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Effect of level of sodium hydroxide treatment and volume of solution on the nutritive value of maize cobs
Animal Feed Science and Technology, 4 ( 1 9 7 9 ) 1 - - 1 5 © Elsevier Scientific P u b l i s h i n g C o m p a n y , A m s t e r d a m - - P r i n t e d in T h e N e t h e r l a n d s
EFFECT OF LEVEL OF SODIUM H Y D R O X I D E T R E A T M E N T A N D VOLUME OF SOLUTION ON THE NUTRITIVE V A L U E OF MAIZE COBS
J.A. K A T E G I L E
Animal Science Department, University o f Dares Salaam, P.O. Box 643, Morogoro (Tanzania) J.H. F R E D E R I K S E N
National Institute o f Animal Science, Department o f Cattle Experiments, Copenhagen (Denmark) ( R e c e i v e d 6 J u n e 1 9 7 8 ; a c c e p t e d for p u b l i c a t i o n 7 F e b r u a r y 1 9 7 9 )
ABSTRACT Kategile, J.A. a n d F r e d e r i k s e n , J.H., 1 9 7 9 . Effect o f level o f s o d i u m h y d r o x i d e treatm e n t a n d v o l u m e o f s o l u t i o n o n t h e n u t r i t i v e value o f m a i z e cobs. Anita. Feed Sci. Technol., 4: 1--15. Maize c o b s were c h o s e n as a t e s t m a t e r i a l as t h e s e are p r o d u c e d c e n t r a l l y in h o m e s t e a d s d u r i n g shelling a n d t h e r e f o r e c o l l e c t i o n a n d t r a n s p o r t c o s t s are e l i m i n a t e d . T h e k n o w l e d g e gained f r o m t h e i m p r o v e m e n t o f t h e i r n u t r i t i v e value b y t h e d r y N a O H t r e a t m e n t m e t h o d c a n b e a d a p t e d easily. T h e e f f e c t o f t r e a t m e n t r a t e s was t e s t e d w i t h r a m s in t h r e e e x p e r i m e n t s . I n t h e first e x p e r i m e n t , c o a r s e l y g r o u n d maize c o b s w e r e t r e a t e d a t 1.67, 3.33 a n d 5.0 kg N a O H / 1 0 0 kg cobs d r y m a t t e r ( D M ) a n d f o r m e d 52% o f t h e r a t i o n s o n a n air-dry basis. Digestibility i n c r e a s e d . s i g n i f i c a n t l y (P < 0.05) a n d a regression e q u a t i o n y = 51.57_ + 2 . 2 8 x was c a l c u l a t e d in w h i c h y = DM digestibility, a n d x = kg N a O H / 1 0 0 c o b s DM. In t h e s e c o n d e x p e r i m e n t , m a i z e c o b s t r e a t e d at 2.5, 5.0, 7.5 a n d 10.0 kg N a O I 4 / t O 0 kg c o b s DM f o r m e d 67% o f t h e r a t i o n a n d t h e digestibility of DM, organic m a t t e r (OM), cell wall c o n s t i t u e n t s (CWC) a n d c r u d e f i b r e (CF) w e r e m a r k e d l y increased f r o m 2.5 t o 5.0 kg N a O H t r e a t m e n t levels a n d n o f u r t h e r r e s p o n s e s were o b t a i n e d t h e r e a f t e r . In t h e t h i r d e x p e r i m e n t , m a i z e c o b s f o r m e d 61% of t h e r a t i o n s a n d t h e m a t e r i a l was t r e a t e d a t 0, 2.5, 5.0 a n d 7.5 kg NaOH. Digestibility o f DM, OM, C F a n d e n e r g y was s i g n i f i c a n t l y (P < 0 . 0 5 ) increased at 5.0 m~d 7.5 kg N a O H levels. V o l u n t a r y feed int a k e f o l l o w e d t h e same t r e n d , values for g DM i n t a k e per kgW °, ~s per d a y b e i n g 60.5, 83.3, 95.7 a n d 9 6 . 0 in t h e o r d e r o f increasing N a O H t r e a t m e n t rates. T h e t o t a l digestibility DM, OM a n d e n e r g y i n t a k e s were m o r e closely c o r r e l a t e d t o v o l u n t a r y feed int a k e t h a n t o d i g e s t i b i l i t y c o e f f i c i e n t s . I t is c o n c l u d e d t h a t 5 kg N a O H / 1 0 0 kg DM is o p t i m u m for b o t h d i g e s t i b i l i t y a n d v o l u n t a r y feed i n t a k e . T h e v o l u m e o f N a O H s o l u t i o n was varied f r o m 25 t o 2 0 0 1 per 1 0 0 kg DM o f m a i z e c o b s in f o u r e x p e r i m e n t s a n d t h e d i g e s t i b i l i t y of DM, OM a n d CWC w i t h s h e e p was n o t a f f e c t e d b y t h i s f a c t o r , e x c e p t t h a t t h e smallest v o l u m e ( 2 5 1) d e p r e s s e d d i g e s t i o n slightly, a p p a r e n t l y b e c a u s e of t h e d i f f i c u l t y o f g e t t i n g e f f e c t i v e m i x i n g w i t h small v o l u m e s . It is c o n c l u d e d t h a t 5 0 1 per 1 0 0 kg DM o f maize c o b s is t h e m i n i m u m volume.
1
2
INTRODUC~ON AS more land is taken over for arable crops to feed man directly, less is available for forage crops and ruminants must make more use of field crop residues. Unfortunately, the energy contained in field crop residues is not readily available, and much effort has been directed towards releasing this energy by alkali treatment. Research has been undertaken in the U.S.A. (Guggolz et al., 1971; Garrett et al., 1974a, b; Klopfenstein et al,, 1974), Canada (Pigden and Heaney, 1969; Pigden and Bender, 1972; Maeng et al., 1971; Ololade and Mowat, 1975), India (Singh and Jackson, 1971; Chandra and Jackson, 1971), Denmark (Thomsen et al., 1973; Rexen et al., 1975), Norway (Homb et al., 1976; Arnasson and Me, 1977), the United Kingdom (Fernandez Carmona and Greenhalgh, 1972; Jayasuriya and Owen, 1975), the East European countries (Todorov, 1975) and Tanzania (Kategile, 1978; Urio, 1978). Among the alkali chemicals tested, sodium hydroxide and ammonia have found practical applications. The Beckmann (1922) method has been used in Norway for about thirty years, but it is becoming less acceptable owing to pollution problems and the need for large volumes of water (Kristensen, 1975). Other techniques involving low volumes of water (Wilson and Pigden, 1964; Rexen et al., 1975) and the recycling of sodium hydroxide (Mattson and Lagerstrom, 1976) have been developed. AS maize cobs are usually produced during shelling in homesteads, they are readily available for alkali treatment. The objectives of this study were to determine the optimum quantity of sodium hydroxide required for attaining high digestibility coefficients and voluntary feed intake, and to establish the minimum volume of sodium hydroxide solution needed for wetting the maize cobs without the application of heat and pressure. MATERIALS AND METHODS The maize cobs were obtained from the University of Dares Salaam Farm, located at Morogoro, Tanzania, the maize being a mass selection variety. The cobs were ground: through a 1.91 or 1.27 cm screen in a Newman Hammermill at 3200 r.p.m, prior to chemical treatment. As a matter of routine, the mixing of the ground maize cob with the sodium hydroxide solution was done with a shovel on a concrete floor. The material was allowed to react in a heap covered with a plastic sheet for 24 h, after which it was spread out thinly in the sun where it dried within a week. Indoor dryhag was sometimes necessitated by seasonal rains and occasional strong winds which blew away the light particles. In all experiments technical grade sodium hydroxide obtained from Dares Salaam Industrial Supply Company (AISCO) was used.
Experiment 1. The effects of quantity of NaOH Experiment 1A. Three amounts of NaOH, 1.67, 3.33 and 5.0 kg per 100
51.7 25.0 . . 1.0 2.0 0.3 20.0
52.0 25.0 . 1.0 2.0 . . 20 "
1.67 52.0 25.0 . 1.0 2. ¢" . 20.0
3.33
.
. 20.0
1.0 2.0
52.0 25.0
5.0
20.0
3.0 2.0
67.0 8.9
Experiment 1B and Experiment 2
59.8 . . 18.0 1.0 2.0 0.2 19.0
0
60.0 . 18.0 1.0 2.0 -19.0
2.5
Experiment 1C
60.0 . 18.0 1.0 2.0 -19.0
5.0
18.0 1.0 2.0 -19.0
60.0
7.5
mg/kg diet).
