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Effects of enzyme supplementation and irradiation of rice bran on the performance of growing Leghorn and broiler chickens
ANIMAL FEED SCIENCE AND TECHNOLOGY
EIAWIER
Animal Feed Science Technology 66 ( 1997) 47-6
I
Effects of enzyme supplementation and irradiation of rice bran on the performance of growing Leghorn and broiler chickens G.J. Wang a*1,R.R. Marquardt a3*, W. Guenter a, Z. Zhang ‘*I, Z. Han b aDepartment of Animal Science, Unioersity of Manitoba. Winnipeg, Man. R37’2N2, Canada b Nanjing Agricultural
l/nicer&,
Nanjing, China, 210095
Accepted 24 October 1996
Abstract Three experiments investigated the effects of different concentrations of a crude enzyme preparation (RM-1) and rice bran from two sources (China and Malaysia) on the performance of growing Leghorn and broiler chicks when added to a wheat or a corn soya-bean meal basal diet. In the first experiment rice bran from Malaysia was also irradiated. In this experiment enzyme supplementation of the wheat-basal diet containing 400 g kg-’ Malaysian rice bran improved (P < 0.05) weight gains up to 9.6% and feed to gain ratio up to 5.4% while irradiation of rice bran at moderate (10 kGy) and high 50 (kGy) doses had no effect (P > 0.05) on these parameters. Chinese rice bran in contrast to Malaysian rice bran did not respond to enzyme treatment (P > 0.05). Similar improvements were obtained in the second experiment with RM-1 addition to the corn basal diet containing 250 and 500 g kg- ’ Malaysian rice bran, but not when added to the corn diet without rice bran. In addition, rice bran did not have any deleterious effects (P < 0.05) on growth and feed conversion efficiency of Leghorn chicks when incorporated into diets without enzyme supplementation. In contrast to the results with Leghorn chicks, the performance of broiler chicks was depressed (P > 0.05) when 250 and 500 g kg- ’ Malaysian rice bran was added to the diet. Chicks fed the diet containing 500 g kg-’ rice bran compared to those fed the control diet had decreased body weight gains (17%) and increased feed to gain ratios (1 l%), relative weights of the gastrointestinal tract (40%), and incidence of vent pasting (from 0 to 67%). Enzyme addition (10 mg kg - ’) to the 500 g kg- ’ rice bran diet improved ( P < 0.05) the feed to gain ratio
* Corresponding author. ’Present address: Nanjing Agricultural University, Nanjing, China, 210095. 0?77-8401/97/$17.00 0 1997 Elsevier Science B.V. All rights reserved. PII SO377-8401(96)01 128-5
G.J. Wang et al. /Animal Feed Science Technology 66 (1997) 47-61
48
(4%), and reduced the size of the gastrointestinal tract (7%) and the incidence of vent pasting (from 67 to 33%). These studies indicate that high concentrations (400-500 g kg-‘) of rice bran can be added to the diet of Leghorn chicks, at least over a relatively short period of time, without a deleterious effect on performance while as low as 250 g kg- ’ rice bran in the diet can depress broiler chick performance. The crude enzyme when added to diets containing rice bran produced equivocal results in chicks as it improved performance with one rice bran but not the other. 0 1997 Elsevier Science B.V.
Keywords:Crude enzymes; Leghorn and broiler chickens; Rice bran; Arabinoxylans; performance
1. Introduction
A total of 40-45 million tonnes of rice bran is produced annually, mainly in the Far East and southeast Asia (Farrell, 1994). It is used largely as animal feed. Only a limited
amount of rice bran is currently being used for food or oil extraction (Takano, 1993). Rice bran is a valuable feed-stuff because it is rich in B vitamins, fat and protein, and compares favourably with other cereal grains in amino acid composition (Warren and Farrell, 1991). It has, however, a high content of fiber (Warren and Farrell, 1990a,b,c,d; Farrell, 1994) that is rich in the hemicelluloses containing highly branched arabinoxylans (Shibuya and Iwasaki, 1985; Ebringerova et al., 1994). Amrison et al. (1995) has recently carried out nutritional studies on the water-soluble arabinoxylan-galactose complex isolated by extraction of rice bran in sodium hydroxide and sodium borohydride. They suggested that this fraction when added to broiler diets at a concentration up to 60 g kg- ’ had no effect on the Apparent Metabolizable Energy (AME) of the diet. A substantial amount of published data, however, has shown that there is a significant decline in performance with increasing inclusion of rice bran in the diet of chicks (Warren and Farrell, 1990a,b,c,d; Farrell, 1994, Madrigal et al., 1995). Studies to improve the nutritive value of rice bran by feed enzymes have been limited (Farrell, 1994). Nevertheless, rice bran having a high content of arabinoxylans may respond to enzymes that are able to hydrolyse this complex carbohydrate. Irradiation has also been shown to be effective at improving the nutritional value of cereal grains (Campbell et al., 1983, 1986, 1987). The purpose of this study was to determine the effect of irradiation and the addition of an enzyme preparation high in xylanase activity on the nutrient value of rice bran when fed to growing chicks.
2. Materials and methods 2.1. General procedures The experimental diets were formulated to meet National Research Council requirements (NRC, 1994) for Leghorn and broiler chickens (Tables 1 and 2). All diets were given free choice in mash form and water was supplied ud libitum. Wheat (variety, Katepwa), corn (cultivar unknown) and soya-bean meal were from local sources.
G.J. Wang et al. /Animal Feed Science Technology 66 (1997) 47-61 Table 1 Diet composition
in Experiment
49
1 Wheat (diet 10)
Ingredient (g kg- ’) Wheat (184.0, 12.36) b Malaysian rice bran (113.0, 12.57) Chinese rice bran, B (146.0, 12.57) Soya-bean meal (455.0, 9.41) Vegetable oil (0, 38.59) Alphacell (cellulose) Limestone Dicalcium phosphate L-lysine Vitamin mix ’ Mineral mix ’ Calculated analysis Protein MEn(MI kg-‘) Lysine Methionine + cystine Ca P available
816.0
55.2 4.05 43.0 13.5 13.2 3.6 10.0 5.0 180 12.2 8.5 6.4 8.0 4.0
Malaysian rice bran (diets l-9)
407.8 400 128.0 23.5 _
Chinese rice bran (diets 11, 12) a a
471.6 400 70 16.5
13.6 11.5 0.6 10.0 5.0
14.0 11.5 2.4 10.0 5.0
180 12.2 8.5 6.0 8.0 4.1
180 12.2 8.6 5.6 8.0 4.0
a The amounts of crude enzyme added to Malaysian (B. type) rice bran diets were 0, 1 and 10 gkg-’ The amounts added to the Chinese rice bran diets were 0 or 10 g kg-‘. No enzyme was added to the wheat diet. See footnotes of Table 3 for a description of individual diets. b Values in brackets are the respective crude protein content (N X 6.25, gkg-’ I and AME values (MI kg- ’1. ’ The vitamin and mineral mix supplied per kg diet: vitamin A, 8250 IU; vitamin, D,, 1000 IU; vitamin E, 10.9 IU; cobalamin, 0.0115 mg; vitamin K, 1.1 mg; riboflavin, 5.5 mg; Ca pantothenate, 11 .O mg; niacin, 53.3 mg; folic acid, 0.75 mg; biotin, 0.25; c h o 1’ me chloride, 1020 mg; Mn, 5.5 mg; Zn, 50 mg; Fe, 80 mg; Cu, 5 mg; Se, 0.1 mg; I, 0.18 mg; NaCl, 2.5 g.
Malaysian rice bran A, B and C were provided by Finnfeeds International Ltd, Singapore and Chinese rice bran by Nanjing Agriculture University, Nanjing, China. They were stored at a temperature below 0°C upon arrival to reduce the degree of peroxidation of the lipids. The protein (N X 6.25) and fat (ether extract) content in rice bran B, a mixture of A and C, and Chinese rice bran were 113 and 140 g kg-‘, 118 and 159 g kg-’ and 146 and 164 g kg-‘, respectively. The rice brans did not contain an appreciable amount of starch as indicated visually and they did not appear to be rancid when tasted. The crude enzyme preparation (KM-1 from Trichodemza longibrachiatum, lot # 94425319) was supplied by Finnfeeds International Ltd (Marlborough, Wiltshire, UK, SN8lAA) and contained 3450 U g- ’ of xylanase and 900 U g- ’ of Pglucanase activity. The enzyme preparation was assayed by Finnfeeds International using the 3,5 dinitrosalicylic acid reducing sugar method for xylanase and pglucanase. Xylan (pH 5.3) was used as the substrate for xylanase (Bailey, 1988) and endo-1,4-pglucan (pH 5.0) as the substrate for P-glucanase (Miller, 1959). The enzyme preparation also
50 Table 2 Diet composition
G.J. Wang et al. /Animal Feed Science Technology 66 (1997) 47-61
in Experiments
2 and 3 a Experiment
Ingredient (g kg-’ ) Corn (99.0, 14.041 Malaysian rice bran, B (113, 12.57) b Malaysian rice bran, A+C (118, 12.57) Soya-bean meal (459,9.41) Vegetable oil (0, 38.54) Limestone Dicalcium phosphate DL-methionine Vitamin mix ’ Mineral mix ’ Calculated analysis Protein MEn (MJkg-‘1 Lysine Methionine + cystine Ca P available
2
Experiment
3
Corn
250RB
500RB
Corn
250RB
500RB
111.5 -
461.8 250
205.7 500.8
562
325.1
88.9
238.0 _ 15.5 14.0 _ 10 5
230.8 14 16.0 12.2 0.2 10 5
223.5 28 16.3 11.0 0.5 10 5
352.1 35.8 17.0 15.2 2.3 10 5
250 340.0 35.8 17.5 14.0 2.6 10 5
500 327.0 35.8 18.0 12.5 2.8 10 5
180 12.3 8.5 6.3 9.0 4.1
180 12.3 9.1 6.2 9.0 4.0
180 12.3 9.1 6.2 9.0 4.1
220 12.6 11.1 9.0 10 4.5
220 12.3 11.6 9.0 10 4.5
220 12.0 12.1 9.0 10 4.5
a The amounts of crude enzyme added to each diet were 0, 1 or 10 kg-‘.
b Values in brackets are the respective crude protein content (NX6.25, ’ The composition
gkg-’ ) and AME values (MJkg-’ of the mineral and vitamin mix are given in the footnotes of Table 1.
