Blend of oil palm slurry and rice bran as feed
ingredient for broiler chickens
C.C. Atuahene, A. Donkoh
*, I. Ntim
Department of Animal Science, University of Science and Technology, Kumasi, Ghana
Received 4 November 1998; received in revised form 2 June 1999; accepted 30 November 1999
Abstract
A 6-week feeding trial was conducted to assess the effect of four types of processed oil palm slurry (OPS) using rice bran (RIB) as an absorbent, hereafter referred to as RIBROPS, to partially replace maize on the growth performance of broiler chicks. Six hundred 14-day-old commercial broiler chicks were randomly allocated to one of the ®ve dietary treatments. The dietary treatments consisted of the control diet, which contained maize as the main energy source, and four other diets each of which contained a ®xed amount of 100 g of one of the four types of RIBROPS kgÿ1. The experimental diets were formulated to be both isoproteic and isoenergetic. Feed and water were provided ad libitum for a period of 6 weeks.
The dietary treatments did not have signi®cant impact on feed intake (rÿ0.48), body weight gain (r0.42) and feed conversion ef®ciency (rÿ0.40). Carcass yields were similar. There were no health-related problems attributable to the dietary treatments. Mortality was unaffected by the dietary treatments.#2000 Elsevier Science B.V. All rights reserved.
Keywords:Oil palm slurry; Rice bran; Growth performance; Chickens, Broilers
1. Introduction
In many developing countries there exists a largely untapped potential for utilising feedstuffs for poultry. Among these is oil palm slurry (OPS), a by-product obtained during the processing of the fruits of the oil palm (Elaeis guinensis) to obtain palm oil. This ef¯uent is a potent pollutant (Davis, 1978). Olie and Tjeng (1971) indicated that it has a Biological Oxygen Demand (BOD) of 20,000 ppm which is 100 times higher than
83 (2000) 185±193
*Corresponding author. Tel.:233-51-60325. E-mail address: [email protected] (A. Donkoh).
that of raw sewage. Its utilisation as an animal feed will minimise the pollution problem as well as supply a cheap energy animal feed (Webb et al., 1977). Studies by Atuahene et al. (1987) indicated the use of unprocessed OPS in broiler chicken diets allowed maize levels to be signi®cantly reduced without affecting performance. However, because of its high moisture content, OPS must be processed before it can be incorporated into poultry feed formulations.
Many researchers have proposed different methods for treatment of the ef¯uent, such as aerobic puri®cation and anaerobic digestion (Olie and Tjeng, 1971) as well as biodegradation (Stanton, 1974). However, these are either impractical or uneconomical. Webb (1975) therefore approached the problem of dehydration of the ef¯uent using mechanically dried cassava meal and palm kernel meal as absorbent for the sludge. In the study reported, herein rice bran was chosen for study as an absorbent as it is currently available in large quantities in Ghana and is reported to contain low levels of energy (Stilborn and Waldroup, 1990). This is aimed to develop a saleable by-product from oil palm slurry and rice bran, by producing a high quality energy feedstuff for poultry.
Regardless of its economic and nutritional status, it is essential that investigations of the feeding potential of OPS should take cognizance of contaminants such as pathogenic bacteria. The number and type of speci®c groups of microorganisms in a product indicates the way it has been handled at all stages, post-harvest, for example, storage, fermentation, processing, packaging and transportation. The level of spoilage microorganisms can be used to predict the potential shelf-life of the product (Bainbridge et al., 1996).
The objective of this study, therefore, was to assess the nutritive quality of resultant four types of products from the combination of OPS and rice bran and the effect of replacing a portion of the maize in broiler diets by the products (OPS plus rice bran in different proportions) on growth performance. The kinds and numbers of the micro¯ora present in fresh and processed oil palm slurry were also determined.
