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Nutritional value for chickens of dried distillers-spent-grain from barley and dehulled barley
Animal Feed Science and Technology, 17 (1987) 145-156
145
Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
Nutritional Value for Chickens of Dried DistillersSpent-Grain from Barley and Dehulled Barley DAN PETTERSSON 1, KLAS HESSELMAN and PER ~,MAN
Department o[ Animal Nutrition and Management, Swedish University of Agricultural Sciences, S-750 07 Uppsala (Sweden) (Received 26 September 1985; accepted for publication 23 September 1986 )
ABSTRACT Pettersson, D., Hesselman, K. and ]tman, P., 1987. Nutritional value for chickens of dried distillers-spent-grain from barley and dehulled barley. Anita. Feed Sci. Technot., 17: 145-156. The chemical composition of barley, dehuUed barley, barley bran and dried distillers-spentgrain from barley and dehuUed barley was determined. The viscosities of buffer extracts of these samples before and after treatment with a fl-glucanase preparation were also investigated. The chemical analysis revealed an efficient fermentation of easily-available carbohydrates and a partial degradation of mixed-linked fl-glucans during the ethanol production process. There was an accumulation of protein, fibre components and ash in the dried distillers-spent-grain. In a combined growth and digestibility trial with chickens, the effect of fl-glucanase supplementation to diets containing 20% dried distillers-spent-grain from barley or dehulled barley was studied. This inclusion level would, with regard to the efficiency of the particular ethanol process used, equal an inclusion level of 80% non-fermented components from the barleys. Compared to a control group receiving a wheat diet, no significant adverse effects on growth and feed intake from feeding dried distillers-spent-grain were observed. When a comparison was made between the chickens which were fed the diet based on dried distillers-spent-grain from barley with or without fl-glucanase supplementation, the enzyme supplement was found to result in a better performance with respect to weight gain and feed conversion ratio. The high viscosity of the dried distillers-spent-grain from dehulled barley did not cause any observable detrimental effect and flglucanase supplementation did not improve the performance of the chickens receiving this diet.
INTRODUCTION
Barley is the major grain crop grown in Sweden and is mainly used as an energy feed in animal production, although its use in the brewing industry is of great economical importance. Overproduction of grain has stimulated an 1Address correspondence to: D. Pettersson, Division of Feed Chemistry, Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, S-750 07 Uppsala, Sweden.
0377-8401/87/$03.50
© 1987 Elsevier Science Publishers B.V.
146 interest in alternative uses of barley. Grain, including barley, can be used as a raw material for ethanol production, and the Swedish Farmers Supply and Crop Marketing Organization together with Alfa Laval have developed a new process (Biostil) for this purpose. Dried distillers-spent-grain with a high protein content is obtained as a by-product from this process. Little is known, however, about the suitability of dried distillers-spent-grain from barley as a component in chicken feed, although brewers dried grain, a similar product, gave a satisfactory performance when included at 10-20% in poultry diets (Thornton and McPherron, 1962; Kienholz et al., 1963; Ademosun, 1973; Onwudike, 1983). There are, however, some doubts concerning the suitability of distillers-spentgrain as a chicken feed. Barley is known to have a low productive value for poultry because mixed-linked fl (1--, 3 ), (1--. 4) -D-glucans, in the following referred to as fl-glucans, in endosperm cell walls can form viscous digesta (Burnett, 1966; Gohl, 1977; Hesselman, 1983 ) and also act as a physical hindrance to uptake of nutrients from intact endosperm cells (Hesselman, 1983; Hesselman and Aman, 1986) within the intestine. These effects, however, can be overcome by fl-glucanase supplementation (Hesselman, 1983). The purpose of this work was to investigate the chemical composition and feeding value for chickens of dried distillers-spent-grain from barley and dehulled barley, and the effects offl-glucanase supplementation of these feeds. MATERIALS AND METHODS
Production of dried distillers-spent-grain Ground barley and dehulled, ground barley were processed in a pilot plant for ethanol production (Biostil) at Alfa Laval, Tumba (Cook and Lincoln, 1984). The crude dehulling was performed in a rotating sieve.The ethanol production procedure included gelatinization and partial hydrolysis of starch with a thermostable ez-amylase, complete hydrolysis with amyloglucosidase and fermentation of sugars to ethanol with bakers yeast. Ethanol was distilled off and the residue was spray dried (in the following called barley distillers-spentgrain and dehulled barley distillers-spent-grain, respectively).
Chemical analyses Prior to chemical analyses, which were carried out in duplicate, all grain samples were ground in a Tecator cyclotec sample mill to pass a 0.5-ram screen. Samples of feed mixtures and freeze-dried excreta were milled in a Wiley mill to pass a 1-mm screen. Dry matter, crude protein (N X 6.25) and ash were analysed according to the Association of Official Analytical Chemists (1980). Crude fat was extracted with diethyl ether in a Tecator Soxtec System HT
147 after acid hydrolysis (Anonymous, 1971 ). ADF-crude protein, crude fibre, calcium and phosphorus were analysed according to standard methods at the laboratory of the Swedish Farmers Supply and Crop Marketing Organization in LidkSping. Soluble sugars were extracted with 0.05 M sodium acetate buffer (pH 5.0 ) at 65 °C and glucose, fructose, sucrose and fructans were determined enzymatically ( Larsson and Bengtsson, 1983 ). Starch was analysed using an enzymatic method (]%man and Hesselman, 1984) and content of total, insoluble and soluble mixed-linked fl-glucans were determined according to ~,man and Graham (1987). Klason lignin and non-starch polysaccharides were determined on the starch-free residue (Theander and Aman, 1979) and dietary fibre calculated as the sum of these two components. Amino acid compositions were analysed at the laboratory of the Swedish Farmers Supply and Crop Marketing Organization in LidkSping on a LKB 4400 amino acid analyser according to Mason et al. (1980) and at the Biomedical Centre of Uppsala University where analyses were performed on a Biotronik amino acid analyser according to Spackman et al. (1958). Urinary and faecal nitrogen were determined according to Hartfiel (1963). Gross energy determinations were performed on a Gallenkamp Adiabatic Calorimeter. For measurement of viscosity (where required, enzyme additions - - 6.2 U k g - 1 dry matter m were made prior to extractions), 7.2 g of sample was mixed with 24 ml of a 0.05 M sodium acetate buffer (pH 5.0 ). The mixture was stirred for exactly five minutes at 20 °C and the suspension centrifuged for five minutes at 3000 g. After filtration of the supernatant through glasswool the viscosity of the extract was measured at 30°C using an Epprecht-Rheomat 15, system '0' (Contraves AG, Ziirich, Switzerland). The relative change in viscosity was obtained by direct calculation from the rheomat readings at a fixed rate of shear (see manual from Contraves AG). Initial viscosity of dehulled barley distillers spent grain was regarded as 100%, while the time reported in Fig. 1 was from the point of initial mixing of sample and extraction buffer.
Growth and digestibility trial A total of 120 unsexed 1-day-old broiler chickens (Hybro) were allotted randomly to five diets with three replicate groups on each diet. The chickens were kept in a window-less, temperature-controlled room and had free access to feed and water throughout the whole experiment ( 28 days). Feed mixtures had been milled to pass a 3-mm screen and were not pelleted. The composition of the diets, which were calculated to be isonitrogenous and isoenergetic, is shown in Table I. A technical fl-glucanase preparation (Glucanase GV-P 10 000 U kg-1, Grindsted, Denmark) was added to two of the diets at a level of 0.5 g kg- 1 feed (Hesselman, 1983 ). Individual animal weights were recorded on Days 8, 12, 24 and 28. During Days 24-28 excreta from each cage were collected quantitatively twice daily
148 (a)
(b} 100
100
~Oo o
o
o o
80 o~ •~,
v
60
60
~4o
20
10
20 30 Time (minutes)
40
50
10
20 30 "nme ( minutes )
~
~
Fig. 1. Changes in relative viscositywith time and fl-glucanaseaddition in bufferextracts (initial viscosityof dehulledbarley distillers-spent-grain= 100%. (a) Barley (with enzyme,I ; without enzyme,[] ) and dehulledbarley (with enzyme,{};without enzyme, C)). (b) Barley distillers-spent-grain (with enzyme,, ; without enzyme, [] ), dehulledbarley distillers-spent-grain (with enzyme,0; without enzyme,C)) and barleybran (with enzyme,A; without enzyme, A ).