1.
contained pectinase, CMC-cellulase, acetyl esterase and /3-xylosidase. Malaysian rice bran B was irradiated with lo-MeV electrons using a model I-10/ 1 electron accelerator (Atomic Energy of Canada, Ltd, Pinawa, MB) at an average dosage of 0, 10 and 50 kGy S ‘. Chick performance was expressed in terms of feed consumption, weight gain and feed to gain ratio. All results were reported on a per bird basis. Analysis of variance was conducted for all data using the general linear models (GLM) procedure of the Statistical Analysis System (1986). Linear contrasts and Duncan’s Multiple Range Test were also used for comparison of the treatments.
2.2. Experiment
I
The objective of this study was to determine if a crude enzyme preparation high in xylanase activity and irradiation of Malaysian rice bran could improve performance of chicks fed diets that contained a high concentration of rice bran. One-day-old male Leghorn chicks were purchased from a commercial hatchery. The chicks were fed a commercial chick starter diet for a 5-day pre-experimental period. The birds, after 4 h of starvation, were randomly distributed on day 5 into Petersime battery brooders (Jamesway Manufacturing Co., Ft. Atkinson, WL, 53538, USA) among 12 treatments using six birds per replicate and six replicates per treatment. The experiment was a completely
Description
Diet contrasts
a
Diet number %
%
P
Body mass gain (g)
Feed intake (g)
- 2.2 (2.22 vs 2.27) 2.3 (2.27 vs 2.22) 0 (2.22 vs 2.22)
NS NS NS
NS NS NS
are g per
(0, 1, 10 1-O; diet diet, diet diets and
NS 0.055 0.002
0.005 0.0001
a Diets l-9 contained rice bran from Malaysia that was subjected to different levels of irradiation (0, 10, 50 kGy) and contained different amounts of enzyme gkg -I, indicated by subscript numbers). The amount of enzyme added to the diets and the irradiation dosages of rice bran in kGy were: diet 1, O-O; diet 2, 3, IO-O; diet 4, O-IO; diet 5, l-10; diet 6 10-10; diet 7, O-50; diet 8, I-50 and diet 9, 10-50, respectively. Diet 10 was the control wheat soya-bean meal 11 contained Chinese rice bran with no enzyme and diet 12 contained Chinese rice bran with 10 gkg-’ enzyme. See Table 1 for the composition of the Section 2 for experimental design. ’ Values in brackets represent average performance values for chicks fed diets listed under Diet contrasts. The units of feed intake or body mass gain chicken over a ‘I-day experimental period.
0.004
0 (2.22 vs 2.22) -3.2 (2.15 vs 2.22) -5.4 (2.10 vs 2.22)
- 3.2 (2.15 vs 2.22) -5.4 (2.10 vs 2.22)
%
NS 0.05
0.0004
0.04
P
Feed to gain ratio
P
rice bran from two different sources and
Percent increase or decrease in first value in brackets relative to the second value b
criteria in Leghorn chicks between 6 and 13 days of age when fed diets containing 1)
rice bran (RBM) diet with enzyme (RBM, or RBM,,) vs RBM without enzyme (RBM,) RBM, -RBM, 2.2 (96.9 vs 94.7) NS 5.6 (45.1 vs 42.7) (2,5,8)-(1,4,7) 2 RBM,, -RBM, 3.7 (98.2 vs 94.7) 0.04 9.6 (46.8 vs 42.7) (3,6,9)-(1,4,7) Malaysian rice bran diet with or without enzyme (RBM,, RBM, or RBM,,) vs control diet (Cc) 3 RBM,-C, (1,4,7)-10 1.4 (94.8 vs 93.4) NS 1.2(42.7 vs 42.2) 4 RBS, -C, (2,5,8)-10 3.8 (96.8 vs 93.4) NS 6.9 (45.1 vs 42.2) 5 RBS,,-C, (3,6,9)-10 5.2 (98.2 vs 93.4) 0.04 10.9 (46.8 vs 42.2) Chinese rice bran (RBCh) diet with or without enzyme (RBCh,, or RBCh,) vs RBCh, or the control diet (C,) - 3.3 (96.7 vs 100.0) NS 6 RBCh,, -RBCh, 12-1 I -0.9 (43.7 vs 44.1) 7 II-10 RBCh, -C, 7.1 (100.0 vs 93.4) 0.025 4.5 (44.1 vs 42.2) 8 RBCh ,a -C, 12-10 3.6 (96.7 vs 93.4) NS 3.6 (43.7 vs 42.2)
1
Malaysian
Contrast number
Table 3 Selected linear contrasts of performance supplemented with enzyme (Experiment
52
G.J. Wang et al. /Animal Feed Science Technology 66 (1997) 47-61
randomized design with a 3 (0, 1 and 10 g RM-1 kg-‘) X 3 (0, 10 and 50 kGy) factorial arrangement of diets 1 to 9. The other treatments included a wheat control diet (diet 10) and Chinese rice bran diets with 0 and 10 g kg-’ enzyme addition (diets 11 and 12). See Table 1 and footnote of Table 3 for further description of diets l- 12. The experiment was conducted during a 7-day period using chicks that were 6-13 days of age. Other procedures for treatment of chickens were as routinely used in our laboratory and as reported by Marquardt et al. (1994). 2.3. Experiment 2 The objective of this study was to determine the response of Leghorn chicks to different concentrations of enzyme supplementation when fed diets containing different concentrations of Malaysian rice bran. The control diet in this study was a corn soya-bean meal diet rather than the wheat soya-bean meal diet used in Experiment 1. All diets were formulated to be isoenergetic and isonitrogenous. The experiment was a completely randomized design with a 3 (0, 1 and 10 g kg-’ RM-1) X 3 (0, 250 and 500 gkg-’ rice bran) factorial arrangement of treatments. The composition of the diets is outlined in Table 2. The weights of the Leghorn chicks were recorded 4 h after removal of feed at 4 and 11 days of age. Feed consumption was determined at day 11 of age. Other procedures are the same as for Experiment 1. 2.4. Experiment 3 The objective of this study was to determine if results similar to those obtained in Experiment 2 could be obtained when broiler rather than Leghorn chicks were fed diets containing different concentrations of Malaysian rice bran and enzymes, and to determine the effect of rice bran and enzyme treatment on the size of the gastro-intestinal tract and incidence of vent pasting. The diets were isonitrogenic but tended to have a lower energy value with increasing concentrations of rice bran. One-day-old male vaccinated (Marek’s) broiler chicks of Arbor Acre X Ross parentage were purchased from a commercial hatchery. The chicks were fed the control corn diets from days 1 to 5 of age. They were randomly distributed on day 5 after 4 h of starvation into Petersime batteries among nine treatments using five birds per replicate and five replicates per treatment. The experiment was a completely randomized design with a 3 (0, 1 and 10 gkg-’ RM-1) X 3 (0, 250 and 500 gkg-’ rice bran) factorial arrangement of the nine diets (Table 2). Bird weights and feed consumption were determined on day 12 after 4 h of starvation. Chicks fed diets 1 (corn diet without enzyme addition), 3 (500 g kg-’ rice bran diet without enzyme), 7 (corn diet with 10 gkg-’ enzyme addition) and 9 (500 gkg-’ rice bran with 10 g kg- ’ enzyme addition) were re-fed the same diets until 15 days of age for the determination of the size of the digestive organs (weight and length). Fifteen birds per treatment were weighed and then killed by cervical dislocation after 18-24 h feed withdrawal. Residual digesta was removed from the gastrointestinal tract by manual compression. The weights of the crop, proventriculus and gizzard, and the lengths and weights of the duodenum, jejunum, ileum, ceca and colon were determined
G.J. Wang et al./Animal
Feed Science Technology 66 (1997) 47-61
53
after blotting to remove free water. The frequency of vent pasting of the birds was also scored on the basis of the amount of excreta entrapped in the surrounding feathers in the area of the cloaca at 15 days of age as outlined by Boros et al. (1995).
3. Results 3.1. Experiment
I
Analysis of variance of the data from experiment one indicated that the addition of enzyme to the rice-bran diets improved body weight gain (P < 0.05) and improved the feed to gain ratio (P < 0.01) but did not affect feed consumption (P > 0.05). Irradiation of the rice bran did not affect chick performance (P > 0.05). There were no enzyme by irradiation interactions (P > 0.05), therefore, these values are not shown. Linear contrasts show some of the effects (Table 3). The linear contrasts were also used to compare performance values for chicks that were fed diets containing rice bran from a different source (Chinese rice bran) and for those fed the control wheat diet. The increases in weight gain by the addition of enzyme to the diets containing the Malaysian rice bran were 5.6% (P = 0.04, contrast 1) and 9.6% (P < 0.01, contrast 2) with 1 and 10 gkg-’ enzyme added to the feed, respectively, while the corresponding improvement in the feed to gain ratio were 3.2 (P = 0.005) and 5.4% (P < 0.001). Linear contrast analysis, in contrast to the analysis of variance results, indicated that feed intake with the high amounts of enzyme was also increased (3.7%, P = 0.04, contrast 2). In contrast to these results enzyme addition to diets containing Chinese rice bran did not affect chick performance (P > 0.05, contrast 6). The performance of chicks fed the Malaysian rice bran diets without enzyme (contrast 3) and the Chinese rice bran with or without enzyme (contrasts 7 and 8) were generally the same (P > 0.05) as for chicks fed the control wheat soya-bean meal containing diets. In contrast, the weight gain of chicks that were fed the diet containing the Malaysian rice bran that was supplemented with 1 or 10 g kg-’ enzyme were 6.9% (P = 0.05, contrast 4) and 10.9% (P = 0.004, contrast 5) higher than for the chicks fed the control wheat-soya diet. The corresponding improvements in the feed to gain ratio were 3.2% (P = 0.055) and 5.4% (P = 0.002). These results, which were obtained during a short experimental period, indicate that the performance of Leghorn chicks can, in some cases, be improved by the addition of enzymes to diets that contain a high content of rice bran (40%) and that the performance of these chicks with or without enzyme addition was similar or superior to that obtained with a control wheat soya-bean meal diet. In contrast, irradiation of rice bran did not affect chick performance (P > 0.05). 3.2. Experiment
2
Analysis of variance of the data from Experiment 2 indicated that there was no interaction (P > 0.05) between the amount of rice bran included in the diet and the concentration of enzyme (0, 1 and 10 g kg-’ 1, and no main effect of enzyme (P > 0.051,
54
G.J. Wang et al. /Animal
Feed Science Technology 66 (1997) 47-61
Table 4 The performance of Leghorn chicks between days 4 and 11 of age when fed diets containing three concentrations of enzyme (0, 1 and 10 g RM-1 kg-‘) and three concentrations of rice bran (0, 250 and 500 g kg-’ ) (Experiment 2) a Diet main effect
Feed intake (g per bird per 7 days)
Body mass gain (g per bird per 7 days)
Feed to gain ratio
Rice bran 0 Rice bran 250 Rice bran 500 Pooled SEM
79.3 84.2(6) b 81.7(3) 1.1
33.5 37.7(12) 35.7(7) 0.78
2.38 2.24(6) 2.30(3) 0.032
NS 0.002 NS
NS 0.016 NS
Analysis of variance, probabilities Enzyme (E) NS Diet (D) 0.013 EXD NS a See Table 5 for linear contrasts. b Values in brackets are the percent improvements
relative to the diet with no rice bran.