2. Materials and methods
2.1. Source of rice bran, oil palm slurry and processing method
The rice bran (RIB) used in the study was obtained as a by-product from local rice mills in Kumasi, while the OPS was obtained from indigenous palm oil producers. The slurry obtained was stored in a barrel and covered for 3 days. This allowed the thickened slurry to settle on top leaving the aqueous layer underneath. The slurry was then scooped, mixed with RIB in different proportions, sun-dried to a moisture content of about 100±120 g kgÿ1DM and then stored in sacks until used in formulations. The four different proportions of OPS and RIB, hereafter referred to as `RIBROPS' were as follows:
RIBROPS I: 100 units of rice bran mixed with 25 units of OPS;
RIBROPS III: 100 units of rice bran mixed with 75 units of OPS;
RIBROPS IV: 100 units of rice bran mixed with 100 units of OPS.
The chemical compositions of the oil palm slurry and rice bran are shown in Table 1.
2.2. Dietary treatments
Five experimental diets (Table 2) were formulated: a control diet, designated as dietary treatment I, contained none of the RIBROPS and four others, designated as dietary treatments II, III, IV and V, which contained a ®xed amount of 100 g RIBROPS I, II, III and IV kgÿ1diet, respectively. The experimental diets were formulated to be isoproteic and isoenergetic.
2.3. Chemical analysis
Proximate analyses of the OPS, rice bran, the four types of RIBROPS and experimental diets (dry matter, crude protein, ether extract, ash and crude ®bre) were analysed by standard procedures (Association of Of®cial Analytical Chemists, 1990). Acid-detergent ®bre (ADF), neutral-detergent ®bre (NDF) and hemicellulose (Goering and van Soest, 1970) were also estimated on the four types of RIBROPS samples. Calcium and phosphorus analyses followed the procedure of Fick et al. (1979). Sixteen 6-week-old broiler chicks were used to determine the nitrogen-corrected true metabolisable energy (TMEn) content of the four types of RIBROPS. Birds were fed ad libitum on a broiler ®nisher diet for 1 week prior to force-feeding (Sibbald, 1986). The birds were housed in individual cages with collection trays, fasted for 24 h and force-fed 30 g of the test ingredients. Eight broilers were kept fasted during the assay to measure endogenous losses. Excreta were collected daily for 48 h after force-feeding, oven-dried at 608C for 48 h, equilibrated to ambient conditions, weighed and ground (Dale and Fuller, 1983). The four types of RIBROPS and fecal samples were analysed for gross energy. Metabolisable energy values for the experimental diets were, however, calculated from values given by the National Research Council (NRC, 1994) and the determined TMEn contents of the RIBROPS.
Table 1
Chemical composition (g kgÿ1DM) of oil palm slurry and rice brana
Component Oil palm slurry Rice bran
Moisture 117.4 93.5
Crude protein 45.6 131.0
Ether extract 716.3 165.3
Crude ®bre Trace 72.6
Ash 33.8 68.3
Calcium 1.9 16.5
Phosphorus 2.6 12.8
Metabolisable energy (MJ kgÿ1) 21.7 8.8
aThe values are the means of three samples.
2.4. Microbiological procedure
Samples of fresh, homogenised oil palm slurry were taken for surface viable microbial counts and isolation (Bainbridge et al., 1996) and identi®cation (ICMSF, 1978 International Commission on Microbiological Speci®cations for Food). For microbial count and isolation, 10 g of OPS were inoculated onto selective agar (Nutrient agar for bacteria, MacConkey agar for coliforms and Sabouraund agar for fungi), and the plates were incubated at 378C for 48 h. The number of colonies on the agar was counted. Plates supporting approximately 30±300 colonies were counted and the mean of duplicate plates noted. If growth was present after incubation, colonies were selected for identi®cation. These procedures involved examination of colonial characteristics, morphology, motility, staining and biochemical properties using the guidelines of ICMSF (1978). Ten grams (10 g) each of the four types of RIBROPS samples were homogenised and diluted in 90 ml sterile maximum recovery diluent to obtain 110ÿ1 suspensions. The diluted suspensions of the four types of RIBROPS were subjected in the same way to surface microbial counting and microbial isolation as the fresh samples of OPS.