for a digestibility study. During the first five days of the growth experiment, four chickens were replaced with birds receiving the same feed. After the fifth day no further substitutions were made. Before the beginning of the collection period one chicken developed perosis and was removed. Analysis of variance of the individual weights were performed by using the GLM-procedure in the Statistical Analysis System according to Barr et al., 1982. RESULTS
Chemical analyses The chemical analysis revealed a starch content of 59% in the barley, and 15% dietary fibres, including 13% carbohydrates and 2.4% Klason lignin. Furthermore, the grain contained 12% crude protein, 2.4% soluble sugars, 2.5% crude fat and 2.7% ash (Table II). The total amino acid, ADF-crude protein, individual fibre carbohydrates, ~-glucans, crude fibre, Ca and P contents are also shown in Table II and the amino acid composition in Table III. The dehulled barley was not from the same batch as the barley, and the
149 TABLEI Composition and content of chemical constituents of the broiler chicken diets (given on an airdry basis) Ingredient
Barley distillers-spent-
Dehulled barley distillers-
grain'
spent-grain'
-
Composition (%) Barley distillers-spent-grain Dehulled barley distillersspent-grain Wheat Maize Soyabean oil meal Fishmeal Meat and bone meal Fat Vitamin and trace element premix2 Limestone Monocalcium phosphate Salt (NaCl) fl-Glucanase Predicted content Methionione (g k g - ' ) Lysine (g k g - ' ) Analysed content Crude protein (g kg- 1) Gross energy (MJkg 1)
÷
20.0
46.8 15.0 6.0 6.0 3.0 1.0 1.0 1.0 0.2
-
Wheat'
+
20.0
46.8 15.0 6.0 6.0 3.0 1.0 1.0 1.0 0.2 0.05
20.0
20.0
46.5 15.3 6.0 6.0 3.0
46.5 15.3 6.0 6.0 3.0
1.0 1.0 1.0 0.2
1.0 1.0 1.0 0.2 0.05
20.0 40.0 22.8 6.0 6.0 2.0 1.0 1.0 1.0 0.2
5.5 14.0
5.5 14.0
5.5 13.9
5.5 13.9
5.5 14.6
234 17.9
233 17.9
233 17.8
234 17.8
236 17.8
'Without ( - ) and with ( + ) fl-glucanase supplementation. 2Composition of vitamin and trace element premix kg-': vitamin A, 1 500 000 IU; vitamin D3, 250 000 IU; vitamin E, 2500 mg; vitamin B1, 100 rag; vitamin B2, 500 mg; Ca-pantothenate, 1200 mg; folic acid, 100 mg; pyridoxin, 300 mg; niacin, 2500 rag; choline chloride, 30 000 mg; vitamin B,2, 1.5 mg; vitamin K3, 300 mg; COS04, 143 mg; Na2Se03, 22 mg; KI, 636 mg; FeS04, 16 g; ZnSO4, 9 g; ZnO, 4.5 g; CuS04, 2 g; MnS04, 25 g; antioxidant, 5 g.
dehulling p r o c e d u r e w a s v e r y crude. H o w e v e r , a higher c o n t e n t of s t a r c h ( 6 4 % ) a n d a lower c o n t e n t o f fibre c a r b o h y d r a t e s ( 1 1 % ) a n d K l a s o n lignin {1.4%) was f o u n d a f t e r r e m o v a l o f t h e hulls. T h e c o n t e n t s of c r u d e fat, c r u d e p r o t e i n a n d a m i n o acids w e r e s i m i l a r in b a r l e y a n d d e h u l l e d b a r l e y while t h e c o n t e n t o f soluble f l - g l u c a n s ( 3.0 vs. 2.1%, r e s p e c t i v e l y ) d i f f e r e d ( T a b l e I I ). T h e c o n t e n t o f e a s i l y - a v a i l a b l e c a r b o h y d r a t e s ( 4 0 % s t a r c h , 1.9% soluble s u g a r s ) w a s l o w e r a n d t h a t o f fibre c a r b o h y d r a t e s ( 30% ) a n d K l a s o n lignin ( 8 . 5 % ) h i g h e r in t h e b r a n c o m p a r e d to b a r l e y a n d d e h u l l e d barley. T h e b a r l e y
150 TABLE II Composition of barley products (% of dry matter) Barley distillersspent-grain
Dehulled barley distillersspent-grain
0.8 9.8 7.6 0.2
4.2 29.0 27.9 6.1
4.1 28.4 27.8 3.3
67.1 0.4 0.1 2.5 0.2 63.9
41.7 0.2 0.1 1.3 0.3 39.8
3.4 0.2 0.1 0.1 Trace 3.0
8.9 1.6 0.2 0.1 Trace 7.0
12.9 1.9 3.7 0.3 0.3 6.7
10.7 1.8 2.7 0.4 0.2 5.6
29.8 3.7 9.7 0.3 0.4 15.7
29.9 3.6 8.6 1.8 0.6 15.3
27.2 4.1 4.7 1.8 0.6 13.0
Mixed-linked fl -glucans Total Insoluble Soluble
4.6 1.6 3.0
4.8 2.7 2.1
4.6 3.2 1.4
7.5 1.3 6.2
6.3 1.4 4.9
Crude fibre Klason lign[n Ash Ca P
4.7 2.4 2.7 0.11 0.36
2.6 1.4 2.2 0.05 0.36
17.2 8.5 3.6 0.05 0.27
10.1 7.6 8.4 0.19 0.73
7.9 5.9 7.4 0.13 0.70
Barley
Dehulled barley
Crude fat Crude protein Amino acids ADF-crude protein
2.5 11.9 12.0 0.2
2.3 11.5 11.3 0.1
Easily-available carbohydrates Glucose Fructose Sucrose Fructans Starch
61.8 0.3 0.1 1.3 0.7 59.4
Fibre carbohydrates Arab[nose Xylose Mannose Galactose Glucose
Barley bran
b r a n also c o n t a i n e d less c r u d e p r o t e i n a n d c r u d e fat, a n d o n l y 73% o f t h e p r o t e i n w a s a c c o u n t e d for as a m i n o acids ( T a b l e I I I ) . T h e c o n t e n t o f t o t a l flg l u c a n s in t h e b a r l e y b r a n w a s v e r y s i m i l a r to t h a t o f b a r l e y a n d d e h u l l e d b a r l e y grain; o n t h e o t h e r h a n d t h e v i s c o s i t y v a l u e a n d c o n t e n t o f soluble f l - g l u c a n s w e r e m a r k e d l y lower. The chemical analysis revealed an extensive fermentation of easily-available c a r b o h y d r a t e s a n d d e g r a d a t i o n o f m i x e d - l i n k e d f l - g l u c a n s d u r i n g t h e Biostil p r o c e s s ( T a b l e I I ) . As a c o n s e q u e n c e p r o t e i n , fibre c o m p o n e n t s a n d a s h w e r e c o n c e n t r a t e d in t h e d i s t i l l e r s - s p e n t - g r a i n s . T h e a m i n o acid c o m p o -
151 TABLE III Amino acid composition of barley products (g amino acids, 16 g N- ~) Amino acid
Cys. Met. Asp. Thr. Ser. Glu. Pro. Gly. Ala. Val. Ile. ~u. Tyr. Phe. His. Lys. A~. Total Ammonia
Dehulled barley
Barley bran
Barley distillers spent-grain
Dehulled barley distillersspent-grain
2.5 1.9 6.9 3.8 4.9 24.0 9.3 4.5 4.6 5.9 4.0 7.5 3.3 5.2 2.8 4.1 6.0
2.4 2.1 7.1 3.7 4.9 22.4 8.5 4.2 4.4 5.6 3.8 7.1 3.2 5.1 3.0 4.0 6.6
2.0 1.5 4.7 2.7 3.5 19.1 7.8 2.7 2.9 3.8 2.9 5.5 2.1 3.9 1.7 2.7 3.9
1.5 1.7 6.5 3.6 4.7 23.9 8.0 4.1 4.1 5.5 4.1 7.4 3.8 4.9 2.2 3.8 5.8
1.6 1.6 6.0 3.7 4.7 25.5 9.9 4.2 4.5 5.3 4.0 7.3 3.7 4.8 2.4 3.5 5.2
101.2 2.5
98.1 2.5
73.4 2.0
96.3 10.1
97.9 9.3
Barley
sition was similar in barley, dehulled barley a n d c o r r e s p o n d i n g distillers-spentgrain p r o d u c t s ( T a b l e I I I ) . H o w e v e r , a slight decrease in lysine, cystine a n d m e t h i o n i n e a n d i n c r e a s e in a m m o n i a was i n d i c a t e d a f t e r t h e f e r m e n t a t i o n . T h e b u f f e r e x t r a c t f r o m d e h u l l e d b a r l e y d i s t i l l e r s - s p e n t - g r a i n was e x t r e m e l y viscous (Fig. 1 ), while t h e c o r r e s p o n d i n g e x t r a c t f r o m b a r l e y distillers-spentgrain was less viscous. T h e e x t r a c t s f r o m b o t h d e h u l l e d b a r l e y a n d b a r l e y b r a n h a d low viscosities. A s t u d y o f t h e c h a n g e in relative viscosity in b u f f e r e x t r a c t s with a n d w i t h o u t t h e a d d i t i o n o f fl-glucanase (Fig. 1 ) d e m o n s t r a t e d t h a t in t h e e x t r a c t f r o m d e h u l l e d b a r l e y d i s t i l l e r s - s p e n t - g r a i n a m a r k e d decrease was n o t i c e d a f t e r t h e a d d i t i o n o f t h e e n z y m e . T h e viscosity o f t h e e x t r a c t f r o m b a r l e y d i s t i l l e r s - s p e n t - g r a i n was less i n f l u e n c e d b y t h e a d d i t i o n o f f l - g l u c a n a s e . T h e viscosity o f t h e e x t r a c t f r o m t h e b a r l e y s a m p l e d e c r e a s e d initially while a more rapid decrease was n o t i c e d o n adding fl-glucanase. E x t r a c t s from dehulled b a r l e y a n d b a r l e y b r a n s h o w e d o n l y small c h a n g e s in viscosity w i t h t i m e a n d e n z y m e addition.