but an effect (P < 0.05) of diet on feed intake, body mass gain and feed to gain ratio (Table 4). The increase in body mass of Leghorn chicks fed the diets containing 250 or 500 g kg-’ rice bran were 12 and 7%, respectively, compared to those fed the control corn soya diet. Corresponding changes in feed to gain ratio were 6 and 3%. Linear contrasts, in contrast to the analysis of variance data, indicated that there was a significant effect of enzyme on the performance of Leghorn chicks when they were fed the rice bran diets (P < 0.05, see contrasts 7-9, Table 5) but not when fed the corn control diet (P > 0.05, contrasts 1 and 2). For example, the overall improvements were 7.1% (P = 0.04) for weight gain and 4.3% (P = 0.05) for feed to gain ratio when the results for diets 5, 6, 8 and 9 (RB, + rO, ie, rice bran with enzyme) were contrasted with those for diets 2 and 3 (RB,, i.e., rice bran with no enzymes). Enzyme addition to the corn diets (C t-C, and CrO-Co) indicated that dietary enzyme did not affect chick performance (P > 0.05). Also, the performance of Leghorn chicks fed the diets containing rice bran with no enzyme (25ORB, and 500RB,) was the same (P > 0.05) as for chicks fed the control diet (C,) (P > 0.05, contrasts 3 and 4), but was superior (P < 0.05) to the control diets in several of the comparisons when enzyme was added to the two bran diets (25ORB,,,, and 5OORB,,,,, contrasts 5 and 6). For example, the diets containing 250 g kg- ’ rice bran plus enzyme (250RB ,,r,,) yielded feed intake, weight gain and feed to gain values that were 7.0% (P = O.Ol), 17% (P = 0.01) and 8.7% (P = 0.05) better than those obtained with the control diet (C,). The differences were less pronounced when the diet contained 500 g kg- ’ rice bran (contrasts 4 and 6). These results again indicate that the performance of Leghorn chicks fed diets containing high levels of rice bran (250 or 500 g kg- ’> yield performance values similar or better than those fed a control (corn) diet and that enzyme addition to rice bran diets appeared to improve chick performance.
Description
Contrasts
Diet number b
chicks fed nine different
diets containing
three concentrations
of enzyme (Experiment
%
Feed intake (g) c,d
P
%
Body mass gain (g) c,d
P
%
0.026 0.065 0.05 2.33) 2.33) 2.33)
” See Table 4 for analysis of variance data. ’ Diets l-9 contained different percentages of Malaysian rice bran (0. 250 or 500 g kg- ’) and different amounts of enzyme (0, 1 or 10 gkg- ’). Dietary designations were: diet I, O-O; oiet 2. 250-O; diet 3, 500-O; diet 4, 0- 1; diet 5. 250-I ; diet 6, 500-l ; diet 7, 0- 10; diet 8, 250- 10; and diet 9, 500- 10 g kg- ’, respectively. ’ Values in brackets represent g feed intake or body mass gain (g) per chick per 7 days and the feed to gain ratio for diets listed under Contrasts. ” In genera1 there were no significant differences for feed intake, weight gain and feed to gain ratio for the following contrasts: 250RB, -250RB, (5-2), 250RB,, -250RB,, (8-2), 5OORB, -5OORB,, (6-3) and 500RB,,,-500RB,, (Y-3). However, among these comparisons there was a significant difference in body mass 2.20 vs 2.36, P
NS NS 0.05 NS
2.42) 2.42) 2.42) 2.42)
P
NS NS
2) ’
2.42) 2.42)
Feed to gain ratio c.d
Percent increase or decrease in first value in brackets relative to the second value
criteria for Leghorn
Control diet (C) with enzyme (C, or C ,“) vs control diet without enzyme (C,) ’ NS 2.0 (33.8 vs 33.0) NS - I .7 (2.38 vs 4-1 1.O (80.2 vs 79.4) I C,-Cll - 3.7( 2.33 vs 2 7-l -1.0 (78.5 vs 79.4) NS 2.5 (33.8 vs 33.0) NS Cl,--” Rice bran (RB) at 250 or 500 gkg- ’in the diet in the presence or absence of enzyme (0 or I, 10) vs the control diet without enzyme CC,,) - 4.5 (2.3 1 vs 9.1 (36.0 vs 33.5) NS 3 250RB, -C, 2-l 3.7 (82.3 vs 79.4) NS - 2.5 (2.36 vs 4 1.O (80.2 vs 79.4) NS 3.3 (34.1 “S 33.5) NS 500RB,, -C,, 3-l - 8.7 (2.2 I vs 17.0 (38.6 vs 33.5) 0.01 5,8-l 7.0 (85.0 vs 79.4) 0.01 5 250RB 1,10- C 0 - 5.8 (2.28 vs 4.0 (82.6 vs 79.4) NS 10.3 (36.4 vs 33.5) 0.05 6,9-l 6 500RB 1.10- C 0 Rice bran with enzyme (RB, or RB,,,) vs rice bran with no enzyme (RB,,) 9.4 (82.8 vs 8 I .2) 0.4 I 7.0 (37.5 “S 35.0) 0.07 -5.6 (2.21 vs 7 RB, -RB, 5,6-2.3 - 3.0 (2.27 vs 4.4 (84.8 vs 81.2) 0.06 7.2 (37.6 vs 35.0) 0.07 8 RB,,-RB, 8.9-2.3 -4.3 (2.24 vs 7. I (37.5 “S 35.0) 0.04 5.6.8.9-2.3 3.2 (83.8 vs 81.2) 0.12 9 RB I,IO-RBo
Contrast number
Table 5 Selected linear contrast of performance
2
2 yZZ
G.J. Wang et al. /Animal Feed Science Technology 66 (1997) 47-61
56
Table 6 The performance of broiler chicks between 5 and 12 days of age when concentrations of enzyme and three concentrations of rice bran (Experiment 3) Treatment
Rice bran (g kg0 250 500
Feed intake (g per bird per 7 days)
Body mass gain (g per bird
Feed to gain ratio a
fed diets
containing
three
Frequence of vent pasting a (%)
per 7 days)
’diet), main effect b 212’ 212(O)‘J 195(8)’
Enzyme (g kg-’ diet), main effect b 0 206 1 208 10 206 Pooled SEM 2.41
150’ 143W 124f17j3 137 137 142 1.89
1.42’ 1.49(-512 1.57(- 1113 1.512 1.52(o)* 1.45(-4)’ 0.016
0’ $ 302 W-53) 14(-53)’ 3.3
Analysis of variance, probabilities Enzyme (E) Rice bran E X Rice bran
0.84 0.0001 0.61
0.15 0.0001 0.51
0.01 0.0001 0.14
0.002 0.0001 0.03
a The vent pasting values (%I for each rice bran (RB) and enzyme (E) treatment were: 0%. for 0 BB, 0 E; 23% for 250 RB, 0 E; 67% for 500 BB, 0 E; 0% for 0 RB, 1 E; 10% for 250 BB, 1 E, 33% for 500 RB, 1 E, 0% for 0 RB, 10 E, 10% for 250 BB, 10 E, and 33% for 500 RB, 10 E. Values were recorded on day 15 of the experiment. b Means for each main effect and within a column with no common superscrips differ significantly (P < 0.05). Values in brackets are the percent increase or decrease obtained relative to the diet with no rice bran.
3.3. Experiment
3
The experimental design was similar to that for Experiment 2 except broiler chicks instead of Leghorn chicks were used and the diets were formulated to be near but not isocaloric since the calculated energy values of the diets containing 250 and 500 g kg- ’ rice bran were 2.4 and 5% lower than the reference corn soya-bean meal diet. Analysis of variance of the data demonstrated that there were main effects (P < 0.05) for both diet and enzyme treatments (Table 6). In general there was a decrease in feed intake and body mass gain and an increase in feed to gain ratio when 250 and 500 g kg-’ rice bran was included in the diet with the effects being much greater than the corresponding change in the energy value of the diets. The inclusion of the high concentrations of enzyme into the diet improved the feed to gain ratio by 4%. Performance data as determined on day 15 of the experiment for chicks fed diets 1, 3, 7 and 9 followed the same trend as for day 12 (data not shown). The inclusion of 500 g kg-’ rice bran into the diets markedly increased (P < 0.05) the relative size and length of all segments of the digestive tract (Table 7). The average percent increase in the weight of the digestive tract was 40% (9.2 to 12.9 g per 100 g body weight) while the corresponding increase in its length was 38% (39.8 to 55.1 cm per 100 g body weight). The inclusion of 10 g kg-’ of enzyme in the diet did not affect (P > 0.05) the weight of the digestive organs of
G.J. Wang et al. /Animal
57
Feed Science Technology 66 (1997) 47-61
Table 7 Relative weight and length of the digestive organs of broilers fed enzyme supplemented diets (0 or 10 g kg-’ 1 containing 0 or 500 gkg-’ Malaysian rice bran , over a lo-day period (Experiment 3) a Diets Corn+++ Corn Relative organ weight, g per 100 g body weight Crop 0.432 0.42’ Proventriculus 0.703 0.693 Gizzard 2.98’ 2.96’ Duodenum 1.26’ 1.192 Jejunum 1.862 1.92’ Ileum 1.28’ 1.29’ Ceca 0.47 2 0.502 Colon 0.273 0.26’ Total 9.253 9.223 Relative organ length, cm per 100 g-’ body weight Duodenum 6.38’ 6.22* Jejunum 14.442 14.86* Ileum 14.26’ 14.032 Ceca 2.98’ 3.032 Colon 1.682 1.63* Total 39.80* 39.72’
Rice bran
Rice bran + E
Pooled SEM
0.51’ 1.04’ 3.41’ 2.02 ’ 2.81’ 2.03 ’ 0.66 ’ 0.37’ 12.86’
0.51’ 0.93*(- 10.6) b 2.98*(- 12.6) 1.98’ 2.64’ 1.92’ 0.65’ 0.342(-8.1) 11.95*(-7.1)
0.011 0.031 0.075 0.04 I 0.074 0.047 0.022 0.0084 0.18
9.18’ 20.77’ 19.18’ 3.90’ 2.07 ’ 55.10’
8.64’ 20.28’ 19.37’ 3.85’ 2.12’ 54.26’
0.25 0.51 0.43 0.080 0.064 1.07
a Organ weights were for 15-day-old chicks. The mean weight of broilers in the groups fed corn, corn plus enzyme, rice bran and rice bran plus enzyme were 306, 302, 241 and 249 g, respectively. b Values in parentheses are percentage decrease obtained following enzyme addition to the rice bran diets. “2’3Means within a row with no common superscripts differ significantly (P < 0.05).
chicks fed the control corn containing diet, but it decreased (P < 0.05) the weight of the proventriculus (1 l%), gizzard (13%), colon (8%) and the total gastrointestinal tract (7%) when present in the diet containing 500 g kg- ’ rice bran. The relative length of the digestive tract was not affected (P < 0.05) by enzyme treatment. The degree of vent pasting also increased (P < 0.05) when measured at 15 days of age when rice bran was added to the diet (Table 6). These chicks had been fed the diet for 10 days. No apparent vent pasting was observed in Experiment 2 when Leghorn chicks were fed the diet containing 500 g kg- ’ rice bran for 7 days (day 5 to day 12). These data also indicated that enzyme addition to the diet improved broiler chick performance and reduced the size of the gastrointestinal tract and incidence of vent pasting.