Table 2
Composition of diets fed to 14-day-old broiler chickens
Dietary treatments
I (Control) II III IV V
Ingredients (g kgÿ1)
Maize 590 490 490 490 490
RIBROPSa 0 100 100 100 100
Fish meal 190 190 190 190 190
Soyabean meal 60 60 60 60 60
Wheat bran 130 130 130 130 130
Oyster shell (ground) 20 20 20 20 20
Vitamin and mineral premixb 5 5 5 5 5
Salt (NaCl) 4 4 4 4 4
Allzyme PTc 1 1 1 1 1
Chemical analysis (g kgÿ1DM)
Crude protein 220.3 225.0 225.6 225.8 226.4
Crude ®bre 33.6 39.0 39.7 40.0 40.3
Ether extract 36.3 41.0 41.0 42.0 42.5
Calcium 15.2 15.3 15.6 15.7 15.9
Phosphorus 8.2 9.5 9.5 9.6 9.6
MEn(MJ kgÿ1) 11.59 11.48 11.51 11.55 11.58
aThe ratio of rice bran (RB) to oil palm slurry (OPS) in RIBROPS incorporated in diets II, III, IV and IV are
100:25; 100:50; 100:75 and 100:100, respectively
bPremix supplied (kgÿ1diet): Vitamin A, 10,000 IU; Vitamin D
3, 2000 IU; Vitamin E, 10 IU; Vitamin K,
3 mg; ribo¯avin, 2.5 g; cobalamin, 0.05 mg; pantothenic acid, 5 mg; niacin, 12.5 mg; choline, 175 mg; folic acid, 0.5 mg; Mg, 2.8 mg; Fe, 0.5 mg; Cu, 50 mg; Zn, 25 mg; Co, 62.5 mg.
cA proprietary feed enzyme complex derived from the fungusAspergillus niger(Alltech, Kentucky, USA).
Allzyme PT, added to diets at 1 kgÿ1ton, contains xylanase and pentosanase (600 XU gÿ1). Other carbohydrases present include galactomannase, betaglucanase, cellulase, hemicellulase and pectinase.
2.5. Experimental animals and management
A total of 600 unsexed 14-day-old commercial broiler chickens (Hybro strain), with an average initial body weight of 0.22 kg, were allotted randomly to the ®ve dietary treatments, in a completely randomised design. Each treatment, consisting of 120 birds, was replicated three times. The birds were placed and reared in deep litter pens. The study was conducted for 42 days (2±8 weeks of age). Before the start of the feeding trial the birds were weighed and subsequently allocated to the treatments in such a way that the mean weights differed as little as possible. Birds had free access to feed and water.
2.6. Parameters measured
Body weight gain, feed consumption and feed conversion ef®ciency (feed:gain ratio) were determined weekly for individual replicates of each dietary treatment. Records of mortality were also kept. All sick and dead chickens were sent to the Veterinary Laboratory for post-mortem examination. At 56 days of age, four broilers from each of the 15 replicates were selected at random, starved of feed for about 18 h to empty their crops, killed by cutting the jugular vein, exsanguinated, defeathered and eviscerated. Carcass yield was calculated from eviscerated weight and liveweight.
2.7. Histological studies
At 56 days of age, the possible deleterious effects of RIBROPS on liver were also assessed. Four chickens from each treatment were randomly selected, killed by cervical dislocation, the liver excised and examined to determine whether the diets had resulted in any gross pathological changes. Liver sections were cut before staining with haematoxylin and eosin (Humason, 1979) and examined microscopically for any abnormalities in the cells.
2.8. Statistical analysis
Data were subjected to linear regression analysis of variance using the General Linear Models procedure of Statistical Analysis Systems (1987). Differences among means were determined by thet-test (Steel et al., 1997) and considered signi®cant ifP<0.05.