152 TABLE
IV
Production resultsof liveweight, feed consumption and feed conversion ratio for chickens
Averagelive weight ( g ) Day 1 Day l2 Day 28 Average ~ e d consumption (g) Days 1-12 Days 12-28 Feed conversion ratio (g airdry feed g- I weight gain) Days 1-12 Days 12-28 Days 1-28
Barley distillersspent-grain~
Dehulledbarley distillers-spentgrain~
_
_
-}-
38 184 729a
312 1044
2.13 1.92~ 1.96~
38 195 794b
321 1059
2.04 1.77bc 1.83bc
Wheat~ - -
Statistical P-value
+
38 197 767~b
282 1068
1.77 1.88a 1.85bc
38 194 760ab
332 1055
2.15 1.86ab 1.92ab
38 185 765ab
281 1023
1.91 1.76c 1.79c
NS2 NS2 P<0.05
NS 2 NS 2
NS 2 P<0.01 P<0.01
1Diet compositionis given in Table I; without ( - ) and with ( + ) fl-glucanasesupplementation. 2NS= not statistically significant. a'b'CMeanswithin a row that do not share a commonsuperscript differ significantly (P<0.05).
Growth and digestibility trial The results of the growth and digestibility trial are shown in Tables IV and V, respectively. There was a statistically significant increase in weight at 28 days as a result of supplementing the barley distillers-spent-grain with flglucanase. The feed conversion ratio for the five diets showed a poor performance for the first 12 days, mainly caused by a large feed wastage during the first week. During Days 12-28 the feed conversion ratios generally improved. The barley distillers-spent-grain diet gave a feed conversion ratio which was significantly ( P < 0.01 ) better t h a n both enzyme-unsupplemented diets. For the total period {1-28 days) the diet containing enzyme-supplemented barley distillers-spentgrain gave a feed conversion ratio which was significantly ( P < 0 . 0 1 ) better t h a n the corresponding unsupplemented diet but not the wheat diet. Enzyme addition significantly ( P < 0 . 0 1 ) increased the ME content of the barley distillers-spent-grain diet to a level (14.1 M J kg -1 DM) equal to t h a t of the wheat diet. The wheat diet had significantly higher values for digestibilities of organic matter, crude protein and crude carbohydrates t h a n all other
153 TABLE V Apparent digestibility coefficients of nutrients, content of metabolizable energy (ME) and dry. matter content of excreta Barley distillersspent-grain ~
24-28 days-of-age Organic matter Crude protein Crude fat Crude carbohydrates3 ME 4 (MJ kg -1 dry matter) Excreta dry matter content
74" 70" 83 75" 13.7" 24.2
Dehulled barley distillersspent-grain ~
+
-
+
75" 71" 85 75"b 14.1b 26.3
75" 70" 81 76b 13.7" 24.1
74" 71" 82 75"b 13.7" 25.9
Wheat 1 Statistical P-value
79b 74b 82 80¢ 14.1b 27.2
P < 0.001 P < 0.001 NS 2 P < 0.001 P<0.01 NS 2
1Diet composition is given in Table I; without ( - ) and with ( + ) fl-glucanase supplementation. 2NS = not statistically significant. 3Crude carbohydrates = organic matter- (crude protein + crude fat). 4Corrected to a nitrogen retention of 33%. "'b'¢Means within a row that do not share a common superscript differ significantly (P < 0.05 ). diets. E n z y m e s u p p l e m e n t a t i o n did n o t significantly i n f l u e n c e d r y m a t t e r cont e n t of e x c r e t a o n e i t h e r o f t h e d i e t a r y t r e a t m e n t s . DISCUSSION A l t h o u g h t h e two s a m p l e s o f d i s t i l l e r s - s p e n t - g r a i n o r i g i n a t e d f r o m two diff e r e n t b a t c h e s o f b a r l e y t h e d i f f e r e n c e in c h e m i c a l c o m p o s i t i o n was small a n d could well be a s s u m e d to r e s u l t m a i n l y f r o m t h e dehulling p r o c e d u r e . T h i s p r o c e d u r e was crude, as is s h o w n b y t h e high a m o u n t o f s t a r c h ( 4 0 % ) in t h e b a r l e y b r a n fraction, i n d i c a t i n g t h e p r e s e n c e o f a c o n s i d e r a b l e q u a n t i t y of e n d o s p e r m . T h e h i g h e r c o n t e n t o f s t a r c h a n d t h e lower c o n t e n t o f fibre carb o h y d r a t e s a n d K l a s o n lignin f o u n d in t h e d e h u l l e d b a r l e y c o r r e s p o n d s , as expected, w i t h results c o n c e r n i n g hulless barleys ( S a l o m o n s s o n et al., 1980). T h e c o m p o s i t i o n o f t h e b a r l e y grain e x a m i n e d was similar t o values typical for Swedish barleys ( ~ , m a n et al., 1985). Since t h e yield o f d r i e d d i s t i l l e r s - s p e n t - g r a i n f r o m t h e e t h a n o l p r o d u c t i o n a v e r a g e d a p p r o x i m a t e l y 25%, a n inclusion o f 20% dried d i s t i l l e r s - s p e n t - g r a i n in a diet would equal a n a d d i t i o n o f 80% n o n - f e r m e n t e d c o m p o u n d s f r o m t h e original barley. T h i s level w o u l d be well above all r e c o m m e n d a t i o n s for b a r l e y inclusion in p o u l t r y r a t i o n s w i t h r e s p e c t t o d e t r i m e n t a l d i e t a r y effects c a u s e d by, for e x a m p l e , fl-glucans. In barley, d e h u l l e d b a r l e y a n d b a r l e y b r a n a similar
154 content of fl-glucans was obtained. The contamination by endosperm of the barley bran could explain this similarity. If no fl-glucans are degraded during the Biostil process a four-fold enrichment in content in the dried distillersspent-grain would be expected. Since only a small increase was obtained, a major degradation offl-glucans had occurred. This would also imply that there are few intact starchy endosperm cells left in the distillers grain, since the flglucans predominate in the endosperm cell walls in barley (Fincher, 1975 ). The viscosity of the buffer extract of the barley sample examined was high relative to that previously found in Swedish barleys (Hesselman, 1983). In buffer extracts from barley, soluble fl-glucans are known to be a major contributor to extract viscosity ( Smith et al., 1980) and would also be expected to be more rapidly accessible to enzymatic degradation than insoluble fl-glucans. It should be noted that, as demonstrated by the dehulled barley distillers-spentgrain and barley (Fig. 1 ), endogenous enzymes are active in the extracts and could greatly reduce the viscosity during the 18 min period necessary for the preparation of samples for viscosity measurements. The endogenous fl-glucanases in the barley diminished the buffer extract viscosity ( Fig. l a ) . After adding fl-glucanase a rapid decrease was obtained while the low values measured after 45 min of incubation were similar to those of the untreated sample. The viscosities of the buffer extracts from the distillers-spent-grains were inversely related to their content of soluble fl-glucans. This, and the fact that fl-glucanase addition did not eliminate viscosity, demonstrate that components other than soluble fl-glucans were contributing to viscosity in those samples. It is also very likely that the viscosity of the partly degraded fl-glucans in these samples significantly differs from those of untreated barley products. Addition offl-glucanase to the dehulled barley distillers-spent-grain rapidly reduced the viscosity ( Fig. lb ), while the effect offl-glucanase was less pronounced for the barley distillers-spent-grain. Addition of fl-glucanase decreased the viscosity to a similar end-value for the two distillers-spent-grain samples. This value was, however, lower than that of the samples without enzyme supplementation but much higher than those of the non-fermented samples. The low viscosity in the buffer extracts from dehulled barley and the higher viscosity in that from whole barley could partly be explained by the difference in content of soluble fl-glucans. The poor performance of chickens fed high viscous barley diets may by overcome by fl-glucanase supplementation (Hesselman, 1983 ). It is, however, not entirely clear whether the fl-glucanase acts by reducing extract viscosity, caused mainly by soluble fl-glucans, or by degrading total or insoluble fl-glucans which act as a physical hindrance to the uptake of nutrients, mainly starch and protein, from the grain endosperm (Hesselman and Aman, 1986). The cell walls of the aleurone layer might also act as a physical hindrance to digestion of, in particular, protein. In the present experiment the inclusion of distillers-spentgrain to the diets would increase the viscosity but not physically hinder diges-