4. Discussion The results of the current study demonstrated that diets containing high quantities of rice bran without enzyme (250 to 500 g kg- ’> yielded weight gains and feed to gain ratios in Leghorn chickens that were similar to those obtained with the corn- or wheat-based control diets. In contrast, similar amounts of rice bran in diets that were fed to broiler chicks decreased feed intakes and weight gains and increased the feed to gain ratio compared to those obtained with broilers fed the corn-based diet. This effect was
58
G.J. Wang et al. /Animal
Feed Science Technology 66 (1997) 47-61
more pronounced for the diet that contained the high concentration of rice bran (250 vs 500 g kg- ’>. Data from the literature has indicated that there is usually a decrease in the weight of broiler chicks as the content of full-fat rice bran in the diet is increased with the magnitude of the effect varying considerably among experiments and in part depending upon the effect that the diet has on feed intake (Kratzer et al., 1974; Warren and Farrell, 1990b; Farrell, 1994). Similarly, the feed conversion ratios are usually poorer with increasing dietary inclusion of rice bran, the point at which this occurs, however, varies (Farrell, 1994). Warren and Farrell (1990b) observed no change in feed conversion ratios to 400 g kg- ’ rice bran in the diet in some experiments while in others a poor conversion was observed at 200 g kg-’ ; clearly some factor(or factors) in rice bran appears to affect chick performance in an unknown manner. It is conceivable that variation in the fiber, protein and oil content, rancidity of the lipid fraction, and other constituents in rice bran may be responsible for this effect (Farrell, 1994). Annison et al. (1995) on the basis of studies with an isolated crude arabinoxylan fraction concluded that rice bran non-starch polysaccharides possessed no anti-nutritive activity. They also reported that this fraction increased (P < 0.05) rather than decreased the AME of the diet when incorporated into the diet at a concentration of 60 g kg-‘. These results are different to those obtained with other arabinoxylans as they are usually considered to be indigestible and as a result do not contribute to the nutritional value of the diet. In addition to affecting the performance of broiler chickens, rice bran substantially increased the size of the gastrointestinal tract. Similar increases have been reported in chickens fed a diet high in soluble (Scout barley) or insoluble fiber (Bedford barley) (Brenes et al., 1993). Studies by Jones et al. (1985), Sirear et al. (1983) and Rompala and Madsen (1989) have also shown that diets high in roughage increased the size of the gastrointestinal tract in other species of animals. Part of the effect in the current study may be attributed to difference in mature size of the broiler in the different treatment groups as younger less-developed birds tend to have larger relative sizes of intestines than more mature birds (Sreemannarayana et al., 1989). These observations, nevertheless, suggest that the high content of neutral detergent fiber in rice bran may have been responsible in the current study for the increased size of the gastrointestinal tract. The arabinoxylan are probably mainly responsible for this effect as they comprise the bulk of the hemicellulose in rice bran (Shibuya and Iwasaki, 1985; Ebringerova et al., 1994). Irradiation in previous studies has been shown to improve the nutritional value of cereals such as oat groats (Campbell et al., 1986, 1987) and rye (Campbell et al., 1983). The beneficial effects of irradiation were attributed to the partial breakage of the polymeric structure of the viscous carbohydrate in the two cereals. This decreased their viscosity and produced a corresponding reduction in their antinutritive effects. In contrast, irradiation of rice bran at 10 or 50 kGy in the current study did not improve its nutritive value. This lack of response was probably not caused by a failure to break the rice bran polysaccharides as the dosage was of sufficient energy to bring this about (Leeson and Marcotte, 1993). Irradiation may have been ineffective due to the absence of viscous carbohydrates in rice bran. Under such conditions no change in viscosity will occur with irradiation. Therefore, the corresponding improvements associated with these changes would not be seen. The addition of a crude enzyme mixture to diets containing high concentrations of
G.J. Wang et al./Animal
Feed Science Technology 66 (1997147-61
s9
rice bran produced equivocal results. For example, the high concentration of enzyme ( 10 gkg -’ in the diet) did not produce any beneficial response in Leghorn chicks when added to the Chinese rice bran diet but it improved weight gain and the feed to gain ratio by 7 and 3.4%, respectively, when added to diets containing Malaysian rice bran. The high concentration of enzyme when added to broiler chicks diets containing the Malaysian rice bran not only improved the feed to gain ratio, but also reduced the incidence of vent pasting and decreased the size of the gastrointestinal tract. The results collectively indicate that enzyme supplementation of chicken diets containing rice bran can improve chick performance in some cases. The reason for the completely different response to enzyme treatment of the rice brans obtained from two different regions in Asia was not established. Part of this difference may be caused by differences in processing methods or to varietal or environmental differences during growth. The limited proximate analysis carried out on the rice brans would indicate that it was not caused by a difference in the content of crude protein or fat. The studies also demonstrated that the weight gain and feed to gain ratio for the Leghorn chickens that were fed the enzyme supplemented rice bran diet, especially the diet containing 250 gkg-’ as compared to 500 g kg-- ’ rice bran, yielded performance values that were superior to the corn control diet. Only a few studies have been reported in the literature on the use of enzyme in poultry diets containing rice bran. (Farrell, 1994). Studies with lipase and two modified enzyme mixtures which targeted the cell wall content essentially did not improved the nutritive value of rice bran in broiler starter diets. The improvement observed in the current study were probably due to the effects of the xylanases or possibly the P-glucanases on the hemicellulose fraction of the rice bran. All of the above studies were of relatively short duration (7 days) and, as a result, it is not known if a similar pattern of response would be obtained over a much larger period of time. The results of this study have, nevertheless, shown that high concentrations of rice bran when fed to Leghorn chicks over a short period of time, especially in association with an enzyme preparations high in xylanase and /_I-glucanase activity, produced weight gains and feed to gain ratios that were equal to or superior to those produced by corn or wheat-based diets. Broiler chicks, however, were not able to utilize rice bran diets as well as the control diets. The high fiber content of the rice bran may have been partially responsible for this effect. Further research needs to be carried out to identify factors that affect the efficacy of enzyme preparations when added to diets that contain rice bran, to establish the degree of corresponding response of these treatments in different classes of chicks and over longer periods of time, and to determine the influence of the type of rice bran and type of enzyme preparations on the response that is obtained. Such studies would assist in clarifying the results obtained in the current study and determine the optimum level of rice bran that can be used in different diets in the presence and absence of the appropriate enzyme mixture.
Acknowledgements This investigation was funded by grants from Finnfeeds International Ltd. (Wiltshire, UK, SN 8lAA), International Research and Development Centre (Ottawa. On, Canada)
60
G. .I. Wang et al. /Animal Feed Science Technology 66 f 1997) 47-61
and the University of Manitoba, Winnipeg, MB. The authors wish to thank J. Borsa, AECL, Pinawa MB, for assistance with the irradiation of rice bran, H. Muc for assistance with the feeding trials, and G.H. Crow for assistance with statistical analysis.
References Annison, G., Moughan, P.J. and Thomas, D.V. 1995. Nutritive activity of soluble rice bran arabinoxylans in broiler diets. Br. Poult. Sci., 36: 479-488. Bailey, M.J. 1988. A note on the use of dinitrosalicylic acid for determining the products of enzymatic reaction. Appl. Microbial. Biotechnol., 29: 494-496. Boros, D., Marquardt, R.R. and &enter, W. 1995. Rye as an alternate grain in commercial broiler feeding. J. Appl. Poult. Res. 4: 341-351. Brenes, A., Smith, M., Guenter, W. and Marquardt, R.R. 1993. Effect of enzyme supplementation on the performance and digestive tract size of broiler chickens fed wheat- and barley-based diets. Poult. Sci., 72: 1731-1739. Campbell, G.L., Classen, H.L. and Ballance, G.M. 1986. Gamma irradiation treatment of cereal grains for chick diets. J. Nutr., 116: 560-569. Campbell, G.L., Classen, H.L., Reichert, R.D. and Campbell, L.D. 1983. Improvement of the nutritive value of rye for broiler chickens by gamma irradiation-induced viscosity reduction. Br. Poult. Sci., 24: 205-211. Campbell, G.L., Sosulski, F.W., Classen, H.L., Balance G.M. 1987. Nutritive value of irradiation and pglucanase-treated wild oats groats (Auenafatua Z_J for broiler chickens. Poult. Sci., 16: 243-252. Ebringerova, A., Hromadkova, I. and Berth, G. 1994. Structural and molecular properties of a water-soluble arabinoxylan-protein complex isolated from rice bran. Carbohydr. Res., 264: 97-109. Farrell, D.J. 1994. Utilization of rice bran in diets for domestic fowl and ducklings. World’s Poult. Sci. J., 50: 115-131. Jones, S.D.M., Rompala, R.E. and Jeremiah, L.E. 1985. Growth and composition of the empty body in steers of different maturity types fed concentrate or forage diets. J. Anim. Sci., 60: 427-433. Kratzer, F.H., Earl, L. and Chiaravanont, C. 1974. Factors influencing the feeding value of rice bran for chickens. Poult. Sci., 53: 1795-1800. Leeson, S. and Marcotte, M. 1993. Irradiation of poultry feed II. Effect on nutrient composition. World’s Poult. Sci. J., 49: 120-131. Madrigal, S.A., Watkins, S.E., Adams, M.H. and Waldroup, P.W. 1995. Defatted rice bran to restrict growth rate in broiler chickens. J. Appl. Poult. Res., 4: 170-181. Marquardt, R.R., Boros, D., Guenter, W. and Crow, G. 1994. The nutrient value of barley, rye, wheat and corn for young chicks as affected by use of a Trichoderma reesei enzyme preparation. Anim. Feed Sci. Technol., 45: 363-378. Miller, G.L. 1959. Use of dinitrosalicylic acid reagent for determination of reducing sugar. Analyt. Chem., 31: 426-428. National Research Council, 1994. Nutrient Requirements of Poultry, 9th edn. National Academy of Science, Washington, DC. Rompala, R.E. and Madsen, F.C. 1989. Diet impacts mass, functional work load of animal gut. Feedstuffs., 61: 16-17. Shibuya, N. and Iwasaki, T. 1985. Structural features of rice bran hemicellulose. Phytochem., 24: 285-289. Sirear, B., Jolinson, L.R. and Lichtenberger L.M. 1983. Effects of synthetic diets on gastrointestinal mucosal DNA synthesis in rats. Am. J. Physiol., 244: G327-335. Sreemannarayana, 0.. Frolilich, A.A., Marquardt, R.R. and Guenter, W. 1989. The relative growth of internal organs of single comb while leghorn bids. Indian Vet. J., 66: 636-639. Statistical Analysis Systems Institute Inc. 1986. SAS User’s Guide: Statistics. SAS Institute Inc., Cary, NC. Takano, K. 1993. Mechanism of lipid hydrolysis in rice bran. Cereal Foods World, 38: 695-698. Warren, B.E. and Farrell, D.J. 1990a. The nutritive value of full-fat and defatted Australian rice bran. 1. Chemical composition. Anim. Feed Sci. Tech., 27: 217-228.
