limit the FI of broilers. Even though information on using DCP in broilers is limited, the results of experiments with broilers fed various levels of cassava have been widely reported [15, 16]. The authors summarized that when cassava was provided in mash form at all levels, poorer growth and feed conversion were obtained than with corn-based diets. However, similar performance was obtained when the diets were pelleted [15, 16]. Therefore, offering DCP in pellet form may overcome the problem of bulkiness and ensure an optimal FI by poultry. In addition, DCP is low in protein (approximately 2% on a DM basis) and deficient in carotene contents. Thus, inclusion of DCP in diets should take these factors into consideration.
There were no significant differences in percentages for carcass traits. It was found that broilers fed a diet containing DCP showed a reduction in abdominal fat. The loss of body fat may be associated with the inhibition of lipid synthesis in the liver and abdominal tissue because of the high fiber content in the test diet. In consideration of the low DM and OM digestibility observed in our experiments in broilers fed DCP diets, it was hypothesized that this phenomenon would also result in poor digestibility of fat (discussed below). Akiba and Matsumoto [17] found that chickens fed a diet high in fiber (cellulose and alfalfa meal) had significant reductions in lipid deposition and plasma lipid content and had accelerated lipoprotein activity in the adipose tissue. This was in accordance with the work of Eruvbetine et al. [7] and Eruvbetine [8], who reported that for broilers and layers fed diets high in cassava, broilers had a reduced abdominal fat content at market weight, and layers had a reduced abdominal fat content after 40 wk in lay. An additional possible factor in the reduction of fat deposition may be related to the decrease in energy intake, and hence reduced energy available for fat deposition. This result agrees with the report of Latshaw [18], who found that in diets containing similar levels of energy and protein but a varied fiber content, increasing levels of fiber caused large decreases in ME intake. The fiber contained in DCP is largely insoluble. Recently, several studies have been conducted to investigate insoluble fiber sources as functional foods for humans and animals [5, 19].
Gizzard weight increased with increasing levels of DCP, particularly at the highest level of inclusion (16%). This was also true for the length of the jejunum and ileum. This supports the data of Eruvbetine et al. [7], who suggested that the increased size of the gizzard in broilers fed a high concentration of cassava could be a result of the bulkiness of the feed. Hetland et al. [5] suggested that insoluble fiber modulates gut development, digestive function, and gizzard activity.
Dry matter digestibility, OM digestibility, and N retention decreased with increasing levels of DCP. In most cases, these parameters did not change significantly when DCP was at or below 8%. The significant changes in digestibility and retention with increasing levels of DCP were similar to those for BW. Similar results have been reported, in which a strong negative correlation was found between the CF content and nutrient digestibility [4–6]. This suggests that the high fiber content in DCP may be the main factor in reducing the digestibility. Fiber may decrease DM digestibility because of its poor digestibility, because it suppresses the digestion of other nutrients, or both. Decreased digestibility would lead to decreased growth performance.
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CONCLUSIONS AND APPLICATIONS
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- Dried cassava pulp can be used as a feed ingredient to supply part of the dietary energy requirement of broilers, but it should be limited to 8% or less in diets.
- Not only is dried cassava pulp useful as an energy source, but it may also improve gut health and reduce abdominal fat deposition in broilers.
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ACKNOWLEDGMENTS
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This study was funded by Suranaree University of Technology in 2007.
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REFERENCES AND NOTES
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- Food and Agriculture Organization of the United Nations. 2008. Food Outlook Global Market Analysis. http://www.fao.org/docrep/011/ai474e/ai474e06.htm Accessed Feb. 2009.
- Sriroth, K., R. Chollakup, S. Chotineeranat, K. Piyachomkwan, and C. G. Oates. 2000. Processing of cassava waste for improve biomass utilization. Bioresour. Technol. 71:63–69.[CrossRef][Web of Science]
- Suksombat, W., P. Lounglawan, and P. Noosen. 2007. Energy and protein evaluation of five feedstuffs used in diet in which cassava pulp as main energy source for lactating dairy cows. Suranaree J. Sci. Technol. 14:99–107.
- Hetland, H., B. Svihus, and M. Choct. 2005. Role of insoluble fiber on gizzard activity in layers. J. Appl. Poult. Res. 14:38–46.[Abstract/Free Full Text]
- Hetland, H., B. Svihus, and A. Krogdahl. 2003. Effect of oat hulls and wood shavings on digestion in broilers and layers fed diets based on whole or ground wheat. Br. Poult. Sci. 44:275–282.[CrossRef][Web of Science][Medline]
- Hetland, H., and B. Svihus. 2001. Effect of oat hulls on performance, gut capacity and feed passage time in broiler chickens. Br. Poult. Sci. 42:354–361.[CrossRef][Web of Science][Medline]
- Eruvbetine, D., I. D. Tajudeen, A. T. Adeosun, and A. A. Olojede. 2003. Cassava (Manihot esculenta) leaf and tuber concentrate in diets for broiler chickens. Bioresour. Technol. 86:277–281.[CrossRef][Web of Science][Medline]
- Eruvbetine, D. 1995. Processing and utilisation of cassava as animal feed for non-ruminant animals. Paper presented at the Workshop on Alternative Feedstuffs for Livestock Organized by the Lagos State Ministry of Agriculture and Co-operative and Rural Development, Lagos, NIgeria.
- Sibbald, I. R. 1976. A bioassay for true metabolizable energy in feedingstuffs. Poult. Sci. 55:303–308.[Web of Science][Medline]
- NRC. 1994. Nutrient Requirements of Poultry. 9th rev. ed. Natl. Acad. Sci., Washington, DC.
- Arbor Acres Thailand Co. Ltd., Bangkok, Thailand.
- AOAC. 1990. Official Methods of Analysis. 15th ed. Assoc. Off. Anal. Chem., Washington, DC.
- SPSS. 2004. User’s Guide, Version 13.0. SPSS Inc., Chicago, IL.
- Weiss, F. G., and M. L. Scott. 1979. Effects of dietary fiber, fat and total energy upon plasma cholesterol and other parameters in chicken. J. Nutr. 109:693–701.[Abstract/Free Full Text]
- Muller, Z., K. C. Chou, and K. C. Nah. 1974. Cassava as total substitute for cereals in livestock and poultry rations. World Anim. Rev. 12:19–35.
- Oke, O. L. 1978. Problems in the use of cassava as animal feed. Anim. Feed Sci. Technol. 3:345–380.[CrossRef]
- Akiba, Y., and T. Matsumoto. 1982. Effects of dietary fibers on lipid metabolism in liver and adipose tissue in chicks. J. Nutr. 112:1577–1585.[Abstract/Free Full Text]
- Latshaw, J. D. 2008. Daily energy intake of broiler chickens is altered by proximate nutrient content and form of the diet. Poult. Sci. 87:89–95.[Abstract/Free Full Text]
- Raupp, D. S., D. A. Rosa, S. H. P. Marques, and D. A. Banzatto. 2004. Digestive and functional properties of a partially hydrolyzed cassava solid waste with high insoluble fiber concentration. Sci. Agric. (Piracicaba, Brazil) 61:286–291.
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SUMMARY
DESCRIPTION OF PROBLEM