155
tion since, as discussed earlier, most of the cell walls of the starchy endosperm were disrupted and most of the nutrients were provided by other dietary components. If viscosity is of less importance, a dramatic effect of enzyme addition such as has been shown by Hesselman (1983) was not likely to occur and, indeed, was not observed. The unsupplemented diet containing barley distillers-spent-grain gave the poorest performance results of all five diets with respect to weight gain and feed conversion efficiency. This product had a lower content of easily-available carbohydrates and higher content of crude fibre, dietary fibre - - including fl-glucans - - and crude protein bound to the ADF fraction. The fibre components of the distillers-spent-grains are resistant to digestion in the small intestine but are partly fermented in the colon, and, as a result, there are only small differences in faecal digestibilities between diets. The improved production results obtained on enzyme supplementation to the barley distillers-spent-grain diet might be the result of the breakdown of the aleurone cell walls, allowing a more complete digestion of the enclosed protein. In the dehulled barley distillers-spent-grain the fibre-rich outer fraction and some of the aleurone layer of the grain was removed. Most of the fl-glucans were soluble and the high extract viscosity of this product was greatly reduced by flglucanase supplementation. However, such supplementation did not influence the productive value of the dehulled barley distillers-spent-grain diet, indicating that viscosity per se is not primarily responsible for the low productive value resulting from the presence offl-glucans in barley-based broiler chicken diets. Results obtained in this investigation show that the inclusion of distillersspent-grain into broiler rations up to 20% does not significantly affect growth rate. This inclusion would reduce the need of protein fortification from, for example, soya bean oil meal, as in the present investigation. It is notable that the highly viscous dehulled barley distillers-spent-grain did not significantly decrease the nutritional value. However, as a precaution, the addition of flglucanase to distillers-spent-grain would seem to be appropriate in order to decrease viscosity and to equalize differences between batches of barley. ACKNOWLEDGEMENTS
The authors thank Agr. R. Erixon at the Swedish Farmers Supply and Crop Marketing Organization who supplied the materials used in this investigation and the staff at the Division of Feed Chemistry for technical assistance.
REFERENCES Ademosun, A.A., 1973. Evaluation of brewers dried grains in the diets of growing chickens. Br~ Poult. Sci., 14: 463-468.
156 Aman, P. and Graham, H., 1987. Content and solubility of mixed-linked fl-(1-.3), (1-~4)-Dglucans in Swedish barleys and oats. In: Proceedings of the 1st European Congress of Food Science and Technology, 1-3 July 1986, Bournemouth, England. Aman, P. and Hesselman, K., 1984. Analysis of starch and other main constituents of cereal grains. Swed. J. Agric. IRes., 14: 135-139. ,~man, P., Hesselman, K. and Tilly, A.-C., 1985. The variation in chemical composition of Swedish barleys. J. Cereal Sci., 3: 73-77. Anonymous, 1971. Determination of crude oils and fats. Off. J. Eur. Comm., L 297: 995-997. Association of Official Analytical Chemists, 1980. Official Methods of Analysis. A.O.A.C. 14th Edn., Washington DC, 1141 pp. Barr, A.J., Goodnight, J.H., Sail, J.P. and Helwig, J.T., 1982. A User's Guide to SAS -82. Raleigh, NC, 584 pp. Burnett, G.S., 1966. Studies of viscosity as the probable factor involved in the improvement of certain barleys for chickens by enzyme supplementation. Br. Poult. Sci., 7: 55-75. Cook, R. and Lincoln, G., 1984. Operating experience from a biostil grain alcohol plant. AC Biotechnics AB, Arl~v, Sweden. AC Biotechnics Inc., Woodburry, U.S.A. {unpublished), 11 pp. Fincher, G.B., 1975. Morphology and chemical composition of barley endosperm cell walls. J. Inst. Brew., 81: 116-122. Gohl, B., 1977. Effects of hydrocolloids on productive value and feeding characteristics of barley. Ph.D. Thesis. Swedish Univ. Agric. Sci., S-750 07 Uppsala, Sweden, 127 pp. Hartfiel, W., 1963. Chemische Untersuchungen bei Stoffwechselversuchen mit Hfinern. Institut Rir Tierzucht und Tierftitterung der Rheinischen Friedrich-Wilhelms-Universi~t, Bonn, 126 pp. Hesselman, K., 1983. Effects of fl-glucanase supplementation to barley based diets for broiler chickens. Ph.D. Thesis. Swedish Univ. Agric. Sci., S-750 07 Uppsala, Sweden, pp. 1-32. Hesselman, K. and Aman, P., 1986. The effect of fl-glucanase on the utilization of starch and nitrogen by broiler chickens fed on barley of low or high-viscosity. Anim. Feed Sci. Technol., 15: 83-93. Kienholz, E.W., Thornton, P.A. and Moreng, R.E., 1963. The use of brewers dried grains in some poultry rations. Poult. Sci., 59: 2361-2364. Larsson, K. and Bengtsson, S., 1983. 'Metodbeskrivning Nr. 22' Statens lantbrukskemiska laboratorium, pp. 1-9 {in Swedish). Mason, V.C., Bech-Andersen, S. and Rudemo, M., 1980. Hydrolysate preparation for amino acid determinations in feed constituents. In: Proceedings of the 3rd EAAP Symposium of Protein Metabolism and Nutrition, Braunschweig, Vol. 1, pp. 351-355. Onwudike, O.C., 1983. Brewers dried grains in the diet of broiler chickens. Nutr. Rep. Int., 28: 1165-1170. Salomonsson, A.C., Theander, O. and Aman, P., 1980. Composition of normal and high-lysine barleys. Swed. J. Agric. Res., 10: 11-16. Smith, D.B. and Morgan, A.G. and Aastrup, S., 1980. Variation in the biochemical composition of acid extracts from barleys of contrasting malting quality. J. Inst. Brew., London, 86: 277-283. Spackman, D.H., Stein, W.H. and Moore, S., 1958. Automatic recording apparatus for use in chromatograph~ of amino acids. Anal. Chem., 30:1190-1206. Theander, O. and Aman, P., 1979. Studies on dietary fibres. 1. Analysis and chemical characterization of water-soluble and water-insoluble dietary fibres. Swed. J. Agric. Res., 9: 97-106. Thornton, P.A. and McPherron, T.A., 1962. Controlling body weight and liver lipid accumulation in the chicken with dietary brewers dried grains. Fed. Proc., 21:397 {abstract).