3. Results and discussion
Results of the chemical analysis (Table 3) of the four types of processed OPS indicated that, on g kgÿ1 dry matter (DM) basis, the crude protein contents were 139.6, 140.6, 142.9 and 148.6 for RIBROPS I, II, III and IV, respectively. The ash contents ranged from 92.6 to 93.8 g kgÿ1DM. The values for the ether extract (fat) were 84.6, 85.2, 95.1 and 100.5 g kgÿ1 DM for RIBROPS I, II, III and IV, respectively with corresponding metabolisable energy contents of 12.9, 13.2, 13.6 and 13.9 MJ kgÿ1, respectively. The crude ®bre content ranged from 76.6 to 83.3 g kgÿ1 DM. The NDF and ADF levels
obtained are reasonably greater than the crude ®bre, which is mostly cellulose, whereas the ADF contains lignin and cellulose. NDF corresponds mainly to the sum of cellulose, hemicellulose and lignin. Neutral detergent ®bre measures all the ®brous constituents in feeds and is inversely related to the energy content (Mertens, 1985). This accrues at least in part from low digestibility of ®bres. The energy content of the blend of rice bran and oil palm slurry, with the highest NDF content (RIBROPS IV), was, therefore, expected to be the lowest instead of being the highest. This could be explained by the fact that in addition to ®bre, other chemical compounds can have large effects on energy value. Fats and oils (which was highest for RIBROPS IV), for example, contain 2.25 times the energy of proteins and carbohydrates, while ash contributes zero energy. This might have in¯uenced the energy contents of the four types of RIBROPS.
In Table 2, however, adding the various types of RIBROPS to the different dietary treatments did not substantially alter the energy concentration of the experimental diets. On a unit weight basis, RIBROPS IV had the highest energy concentration, it was, therefore, expected that there would be a great impact on the energy concentration of dietary treatment V. However, the contribution of 100 g RIBROPS IV to the total energy content of dietary treatment V was 1.39 MJ kgÿ1compared to a value of 1.29 MJ kgÿ1 contributed by RIBROPS I to the energy content of dietary treatment II. This might explain the isocaloric nature of the experimental diets. Similarly, there were apparent differences in the calcium contents of the various types of RIBROPS (i.e. two and half times increase in calcium content between RIBROPS I and IV), yet this did not result in any considerable differences in the calcium contents of the dietary treatments
There was no impact of increasing oil palm slurry on the mean total viable micro¯ora count of the four types of processed slurry but that all treatments were lower than the fresh OPS samples (Table 4). Micro¯ora isolated from the fresh OPS samples included
Table 3
Chemical composition (g kgÿ1DM) of the four types of processed oil palm slurrya
Component Type of RIBROPS
Neutral detergent ®bre 114.0 123.5 128.0 132.4
Acid detergent ®bre 93.3 101.1 104.8 108.4
Hemicellulose 20.7 22.4 23.2 24.0
Mineral elements
Calcium 2.5 4.2 6.0 7.7
Phosphorus 15.6 16.2 16.7 17.3
TMEn(MJ kgÿ1)b 12.9 13.2 13.6 13.9
aThe values are the means of four samples.
bEstimated according to the method of Sibbald (1986).
Staphylococcusspp., coliforms,Escherichia coli,Proteusspp.andMucorspp.(Table 4). The samples were, however, free from pathogenic bacteria such as, faecal coliform bacteria and Salmonella. Similarly, Staphylococcus spp., coliforms, Escherichia coli, Proteusspp.andMucorspp. were recovered from the processed OPS, though at relatively lower numbers. The differences in the mean viable counts between the fresh and the processed types could be attributed to the bacteriocidal effect of sunlight on the processed ones (Jacobs and Gestein, 1968). The lethal effect of sunlight is attributable not only to the ultra-violet component but also to certain visible wavelengths. Salle (1961) reported that ultra-violet rays may kill a cell, delay its growth or change its properties by causing gene mutation. Zindel (1970) used a higher temperature range of 204±6708C to dry poultry waste, but isolated ®ve bacteria from the dried samples and concluded that their presence was of little importance, indicating recontamination after drying.