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Warren, B.E. and Farrell, D.J. 1990b. The nutritive value of full-fat and defatted rice bran II. Growth studies with chickens, rats and pigs. Anim. Feed Sci. Tech., 27: 229-246. Warren, B.E. and Farrell, D.J. 1990~. The nutritive value of full-fat and defatted rice bran III. The apparent digestible energy content of defatted rice bran in rats and pigs and the metabolizability of energy and nutrients in defatted and full-fat bran in chickens and adult cockerels. Anim. Feed Sci. Tech., 27: 245-247. Warren, BE. and Farrell, D.J. 199Od. The nutrient value of full-fat and defatted rice bran. IV. Egg production of bens on diets with defatted rice bran. Anim. Feed Sci. Tech., 27: 259-268. Warren, B.C. and Farrell, D.J. 1991, The nutritive value of full-fat and defatted Australian rice bran V. The apparent retention of minerals and apparent digestibility of amino acids in chickens and adult cocker& with ileal cannulac. Anim. Feed Sci. Tech., 34: 323-347.
EIAWIER
Animal Feed Science Technology 66 ( 1997) 47-6
I
Effects of enzyme supplementation and irradiation of rice bran on the performance of growing Leghorn and broiler chickens G.J. Wang a*1,R.R. Marquardt a3*, W. Guenter a, Z. Zhang ‘*I, Z. Han b aDepartment of Animal Science, Unioersity of Manitoba. Winnipeg, Man. R37’2N2, Canada b Nanjing Agricultural
l/nicer&,
Nanjing, China, 210095
Accepted 24 October 1996
Abstract Three experiments investigated the effects of different concentrations of a crude enzyme preparation (RM-1) and rice bran from two sources (China and Malaysia) on the performance of growing Leghorn and broiler chicks when added to a wheat or a corn soya-bean meal basal diet. In the first experiment rice bran from Malaysia was also irradiated. In this experiment enzyme supplementation of the wheat-basal diet containing 400 g kg-’ Malaysian rice bran improved (P < 0.05) weight gains up to 9.6% and feed to gain ratio up to 5.4% while irradiation of rice bran at moderate (10 kGy) and high 50 (kGy) doses had no effect (P > 0.05) on these parameters. Chinese rice bran in contrast to Malaysian rice bran did not respond to enzyme treatment (P > 0.05). Similar improvements were obtained in the second experiment with RM-1 addition to the corn basal diet containing 250 and 500 g kg- ’ Malaysian rice bran, but not when added to the corn diet without rice bran. In addition, rice bran did not have any deleterious effects (P < 0.05) on growth and feed conversion efficiency of Leghorn chicks when incorporated into diets without enzyme supplementation. In contrast to the results with Leghorn chicks, the performance of broiler chicks was depressed (P > 0.05) when 250 and 500 g kg- ’ Malaysian rice bran was added to the diet. Chicks fed the diet containing 500 g kg-’ rice bran compared to those fed the control diet had decreased body weight gains (17%) and increased feed to gain ratios (1 l%), relative weights of the gastrointestinal tract (40%), and incidence of vent pasting (from 0 to 67%). Enzyme addition (10 mg kg - ’) to the 500 g kg- ’ rice bran diet improved ( P < 0.05) the feed to gain ratio
* Corresponding author. ’Present address: Nanjing Agricultural University, Nanjing, China, 210095. 0?77-8401/97/$17.00 0 1997 Elsevier Science B.V. All rights reserved. PII SO377-8401(96)01 128-5
G.J. Wang et al. /Animal Feed Science Technology 66 (1997) 47-61
48
(4%), and reduced the size of the gastrointestinal tract (7%) and the incidence of vent pasting (from 67 to 33%). These studies indicate that high concentrations (400-500 g kg-‘) of rice bran can be added to the diet of Leghorn chicks, at least over a relatively short period of time, without a deleterious effect on performance while as low as 250 g kg- ’ rice bran in the diet can depress broiler chick performance. The crude enzyme when added to diets containing rice bran produced equivocal results in chicks as it improved performance with one rice bran but not the other. 0 1997 Elsevier Science B.V.
Keywords:Crude enzymes; Leghorn and broiler chickens; Rice bran; Arabinoxylans; performance
1. Introduction
A total of 40-45 million tonnes of rice bran is produced annually, mainly in the Far East and southeast Asia (Farrell, 1994). It is used largely as animal feed. Only a limited
amount of rice bran is currently being used for food or oil extraction (Takano, 1993). Rice bran is a valuable feed-stuff because it is rich in B vitamins, fat and protein, and compares favourably with other cereal grains in amino acid composition (Warren and Farrell, 1991). It has, however, a high content of fiber (Warren and Farrell, 1990a,b,c,d; Farrell, 1994) that is rich in the hemicelluloses containing highly branched arabinoxylans (Shibuya and Iwasaki, 1985; Ebringerova et al., 1994). Amrison et al. (1995) has recently carried out nutritional studies on the water-soluble arabinoxylan-galactose complex isolated by extraction of rice bran in sodium hydroxide and sodium borohydride. They suggested that this fraction when added to broiler diets at a concentration up to 60 g kg- ’ had no effect on the Apparent Metabolizable Energy (AME) of the diet. A substantial amount of published data, however, has shown that there is a significant decline in performance with increasing inclusion of rice bran in the diet of chicks (Warren and Farrell, 1990a,b,c,d; Farrell, 1994, Madrigal et al., 1995). Studies to improve the nutritive value of rice bran by feed enzymes have been limited (Farrell, 1994). Nevertheless, rice bran having a high content of arabinoxylans may respond to enzymes that are able to hydrolyse this complex carbohydrate. Irradiation has also been shown to be effective at improving the nutritional value of cereal grains (Campbell et al., 1983, 1986, 1987). The purpose of this study was to determine the effect of irradiation and the addition of an enzyme preparation high in xylanase activity on the nutrient value of rice bran when fed to growing chicks.
2. Materials and methods 2.1. General procedures The experimental diets were formulated to meet National Research Council requirements (NRC, 1994) for Leghorn and broiler chickens (Tables 1 and 2). All diets were given free choice in mash form and water was supplied ud libitum. Wheat (variety, Katepwa), corn (cultivar unknown) and soya-bean meal were from local sources.
G.J. Wang et al. /Animal Feed Science Technology 66 (1997) 47-61 Table 1 Diet composition
in Experiment
49
1 Wheat (diet 10)
Ingredient (g kg- ’) Wheat (184.0, 12.36) b Malaysian rice bran (113.0, 12.57) Chinese rice bran, B (146.0, 12.57) Soya-bean meal (455.0, 9.41) Vegetable oil (0, 38.59) Alphacell (cellulose) Limestone Dicalcium phosphate L-lysine Vitamin mix ’ Mineral mix ’ Calculated analysis Protein MEn(MI kg-‘) Lysine Methionine + cystine Ca P available
816.0
55.2 4.05 43.0 13.5 13.2 3.6 10.0 5.0 180 12.2 8.5 6.4 8.0 4.0
Malaysian rice bran (diets l-9)
407.8 400 128.0 23.5 _
Chinese rice bran (diets 11, 12) a a
471.6 400 70 16.5
13.6 11.5 0.6 10.0 5.0
14.0 11.5 2.4 10.0 5.0
180 12.2 8.5 6.0 8.0 4.1
180 12.2 8.6 5.6 8.0 4.0
a The amounts of crude enzyme added to Malaysian (B. type) rice bran diets were 0, 1 and 10 gkg-’ The amounts added to the Chinese rice bran diets were 0 or 10 g kg-‘. No enzyme was added to the wheat diet. See footnotes of Table 3 for a description of individual diets. b Values in brackets are the respective crude protein content (N X 6.25, gkg-’ I and AME values (MI kg- ’1. ’ The vitamin and mineral mix supplied per kg diet: vitamin A, 8250 IU; vitamin, D,, 1000 IU; vitamin E, 10.9 IU; cobalamin, 0.0115 mg; vitamin K, 1.1 mg; riboflavin, 5.5 mg; Ca pantothenate, 11 .O mg; niacin, 53.3 mg; folic acid, 0.75 mg; biotin, 0.25; c h o 1’ me chloride, 1020 mg; Mn, 5.5 mg; Zn, 50 mg; Fe, 80 mg; Cu, 5 mg; Se, 0.1 mg; I, 0.18 mg; NaCl, 2.5 g.