1 All diets were supplemented with vitamin A (10 000 I.U./kg diet), vitamin D (4 000 I.U.]kg diet) and vitamin E (200
Maize cobs Kapok cake meal Simsim meal (sesame) Urea Bonemeai Salt Molasses
0
• Experiment 1A
NaOH (kg/100 kg cobs DM)
Composition of the rations used (%)1
TABLE I
kg dry matter (DM) o f ground maize cobs, were used, the respective quantities of NaOH being dissolved to make up 100 1 of solution per 100 kg o f cobs DM. The air-dry maize cobs were mixed with other ingredients as in Table I. Digestibility was determined with individually caged 7--9 monthold growing Black Headed Persian rams weighing an average of 19 kg. Sixteen animals were r a n d o m l y allocated to the treatments. A preliminary period o f 10 days was followed by a faecal collection period o f 7 days. During the collection period, 80% of the faeces were dried dally. At the end of the collection period samples were bulked and sampled for chemical analysis. A restricted feeding regime of 500 g of air-dry feed per d a y per animal was followed.
Experiment lB. Four treatment levels o f 2.5, 5.0, 7.5 and 10.0 kg NaOH/ 100 kg cobs DM were used and the volume o f solution was as in Experiment 1A. The feed ingredients were mixed in the proportions given in Table I. The animals used in the determination of digestibility were 8--10 monthold Black Headed Persian rams weighing 19.5 kg on average and four animals were assigned per t r e a t m e n t group. The feeding rate was again 500 g of the ration per d a y and faeces were collected for seven days after a preliminary period of 10 days. Experiment 1C. Four treatments of 0, 2.5, 5.0 and 10.0 kg NaOH/100 kg cobs DM were used and the volume o f solution used was 75 1 per 100 kg. The composition of the various rations is given in Table I. Four adult Black Headed Persian rams weighing on average 33,1 kg were assigned to each treatment at r a n d o m and were fed once per day ad libitum. Daily adjustments for 10% rejection were made in the first 13 days of the preliminary period, after which individual feeding levels were adopted w i t h o u t further adjustments. Faeces o u t p u t and feed intake were measured for seven days. Refusals were collected daily and bulked during the collection period. Experiment 2. The effects o f volume of NaOH solution on the digestibility o f maize cobs Experiment 2A. One level o f 5 kg NaOH/100 kg cobs DM was used, with 50, 100, 150 and 200 1 of aqueous solutions per 100 kg cobs DM. The materials were allowed to react for 24 h and dried as in the previous experiments. The composition of the rations is given in Table I; t h e y were given at 550 g/ day to one-year-old Black Headed Persian rams weighing on average 22 kg. The preliminary and faecal collection periods were 7 days each. Experiment 2B. The volumes tested were 50, 75 and 100 1 per 100 kg cobs DM with 5 kg NaOH/100 kg cobs DM. The rations were similar in composition to those in Experiment 2A. The feeding rate and sample collection were as in Experiment 2A.
Experiment 2C. Small volumes of 25, 50 and 100 1/100 kg cobs DM were used with 5 kg N a O H / 1 0 0 kg cobs DM. The procedures for feeding and sample collection were the same as those of Experiments 2A and 2B. Experiment 2D. Again with 5 kg NaOH/100 kg cobs DM, volumes of 25.0, 37.5 and 50.0 1 were tested against a control treatment (no alkali). The experimental procedure was similar to those in Experiments 2A, 2B and 2C. Chemical analysis. The cell wall constituents (CWC) were determined b y the procedure developed b y Van Soest and Wine (1967). Crude protein was determined b y the Kjeldahl m e t h o d (Association of Official Agricultural Chemists, 1965). Dry matter, organic matter (OM) and ash were analysed according to Association of Official Agricultural Chemists (1960) and crude fibre (CF) was determined as outlined b y Van Soest (1963). The energy (kcal) in feeds and faeces was determined in a Gallenkamp adiabatic b o m b calorimeter. Chemical analysis was made on c o m p o u n d e d feed samples and dried faecal samples. All statistical analysis was carried o u t according to Fryer (1966); the Least Squares Difference (LSD) test was used for comparison between means. RESULTS AND DISCUSSION
Experiment 1 The results of Experiment 1A are illustrated in Fig. 1. There was a linear response in DM digestibility, the equation being shown in Fig. 1. 70
+ "~65
¢-
:t
v :-= 8 0 "E,
$
r~
:'5 55 +
y = 51.57+
~ 5o
2 28x
S b = 0.17 Sy/x =9.47 r' = 0 . 8 3 P
2
3
4
5
NaOH l e v e l (kg//lOOkg c o b s DM, x )
Fig. 1. Experiment 1A. Correlation between NaOH application and dry matter digestibility of maize cob-based rations.
6
A response of 2.28 digestibility units per 1 kg NaOH/100 kg DM compares well with responses obtained in other investigations. Singh and Jackson (1971) obtained a response of 3.03% units for a ration containing 76% straw; Klopfenstein et al. (1972) recorded a response of 4.07% units with rations containing 77% maize cobs; Jayasuriya and Owen (1975) obtained a 1.87% units response; and Ololade and Mowat (1975) recorded a response of 2.80% units in a ration containing 89% treated straw/grain mixture. The data of Experiment 1B are given in Table II and illustrated in Fig. 2. The digestibility coefficients increased markedly from the 2.5 kg NaOH treatment to the 5.0 kg treatment, and further increases in NaOH levels had no effect. The results o f Experiment 1B indicated that the m a x i m u m response in digestibility of DM, OM, CWC and CF was obtained with 5 kg NaOH/100 kg cobs DM, and agree with the observations of Singh and Jackson (1971), Thomsen et al. (1973), Klopfenstein et al. (1972) and Ololade and Mowat (1975). The results o f Experiment 1C are given in Table III and Fig. 3. Daily DM and OM intake were significantly (P < 0.05) increased by the 2.5 kg NaOH t r e a t m e n t and thereafter the trend continued to a lesser extent up to 5.0 kg NaOH and no further increases were recorded b e y o n d this level. The digestion coefficients o f DM, OM and energy were significantly (P < 0.05) improved by NaOH treatment at 5.0 and 7.5 kg NaOH but not by 2.5 kg NaOH. The quantities of DM, OM and energy digested per day increased T A B L E II E x p e r i m e n t l B . T h e c h e m i c a l c o m p o s i t i o n a n d digestibility o f dry m a t t e r (DM), cell wall c o n s t i t u e n t s (CWC), organic m a t t e r (OM), c r u d e f i b r e (CF) and n i t r o g e n o f r a t i o n s b a s e d o n maize c o b s Chemical
T r e a t m e n t (kg N a O H / 1 0 0 kg c o b s DM)
composition (% DM) 2.5
5.0
7.5
10.0
DM OM CWC CF Nitrogen
75.2 92.9 65.1 25.7 2.35
78.7 91.9 66.9 26.4 2.41
71.0 91.6 65.3 25.9 2.39
66.3 89.9 71.7 26.0 2.40
Digestibility c o e f f i c i e n t s1 DM OM CWC CF
43.1 a 43.8 a 47.7 a 27.9 a
55.4 b 53.8 D 59.2 b 62.2 b
54.2 b 52.6 b 57.2 b 62.8 b
56.6 b 54.4 b 57.2 b 63.4 b
S.E. o f m e a n s and significance of differences m
m
D
3.5* 3.0* 3.0*
1 Means w i t h i n a r o w w i t h d i f f e r e n t s u p e r s c r i p t s are significantly d i f f e r e n t , * (P < 0.05),
• * (P < 0.01).
65 :
60
# ]
io l:
l
55
g///'
50
?.
45
4o
35
a~l o--o o-.-o a,...a
30 £
Dry m a t t e r Organic m a t t e r Cell wall constituents Crude fibre
25
20
2
4
6
8
10
N a O H level (Kg/lOOkg cobs[2M)
Fig. 2. Experiment lB. The digestibility coefficients o f dry matter, organic matter, cell wall constituents and crude fibre o f rations based on NaOH treated maize cob-based rations.
substantially and significantly from the control group to the 2.5 kg NaOH treatment, and further significant (P < 0.05) increases were obtained with 5.0 kg NaOH for DM and energy but not for OM. The amount of CF digested per day was only slightly increased by the 2.5 kg NaOH treatment while significant (P < 0.05) increases were obtained with the 5.0 kg NaOH treat~ ment. The 7.5 kg treatment caused no improvements over the 5.0 kg treatment, and in fact there were slight depressions in the quantities of DM, OM and CF digested. Calculated metabolisable energy concentration (ME Mcal/ kg DM diet) was n o t influenced by NaOH tzeatment, except for a small increase at the 7.5 kg NaOH treatment level. This trend confirms the earlier observations of Singh and Jackson (1971) and Jayasuriya and Owen (1975). The increase in feed intake caused by NaOH treatment was high. It was" ~eater than the responses obtained by Singh and Jackson (1971), Hasimoglu et al. (1969) and Garrett et al. (1974a, b), comparable to the values obtained by Saxena et al. (1971) and Jayasuriya and Owen (1975), but below the responses obtained by Donefer (1968) Donefer et al. (1969) and Klopfenstein et al. (1974).