145
Elsevier Science Publishers B.V., Amsterdam - - Printed in The Netherlands
Nutritional Value for Chickens of Dried DistillersSpent-Grain from Barley and Dehulled Barley DAN PETTERSSON 1, KLAS HESSELMAN and PER ~,MAN
Department o[ Animal Nutrition and Management, Swedish University of Agricultural Sciences, S-750 07 Uppsala (Sweden) (Received 26 September 1985; accepted for publication 23 September 1986 )
ABSTRACT Pettersson, D., Hesselman, K. and ]tman, P., 1987. Nutritional value for chickens of dried distillers-spent-grain from barley and dehulled barley. Anita. Feed Sci. Technot., 17: 145-156. The chemical composition of barley, dehuUed barley, barley bran and dried distillers-spentgrain from barley and dehuUed barley was determined. The viscosities of buffer extracts of these samples before and after treatment with a fl-glucanase preparation were also investigated. The chemical analysis revealed an efficient fermentation of easily-available carbohydrates and a partial degradation of mixed-linked fl-glucans during the ethanol production process. There was an accumulation of protein, fibre components and ash in the dried distillers-spent-grain. In a combined growth and digestibility trial with chickens, the effect of fl-glucanase supplementation to diets containing 20% dried distillers-spent-grain from barley or dehulled barley was studied. This inclusion level would, with regard to the efficiency of the particular ethanol process used, equal an inclusion level of 80% non-fermented components from the barleys. Compared to a control group receiving a wheat diet, no significant adverse effects on growth and feed intake from feeding dried distillers-spent-grain were observed. When a comparison was made between the chickens which were fed the diet based on dried distillers-spent-grain from barley with or without fl-glucanase supplementation, the enzyme supplement was found to result in a better performance with respect to weight gain and feed conversion ratio. The high viscosity of the dried distillers-spent-grain from dehulled barley did not cause any observable detrimental effect and flglucanase supplementation did not improve the performance of the chickens receiving this diet.
INTRODUCTION
Barley is the major grain crop grown in Sweden and is mainly used as an energy feed in animal production, although its use in the brewing industry is of great economical importance. Overproduction of grain has stimulated an 1Address correspondence to: D. Pettersson, Division of Feed Chemistry, Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, S-750 07 Uppsala, Sweden.
0377-8401/87/$03.50
© 1987 Elsevier Science Publishers B.V.
146 interest in alternative uses of barley. Grain, including barley, can be used as a raw material for ethanol production, and the Swedish Farmers Supply and Crop Marketing Organization together with Alfa Laval have developed a new process (Biostil) for this purpose. Dried distillers-spent-grain with a high protein content is obtained as a by-product from this process. Little is known, however, about the suitability of dried distillers-spent-grain from barley as a component in chicken feed, although brewers dried grain, a similar product, gave a satisfactory performance when included at 10-20% in poultry diets (Thornton and McPherron, 1962; Kienholz et al., 1963; Ademosun, 1973; Onwudike, 1983). There are, however, some doubts concerning the suitability of distillers-spentgrain as a chicken feed. Barley is known to have a low productive value for poultry because mixed-linked fl (1--, 3 ), (1--. 4) -D-glucans, in the following referred to as fl-glucans, in endosperm cell walls can form viscous digesta (Burnett, 1966; Gohl, 1977; Hesselman, 1983 ) and also act as a physical hindrance to uptake of nutrients from intact endosperm cells (Hesselman, 1983; Hesselman and Aman, 1986) within the intestine. These effects, however, can be overcome by fl-glucanase supplementation (Hesselman, 1983). The purpose of this work was to investigate the chemical composition and feeding value for chickens of dried distillers-spent-grain from barley and dehulled barley, and the effects offl-glucanase supplementation of these feeds. MATERIALS AND METHODS
Production of dried distillers-spent-grain Ground barley and dehulled, ground barley were processed in a pilot plant for ethanol production (Biostil) at Alfa Laval, Tumba (Cook and Lincoln, 1984). The crude dehulling was performed in a rotating sieve.The ethanol production procedure included gelatinization and partial hydrolysis of starch with a thermostable ez-amylase, complete hydrolysis with amyloglucosidase and fermentation of sugars to ethanol with bakers yeast. Ethanol was distilled off and the residue was spray dried (in the following called barley distillers-spentgrain and dehulled barley distillers-spent-grain, respectively).
Chemical analyses Prior to chemical analyses, which were carried out in duplicate, all grain samples were ground in a Tecator cyclotec sample mill to pass a 0.5-ram screen. Samples of feed mixtures and freeze-dried excreta were milled in a Wiley mill to pass a 1-mm screen. Dry matter, crude protein (N X 6.25) and ash were analysed according to the Association of Official Analytical Chemists (1980). Crude fat was extracted with diethyl ether in a Tecator Soxtec System HT
147 after acid hydrolysis (Anonymous, 1971 ). ADF-crude protein, crude fibre, calcium and phosphorus were analysed according to standard methods at the laboratory of the Swedish Farmers Supply and Crop Marketing Organization in LidkSping. Soluble sugars were extracted with 0.05 M sodium acetate buffer (pH 5.0 ) at 65 °C and glucose, fructose, sucrose and fructans were determined enzymatically ( Larsson and Bengtsson, 1983 ). Starch was analysed using an enzymatic method (]%man and Hesselman, 1984) and content of total, insoluble and soluble mixed-linked fl-glucans were determined according to ~,man and Graham (1987). Klason lignin and non-starch polysaccharides were determined on the starch-free residue (Theander and Aman, 1979) and dietary fibre calculated as the sum of these two components. Amino acid compositions were analysed at the laboratory of the Swedish Farmers Supply and Crop Marketing Organization in LidkSping on a LKB 4400 amino acid analyser according to Mason et al. (1980) and at the Biomedical Centre of Uppsala University where analyses were performed on a Biotronik amino acid analyser according to Spackman et al. (1958). Urinary and faecal nitrogen were determined according to Hartfiel (1963). Gross energy determinations were performed on a Gallenkamp Adiabatic Calorimeter. For measurement of viscosity (where required, enzyme additions - - 6.2 U k g - 1 dry matter m were made prior to extractions), 7.2 g of sample was mixed with 24 ml of a 0.05 M sodium acetate buffer (pH 5.0 ). The mixture was stirred for exactly five minutes at 20 °C and the suspension centrifuged for five minutes at 3000 g. After filtration of the supernatant through glasswool the viscosity of the extract was measured at 30°C using an Epprecht-Rheomat 15, system '0' (Contraves AG, Ziirich, Switzerland). The relative change in viscosity was obtained by direct calculation from the rheomat readings at a fixed rate of shear (see manual from Contraves AG). Initial viscosity of dehulled barley distillers spent grain was regarded as 100%, while the time reported in Fig. 1 was from the point of initial mixing of sample and extraction buffer.
Growth and digestibility trial A total of 120 unsexed 1-day-old broiler chickens (Hybro) were allotted randomly to five diets with three replicate groups on each diet. The chickens were kept in a window-less, temperature-controlled room and had free access to feed and water throughout the whole experiment ( 28 days). Feed mixtures had been milled to pass a 3-mm screen and were not pelleted. The composition of the diets, which were calculated to be isonitrogenous and isoenergetic, is shown in Table I. A technical fl-glucanase preparation (Glucanase GV-P 10 000 U kg-1, Grindsted, Denmark) was added to two of the diets at a level of 0.5 g kg- 1 feed (Hesselman, 1983 ). Individual animal weights were recorded on Days 8, 12, 24 and 28. During Days 24-28 excreta from each cage were collected quantitatively twice daily
148 (a)
(b} 100
100
~Oo o
o
o o
80 o~ •~,
v
60
60
~4o
20
10
20 30 Time (minutes)
40
50
10
20 30 "nme ( minutes )
~
~
Fig. 1. Changes in relative viscositywith time and fl-glucanaseaddition in bufferextracts (initial viscosityof dehulledbarley distillers-spent-grain= 100%. (a) Barley (with enzyme,I ; without enzyme,[] ) and dehulledbarley (with enzyme,{};without enzyme, C)). (b) Barley distillers-spent-grain (with enzyme,, ; without enzyme, [] ), dehulledbarley distillers-spent-grain (with enzyme,0; without enzyme,C)) and barleybran (with enzyme,A; without enzyme, A ).