Malaysian rice bran A, B and C were provided by Finnfeeds International Ltd, Singapore and Chinese rice bran by Nanjing Agriculture University, Nanjing, China. They were stored at a temperature below 0°C upon arrival to reduce the degree of peroxidation of the lipids. The protein (N X 6.25) and fat (ether extract) content in rice bran B, a mixture of A and C, and Chinese rice bran were 113 and 140 g kg-‘, 118 and 159 g kg-’ and 146 and 164 g kg-‘, respectively. The rice brans did not contain an appreciable amount of starch as indicated visually and they did not appear to be rancid when tasted. The crude enzyme preparation (KM-1 from Trichodemza longibrachiatum, lot # 94425319) was supplied by Finnfeeds International Ltd (Marlborough, Wiltshire, UK, SN8lAA) and contained 3450 U g- ’ of xylanase and 900 U g- ’ of Pglucanase activity. The enzyme preparation was assayed by Finnfeeds International using the 3,5 dinitrosalicylic acid reducing sugar method for xylanase and pglucanase. Xylan (pH 5.3) was used as the substrate for xylanase (Bailey, 1988) and endo-1,4-pglucan (pH 5.0) as the substrate for P-glucanase (Miller, 1959). The enzyme preparation also
50 Table 2 Diet composition
G.J. Wang et al. /Animal Feed Science Technology 66 (1997) 47-61
in Experiments
2 and 3 a Experiment
Ingredient (g kg-’ ) Corn (99.0, 14.041 Malaysian rice bran, B (113, 12.57) b Malaysian rice bran, A+C (118, 12.57) Soya-bean meal (459,9.41) Vegetable oil (0, 38.54) Limestone Dicalcium phosphate DL-methionine Vitamin mix ’ Mineral mix ’ Calculated analysis Protein MEn (MJkg-‘1 Lysine Methionine + cystine Ca P available
2
Experiment
3
Corn
250RB
500RB
Corn
250RB
500RB
111.5 -
461.8 250
205.7 500.8
562
325.1
88.9
238.0 _ 15.5 14.0 _ 10 5
230.8 14 16.0 12.2 0.2 10 5
223.5 28 16.3 11.0 0.5 10 5
352.1 35.8 17.0 15.2 2.3 10 5
250 340.0 35.8 17.5 14.0 2.6 10 5
500 327.0 35.8 18.0 12.5 2.8 10 5
180 12.3 8.5 6.3 9.0 4.1
180 12.3 9.1 6.2 9.0 4.0
180 12.3 9.1 6.2 9.0 4.1
220 12.6 11.1 9.0 10 4.5
220 12.3 11.6 9.0 10 4.5
220 12.0 12.1 9.0 10 4.5
a The amounts of crude enzyme added to each diet were 0, 1 or 10 kg-‘.
b Values in brackets are the respective crude protein content (NX6.25, ’ The composition
gkg-’ ) and AME values (MJkg-’ of the mineral and vitamin mix are given in the footnotes of Table 1.
1.
contained pectinase, CMC-cellulase, acetyl esterase and /3-xylosidase. Malaysian rice bran B was irradiated with lo-MeV electrons using a model I-10/ 1 electron accelerator (Atomic Energy of Canada, Ltd, Pinawa, MB) at an average dosage of 0, 10 and 50 kGy S ‘. Chick performance was expressed in terms of feed consumption, weight gain and feed to gain ratio. All results were reported on a per bird basis. Analysis of variance was conducted for all data using the general linear models (GLM) procedure of the Statistical Analysis System (1986). Linear contrasts and Duncan’s Multiple Range Test were also used for comparison of the treatments.
2.2. Experiment
I
The objective of this study was to determine if a crude enzyme preparation high in xylanase activity and irradiation of Malaysian rice bran could improve performance of chicks fed diets that contained a high concentration of rice bran. One-day-old male Leghorn chicks were purchased from a commercial hatchery. The chicks were fed a commercial chick starter diet for a 5-day pre-experimental period. The birds, after 4 h of starvation, were randomly distributed on day 5 into Petersime battery brooders (Jamesway Manufacturing Co., Ft. Atkinson, WL, 53538, USA) among 12 treatments using six birds per replicate and six replicates per treatment. The experiment was a completely
Description
Diet contrasts
a
Diet number %
%
P
Body mass gain (g)
Feed intake (g)
- 2.2 (2.22 vs 2.27) 2.3 (2.27 vs 2.22) 0 (2.22 vs 2.22)
NS NS NS
NS NS NS
are g per
(0, 1, 10 1-O; diet diet, diet diets and
NS 0.055 0.002
0.005 0.0001
a Diets l-9 contained rice bran from Malaysia that was subjected to different levels of irradiation (0, 10, 50 kGy) and contained different amounts of enzyme gkg -I, indicated by subscript numbers). The amount of enzyme added to the diets and the irradiation dosages of rice bran in kGy were: diet 1, O-O; diet 2, 3, IO-O; diet 4, O-IO; diet 5, l-10; diet 6 10-10; diet 7, O-50; diet 8, I-50 and diet 9, 10-50, respectively. Diet 10 was the control wheat soya-bean meal 11 contained Chinese rice bran with no enzyme and diet 12 contained Chinese rice bran with 10 gkg-’ enzyme. See Table 1 for the composition of the Section 2 for experimental design. ’ Values in brackets represent average performance values for chicks fed diets listed under Diet contrasts. The units of feed intake or body mass gain chicken over a ‘I-day experimental period.
0.004
0 (2.22 vs 2.22) -3.2 (2.15 vs 2.22) -5.4 (2.10 vs 2.22)
- 3.2 (2.15 vs 2.22) -5.4 (2.10 vs 2.22)
%
NS 0.05
0.0004
0.04
P
Feed to gain ratio
P
rice bran from two different sources and
Percent increase or decrease in first value in brackets relative to the second value b
criteria in Leghorn chicks between 6 and 13 days of age when fed diets containing 1)
rice bran (RBM) diet with enzyme (RBM, or RBM,,) vs RBM without enzyme (RBM,) RBM, -RBM, 2.2 (96.9 vs 94.7) NS 5.6 (45.1 vs 42.7) (2,5,8)-(1,4,7) 2 RBM,, -RBM, 3.7 (98.2 vs 94.7) 0.04 9.6 (46.8 vs 42.7) (3,6,9)-(1,4,7) Malaysian rice bran diet with or without enzyme (RBM,, RBM, or RBM,,) vs control diet (Cc) 3 RBM,-C, (1,4,7)-10 1.4 (94.8 vs 93.4) NS 1.2(42.7 vs 42.2) 4 RBS, -C, (2,5,8)-10 3.8 (96.8 vs 93.4) NS 6.9 (45.1 vs 42.2) 5 RBS,,-C, (3,6,9)-10 5.2 (98.2 vs 93.4) 0.04 10.9 (46.8 vs 42.2) Chinese rice bran (RBCh) diet with or without enzyme (RBCh,, or RBCh,) vs RBCh, or the control diet (C,) - 3.3 (96.7 vs 100.0) NS 6 RBCh,, -RBCh, 12-1 I -0.9 (43.7 vs 44.1) 7 II-10 RBCh, -C, 7.1 (100.0 vs 93.4) 0.025 4.5 (44.1 vs 42.2) 8 RBCh ,a -C, 12-10 3.6 (96.7 vs 93.4) NS 3.6 (43.7 vs 42.2)
1
Malaysian
Contrast number
Table 3 Selected linear contrasts of performance supplemented with enzyme (Experiment
52
G.J. Wang et al. /Animal Feed Science Technology 66 (1997) 47-61
randomized design with a 3 (0, 1 and 10 g RM-1 kg-‘) X 3 (0, 10 and 50 kGy) factorial arrangement of diets 1 to 9. The other treatments included a wheat control diet (diet 10) and Chinese rice bran diets with 0 and 10 g kg-’ enzyme addition (diets 11 and 12). See Table 1 and footnote of Table 3 for further description of diets l- 12. The experiment was conducted during a 7-day period using chicks that were 6-13 days of age. Other procedures for treatment of chickens were as routinely used in our laboratory and as reported by Marquardt et al. (1994). 2.3. Experiment 2 The objective of this study was to determine the response of Leghorn chicks to different concentrations of enzyme supplementation when fed diets containing different concentrations of Malaysian rice bran. The control diet in this study was a corn soya-bean meal diet rather than the wheat soya-bean meal diet used in Experiment 1. All diets were formulated to be isoenergetic and isonitrogenous. The experiment was a completely randomized design with a 3 (0, 1 and 10 g kg-’ RM-1) X 3 (0, 250 and 500 gkg-’ rice bran) factorial arrangement of treatments. The composition of the diets is outlined in Table 2. The weights of the Leghorn chicks were recorded 4 h after removal of feed at 4 and 11 days of age. Feed consumption was determined at day 11 of age. Other procedures are the same as for Experiment 1. 2.4. Experiment 3 The objective of this study was to determine if results similar to those obtained in Experiment 2 could be obtained when broiler rather than Leghorn chicks were fed diets containing different concentrations of Malaysian rice bran and enzymes, and to determine the effect of rice bran and enzyme treatment on the size of the gastro-intestinal tract and incidence of vent pasting. The diets were isonitrogenic but tended to have a lower energy value with increasing concentrations of rice bran. One-day-old male vaccinated (Marek’s) broiler chicks of Arbor Acre X Ross parentage were purchased from a commercial hatchery. The chicks were fed the control corn diets from days 1 to 5 of age. They were randomly distributed on day 5 after 4 h of starvation into Petersime batteries among nine treatments using five birds per replicate and five replicates per treatment. The experiment was a completely randomized design with a 3 (0, 1 and 10 gkg-’ RM-1) X 3 (0, 250 and 500 gkg-’ rice bran) factorial arrangement of the nine diets (Table 2). Bird weights and feed consumption were determined on day 12 after 4 h of starvation. Chicks fed diets 1 (corn diet without enzyme addition), 3 (500 g kg-’ rice bran diet without enzyme), 7 (corn diet with 10 gkg-’ enzyme addition) and 9 (500 gkg-’ rice bran with 10 g kg- ’ enzyme addition) were re-fed the same diets until 15 days of age for the determination of the size of the digestive organs (weight and length). Fifteen birds per treatment were weighed and then killed by cervical dislocation after 18-24 h feed withdrawal. Residual digesta was removed from the gastrointestinal tract by manual compression. The weights of the crop, proventriculus and gizzard, and the lengths and weights of the duodenum, jejunum, ileum, ceca and colon were determined
G.J. Wang et al./Animal
Feed Science Technology 66 (1997) 47-61
53
after blotting to remove free water. The frequency of vent pasting of the birds was also scored on the basis of the amount of excreta entrapped in the surrounding feathers in the area of the cloaca at 15 days of age as outlined by Boros et al. (1995).