8
TABLE
IIi
Experiment
1C. Chemical
composition
Treatment
of rations,
(kg NaOH/100
voluntary
feed intake
kg cobs DM)
and digestibility
0
2.5
5.0
7.5
S.E. of means and significance of difference
0.641 a 60.5 a 0.721 a 51.9 a
1.189 b 83.3 b 1.105 b 73.9 b
1.314 b 95.5 c 1.131 b 82.4b
1.263 bc 96.0 c 1.068 b 81.3 b
0.041" 5.29* 0.067** 5.43**
59.6 a 59.7 a 64.1 57.6 a
65.4b 64.6 b 69.7 64.4 c
67.3 b 66.0b 70.7 70.0 d
1.46"* 1.51'* 2.66 1.75"
Daily f e e d i n t a k e 1 DM DM OM OM
(kg) ( g / k g W°'Ts) (kg) ( g / k g W, ° -7s)
Digestibility coefficients DM 61.3 a OM 59.9 a CF 70.2 Energy 61.5b Quantities of digested fractions (kg/day) DM 0.517 a OM 0.4329 CF 0.183 a Energy (Mcal/day) 2.14 a C a l c u l a t e d e n e r g y ( M c a l / k g d i e t DM) Digestible energy 2.55 M e t a b olisable energy 2.07 C h e m i c a l c o m p o s i t i o n o n D M b a s i s (%) OM 85.7 CF 27.5 Nitrogen 2.17 1 Means within • * (P < 0.01).
a row with different
0.708 b 0.626 b 0.204 a 2.73 b
0.857 c 0.729 b 0.253 b 3.38 c
0.849 c 0.705 b 0.222 b 3.57 c
2.32
2.57
2.84
!.86
2.09
2.34
88.7 24.6 1.97
86.1 24.4 1.94
84.6 22.9 1.97
superscripts
are significantly
0.064* 0.065* 0.012" 0.156"
different,
* ( P < 0 . 0 5 ),
The digestion coefficients in Experiment 1C for DM, OM and energy were significantly improved by NaOH treatment at the 5.0 and 7.5 kg and not at the 2.5 kg level, This contradicts the results of Experiment 1A and also contradicts the literature cited in t h a t section. It is probable that the small effect o f NaOH treatment at 2.5 kg was countered by the depressing effect on digestion of elevated feed intake (Blaxter and Graham, 1955; Freer and Campling, 1963; Leaver et al., 1969; Milne and Campling, 1972). While Woodman and Evans (1947), Randel (1972) and Jayasuriya and Owen (1975) reported consistent increases in the digestion of CF, the results obtained in the experiment showed neither a significant effect nor any definite ~rend. However, there were significant increases in the q u a n t i t y of crude fibre digested per day with 5.0 and 7.5 kg NaOH in comparison to the control.
90
70
o.
~0.8 80 L--> U
I 07
t 0.6
7o ~
8C •
.."
t
0.5
i/ /
6o ~
iI
E
t0.4
/
u
.~.
-~ ".,~
Jo.3 5
o
~ 5o
~--~
O
o-...o
m--i
OM digestibility OM intake Digestible OM intake
c
g
L 0
o
2's
~
7'5
NaOH level (kg/lOOkg cobsDM)
Fig. 3. Experiment 1C. Organic matter digestibility, total organic matter digested and organic matter voluntary intake for sheep fed on diets based on m a i z e cobs treated w i t h graded levels o f s o d i u m hydroxide.
Crampton et al. ( 1 9 6 0 , 1 9 6 2 ) proposed the use o f the Nutritive Value Index (NVI) which is a product of relative intake ( 8 0 g D M / k g W°'Ts as a standard) and percentage digestibility of energy, as a parameter o f the nutritive value of forages. Interest was then taken in developing a mathematical model which w o u l d predict the intakes o f OM, DM and energy/kg W°'Ts by using digestibility and feed intake per unit o f metabolic b o d y weight (kg W°'Ts ) as variables. The multiple regreskion equation was y = - 2 . 9 3 1 + 0 . 0 5 4 0 x , + 0.0344x2 where y = Mcal of D E / d a y / k g W°'Ts, x l = digestion coefficient o f energy and x2 = g intake OM/kg W°°Ts. Equations for DM and OM were similar. The statistical analysis o f the multiple regression indicated that o f the t w o independent variables, voluntary intake was a better index of the nutritive value o f a feed than was the digestion coefficient.
Experiment 2 In Experiment 2A, the digestibility coefficients o f DM, OM and CWC of the rations did n o t differ, the variation was small, and the o n l y difference was the l o w digestibility o f CF at 50:1 v o l u m e (Table IV). The results of Experiment 2B confirmed those of 2A. In Experiment 2C, DM and OM digestibility decreased with decreasing volume. Statistically, ' the 1 0 0 1 treatment was superior to the 25 1 treatment for digestibility o f DM and OM, but n o t superior to the 50 1 treatment. In Experiment 2D, DM and OM digestibility for the 25.0, 37.5 and 50.0 1 treatments were similar but signi-
IV
-----
-----
-----i
----~ ----
(% D M )
D M (%) -OM -CWC -Nitrogen -Digestibility coefficients DM -OM -CWC --
Experiment 2B Chemical composition
DM OM CWC CF
37.5
(% D M )
D M (%) -OM -CWC -CF -Nitrogen -Digestibility coefficients
Experiment 2A Chemical composition
25
Volume of solution
72,3 a 73.4 b 72.6 a
70.6 a 70.4 a 71.2 a
-----
84,7 94.5 63.5 1.91
a a a a
-------
75
85.5 95~5 61,8 2.26
71.5 71.8 69.4 62.6
87.5 89.2, 59.9 42.7 2.41
50
a a a ab
70.1 a 70.9 a 70.6 a
81.5 94.1 65.2 1.88
70.1 70.5 67.4 67,4
86.4 90.1 60.4 45.3 2.34
100
per 100 kg DM of maize cobs (I)
m
m
m
D
u
71.3 72.4 69.7 71.4
m
a a a a
a a a ab
87.8 90.0 63.3 45.2 2.45
200
n
m
m
70.1 70.4 67.9 63.0
86.6 89.9 61.7 44.4 2.44
150
Chemical composition and digestibility of rations based on maize cobs treated with 5 kg NaOH/100 kg DM in various volumes of solution
TABLE
u
m
B
m
m
0
0.98 0.93* 2.50
0.99 0.97 0.96 3.70*
m
B
m
i
SE of mean and significance of differences
O
----
6 7 . 5 ab 6 7 . 0 ab 63.9 a
----
2.03 68.4 b 69.3 b 66.7 c
64.2
-----
86.0 88.8
-----
83.5 91.9 63.2 1.64
m
69.6 b 69.3 b 68.8 b
84.5 92.7 62.6 2.18
n
m
m
m
m
m
m
E
m
m
m
m
m
m
m
61.1 a 62.6 52.9
89.8 92.7 70.7 2.26
m
m
' Means within a row with different superscripts are significantly different, * (P < 0.05), ** (P < 0.01).
Experiment 2D C h e m i c a l c o m p o s i t i o n (% D M ) D M (%) 85.7 87.2 OM 89.2 88.0 CWC 59.2 60.9 Nitrogen 2.30 2.22 Digestibility coefficients ~ DM 68.5 b 69.0 b OM 68.8 b 69.3 b CWC 63.3 b 66.2 c
Experiment 2C C h e m i c a l c o m p o s i t i o n (% D M ) DM(%) 85.4 -OM 92.9 -CWC 64.2 -Nitrogen 1.86 -Digestibility coefficients ~ DM 65.9 a -OM 65.7 a -CWC 63.2 a --
1.44"* 1.58" 1.35"
m
m
1.20" 1.07" 2.08*
E
k.A
12
ficantly higher than the values for the control group (Table IV). The variation in volume did n o t affect digestibility of DM, OM and CWC, except for the 25 1 volume which resulted in slightly lower values than the others in Experiment 2C b u t not in 2D. Jayasuriya and Owen (1975) reported lower values with 30 1 volume per 100 kg of straw than with 60 1 and 120 1/100 kg. Donefer et al. (1969) and Phoenix et al, (1974) demonstrated the same effect b y varying the NaOH volume and measuring digestibility in vitro. Waiss et al. (1972) reported an o p t i m u m moisture c o n t e n t o f 30% for ammonia to react with straw. Water is a carrier of the reactants and a medium o f chemical reaction. It appears that mixing is the limiting factor with the low volume treatments. TABLE V T h e c a l c u l a t e d OM d i g e s t i b i l i t y c o e f f i c i e n t o f m a i z e c o b s a l o n e Experiment no.
1A
N a O H treatm e n t (kg/ 1 0 0 kg c o b s DM) 0.0 1.67 3.33 5.0
Volume of solution ( 1 [ 1 0 0 kg c o b s DM)
C a l c u l a t e d OM digestibility of maize cobs alone
100 100 100 100
15.3a 22.0a 23.1a 30.4a
IB
2.5 5.0 7.5 10.0
100 100 100 100
21.8 31.8 30.6 32.4
IC
0.0 2.5 5.0 7.5
75 75 75 75
29.1 28.9 33.8 35.2
2A
5.0 5.0 5.0 5.0
50 100 150 200
46.8 45.4 45.4 46.6
2B
5.0 5.0 5.0
50 75 100
45.7 48.7 46.2
2C
5.0 5.0 5.0
25 50 100
41.0 42.3 44.6
2D
0.0 5.0 5.0 5.0
a = DM digestibility.