for a digestibility study. During the first five days of the growth experiment, four chickens were replaced with birds receiving the same feed. After the fifth day no further substitutions were made. Before the beginning of the collection period one chicken developed perosis and was removed. Analysis of variance of the individual weights were performed by using the GLM-procedure in the Statistical Analysis System according to Barr et al., 1982. RESULTS
Chemical analyses The chemical analysis revealed a starch content of 59% in the barley, and 15% dietary fibres, including 13% carbohydrates and 2.4% Klason lignin. Furthermore, the grain contained 12% crude protein, 2.4% soluble sugars, 2.5% crude fat and 2.7% ash (Table II). The total amino acid, ADF-crude protein, individual fibre carbohydrates, ~-glucans, crude fibre, Ca and P contents are also shown in Table II and the amino acid composition in Table III. The dehulled barley was not from the same batch as the barley, and the
149 TABLEI Composition and content of chemical constituents of the broiler chicken diets (given on an airdry basis) Ingredient
Barley distillers-spent-
Dehulled barley distillers-
grain'
spent-grain'
-
Composition (%) Barley distillers-spent-grain Dehulled barley distillersspent-grain Wheat Maize Soyabean oil meal Fishmeal Meat and bone meal Fat Vitamin and trace element premix2 Limestone Monocalcium phosphate Salt (NaCl) fl-Glucanase Predicted content Methionione (g k g - ' ) Lysine (g k g - ' ) Analysed content Crude protein (g kg- 1) Gross energy (MJkg 1)
÷
20.0
46.8 15.0 6.0 6.0 3.0 1.0 1.0 1.0 0.2
-
Wheat'
+
20.0
46.8 15.0 6.0 6.0 3.0 1.0 1.0 1.0 0.2 0.05
20.0
20.0
46.5 15.3 6.0 6.0 3.0
46.5 15.3 6.0 6.0 3.0
1.0 1.0 1.0 0.2
1.0 1.0 1.0 0.2 0.05
20.0 40.0 22.8 6.0 6.0 2.0 1.0 1.0 1.0 0.2
5.5 14.0
5.5 14.0
5.5 13.9
5.5 13.9
5.5 14.6
234 17.9
233 17.9
233 17.8
234 17.8
236 17.8
'Without ( - ) and with ( + ) fl-glucanase supplementation. 2Composition of vitamin and trace element premix kg-': vitamin A, 1 500 000 IU; vitamin D3, 250 000 IU; vitamin E, 2500 mg; vitamin B1, 100 rag; vitamin B2, 500 mg; Ca-pantothenate, 1200 mg; folic acid, 100 mg; pyridoxin, 300 mg; niacin, 2500 rag; choline chloride, 30 000 mg; vitamin B,2, 1.5 mg; vitamin K3, 300 mg; COS04, 143 mg; Na2Se03, 22 mg; KI, 636 mg; FeS04, 16 g; ZnSO4, 9 g; ZnO, 4.5 g; CuS04, 2 g; MnS04, 25 g; antioxidant, 5 g.
dehulling p r o c e d u r e w a s v e r y crude. H o w e v e r , a higher c o n t e n t of s t a r c h ( 6 4 % ) a n d a lower c o n t e n t o f fibre c a r b o h y d r a t e s ( 1 1 % ) a n d K l a s o n lignin {1.4%) was f o u n d a f t e r r e m o v a l o f t h e hulls. T h e c o n t e n t s of c r u d e fat, c r u d e p r o t e i n a n d a m i n o acids w e r e s i m i l a r in b a r l e y a n d d e h u l l e d b a r l e y while t h e c o n t e n t o f soluble f l - g l u c a n s ( 3.0 vs. 2.1%, r e s p e c t i v e l y ) d i f f e r e d ( T a b l e I I ). T h e c o n t e n t o f e a s i l y - a v a i l a b l e c a r b o h y d r a t e s ( 4 0 % s t a r c h , 1.9% soluble s u g a r s ) w a s l o w e r a n d t h a t o f fibre c a r b o h y d r a t e s ( 30% ) a n d K l a s o n lignin ( 8 . 5 % ) h i g h e r in t h e b r a n c o m p a r e d to b a r l e y a n d d e h u l l e d barley. T h e b a r l e y
150 TABLE II Composition of barley products (% of dry matter) Barley distillersspent-grain
Dehulled barley distillersspent-grain
0.8 9.8 7.6 0.2
4.2 29.0 27.9 6.1
4.1 28.4 27.8 3.3
67.1 0.4 0.1 2.5 0.2 63.9
41.7 0.2 0.1 1.3 0.3 39.8
3.4 0.2 0.1 0.1 Trace 3.0
8.9 1.6 0.2 0.1 Trace 7.0
12.9 1.9 3.7 0.3 0.3 6.7
10.7 1.8 2.7 0.4 0.2 5.6
29.8 3.7 9.7 0.3 0.4 15.7
29.9 3.6 8.6 1.8 0.6 15.3
27.2 4.1 4.7 1.8 0.6 13.0
Mixed-linked fl -glucans Total Insoluble Soluble
4.6 1.6 3.0
4.8 2.7 2.1
4.6 3.2 1.4
7.5 1.3 6.2
6.3 1.4 4.9
Crude fibre Klason lign[n Ash Ca P
4.7 2.4 2.7 0.11 0.36
2.6 1.4 2.2 0.05 0.36
17.2 8.5 3.6 0.05 0.27
10.1 7.6 8.4 0.19 0.73
7.9 5.9 7.4 0.13 0.70
Barley
Dehulled barley
Crude fat Crude protein Amino acids ADF-crude protein
2.5 11.9 12.0 0.2
2.3 11.5 11.3 0.1
Easily-available carbohydrates Glucose Fructose Sucrose Fructans Starch
61.8 0.3 0.1 1.3 0.7 59.4
Fibre carbohydrates Arab[nose Xylose Mannose Galactose Glucose
Barley bran
b r a n also c o n t a i n e d less c r u d e p r o t e i n a n d c r u d e fat, a n d o n l y 73% o f t h e p r o t e i n w a s a c c o u n t e d for as a m i n o acids ( T a b l e I I I ) . T h e c o n t e n t o f t o t a l flg l u c a n s in t h e b a r l e y b r a n w a s v e r y s i m i l a r to t h a t o f b a r l e y a n d d e h u l l e d b a r l e y grain; o n t h e o t h e r h a n d t h e v i s c o s i t y v a l u e a n d c o n t e n t o f soluble f l - g l u c a n s w e r e m a r k e d l y lower. The chemical analysis revealed an extensive fermentation of easily-available c a r b o h y d r a t e s a n d d e g r a d a t i o n o f m i x e d - l i n k e d f l - g l u c a n s d u r i n g t h e Biostil p r o c e s s ( T a b l e I I ) . As a c o n s e q u e n c e p r o t e i n , fibre c o m p o n e n t s a n d a s h w e r e c o n c e n t r a t e d in t h e d i s t i l l e r s - s p e n t - g r a i n s . T h e a m i n o acid c o m p o -
151 TABLE III Amino acid composition of barley products (g amino acids, 16 g N- ~) Amino acid
Cys. Met. Asp. Thr. Ser. Glu. Pro. Gly. Ala. Val. Ile. ~u. Tyr. Phe. His. Lys. A~. Total Ammonia
Dehulled barley
Barley bran
Barley distillers spent-grain
Dehulled barley distillersspent-grain
2.5 1.9 6.9 3.8 4.9 24.0 9.3 4.5 4.6 5.9 4.0 7.5 3.3 5.2 2.8 4.1 6.0
2.4 2.1 7.1 3.7 4.9 22.4 8.5 4.2 4.4 5.6 3.8 7.1 3.2 5.1 3.0 4.0 6.6
2.0 1.5 4.7 2.7 3.5 19.1 7.8 2.7 2.9 3.8 2.9 5.5 2.1 3.9 1.7 2.7 3.9
1.5 1.7 6.5 3.6 4.7 23.9 8.0 4.1 4.1 5.5 4.1 7.4 3.8 4.9 2.2 3.8 5.8
1.6 1.6 6.0 3.7 4.7 25.5 9.9 4.2 4.5 5.3 4.0 7.3 3.7 4.8 2.4 3.5 5.2
101.2 2.5
98.1 2.5
73.4 2.0
96.3 10.1
97.9 9.3
Barley
sition was similar in barley, dehulled barley a n d c o r r e s p o n d i n g distillers-spentgrain p r o d u c t s ( T a b l e I I I ) . H o w e v e r , a slight decrease in lysine, cystine a n d m e t h i o n i n e a n d i n c r e a s e in a m m o n i a was i n d i c a t e d a f t e r t h e f e r m e n t a t i o n . T h e b u f f e r e x t r a c t f r o m d e h u l l e d b a r l e y d i s t i l l e r s - s p e n t - g r a i n was e x t r e m e l y viscous (Fig. 1 ), while t h e c o r r e s p o n d i n g e x t r a c t f r o m b a r l e y distillers-spentgrain was less viscous. T h e e x t r a c t s f r o m b o t h d e h u l l e d b a r l e y a n d b a r l e y b r a n h a d low viscosities. A s t u d y o f t h e c h a n g e in relative viscosity in b u f f e r e x t r a c t s with a n d w i t h o u t t h e a d d i t i o n o f fl-glucanase (Fig. 1 ) d e m o n s t r a t e d t h a t in t h e e x t r a c t f r o m d e h u l l e d b a r l e y d i s t i l l e r s - s p e n t - g r a i n a m a r k e d decrease was n o t i c e d a f t e r t h e a d d i t i o n o f t h e e n z y m e . T h e viscosity o f t h e e x t r a c t f r o m b a r l e y d i s t i l l e r s - s p e n t - g r a i n was less i n f l u e n c e d b y t h e a d d i t i o n o f f l - g l u c a n a s e . T h e viscosity o f t h e e x t r a c t f r o m t h e b a r l e y s a m p l e d e c r e a s e d initially while a more rapid decrease was n o t i c e d o n adding fl-glucanase. E x t r a c t s from dehulled b a r l e y a n d b a r l e y b r a n s h o w e d o n l y small c h a n g e s in viscosity w i t h t i m e a n d e n z y m e addition.