3. Results 3.1. Experiment
I
Analysis of variance of the data from experiment one indicated that the addition of enzyme to the rice-bran diets improved body weight gain (P < 0.05) and improved the feed to gain ratio (P < 0.01) but did not affect feed consumption (P > 0.05). Irradiation of the rice bran did not affect chick performance (P > 0.05). There were no enzyme by irradiation interactions (P > 0.05), therefore, these values are not shown. Linear contrasts show some of the effects (Table 3). The linear contrasts were also used to compare performance values for chicks that were fed diets containing rice bran from a different source (Chinese rice bran) and for those fed the control wheat diet. The increases in weight gain by the addition of enzyme to the diets containing the Malaysian rice bran were 5.6% (P = 0.04, contrast 1) and 9.6% (P < 0.01, contrast 2) with 1 and 10 gkg-’ enzyme added to the feed, respectively, while the corresponding improvement in the feed to gain ratio were 3.2 (P = 0.005) and 5.4% (P < 0.001). Linear contrast analysis, in contrast to the analysis of variance results, indicated that feed intake with the high amounts of enzyme was also increased (3.7%, P = 0.04, contrast 2). In contrast to these results enzyme addition to diets containing Chinese rice bran did not affect chick performance (P > 0.05, contrast 6). The performance of chicks fed the Malaysian rice bran diets without enzyme (contrast 3) and the Chinese rice bran with or without enzyme (contrasts 7 and 8) were generally the same (P > 0.05) as for chicks fed the control wheat soya-bean meal containing diets. In contrast, the weight gain of chicks that were fed the diet containing the Malaysian rice bran that was supplemented with 1 or 10 g kg-’ enzyme were 6.9% (P = 0.05, contrast 4) and 10.9% (P = 0.004, contrast 5) higher than for the chicks fed the control wheat-soya diet. The corresponding improvements in the feed to gain ratio were 3.2% (P = 0.055) and 5.4% (P = 0.002). These results, which were obtained during a short experimental period, indicate that the performance of Leghorn chicks can, in some cases, be improved by the addition of enzymes to diets that contain a high content of rice bran (40%) and that the performance of these chicks with or without enzyme addition was similar or superior to that obtained with a control wheat soya-bean meal diet. In contrast, irradiation of rice bran did not affect chick performance (P > 0.05). 3.2. Experiment
2
Analysis of variance of the data from Experiment 2 indicated that there was no interaction (P > 0.05) between the amount of rice bran included in the diet and the concentration of enzyme (0, 1 and 10 g kg-’ 1, and no main effect of enzyme (P > 0.051,
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Table 4 The performance of Leghorn chicks between days 4 and 11 of age when fed diets containing three concentrations of enzyme (0, 1 and 10 g RM-1 kg-‘) and three concentrations of rice bran (0, 250 and 500 g kg-’ ) (Experiment 2) a Diet main effect
Feed intake (g per bird per 7 days)
Body mass gain (g per bird per 7 days)
Feed to gain ratio
Rice bran 0 Rice bran 250 Rice bran 500 Pooled SEM
79.3 84.2(6) b 81.7(3) 1.1
33.5 37.7(12) 35.7(7) 0.78
2.38 2.24(6) 2.30(3) 0.032
NS 0.002 NS
NS 0.016 NS
Analysis of variance, probabilities Enzyme (E) NS Diet (D) 0.013 EXD NS a See Table 5 for linear contrasts. b Values in brackets are the percent improvements
relative to the diet with no rice bran.
but an effect (P < 0.05) of diet on feed intake, body mass gain and feed to gain ratio (Table 4). The increase in body mass of Leghorn chicks fed the diets containing 250 or 500 g kg-’ rice bran were 12 and 7%, respectively, compared to those fed the control corn soya diet. Corresponding changes in feed to gain ratio were 6 and 3%. Linear contrasts, in contrast to the analysis of variance data, indicated that there was a significant effect of enzyme on the performance of Leghorn chicks when they were fed the rice bran diets (P < 0.05, see contrasts 7-9, Table 5) but not when fed the corn control diet (P > 0.05, contrasts 1 and 2). For example, the overall improvements were 7.1% (P = 0.04) for weight gain and 4.3% (P = 0.05) for feed to gain ratio when the results for diets 5, 6, 8 and 9 (RB, + rO, ie, rice bran with enzyme) were contrasted with those for diets 2 and 3 (RB,, i.e., rice bran with no enzymes). Enzyme addition to the corn diets (C t-C, and CrO-Co) indicated that dietary enzyme did not affect chick performance (P > 0.05). Also, the performance of Leghorn chicks fed the diets containing rice bran with no enzyme (25ORB, and 500RB,) was the same (P > 0.05) as for chicks fed the control diet (C,) (P > 0.05, contrasts 3 and 4), but was superior (P < 0.05) to the control diets in several of the comparisons when enzyme was added to the two bran diets (25ORB,,,, and 5OORB,,,,, contrasts 5 and 6). For example, the diets containing 250 g kg- ’ rice bran plus enzyme (250RB ,,r,,) yielded feed intake, weight gain and feed to gain values that were 7.0% (P = O.Ol), 17% (P = 0.01) and 8.7% (P = 0.05) better than those obtained with the control diet (C,). The differences were less pronounced when the diet contained 500 g kg- ’ rice bran (contrasts 4 and 6). These results again indicate that the performance of Leghorn chicks fed diets containing high levels of rice bran (250 or 500 g kg- ’> yield performance values similar or better than those fed a control (corn) diet and that enzyme addition to rice bran diets appeared to improve chick performance.
Description
Contrasts
Diet number b
chicks fed nine different
diets containing
three concentrations
of enzyme (Experiment
%
Feed intake (g) c,d
P
%
Body mass gain (g) c,d
P
%
0.026 0.065 0.05 2.33) 2.33) 2.33)
” See Table 4 for analysis of variance data. ’ Diets l-9 contained different percentages of Malaysian rice bran (0. 250 or 500 g kg- ’) and different amounts of enzyme (0, 1 or 10 gkg- ’). Dietary designations were: diet I, O-O; oiet 2. 250-O; diet 3, 500-O; diet 4, 0- 1; diet 5. 250-I ; diet 6, 500-l ; diet 7, 0- 10; diet 8, 250- 10; and diet 9, 500- 10 g kg- ’, respectively. ’ Values in brackets represent g feed intake or body mass gain (g) per chick per 7 days and the feed to gain ratio for diets listed under Contrasts. ” In genera1 there were no significant differences for feed intake, weight gain and feed to gain ratio for the following contrasts: 250RB, -250RB, (5-2), 250RB,, -250RB,, (8-2), 5OORB, -5OORB,, (6-3) and 500RB,,,-500RB,, (Y-3). However, among these comparisons there was a significant difference in body mass 2.20 vs 2.36, P
NS NS 0.05 NS
2.42) 2.42) 2.42) 2.42)
P
NS NS
2) ’
2.42) 2.42)
Feed to gain ratio c.d
Percent increase or decrease in first value in brackets relative to the second value
criteria for Leghorn
Control diet (C) with enzyme (C, or C ,“) vs control diet without enzyme (C,) ’ NS 2.0 (33.8 vs 33.0) NS - I .7 (2.38 vs 4-1 1.O (80.2 vs 79.4) I C,-Cll - 3.7( 2.33 vs 2 7-l -1.0 (78.5 vs 79.4) NS 2.5 (33.8 vs 33.0) NS Cl,--” Rice bran (RB) at 250 or 500 gkg- ’in the diet in the presence or absence of enzyme (0 or I, 10) vs the control diet without enzyme CC,,) - 4.5 (2.3 1 vs 9.1 (36.0 vs 33.5) NS 3 250RB, -C, 2-l 3.7 (82.3 vs 79.4) NS - 2.5 (2.36 vs 4 1.O (80.2 vs 79.4) NS 3.3 (34.1 “S 33.5) NS 500RB,, -C,, 3-l - 8.7 (2.2 I vs 17.0 (38.6 vs 33.5) 0.01 5,8-l 7.0 (85.0 vs 79.4) 0.01 5 250RB 1,10- C 0 - 5.8 (2.28 vs 4.0 (82.6 vs 79.4) NS 10.3 (36.4 vs 33.5) 0.05 6,9-l 6 500RB 1.10- C 0 Rice bran with enzyme (RB, or RB,,,) vs rice bran with no enzyme (RB,,) 9.4 (82.8 vs 8 I .2) 0.4 I 7.0 (37.5 “S 35.0) 0.07 -5.6 (2.21 vs 7 RB, -RB, 5,6-2.3 - 3.0 (2.27 vs 4.4 (84.8 vs 81.2) 0.06 7.2 (37.6 vs 35.0) 0.07 8 RB,,-RB, 8.9-2.3 -4.3 (2.24 vs 7. I (37.5 “S 35.0) 0.04 5.6.8.9-2.3 3.2 (83.8 vs 81.2) 0.12 9 RB I,IO-RBo
Contrast number
Table 5 Selected linear contrast of performance
2
2 yZZ
G.J. Wang et al. /Animal Feed Science Technology 66 (1997) 47-61
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Table 6 The performance of broiler chicks between 5 and 12 days of age when concentrations of enzyme and three concentrations of rice bran (Experiment 3) Treatment
Rice bran (g kg0 250 500
Feed intake (g per bird per 7 days)
Body mass gain (g per bird
Feed to gain ratio a
fed diets
containing
three
Frequence of vent pasting a (%)
per 7 days)
’diet), main effect b 212’ 212(O)‘J 195(8)’
Enzyme (g kg-’ diet), main effect b 0 206 1 208 10 206 Pooled SEM 2.41
150’ 143W 124f17j3 137 137 142 1.89
1.42’ 1.49(-512 1.57(- 1113 1.512 1.52(o)* 1.45(-4)’ 0.016
0’ $ 302 W-53) 14(-53)’ 3.3
Analysis of variance, probabilities Enzyme (E) Rice bran E X Rice bran
0.84 0.0001 0.61
0.15 0.0001 0.51
0.01 0.0001 0.14
0.002 0.0001 0.03
a The vent pasting values (%I for each rice bran (RB) and enzyme (E) treatment were: 0%. for 0 BB, 0 E; 23% for 250 RB, 0 E; 67% for 500 BB, 0 E; 0% for 0 RB, 1 E; 10% for 250 BB, 1 E, 33% for 500 RB, 1 E, 0% for 0 RB, 10 E, 10% for 250 BB, 10 E, and 33% for 500 RB, 10 E. Values were recorded on day 15 of the experiment. b Means for each main effect and within a column with no common superscrips differ significantly (P < 0.05). Values in brackets are the percent increase or decrease obtained relative to the diet with no rice bran.