The general performance of birds fed diets containing different types of RIBROPS are given in Table 5, along with data for birds fed the RIBROPS-free (control) diet for comparison. When performance data were compared, the birds fed diets containing
Table 4
Mean total viable counts (X 102) gÿ1, kinds and numbers (X 102) gÿ1of micro¯ora isolated from fresh and
processed oil palm slurrya
Item Fresh sample RIBROPS I RIBROPS II RIBROPS IV RIBROPS III
Mean viable count 18.10.49 3.50.18 3.60.15 3.50.17 3.70.16
SEM) is the average of duplicate samples
Table 5
Effect of processed oil palm slurry on the performance of broiler chickens over the period from 14 to 56 days of agea
Response criteria Dietary treatments SEM r
I (control) II III IV V
Feed intake (kg) 3.67 3.74 3.66 3.65 3.62 0.02 ÿ0.48
Protein intake (kg) 0.81 0.84 0.83 0.83 0.82 0.01 0.14 ME intake (MJ) 42.54 42.93 42.13 42.16 41.92 0.16 ÿ0.59*
Initial body weight (kg) 0.222 0.216 0.225 0.230 0.219
Weight gain (kg) 2.01 1.93 1.94 1.97 2.00 0.01 0.42
Feed conversion ratio 1.83 1.94 1.89 1.85 1.81 0.02 ÿ0.40
Mortality (%) 2.50 1.67 0.83 2.50 0.83 0.33 ÿ0.48
Carcass yield 0.81 0.79 0.80 0.80 0.80 0.0025 ÿ0.22
an120 birds for each dietary treatment, with 3 replications per treatment; SEM-standard error of means;r
-correlation coef®cient;determined with treatments II, III, IV and V.
*(P<0.05)
RIBROPS did not differ markedly from those on the control diet. Even though there was a trend towards decreasing feed consumption with increasing levels of OPS fraction of RIBROPS in the diet, feed intake by birds was not signi®cantly (P>0.05) in¯uenced by the inclusion of the four types of RIBROPS in the experimental diets suggesting that broilers will consume diets containing 100 g kgÿ1of the different types of RIBROPS. Regression of feed intake against level of OPS fraction of RIBROPS in the diet yielded the equation:
Y feed intake 3:71 0:25 ÿ0:0008 0:00004X r ÿ0:48;P>0:05
whereXis the level of OPS fraction of RIBROPS in the diet.
In general, there was no substantial difference in mean body weight gain during the period of 2±8 weeks of age between birds fed the control diet and the RIBROPS containing diets. The ef®ciency with which feed was converted to gain (feed: gain ratios) was also unaffected by dietary treatments. Comparing the performance of birds fed the four RIBROPS-containing diets, the highest rate of gain, though non-signi®cant was observed in birds fed RIBROPS IV-containing diet (i.e. dietary treatment V). This may be due to the high content of OPS fraction of RIBROPS in the diet. Earlier study (Atuahene et al., 1987) showed that a corresponding increase in the OPS level resulted in faster weight gains. The following correlations between the level of OPS fraction of RIBROPS in the diet and weight gain and feed conversion ratio were found:
Y weight gain 1:97 0:091 0:0001 0:00005X r0:42;P>0:05
Y feed: gain 1:89 0:24 0:0005 0:00003X r ÿ0:40;P>0:05:
Likewise, the carcass yields of broiler chickens fed diets with or without RIBROPS were similar. This observation is similar to that of Webb et al. (1977). The level of OPS fraction of RBROPS in the diet gave a correlation coef®cient of ÿ0.22 when linearly regressed against carcass yield indicating OPS exerted no signi®cant impact on this parameter.
A total of 10 mortality cases were recorded during the experimental period (Table 5). The mortality values were rather variable and show no trends that can be attributed to RIBROPS. Out of the 10 mortality cases, three (2.5%) each occurred among birds fed on the control and RIBROPS IIcontaining diets, two (1.67%) from the RIBROPS I-containing diet and one (0.83%) each from those on the other remaining RIBROPS containing diets. Post-mortem autopsies indicated no speci®c causes for deaths.
The ®ndings, under the conditions of this study, showed no toxic effects in terms of gross tissue changes in the liver. The histological characteristics of the liver from birds on the control diet were similar to those from birds on RIBROPS based diets.
Based on results obtained with the by-products tested in this study, it is concluded that RIBROPS is a suitable alternative energy source to be investigated in greater detail.
Acknowledgements
The authors thank Gyedu-Baah Apanin and T. Edusei for technical assistance, M. Pobee of the Faculty of Pharmacy, UST for microbial analysis, P.Wallace of the Animal
Research Institute of Ghana for the chemical analysis and Ms. Gladys Ndziba for her secretarial assistance. We acknowledge the ®nancial support of the National Agricultural Research Project of the Council for Scienti®c and Industrial Research of Ghana for conducting this study.
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