0 25 37.5 50
37.9 44.1 44.6 44.6
13
The calculated digestibility o f maize cobs alone The digestibility values in Table V f o r m a i z e c o b s alone were c a l c u l a t e d b y assuming t h a t t h e digestibility o f t h e c o n c e n t r a t e f r a c t i o n was n o t affected b y t h e various levels o f r o u g h a g e (i.e. b y t h e d i f f e r e n c e m e t h o d ) . Alt h o u g h t h e s e c a l c u l a t e d values varied, t h e N a O H t r e a t m e n t i m p r o v e d OM or D M digestibility b y 5 - - 1 0 % units. These increases are similar t o t h o s e r e p o r t e d b y Maeng et al. ( 1 9 7 1 ) , F e r n a n d e z C a r m o n a and G r e e n h a l g h ( 1 9 7 2 ) and J a y a s u r i y a a n d O w e n ( 1 9 7 5 ) . T h e variation o f v o l u m e o f N a O H treatm e n t s o l u t i o n h a d no e f f e c t o n digestibility o f m a i z e cobs. A p p a r e n t l y , t h e digestibility was l o w e r in t h e E x p e r i m e n t 1 series t h a n in t h e E x p e r i m e n t 2 series. While it is possible t o a t t r i b u t e t h e l o w digestibility in E x p e r i m e n t 1 A t o t h e high p r o p o r t i o n o f c o n c e n t r a t e s , as was d e m o n s t r a t e d b y B u r r o u g h s et al. ( 1 9 4 9 ) , it is d i f f i c u l t t o explain t h e l o w values o b t a i n e d in E x p e r i m e n t 1B w i t h similar c o n c e n t r a t e levels. H o w e v e r , the d e p r e s s e d digestibility values o b t a i n e d in E x p e r i m e n t 1C m i g h t have b e e n c o n t r i b u t e d b y high v o l u n t a r y feed i n t a k e (Blaxter and G r a h a m , 1 9 5 5 ; Freer and Campling, 1 9 6 3 ) . T h e d a t a f r o m t h e E x p e r i m e n t 2 series indicate t h a t N a O H - t r e a t e d m a i z e c o b s are a r e a s o n a b l e s o u r c e o f energy. REFERENCES Arnasson, J. and Mo, M., 1977. Ammonia treatment of straw. Paper presented at the Third Straw Utilization Conference, Oxford, pp. 1--13. Association of Official Agricultural Chemists, 1960. Official Methods of Analysis, 9th edn., Assoc. Off. Agric. Chem., Washington, D.C. Association of Official Agricultural Chemists, 1965. Official Methods of Analysis, 10th edn., Assoc. Off. Agric. Chem., Washington, D.C. Beckmann, E., 1922. Conversion of grain straw and tupins into feeds of high nutritive value. Chem. Abstr., 16: 765. Blaxter, K.L. and Graham, N. Mc., 1955. Plane of nutrition and starch equivalents. J. Agric. Sci., Cambridge, 46: 292--306. Burroughs, W., Gerlaugh, P., Edgington, B.H. and Bethke, R.M., 1949. The influence of corn starch upon roughage digestion in cattle. J. Anita. Sci., 8: 271--278. Chandra, S. and Jackson, M.G., 1971. A study of various chemical treatments to remove lignin from coarse roughages and increase their digestibility. J. Agric. Sci., Cambridge, 77: 11--17, Crampton, E.W., Donefer, E. and Lloyd, L.E., 1960. A nutritive value index for forages. J. Anita. Sci., 19: 538--544. Crampton, E.W., Donefer, E. and Lloyd, L.E., 1962. Caloric equivalent of the nutritive value index. J. Anim. Sci., 21: 628--632. Donefer, E., 1968. Effect of sodium hydroxide treatment on the digestibility and voluntary feed intake of straw. Proc. 2nd World Conf. Anim. Prod., Maryland, pp. 446--447. Donefer, E., Adeleye, I.O.A. and Jones, T.A.O.C., 1969. Effect of urea supplementation on the nutritive value of NaOH-treated oat straw. Cellulases and their Applications. Adv. Chem. Set., 95: 328- -342. Fernandez Carmona, J. and Greenhalgh, J.F.D., 1972. The digestibility and acceptability to sheep of chopped or milled barley straw soaked or sprayed with alkali. J. Agric. Sci., Cambridge, 78: 477--485.
14 Freer, M. and Campling, R.C., 1963. Factors affecting the voluntary intake o f food b y cows. 5. The relationship between the voluntary intake of food, the a m o u n t of digesta in the reticulo-rumen and the rate o f disappearance of digesta from the alimentary tract with diets of hay, dried grass or concentrates. Br. J. Nutr., 17: 79--88. Fryer, H.C., 1966. Concepts and Methods of Experimental Statistics. Allyn and Bacon, Boston, U.S.A., pp 1--602. Garrett, W.N., Walker, H.G., Kohler, G.O., Waiss, A.C., Graham, R.P., East, N.E. and Hart, M.R., 1974a. Nutritive value of NaOH and NH3treated rice straw. J. Anita. Sci., 38: 13~2. Garrett, W.N., Walker, H.G., Kohler, G.O., Waiss, A.C., Graham, R.P., East, N.E. and Hart, M.R., 1974b. Nutritive value of NaOH and NH3 treated rice straw. Proc. West. Sect. Am. Soc. Anita. Sci.0 25: 317--320. Guggolz, J.~ Kohler, G.O. and Klopfenstein, T.J., 1971. Composition and improvement o f grass straw for ruminant nutrition. J° Anita. Sci.: 33: 151--156. Hasimoglu, S., Klopfenstein, T.J. and Doane, T.H., 1969. Nitrogen source with sodium hydroxide treated wheat straw. J. Anita. Sci., 29: 160. Homb, T., Sundst~l, Fi and Arnasson, J., 1976. Chemical treatment of straw at commercial and farm level. In: New Feed Resources: Proceedings o f a Technical ConsuItation. FAO, Rome, Italy. lap 25--37. Jayasuriya, M.C.N. and Owen, E., 1975. Sodium hydroxide treatment of barley straw. Effect o f volume and concentration of solution on digestibility and intake b y sheep. Anim. Prod., 2 I : 313--322. Kategile, J,A., 1978. Improvement of the nutritive value of maize cob using sodium hydroxide. Ph. D. Thesis, University o f D a r e s Salaam. Klopfenstein, T.J., Krause, V.E., Jones, M.J. and Woods, W., 1972. Chemical treatment o f low quality roughages. J. Anita. Sci., 35: 418--422. Klopfenstein, T.J., Graham, R.P., Walker, H.C. and Kohler, G.O., 1974. Chemicals with pressure treated cobs. J. Anita. Sci., 39: 243. Kristensen, V.F.~ 1975. Chemicad and physical treatment of straw. A Seminar in EEC Programme of Coordination of Research on Beef Production. In: Improving the Nutritional Efficiency o f Beef Production. J.C. Tayler and J.M. Wilkinson (Editors), pp. 2 6 3 - 2 7 6 . Leaver, J.D., Campling, R.C. and Holmes, W., 1969. The effect of level of feeding on the digestibility of diets for sheep and cattle. Anita. Prod., 1 1 : 1 1 - - 1 8 . Maeng, W.J., Mowat, D.N. and Bilanski, W.K., 1971. Digestibility of sodium hydroxidetreated straw fed alone or in combination with alfalfa silage. Can. J. Anita. Sci., 51: 743--747. Mattson, L.A. and Lagerstrom, G,, 1976. Boliden-metoden for lutning och naringsberikning av halm. Foder Journalen, (3--4) pp. 77--87. Milne, J.A. and Campling, R.C., 1972. Intake and digestibility b y sheep of artificially dried forages in several physical forms. J. Agric. Sci., Cambridge, 78; 79--86. Ololade, B.G. and Mowat, D.N.,'1975. Influence of wholeplant barley reconstituted with sodium hydroxide on digestibility, tureen fluid and plasma metabolism of sheep. J. Anim. Sci., 40: 351--357. Phoenix, S.L., Bilanski, W.K. and Mowat, D.N., 1974, In vitro digestibility of barley straw treated with sodium hydroxide at elevated temperatures. Trans. Am. Soc. Agric. Eng., 17"- 780--782. Pigden~ W.J. a n d Bender~ F., 1972. Utilisation o f Iignoceilulose by ruminants. WorId Anita, Rev., 4: 7--10. Pigden, W.J. and Heaney, D.P., 1969. Lignocellulose in ruminant nutrition.' Cellulases. and their Applications. Adv. Chem. Ser.~ 95: 245--261. Randel, P.F., 1972. A comparison of the digestibility of two complete rations containing either raw or alkali-treated sugarcane bagasse. J. Agric. Univ, P.R., 52: 18--25.