3.3. Experiment
3
The experimental design was similar to that for Experiment 2 except broiler chicks instead of Leghorn chicks were used and the diets were formulated to be near but not isocaloric since the calculated energy values of the diets containing 250 and 500 g kg- ’ rice bran were 2.4 and 5% lower than the reference corn soya-bean meal diet. Analysis of variance of the data demonstrated that there were main effects (P < 0.05) for both diet and enzyme treatments (Table 6). In general there was a decrease in feed intake and body mass gain and an increase in feed to gain ratio when 250 and 500 g kg-’ rice bran was included in the diet with the effects being much greater than the corresponding change in the energy value of the diets. The inclusion of the high concentrations of enzyme into the diet improved the feed to gain ratio by 4%. Performance data as determined on day 15 of the experiment for chicks fed diets 1, 3, 7 and 9 followed the same trend as for day 12 (data not shown). The inclusion of 500 g kg-’ rice bran into the diets markedly increased (P < 0.05) the relative size and length of all segments of the digestive tract (Table 7). The average percent increase in the weight of the digestive tract was 40% (9.2 to 12.9 g per 100 g body weight) while the corresponding increase in its length was 38% (39.8 to 55.1 cm per 100 g body weight). The inclusion of 10 g kg-’ of enzyme in the diet did not affect (P > 0.05) the weight of the digestive organs of
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Feed Science Technology 66 (1997) 47-61
Table 7 Relative weight and length of the digestive organs of broilers fed enzyme supplemented diets (0 or 10 g kg-’ 1 containing 0 or 500 gkg-’ Malaysian rice bran , over a lo-day period (Experiment 3) a Diets Corn+++ Corn Relative organ weight, g per 100 g body weight Crop 0.432 0.42’ Proventriculus 0.703 0.693 Gizzard 2.98’ 2.96’ Duodenum 1.26’ 1.192 Jejunum 1.862 1.92’ Ileum 1.28’ 1.29’ Ceca 0.47 2 0.502 Colon 0.273 0.26’ Total 9.253 9.223 Relative organ length, cm per 100 g-’ body weight Duodenum 6.38’ 6.22* Jejunum 14.442 14.86* Ileum 14.26’ 14.032 Ceca 2.98’ 3.032 Colon 1.682 1.63* Total 39.80* 39.72’
Rice bran
Rice bran + E
Pooled SEM
0.51’ 1.04’ 3.41’ 2.02 ’ 2.81’ 2.03 ’ 0.66 ’ 0.37’ 12.86’
0.51’ 0.93*(- 10.6) b 2.98*(- 12.6) 1.98’ 2.64’ 1.92’ 0.65’ 0.342(-8.1) 11.95*(-7.1)
0.011 0.031 0.075 0.04 I 0.074 0.047 0.022 0.0084 0.18
9.18’ 20.77’ 19.18’ 3.90’ 2.07 ’ 55.10’
8.64’ 20.28’ 19.37’ 3.85’ 2.12’ 54.26’
0.25 0.51 0.43 0.080 0.064 1.07
a Organ weights were for 15-day-old chicks. The mean weight of broilers in the groups fed corn, corn plus enzyme, rice bran and rice bran plus enzyme were 306, 302, 241 and 249 g, respectively. b Values in parentheses are percentage decrease obtained following enzyme addition to the rice bran diets. “2’3Means within a row with no common superscripts differ significantly (P < 0.05).
chicks fed the control corn containing diet, but it decreased (P < 0.05) the weight of the proventriculus (1 l%), gizzard (13%), colon (8%) and the total gastrointestinal tract (7%) when present in the diet containing 500 g kg- ’ rice bran. The relative length of the digestive tract was not affected (P < 0.05) by enzyme treatment. The degree of vent pasting also increased (P < 0.05) when measured at 15 days of age when rice bran was added to the diet (Table 6). These chicks had been fed the diet for 10 days. No apparent vent pasting was observed in Experiment 2 when Leghorn chicks were fed the diet containing 500 g kg- ’ rice bran for 7 days (day 5 to day 12). These data also indicated that enzyme addition to the diet improved broiler chick performance and reduced the size of the gastrointestinal tract and incidence of vent pasting.
4. Discussion The results of the current study demonstrated that diets containing high quantities of rice bran without enzyme (250 to 500 g kg- ’> yielded weight gains and feed to gain ratios in Leghorn chickens that were similar to those obtained with the corn- or wheat-based control diets. In contrast, similar amounts of rice bran in diets that were fed to broiler chicks decreased feed intakes and weight gains and increased the feed to gain ratio compared to those obtained with broilers fed the corn-based diet. This effect was
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more pronounced for the diet that contained the high concentration of rice bran (250 vs 500 g kg- ’>. Data from the literature has indicated that there is usually a decrease in the weight of broiler chicks as the content of full-fat rice bran in the diet is increased with the magnitude of the effect varying considerably among experiments and in part depending upon the effect that the diet has on feed intake (Kratzer et al., 1974; Warren and Farrell, 1990b; Farrell, 1994). Similarly, the feed conversion ratios are usually poorer with increasing dietary inclusion of rice bran, the point at which this occurs, however, varies (Farrell, 1994). Warren and Farrell (1990b) observed no change in feed conversion ratios to 400 g kg- ’ rice bran in the diet in some experiments while in others a poor conversion was observed at 200 g kg-’ ; clearly some factor(or factors) in rice bran appears to affect chick performance in an unknown manner. It is conceivable that variation in the fiber, protein and oil content, rancidity of the lipid fraction, and other constituents in rice bran may be responsible for this effect (Farrell, 1994). Annison et al. (1995) on the basis of studies with an isolated crude arabinoxylan fraction concluded that rice bran non-starch polysaccharides possessed no anti-nutritive activity. They also reported that this fraction increased (P < 0.05) rather than decreased the AME of the diet when incorporated into the diet at a concentration of 60 g kg-‘. These results are different to those obtained with other arabinoxylans as they are usually considered to be indigestible and as a result do not contribute to the nutritional value of the diet. In addition to affecting the performance of broiler chickens, rice bran substantially increased the size of the gastrointestinal tract. Similar increases have been reported in chickens fed a diet high in soluble (Scout barley) or insoluble fiber (Bedford barley) (Brenes et al., 1993). Studies by Jones et al. (1985), Sirear et al. (1983) and Rompala and Madsen (1989) have also shown that diets high in roughage increased the size of the gastrointestinal tract in other species of animals. Part of the effect in the current study may be attributed to difference in mature size of the broiler in the different treatment groups as younger less-developed birds tend to have larger relative sizes of intestines than more mature birds (Sreemannarayana et al., 1989). These observations, nevertheless, suggest that the high content of neutral detergent fiber in rice bran may have been responsible in the current study for the increased size of the gastrointestinal tract. The arabinoxylan are probably mainly responsible for this effect as they comprise the bulk of the hemicellulose in rice bran (Shibuya and Iwasaki, 1985; Ebringerova et al., 1994). Irradiation in previous studies has been shown to improve the nutritional value of cereals such as oat groats (Campbell et al., 1986, 1987) and rye (Campbell et al., 1983). The beneficial effects of irradiation were attributed to the partial breakage of the polymeric structure of the viscous carbohydrate in the two cereals. This decreased their viscosity and produced a corresponding reduction in their antinutritive effects. In contrast, irradiation of rice bran at 10 or 50 kGy in the current study did not improve its nutritive value. This lack of response was probably not caused by a failure to break the rice bran polysaccharides as the dosage was of sufficient energy to bring this about (Leeson and Marcotte, 1993). Irradiation may have been ineffective due to the absence of viscous carbohydrates in rice bran. Under such conditions no change in viscosity will occur with irradiation. Therefore, the corresponding improvements associated with these changes would not be seen. The addition of a crude enzyme mixture to diets containing high concentrations of
G.J. Wang et al./Animal
Feed Science Technology 66 (1997147-61
s9
rice bran produced equivocal results. For example, the high concentration of enzyme ( 10 gkg -’ in the diet) did not produce any beneficial response in Leghorn chicks when added to the Chinese rice bran diet but it improved weight gain and the feed to gain ratio by 7 and 3.4%, respectively, when added to diets containing Malaysian rice bran. The high concentration of enzyme when added to broiler chicks diets containing the Malaysian rice bran not only improved the feed to gain ratio, but also reduced the incidence of vent pasting and decreased the size of the gastrointestinal tract. The results collectively indicate that enzyme supplementation of chicken diets containing rice bran can improve chick performance in some cases. The reason for the completely different response to enzyme treatment of the rice brans obtained from two different regions in Asia was not established. Part of this difference may be caused by differences in processing methods or to varietal or environmental differences during growth. The limited proximate analysis carried out on the rice brans would indicate that it was not caused by a difference in the content of crude protein or fat. The studies also demonstrated that the weight gain and feed to gain ratio for the Leghorn chickens that were fed the enzyme supplemented rice bran diet, especially the diet containing 250 gkg-’ as compared to 500 g kg-- ’ rice bran, yielded performance values that were superior to the corn control diet. Only a few studies have been reported in the literature on the use of enzyme in poultry diets containing rice bran. (Farrell, 1994). Studies with lipase and two modified enzyme mixtures which targeted the cell wall content essentially did not improved the nutritive value of rice bran in broiler starter diets. The improvement observed in the current study were probably due to the effects of the xylanases or possibly the P-glucanases on the hemicellulose fraction of the rice bran. All of the above studies were of relatively short duration (7 days) and, as a result, it is not known if a similar pattern of response would be obtained over a much larger period of time. The results of this study have, nevertheless, shown that high concentrations of rice bran when fed to Leghorn chicks over a short period of time, especially in association with an enzyme preparations high in xylanase and /_I-glucanase activity, produced weight gains and feed to gain ratios that were equal to or superior to those produced by corn or wheat-based diets. Broiler chicks, however, were not able to utilize rice bran diets as well as the control diets. The high fiber content of the rice bran may have been partially responsible for this effect. Further research needs to be carried out to identify factors that affect the efficacy of enzyme preparations when added to diets that contain rice bran, to establish the degree of corresponding response of these treatments in different classes of chicks and over longer periods of time, and to determine the influence of the type of rice bran and type of enzyme preparations on the response that is obtained. Such studies would assist in clarifying the results obtained in the current study and determine the optimum level of rice bran that can be used in different diets in the presence and absence of the appropriate enzyme mixture.
Acknowledgements This investigation was funded by grants from Finnfeeds International Ltd. (Wiltshire, UK, SN 8lAA), International Research and Development Centre (Ottawa. On, Canada)
60
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and the University of Manitoba, Winnipeg, MB. The authors wish to thank J. Borsa, AECL, Pinawa MB, for assistance with the irradiation of rice bran, H. Muc for assistance with the feeding trials, and G.H. Crow for assistance with statistical analysis.
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