152 TABLE
IV
Production resultsof liveweight, feed consumption and feed conversion ratio for chickens
Averagelive weight ( g ) Day 1 Day l2 Day 28 Average ~ e d consumption (g) Days 1-12 Days 12-28 Feed conversion ratio (g airdry feed g- I weight gain) Days 1-12 Days 12-28 Days 1-28
Barley distillersspent-grain~
Dehulledbarley distillers-spentgrain~
_
_
-}-
38 184 729a
312 1044
2.13 1.92~ 1.96~
38 195 794b
321 1059
2.04 1.77bc 1.83bc
Wheat~ - -
Statistical P-value
+
38 197 767~b
282 1068
1.77 1.88a 1.85bc
38 194 760ab
332 1055
2.15 1.86ab 1.92ab
38 185 765ab
281 1023
1.91 1.76c 1.79c
NS2 NS2 P<0.05
NS 2 NS 2
NS 2 P<0.01 P<0.01
1Diet compositionis given in Table I; without ( - ) and with ( + ) fl-glucanasesupplementation. 2NS= not statistically significant. a'b'CMeanswithin a row that do not share a commonsuperscript differ significantly (P<0.05).
Growth and digestibility trial The results of the growth and digestibility trial are shown in Tables IV and V, respectively. There was a statistically significant increase in weight at 28 days as a result of supplementing the barley distillers-spent-grain with flglucanase. The feed conversion ratio for the five diets showed a poor performance for the first 12 days, mainly caused by a large feed wastage during the first week. During Days 12-28 the feed conversion ratios generally improved. The barley distillers-spent-grain diet gave a feed conversion ratio which was significantly ( P < 0.01 ) better t h a n both enzyme-unsupplemented diets. For the total period {1-28 days) the diet containing enzyme-supplemented barley distillers-spentgrain gave a feed conversion ratio which was significantly ( P < 0 . 0 1 ) better t h a n the corresponding unsupplemented diet but not the wheat diet. Enzyme addition significantly ( P < 0 . 0 1 ) increased the ME content of the barley distillers-spent-grain diet to a level (14.1 M J kg -1 DM) equal to t h a t of the wheat diet. The wheat diet had significantly higher values for digestibilities of organic matter, crude protein and crude carbohydrates t h a n all other
153 TABLE V Apparent digestibility coefficients of nutrients, content of metabolizable energy (ME) and dry. matter content of excreta Barley distillersspent-grain ~
24-28 days-of-age Organic matter Crude protein Crude fat Crude carbohydrates3 ME 4 (MJ kg -1 dry matter) Excreta dry matter content
74" 70" 83 75" 13.7" 24.2
Dehulled barley distillersspent-grain ~
+
-
+
75" 71" 85 75"b 14.1b 26.3
75" 70" 81 76b 13.7" 24.1
74" 71" 82 75"b 13.7" 25.9
Wheat 1 Statistical P-value
79b 74b 82 80¢ 14.1b 27.2
P < 0.001 P < 0.001 NS 2 P < 0.001 P<0.01 NS 2
1Diet composition is given in Table I; without ( - ) and with ( + ) fl-glucanase supplementation. 2NS = not statistically significant. 3Crude carbohydrates = organic matter- (crude protein + crude fat). 4Corrected to a nitrogen retention of 33%. "'b'¢Means within a row that do not share a common superscript differ significantly (P < 0.05 ). diets. E n z y m e s u p p l e m e n t a t i o n did n o t significantly i n f l u e n c e d r y m a t t e r cont e n t of e x c r e t a o n e i t h e r o f t h e d i e t a r y t r e a t m e n t s . DISCUSSION A l t h o u g h t h e two s a m p l e s o f d i s t i l l e r s - s p e n t - g r a i n o r i g i n a t e d f r o m two diff e r e n t b a t c h e s o f b a r l e y t h e d i f f e r e n c e in c h e m i c a l c o m p o s i t i o n was small a n d could well be a s s u m e d to r e s u l t m a i n l y f r o m t h e dehulling p r o c e d u r e . T h i s p r o c e d u r e was crude, as is s h o w n b y t h e high a m o u n t o f s t a r c h ( 4 0 % ) in t h e b a r l e y b r a n fraction, i n d i c a t i n g t h e p r e s e n c e o f a c o n s i d e r a b l e q u a n t i t y of e n d o s p e r m . T h e h i g h e r c o n t e n t o f s t a r c h a n d t h e lower c o n t e n t o f fibre carb o h y d r a t e s a n d K l a s o n lignin f o u n d in t h e d e h u l l e d b a r l e y c o r r e s p o n d s , as expected, w i t h results c o n c e r n i n g hulless barleys ( S a l o m o n s s o n et al., 1980). T h e c o m p o s i t i o n o f t h e b a r l e y grain e x a m i n e d was similar t o values typical for Swedish barleys ( ~ , m a n et al., 1985). Since t h e yield o f d r i e d d i s t i l l e r s - s p e n t - g r a i n f r o m t h e e t h a n o l p r o d u c t i o n a v e r a g e d a p p r o x i m a t e l y 25%, a n inclusion o f 20% dried d i s t i l l e r s - s p e n t - g r a i n in a diet would equal a n a d d i t i o n o f 80% n o n - f e r m e n t e d c o m p o u n d s f r o m t h e original barley. T h i s level w o u l d be well above all r e c o m m e n d a t i o n s for b a r l e y inclusion in p o u l t r y r a t i o n s w i t h r e s p e c t t o d e t r i m e n t a l d i e t a r y effects c a u s e d by, for e x a m p l e , fl-glucans. In barley, d e h u l l e d b a r l e y a n d b a r l e y b r a n a similar
154 content of fl-glucans was obtained. The contamination by endosperm of the barley bran could explain this similarity. If no fl-glucans are degraded during the Biostil process a four-fold enrichment in content in the dried distillersspent-grain would be expected. Since only a small increase was obtained, a major degradation offl-glucans had occurred. This would also imply that there are few intact starchy endosperm cells left in the distillers grain, since the flglucans predominate in the endosperm cell walls in barley (Fincher, 1975 ). The viscosity of the buffer extract of the barley sample examined was high relative to that previously found in Swedish barleys (Hesselman, 1983). In buffer extracts from barley, soluble fl-glucans are known to be a major contributor to extract viscosity ( Smith et al., 1980) and would also be expected to be more rapidly accessible to enzymatic degradation than insoluble fl-glucans. It should be noted that, as demonstrated by the dehulled barley distillers-spentgrain and barley (Fig. 1 ), endogenous enzymes are active in the extracts and could greatly reduce the viscosity during the 18 min period necessary for the preparation of samples for viscosity measurements. The endogenous fl-glucanases in the barley diminished the buffer extract viscosity ( Fig. l a ) . After adding fl-glucanase a rapid decrease was obtained while the low values measured after 45 min of incubation were similar to those of the untreated sample. The viscosities of the buffer extracts from the distillers-spent-grains were inversely related to their content of soluble fl-glucans. This, and the fact that fl-glucanase addition did not eliminate viscosity, demonstrate that components other than soluble fl-glucans were contributing to viscosity in those samples. It is also very likely that the viscosity of the partly degraded fl-glucans in these samples significantly differs from those of untreated barley products. Addition offl-glucanase to the dehulled barley distillers-spent-grain rapidly reduced the viscosity ( Fig. lb ), while the effect offl-glucanase was less pronounced for the barley distillers-spent-grain. Addition of fl-glucanase decreased the viscosity to a similar end-value for the two distillers-spent-grain samples. This value was, however, lower than that of the samples without enzyme supplementation but much higher than those of the non-fermented samples. The low viscosity in the buffer extracts from dehulled barley and the higher viscosity in that from whole barley could partly be explained by the difference in content of soluble fl-glucans. The poor performance of chickens fed high viscous barley diets may by overcome by fl-glucanase supplementation (Hesselman, 1983 ). It is, however, not entirely clear whether the fl-glucanase acts by reducing extract viscosity, caused mainly by soluble fl-glucans, or by degrading total or insoluble fl-glucans which act as a physical hindrance to the uptake of nutrients, mainly starch and protein, from the grain endosperm (Hesselman and Aman, 1986). The cell walls of the aleurone layer might also act as a physical hindrance to digestion of, in particular, protein. In the present experiment the inclusion of distillers-spentgrain to the diets would increase the viscosity but not physically hinder diges-