Rexen~ F., Stigsen, P. and Kristensen, V.F., 1975. The effect of a new alkali technique on the nutritive value of straws. Ninth Conf. Feed Manufacturers, University of Nottingham, pp. 65--82. Saxena, S.K., Otterby, D.E., Donker, J.D. and Good, A.L., 1971. Effects of feeding alkali-treated oat straw supplemented with soybean meal or non-protein nitrogen o n growth of lambs and o n certain blood and rumen liquor parameters. J. Anita. Sci., 33: 485--490. Singh, M. and Jackson, M.G., 1971. The effect of different levels of sodium hydroxide spray treatment of wheat straw on consumption and digestibility b y cattle. J. Agric. Sci., Cambridge, 77 : 5--10. Thomsen, K.V., Rexen, F. and Kristensen~ V.F., 1973. Experiments with NaOH treatment o f straw. Ugeskrift for Agronomer og Hortonomer, No. 25, pp. 1--15. Todorov, N.A., 1975. Recent developments in animal nutrition research in Eastern Europe. J. Anim. Sci., 40: 1284--1299. Urio, N.A., 1978. Improvement of low quality roughages by alkali treatment under Tanzanian conditions. M. Sco Thesis, University of Dar es Salaam° Van Soest, P.J., 1963. Use of detergents in the analysis of fibrous feeds. 11. A rapid method for the determination of fibre and lignin. J. Assoc° Off. Agric. Chem., 46: 829--835. Van Soest, P.J. and Wine, R.H., 1967. Use of detergents in the analysis of fibrous feeds. IV. Determination of plant cell wall constituents. J. Assoc. Off. Agric. Chem., 56: 50--55. Waiss, .a_C., Guggolz, J., Kohler, G.O., Walker, H.G. and Garrett, W.N., 1972. Improving digestibility of straws for ruminant feed by aqueous ammonia. J. Anita. Sci., 35: 109--112. Wilson, ILK. and Pigden, W.J., 1964. Effect of sodium hydroxide treatment on the utilization o f wheat straw and poplar wood by rumen microorganisms. Can. J. Anita. Sci., 44: 122--123. Woodman, H.E. and Evans, R.E., 1947. The nutritive value of fodder cellulose from wheat straw. J° Agric. Sci., Cambridge, 37: 202--210.
EFFECT OF LEVEL OF SODIUM H Y D R O X I D E T R E A T M E N T A N D VOLUME OF SOLUTION ON THE NUTRITIVE V A L U E OF MAIZE COBS
J.A. K A T E G I L E
Animal Science Department, University o f Dares Salaam, P.O. Box 643, Morogoro (Tanzania) J.H. F R E D E R I K S E N
National Institute o f Animal Science, Department o f Cattle Experiments, Copenhagen (Denmark) ( R e c e i v e d 6 J u n e 1 9 7 8 ; a c c e p t e d for p u b l i c a t i o n 7 F e b r u a r y 1 9 7 9 )
ABSTRACT Kategile, J.A. a n d F r e d e r i k s e n , J.H., 1 9 7 9 . Effect o f level o f s o d i u m h y d r o x i d e treatm e n t a n d v o l u m e o f s o l u t i o n o n t h e n u t r i t i v e value o f m a i z e cobs. Anita. Feed Sci. Technol., 4: 1--15. Maize c o b s were c h o s e n as a t e s t m a t e r i a l as t h e s e are p r o d u c e d c e n t r a l l y in h o m e s t e a d s d u r i n g shelling a n d t h e r e f o r e c o l l e c t i o n a n d t r a n s p o r t c o s t s are e l i m i n a t e d . T h e k n o w l e d g e gained f r o m t h e i m p r o v e m e n t o f t h e i r n u t r i t i v e value b y t h e d r y N a O H t r e a t m e n t m e t h o d c a n b e a d a p t e d easily. T h e e f f e c t o f t r e a t m e n t r a t e s was t e s t e d w i t h r a m s in t h r e e e x p e r i m e n t s . I n t h e first e x p e r i m e n t , c o a r s e l y g r o u n d maize c o b s w e r e t r e a t e d a t 1.67, 3.33 a n d 5.0 kg N a O H / 1 0 0 kg cobs d r y m a t t e r ( D M ) a n d f o r m e d 52% o f t h e r a t i o n s o n a n air-dry basis. Digestibility i n c r e a s e d . s i g n i f i c a n t l y (P < 0.05) a n d a regression e q u a t i o n y = 51.57_ + 2 . 2 8 x was c a l c u l a t e d in w h i c h y = DM digestibility, a n d x = kg N a O H / 1 0 0 c o b s DM. In t h e s e c o n d e x p e r i m e n t , m a i z e c o b s t r e a t e d at 2.5, 5.0, 7.5 a n d 10.0 kg N a O I 4 / t O 0 kg c o b s DM f o r m e d 67% o f t h e r a t i o n a n d t h e digestibility of DM, organic m a t t e r (OM), cell wall c o n s t i t u e n t s (CWC) a n d c r u d e f i b r e (CF) w e r e m a r k e d l y increased f r o m 2.5 t o 5.0 kg N a O H t r e a t m e n t levels a n d n o f u r t h e r r e s p o n s e s were o b t a i n e d t h e r e a f t e r . In t h e t h i r d e x p e r i m e n t , m a i z e c o b s f o r m e d 61% of t h e r a t i o n s a n d t h e m a t e r i a l was t r e a t e d a t 0, 2.5, 5.0 a n d 7.5 kg NaOH. Digestibility o f DM, OM, C F a n d e n e r g y was s i g n i f i c a n t l y (P < 0 . 0 5 ) increased at 5.0 m~d 7.5 kg N a O H levels. V o l u n t a r y feed int a k e f o l l o w e d t h e same t r e n d , values for g DM i n t a k e per kgW °, ~s per d a y b e i n g 60.5, 83.3, 95.7 a n d 9 6 . 0 in t h e o r d e r o f increasing N a O H t r e a t m e n t rates. T h e t o t a l digestibility DM, OM a n d e n e r g y i n t a k e s were m o r e closely c o r r e l a t e d t o v o l u n t a r y feed int a k e t h a n t o d i g e s t i b i l i t y c o e f f i c i e n t s . I t is c o n c l u d e d t h a t 5 kg N a O H / 1 0 0 kg DM is o p t i m u m for b o t h d i g e s t i b i l i t y a n d v o l u n t a r y feed i n t a k e . T h e v o l u m e o f N a O H s o l u t i o n was varied f r o m 25 t o 2 0 0 1 per 1 0 0 kg DM o f m a i z e c o b s in f o u r e x p e r i m e n t s a n d t h e d i g e s t i b i l i t y of DM, OM a n d CWC w i t h s h e e p was n o t a f f e c t e d b y t h i s f a c t o r , e x c e p t t h a t t h e smallest v o l u m e ( 2 5 1) d e p r e s s e d d i g e s t i o n slightly, a p p a r e n t l y b e c a u s e of t h e d i f f i c u l t y o f g e t t i n g e f f e c t i v e m i x i n g w i t h small v o l u m e s . It is c o n c l u d e d t h a t 5 0 1 per 1 0 0 kg DM o f maize c o b s is t h e m i n i m u m volume.
1
2
INTRODUC~ON AS more land is taken over for arable crops to feed man directly, less is available for forage crops and ruminants must make more use of field crop residues. Unfortunately, the energy contained in field crop residues is not readily available, and much effort has been directed towards releasing this energy by alkali treatment. Research has been undertaken in the U.S.A. (Guggolz et al., 1971; Garrett et al., 1974a, b; Klopfenstein et al,, 1974), Canada (Pigden and Heaney, 1969; Pigden and Bender, 1972; Maeng et al., 1971; Ololade and Mowat, 1975), India (Singh and Jackson, 1971; Chandra and Jackson, 1971), Denmark (Thomsen et al., 1973; Rexen et al., 1975), Norway (Homb et al., 1976; Arnasson and Me, 1977), the United Kingdom (Fernandez Carmona and Greenhalgh, 1972; Jayasuriya and Owen, 1975), the East European countries (Todorov, 1975) and Tanzania (Kategile, 1978; Urio, 1978). Among the alkali chemicals tested, sodium hydroxide and ammonia have found practical applications. The Beckmann (1922) method has been used in Norway for about thirty years, but it is becoming less acceptable owing to pollution problems and the need for large volumes of water (Kristensen, 1975). Other techniques involving low volumes of water (Wilson and Pigden, 1964; Rexen et al., 1975) and the recycling of sodium hydroxide (Mattson and Lagerstrom, 1976) have been developed. AS maize cobs are usually produced during shelling in homesteads, they are readily available for alkali treatment. The objectives of this study were to determine the optimum quantity of sodium hydroxide required for attaining high digestibility coefficients and voluntary feed intake, and to establish the minimum volume of sodium hydroxide solution needed for wetting the maize cobs without the application of heat and pressure. MATERIALS AND METHODS The maize cobs were obtained from the University of Dares Salaam Farm, located at Morogoro, Tanzania, the maize being a mass selection variety. The cobs were ground: through a 1.91 or 1.27 cm screen in a Newman Hammermill at 3200 r.p.m, prior to chemical treatment. As a matter of routine, the mixing of the ground maize cob with the sodium hydroxide solution was done with a shovel on a concrete floor. The material was allowed to react in a heap covered with a plastic sheet for 24 h, after which it was spread out thinly in the sun where it dried within a week. Indoor dryhag was sometimes necessitated by seasonal rains and occasional strong winds which blew away the light particles. In all experiments technical grade sodium hydroxide obtained from Dares Salaam Industrial Supply Company (AISCO) was used.
Experiment 1. The effects of quantity of NaOH Experiment 1A. Three amounts of NaOH, 1.67, 3.33 and 5.0 kg per 100
51.7 25.0 . . 1.0 2.0 0.3 20.0
52.0 25.0 . 1.0 2.0 . . 20 "
1.67 52.0 25.0 . 1.0 2. ¢" . 20.0
3.33
.
. 20.0
1.0 2.0
52.0 25.0
5.0
20.0
3.0 2.0
67.0 8.9
Experiment 1B and Experiment 2
59.8 . . 18.0 1.0 2.0 0.2 19.0
0
60.0 . 18.0 1.0 2.0 -19.0
2.5
Experiment 1C
60.0 . 18.0 1.0 2.0 -19.0
5.0
18.0 1.0 2.0 -19.0
60.0
7.5
mg/kg diet).
1 All diets were supplemented with vitamin A (10 000 I.U./kg diet), vitamin D (4 000 I.U.]kg diet) and vitamin E (200
Maize cobs Kapok cake meal Simsim meal (sesame) Urea Bonemeai Salt Molasses
0
• Experiment 1A
NaOH (kg/100 kg cobs DM)
Composition of the rations used (%)1
TABLE I
kg dry matter (DM) o f ground maize cobs, were used, the respective quantities of NaOH being dissolved to make up 100 1 of solution per 100 kg o f cobs DM. The air-dry maize cobs were mixed with other ingredients as in Table I. Digestibility was determined with individually caged 7--9 monthold growing Black Headed Persian rams weighing an average of 19 kg. Sixteen animals were r a n d o m l y allocated to the treatments. A preliminary period o f 10 days was followed by a faecal collection period o f 7 days. During the collection period, 80% of the faeces were dried dally. At the end of the collection period samples were bulked and sampled for chemical analysis. A restricted feeding regime of 500 g of air-dry feed per d a y per animal was followed.
Experiment lB. Four treatment levels o f 2.5, 5.0, 7.5 and 10.0 kg NaOH/ 100 kg cobs DM were used and the volume o f solution was as in Experiment 1A. The feed ingredients were mixed in the proportions given in Table I. The animals used in the determination of digestibility were 8--10 monthold Black Headed Persian rams weighing 19.5 kg on average and four animals were assigned per t r e a t m e n t group. The feeding rate was again 500 g of the ration per d a y and faeces were collected for seven days after a preliminary period of 10 days. Experiment 1C. Four treatments of 0, 2.5, 5.0 and 10.0 kg NaOH/100 kg cobs DM were used and the volume o f solution used was 75 1 per 100 kg. The composition of the various rations is given in Table I. Four adult Black Headed Persian rams weighing on average 33,1 kg were assigned to each treatment at r a n d o m and were fed once per day ad libitum. Daily adjustments for 10% rejection were made in the first 13 days of the preliminary period, after which individual feeding levels were adopted w i t h o u t further adjustments. Faeces o u t p u t and feed intake were measured for seven days. Refusals were collected daily and bulked during the collection period. Experiment 2. The effects o f volume of NaOH solution on the digestibility o f maize cobs Experiment 2A. One level o f 5 kg NaOH/100 kg cobs DM was used, with 50, 100, 150 and 200 1 of aqueous solutions per 100 kg cobs DM. The materials were allowed to react for 24 h and dried as in the previous experiments. The composition of the rations is given in Table I; t h e y were given at 550 g/ day to one-year-old Black Headed Persian rams weighing on average 22 kg. The preliminary and faecal collection periods were 7 days each. Experiment 2B. The volumes tested were 50, 75 and 100 1 per 100 kg cobs DM with 5 kg NaOH/100 kg cobs DM. The rations were similar in composition to those in Experiment 2A. The feeding rate and sample collection were as in Experiment 2A.
Experiment 2C. Small volumes of 25, 50 and 100 1/100 kg cobs DM were used with 5 kg N a O H / 1 0 0 kg cobs DM. The procedures for feeding and sample collection were the same as those of Experiments 2A and 2B. Experiment 2D. Again with 5 kg NaOH/100 kg cobs DM, volumes of 25.0, 37.5 and 50.0 1 were tested against a control treatment (no alkali). The experimental procedure was similar to those in Experiments 2A, 2B and 2C. Chemical analysis. The cell wall constituents (CWC) were determined b y the procedure developed b y Van Soest and Wine (1967). Crude protein was determined b y the Kjeldahl m e t h o d (Association of Official Agricultural Chemists, 1965). Dry matter, organic matter (OM) and ash were analysed according to Association of Official Agricultural Chemists (1960) and crude fibre (CF) was determined as outlined b y Van Soest (1963). The energy (kcal) in feeds and faeces was determined in a Gallenkamp adiabatic b o m b calorimeter. Chemical analysis was made on c o m p o u n d e d feed samples and dried faecal samples. All statistical analysis was carried o u t according to Fryer (1966); the Least Squares Difference (LSD) test was used for comparison between means. RESULTS AND DISCUSSION
Experiment 1 The results of Experiment 1A are illustrated in Fig. 1. There was a linear response in DM digestibility, the equation being shown in Fig. 1. 70
+ "~65
¢-
:t
v :-= 8 0 "E,
$
r~
:'5 55 +
y = 51.57+
~ 5o
2 28x
S b = 0.17 Sy/x =9.47 r' = 0 . 8 3 P
2
3
4
5
NaOH l e v e l (kg//lOOkg c o b s DM, x )
Fig. 1. Experiment 1A. Correlation between NaOH application and dry matter digestibility of maize cob-based rations.
6
A response of 2.28 digestibility units per 1 kg NaOH/100 kg DM compares well with responses obtained in other investigations. Singh and Jackson (1971) obtained a response of 3.03% units for a ration containing 76% straw; Klopfenstein et al. (1972) recorded a response of 4.07% units with rations containing 77% maize cobs; Jayasuriya and Owen (1975) obtained a 1.87% units response; and Ololade and Mowat (1975) recorded a response of 2.80% units in a ration containing 89% treated straw/grain mixture. The data of Experiment 1B are given in Table II and illustrated in Fig. 2. The digestibility coefficients increased markedly from the 2.5 kg NaOH treatment to the 5.0 kg treatment, and further increases in NaOH levels had no effect. The results o f Experiment 1B indicated that the m a x i m u m response in digestibility of DM, OM, CWC and CF was obtained with 5 kg NaOH/100 kg cobs DM, and agree with the observations of Singh and Jackson (1971), Thomsen et al. (1973), Klopfenstein et al. (1972) and Ololade and Mowat (1975). The results o f Experiment 1C are given in Table III and Fig. 3. Daily DM and OM intake were significantly (P < 0.05) increased by the 2.5 kg NaOH t r e a t m e n t and thereafter the trend continued to a lesser extent up to 5.0 kg NaOH and no further increases were recorded b e y o n d this level. The digestion coefficients o f DM, OM and energy were significantly (P < 0.05) improved by NaOH treatment at 5.0 and 7.5 kg NaOH but not by 2.5 kg NaOH. The quantities of DM, OM and energy digested per day increased T A B L E II E x p e r i m e n t l B . T h e c h e m i c a l c o m p o s i t i o n a n d digestibility o f dry m a t t e r (DM), cell wall c o n s t i t u e n t s (CWC), organic m a t t e r (OM), c r u d e f i b r e (CF) and n i t r o g e n o f r a t i o n s b a s e d o n maize c o b s Chemical
T r e a t m e n t (kg N a O H / 1 0 0 kg c o b s DM)
composition (% DM) 2.5
5.0
7.5
10.0
DM OM CWC CF Nitrogen
75.2 92.9 65.1 25.7 2.35
78.7 91.9 66.9 26.4 2.41
71.0 91.6 65.3 25.9 2.39
66.3 89.9 71.7 26.0 2.40
Digestibility c o e f f i c i e n t s1 DM OM CWC CF
43.1 a 43.8 a 47.7 a 27.9 a
55.4 b 53.8 D 59.2 b 62.2 b
54.2 b 52.6 b 57.2 b 62.8 b
56.6 b 54.4 b 57.2 b 63.4 b
S.E. o f m e a n s and significance of differences m
m
D
3.5* 3.0* 3.0*
1 Means w i t h i n a r o w w i t h d i f f e r e n t s u p e r s c r i p t s are significantly d i f f e r e n t , * (P < 0.05),
• * (P < 0.01).