155
tion since, as discussed earlier, most of the cell walls of the starchy endosperm were disrupted and most of the nutrients were provided by other dietary components. If viscosity is of less importance, a dramatic effect of enzyme addition such as has been shown by Hesselman (1983) was not likely to occur and, indeed, was not observed. The unsupplemented diet containing barley distillers-spent-grain gave the poorest performance results of all five diets with respect to weight gain and feed conversion efficiency. This product had a lower content of easily-available carbohydrates and higher content of crude fibre, dietary fibre - - including fl-glucans - - and crude protein bound to the ADF fraction. The fibre components of the distillers-spent-grains are resistant to digestion in the small intestine but are partly fermented in the colon, and, as a result, there are only small differences in faecal digestibilities between diets. The improved production results obtained on enzyme supplementation to the barley distillers-spent-grain diet might be the result of the breakdown of the aleurone cell walls, allowing a more complete digestion of the enclosed protein. In the dehulled barley distillers-spent-grain the fibre-rich outer fraction and some of the aleurone layer of the grain was removed. Most of the fl-glucans were soluble and the high extract viscosity of this product was greatly reduced by flglucanase supplementation. However, such supplementation did not influence the productive value of the dehulled barley distillers-spent-grain diet, indicating that viscosity per se is not primarily responsible for the low productive value resulting from the presence offl-glucans in barley-based broiler chicken diets. Results obtained in this investigation show that the inclusion of distillersspent-grain into broiler rations up to 20% does not significantly affect growth rate. This inclusion would reduce the need of protein fortification from, for example, soya bean oil meal, as in the present investigation. It is notable that the highly viscous dehulled barley distillers-spent-grain did not significantly decrease the nutritional value. However, as a precaution, the addition of flglucanase to distillers-spent-grain would seem to be appropriate in order to decrease viscosity and to equalize differences between batches of barley. ACKNOWLEDGEMENTS
The authors thank Agr. R. Erixon at the Swedish Farmers Supply and Crop Marketing Organization who supplied the materials used in this investigation and the staff at the Division of Feed Chemistry for technical assistance.
REFERENCES Ademosun, A.A., 1973. Evaluation of brewers dried grains in the diets of growing chickens. Br~ Poult. Sci., 14: 463-468.
156 Aman, P. and Graham, H., 1987. Content and solubility of mixed-linked fl-(1-.3), (1-~4)-Dglucans in Swedish barleys and oats. In: Proceedings of the 1st European Congress of Food Science and Technology, 1-3 July 1986, Bournemouth, England. Aman, P. and Hesselman, K., 1984. Analysis of starch and other main constituents of cereal grains. Swed. J. Agric. IRes., 14: 135-139. ,~man, P., Hesselman, K. and Tilly, A.-C., 1985. The variation in chemical composition of Swedish barleys. J. Cereal Sci., 3: 73-77. Anonymous, 1971. Determination of crude oils and fats. Off. J. Eur. Comm., L 297: 995-997. Association of Official Analytical Chemists, 1980. Official Methods of Analysis. A.O.A.C. 14th Edn., Washington DC, 1141 pp. Barr, A.J., Goodnight, J.H., Sail, J.P. and Helwig, J.T., 1982. A User's Guide to SAS -82. Raleigh, NC, 584 pp. Burnett, G.S., 1966. Studies of viscosity as the probable factor involved in the improvement of certain barleys for chickens by enzyme supplementation. Br. Poult. Sci., 7: 55-75. Cook, R. and Lincoln, G., 1984. Operating experience from a biostil grain alcohol plant. AC Biotechnics AB, Arl~v, Sweden. AC Biotechnics Inc., Woodburry, U.S.A. {unpublished), 11 pp. Fincher, G.B., 1975. Morphology and chemical composition of barley endosperm cell walls. J. Inst. Brew., 81: 116-122. Gohl, B., 1977. Effects of hydrocolloids on productive value and feeding characteristics of barley. Ph.D. Thesis. Swedish Univ. Agric. Sci., S-750 07 Uppsala, Sweden, 127 pp. Hartfiel, W., 1963. Chemische Untersuchungen bei Stoffwechselversuchen mit Hfinern. Institut Rir Tierzucht und Tierftitterung der Rheinischen Friedrich-Wilhelms-Universi~t, Bonn, 126 pp. Hesselman, K., 1983. Effects of fl-glucanase supplementation to barley based diets for broiler chickens. Ph.D. Thesis. Swedish Univ. Agric. Sci., S-750 07 Uppsala, Sweden, pp. 1-32. Hesselman, K. and Aman, P., 1986. The effect of fl-glucanase on the utilization of starch and nitrogen by broiler chickens fed on barley of low or high-viscosity. Anim. Feed Sci. Technol., 15: 83-93. Kienholz, E.W., Thornton, P.A. and Moreng, R.E., 1963. The use of brewers dried grains in some poultry rations. Poult. Sci., 59: 2361-2364. Larsson, K. and Bengtsson, S., 1983. 'Metodbeskrivning Nr. 22' Statens lantbrukskemiska laboratorium, pp. 1-9 {in Swedish). Mason, V.C., Bech-Andersen, S. and Rudemo, M., 1980. Hydrolysate preparation for amino acid determinations in feed constituents. In: Proceedings of the 3rd EAAP Symposium of Protein Metabolism and Nutrition, Braunschweig, Vol. 1, pp. 351-355. Onwudike, O.C., 1983. Brewers dried grains in the diet of broiler chickens. Nutr. Rep. Int., 28: 1165-1170. Salomonsson, A.C., Theander, O. and Aman, P., 1980. Composition of normal and high-lysine barleys. Swed. J. Agric. Res., 10: 11-16. Smith, D.B. and Morgan, A.G. and Aastrup, S., 1980. Variation in the biochemical composition of acid extracts from barleys of contrasting malting quality. J. Inst. Brew., London, 86: 277-283. Spackman, D.H., Stein, W.H. and Moore, S., 1958. Automatic recording apparatus for use in chromatograph~ of amino acids. Anal. Chem., 30:1190-1206. Theander, O. and Aman, P., 1979. Studies on dietary fibres. 1. Analysis and chemical characterization of water-soluble and water-insoluble dietary fibres. Swed. J. Agric. Res., 9: 97-106. Thornton, P.A. and McPherron, T.A., 1962. Controlling body weight and liver lipid accumulation in the chicken with dietary brewers dried grains. Fed. Proc., 21:397 {abstract).