65 :
60
# ]
io l:
l
55
g///'
50
?.
45
4o
35
a~l o--o o-.-o a,...a
30 £
Dry m a t t e r Organic m a t t e r Cell wall constituents Crude fibre
25
20
2
4
6
8
10
N a O H level (Kg/lOOkg cobs[2M)
Fig. 2. Experiment lB. The digestibility coefficients o f dry matter, organic matter, cell wall constituents and crude fibre o f rations based on NaOH treated maize cob-based rations.
substantially and significantly from the control group to the 2.5 kg NaOH treatment, and further significant (P < 0.05) increases were obtained with 5.0 kg NaOH for DM and energy but not for OM. The amount of CF digested per day was only slightly increased by the 2.5 kg NaOH treatment while significant (P < 0.05) increases were obtained with the 5.0 kg NaOH treat~ ment. The 7.5 kg treatment caused no improvements over the 5.0 kg treatment, and in fact there were slight depressions in the quantities of DM, OM and CF digested. Calculated metabolisable energy concentration (ME Mcal/ kg DM diet) was n o t influenced by NaOH tzeatment, except for a small increase at the 7.5 kg NaOH treatment level. This trend confirms the earlier observations of Singh and Jackson (1971) and Jayasuriya and Owen (1975). The increase in feed intake caused by NaOH treatment was high. It was" ~eater than the responses obtained by Singh and Jackson (1971), Hasimoglu et al. (1969) and Garrett et al. (1974a, b), comparable to the values obtained by Saxena et al. (1971) and Jayasuriya and Owen (1975), but below the responses obtained by Donefer (1968) Donefer et al. (1969) and Klopfenstein et al. (1974).
8
TABLE
IIi
Experiment
1C. Chemical
composition
Treatment
of rations,
(kg NaOH/100
voluntary
feed intake
kg cobs DM)
and digestibility
0
2.5
5.0
7.5
S.E. of means and significance of difference
0.641 a 60.5 a 0.721 a 51.9 a
1.189 b 83.3 b 1.105 b 73.9 b
1.314 b 95.5 c 1.131 b 82.4b
1.263 bc 96.0 c 1.068 b 81.3 b
0.041" 5.29* 0.067** 5.43**
59.6 a 59.7 a 64.1 57.6 a
65.4b 64.6 b 69.7 64.4 c
67.3 b 66.0b 70.7 70.0 d
1.46"* 1.51'* 2.66 1.75"
Daily f e e d i n t a k e 1 DM DM OM OM
(kg) ( g / k g W°'Ts) (kg) ( g / k g W, ° -7s)
Digestibility coefficients DM 61.3 a OM 59.9 a CF 70.2 Energy 61.5b Quantities of digested fractions (kg/day) DM 0.517 a OM 0.4329 CF 0.183 a Energy (Mcal/day) 2.14 a C a l c u l a t e d e n e r g y ( M c a l / k g d i e t DM) Digestible energy 2.55 M e t a b olisable energy 2.07 C h e m i c a l c o m p o s i t i o n o n D M b a s i s (%) OM 85.7 CF 27.5 Nitrogen 2.17 1 Means within • * (P < 0.01).
a row with different
0.708 b 0.626 b 0.204 a 2.73 b
0.857 c 0.729 b 0.253 b 3.38 c
0.849 c 0.705 b 0.222 b 3.57 c
2.32
2.57
2.84
!.86
2.09
2.34
88.7 24.6 1.97
86.1 24.4 1.94
84.6 22.9 1.97
superscripts
are significantly
0.064* 0.065* 0.012" 0.156"
different,
* ( P < 0 . 0 5 ),
The digestion coefficients in Experiment 1C for DM, OM and energy were significantly improved by NaOH treatment at the 5.0 and 7.5 kg and not at the 2.5 kg level, This contradicts the results of Experiment 1A and also contradicts the literature cited in t h a t section. It is probable that the small effect o f NaOH treatment at 2.5 kg was countered by the depressing effect on digestion of elevated feed intake (Blaxter and Graham, 1955; Freer and Campling, 1963; Leaver et al., 1969; Milne and Campling, 1972). While Woodman and Evans (1947), Randel (1972) and Jayasuriya and Owen (1975) reported consistent increases in the digestion of CF, the results obtained in the experiment showed neither a significant effect nor any definite ~rend. However, there were significant increases in the q u a n t i t y of crude fibre digested per day with 5.0 and 7.5 kg NaOH in comparison to the control.
90
70
o.
~0.8 80 L--> U
I 07
t 0.6
7o ~
8C •
.."
t
0.5
i/ /
6o ~
iI
E
t0.4
/
u
.~.
-~ ".,~
Jo.3 5
o
~ 5o
~--~
O
o-...o
m--i
OM digestibility OM intake Digestible OM intake
c
g
L 0
o
2's
~
7'5
NaOH level (kg/lOOkg cobsDM)
Fig. 3. Experiment 1C. Organic matter digestibility, total organic matter digested and organic matter voluntary intake for sheep fed on diets based on m a i z e cobs treated w i t h graded levels o f s o d i u m hydroxide.
Crampton et al. ( 1 9 6 0 , 1 9 6 2 ) proposed the use o f the Nutritive Value Index (NVI) which is a product of relative intake ( 8 0 g D M / k g W°'Ts as a standard) and percentage digestibility of energy, as a parameter o f the nutritive value of forages. Interest was then taken in developing a mathematical model which w o u l d predict the intakes o f OM, DM and energy/kg W°'Ts by using digestibility and feed intake per unit o f metabolic b o d y weight (kg W°'Ts ) as variables. The multiple regreskion equation was y = - 2 . 9 3 1 + 0 . 0 5 4 0 x , + 0.0344x2 where y = Mcal of D E / d a y / k g W°'Ts, x l = digestion coefficient o f energy and x2 = g intake OM/kg W°°Ts. Equations for DM and OM were similar. The statistical analysis o f the multiple regression indicated that o f the t w o independent variables, voluntary intake was a better index of the nutritive value o f a feed than was the digestion coefficient.
Experiment 2 In Experiment 2A, the digestibility coefficients o f DM, OM and CWC of the rations did n o t differ, the variation was small, and the o n l y difference was the l o w digestibility o f CF at 50:1 v o l u m e (Table IV). The results of Experiment 2B confirmed those of 2A. In Experiment 2C, DM and OM digestibility decreased with decreasing volume. Statistically, ' the 1 0 0 1 treatment was superior to the 25 1 treatment for digestibility o f DM and OM, but n o t superior to the 50 1 treatment. In Experiment 2D, DM and OM digestibility for the 25.0, 37.5 and 50.0 1 treatments were similar but signi-
IV
-----
-----
-----i
----~ ----
(% D M )
D M (%) -OM -CWC -Nitrogen -Digestibility coefficients DM -OM -CWC --
Experiment 2B Chemical composition
DM OM CWC CF
37.5
(% D M )
D M (%) -OM -CWC -CF -Nitrogen -Digestibility coefficients
Experiment 2A Chemical composition
25
Volume of solution
72,3 a 73.4 b 72.6 a
70.6 a 70.4 a 71.2 a
-----
84,7 94.5 63.5 1.91
a a a a
-------
75
85.5 95~5 61,8 2.26
71.5 71.8 69.4 62.6
87.5 89.2, 59.9 42.7 2.41
50
a a a ab
70.1 a 70.9 a 70.6 a
81.5 94.1 65.2 1.88
70.1 70.5 67.4 67,4
86.4 90.1 60.4 45.3 2.34
100
per 100 kg DM of maize cobs (I)
m
m
m
D
u
71.3 72.4 69.7 71.4
m
a a a a
a a a ab
87.8 90.0 63.3 45.2 2.45
200
n
m
m
70.1 70.4 67.9 63.0
86.6 89.9 61.7 44.4 2.44
150
Chemical composition and digestibility of rations based on maize cobs treated with 5 kg NaOH/100 kg DM in various volumes of solution
TABLE
u
m
B
m
m
0
0.98 0.93* 2.50
0.99 0.97 0.96 3.70*
m
B
m
i
SE of mean and significance of differences
O
----
6 7 . 5 ab 6 7 . 0 ab 63.9 a
----
2.03 68.4 b 69.3 b 66.7 c
64.2
-----
86.0 88.8
-----
83.5 91.9 63.2 1.64
m
69.6 b 69.3 b 68.8 b
84.5 92.7 62.6 2.18
n
m
m
m
m
m
m
E
m
m
m
m
m
m
m
61.1 a 62.6 52.9
89.8 92.7 70.7 2.26
m
m
' Means within a row with different superscripts are significantly different, * (P < 0.05), ** (P < 0.01).
Experiment 2D C h e m i c a l c o m p o s i t i o n (% D M ) D M (%) 85.7 87.2 OM 89.2 88.0 CWC 59.2 60.9 Nitrogen 2.30 2.22 Digestibility coefficients ~ DM 68.5 b 69.0 b OM 68.8 b 69.3 b CWC 63.3 b 66.2 c
Experiment 2C C h e m i c a l c o m p o s i t i o n (% D M ) DM(%) 85.4 -OM 92.9 -CWC 64.2 -Nitrogen 1.86 -Digestibility coefficients ~ DM 65.9 a -OM 65.7 a -CWC 63.2 a --
1.44"* 1.58" 1.35"
m
m
1.20" 1.07" 2.08*
E
k.A
12
ficantly higher than the values for the control group (Table IV). The variation in volume did n o t affect digestibility of DM, OM and CWC, except for the 25 1 volume which resulted in slightly lower values than the others in Experiment 2C b u t not in 2D. Jayasuriya and Owen (1975) reported lower values with 30 1 volume per 100 kg of straw than with 60 1 and 120 1/100 kg. Donefer et al. (1969) and Phoenix et al, (1974) demonstrated the same effect b y varying the NaOH volume and measuring digestibility in vitro. Waiss et al. (1972) reported an o p t i m u m moisture c o n t e n t o f 30% for ammonia to react with straw. Water is a carrier of the reactants and a medium o f chemical reaction. It appears that mixing is the limiting factor with the low volume treatments. TABLE V T h e c a l c u l a t e d OM d i g e s t i b i l i t y c o e f f i c i e n t o f m a i z e c o b s a l o n e Experiment no.
1A
N a O H treatm e n t (kg/ 1 0 0 kg c o b s DM) 0.0 1.67 3.33 5.0
Volume of solution ( 1 [ 1 0 0 kg c o b s DM)
C a l c u l a t e d OM digestibility of maize cobs alone
100 100 100 100
15.3a 22.0a 23.1a 30.4a
IB
2.5 5.0 7.5 10.0
100 100 100 100
21.8 31.8 30.6 32.4
IC
0.0 2.5 5.0 7.5
75 75 75 75
29.1 28.9 33.8 35.2
2A
5.0 5.0 5.0 5.0
50 100 150 200
46.8 45.4 45.4 46.6
2B
5.0 5.0 5.0
50 75 100
45.7 48.7 46.2
2C
5.0 5.0 5.0
25 50 100
41.0 42.3 44.6
2D
0.0 5.0 5.0 5.0
a = DM digestibility.
0 25 37.5 50
37.9 44.1 44.6 44.6
13
The calculated digestibility o f maize cobs alone The digestibility values in Table V f o r m a i z e c o b s alone were c a l c u l a t e d b y assuming t h a t t h e digestibility o f t h e c o n c e n t r a t e f r a c t i o n was n o t affected b y t h e various levels o f r o u g h a g e (i.e. b y t h e d i f f e r e n c e m e t h o d ) . Alt h o u g h t h e s e c a l c u l a t e d values varied, t h e N a O H t r e a t m e n t i m p r o v e d OM or D M digestibility b y 5 - - 1 0 % units. These increases are similar t o t h o s e r e p o r t e d b y Maeng et al. ( 1 9 7 1 ) , F e r n a n d e z C a r m o n a and G r e e n h a l g h ( 1 9 7 2 ) and J a y a s u r i y a a n d O w e n ( 1 9 7 5 ) . T h e variation o f v o l u m e o f N a O H treatm e n t s o l u t i o n h a d no e f f e c t o n digestibility o f m a i z e cobs. A p p a r e n t l y , t h e digestibility was l o w e r in t h e E x p e r i m e n t 1 series t h a n in t h e E x p e r i m e n t 2 series. While it is possible t o a t t r i b u t e t h e l o w digestibility in E x p e r i m e n t 1 A t o t h e high p r o p o r t i o n o f c o n c e n t r a t e s , as was d e m o n s t r a t e d b y B u r r o u g h s et al. ( 1 9 4 9 ) , it is d i f f i c u l t t o explain t h e l o w values o b t a i n e d in E x p e r i m e n t 1B w i t h similar c o n c e n t r a t e levels. H o w e v e r , the d e p r e s s e d digestibility values o b t a i n e d in E x p e r i m e n t 1C m i g h t have b e e n c o n t r i b u t e d b y high v o l u n t a r y feed i n t a k e (Blaxter and G r a h a m , 1 9 5 5 ; Freer and Campling, 1 9 6 3 ) . T h e d a t a f r o m t h e E x p e r i m e n t 2 series indicate t h a t N a O H - t r e a t e d m a i z e c o b s are a r e a s o n a b l e s o u r c e o f energy. REFERENCES Arnasson, J. and Mo, M., 1977. Ammonia treatment of straw. Paper presented at the Third Straw Utilization Conference, Oxford, pp. 1--13. Association of Official Agricultural Chemists, 1960. Official Methods of Analysis, 9th edn., Assoc. Off. Agric. Chem., Washington, D.C. Association of Official Agricultural Chemists, 1965. Official Methods of Analysis, 10th edn., Assoc. Off. Agric. Chem., Washington, D.C. Beckmann, E., 1922. Conversion of grain straw and tupins into feeds of high nutritive value. Chem. Abstr., 16: 765. Blaxter, K.L. and Graham, N. Mc., 1955. Plane of nutrition and starch equivalents. J. Agric. Sci., Cambridge, 46: 292--306. Burroughs, W., Gerlaugh, P., Edgington, B.H. and Bethke, R.M., 1949. The influence of corn starch upon roughage digestion in cattle. J. Anita. Sci., 8: 271--278. Chandra, S. and Jackson, M.G., 1971. A study of various chemical treatments to remove lignin from coarse roughages and increase their digestibility. J. Agric. Sci., Cambridge, 77: 11--17, Crampton, E.W., Donefer, E. and Lloyd, L.E., 1960. A nutritive value index for forages. J. Anita. Sci., 19: 538--544. Crampton, E.W., Donefer, E. and Lloyd, L.E., 1962. Caloric equivalent of the nutritive value index. J. Anim. Sci., 21: 628--632. Donefer, E., 1968. Effect of sodium hydroxide treatment on the digestibility and voluntary feed intake of straw. Proc. 2nd World Conf. Anim. Prod., Maryland, pp. 446--447. Donefer, E., Adeleye, I.O.A. and Jones, T.A.O.C., 1969. Effect of urea supplementation on the nutritive value of NaOH-treated oat straw. Cellulases and their Applications. Adv. Chem. Set., 95: 328- -342. Fernandez Carmona, J. and Greenhalgh, J.F.D., 1972. The digestibility and acceptability to sheep of chopped or milled barley straw soaked or sprayed with alkali. J. Agric. Sci., Cambridge, 78: 477--485.
14 Freer, M. and Campling, R.C., 1963. Factors affecting the voluntary intake o f food b y cows. 5. The relationship between the voluntary intake of food, the a m o u n t of digesta in the reticulo-rumen and the rate o f disappearance of digesta from the alimentary tract with diets of hay, dried grass or concentrates. Br. J. Nutr., 17: 79--88. Fryer, H.C., 1966. Concepts and Methods of Experimental Statistics. Allyn and Bacon, Boston, U.S.A., pp 1--602. Garrett, W.N., Walker, H.G., Kohler, G.O., Waiss, A.C., Graham, R.P., East, N.E. and Hart, M.R., 1974a. Nutritive value of NaOH and NH3treated rice straw. J. Anita. Sci., 38: 13~2. Garrett, W.N., Walker, H.G., Kohler, G.O., Waiss, A.C., Graham, R.P., East, N.E. and Hart, M.R., 1974b. Nutritive value of NaOH and NH3 treated rice straw. Proc. West. Sect. Am. Soc. Anita. Sci.0 25: 317--320. Guggolz, J.~ Kohler, G.O. and Klopfenstein, T.J., 1971. Composition and improvement o f grass straw for ruminant nutrition. J° Anita. Sci.: 33: 151--156. Hasimoglu, S., Klopfenstein, T.J. and Doane, T.H., 1969. Nitrogen source with sodium hydroxide treated wheat straw. J. Anita. Sci., 29: 160. Homb, T., Sundst~l, Fi and Arnasson, J., 1976. Chemical treatment of straw at commercial and farm level. In: New Feed Resources: Proceedings o f a Technical ConsuItation. FAO, Rome, Italy. lap 25--37. Jayasuriya, M.C.N. and Owen, E., 1975. Sodium hydroxide treatment of barley straw. Effect o f volume and concentration of solution on digestibility and intake b y sheep. Anim. Prod., 2 I : 313--322. Kategile, J,A., 1978. Improvement of the nutritive value of maize cob using sodium hydroxide. Ph. D. Thesis, University o f D a r e s Salaam. Klopfenstein, T.J., Krause, V.E., Jones, M.J. and Woods, W., 1972. Chemical treatment o f low quality roughages. J. Anita. Sci., 35: 418--422. Klopfenstein, T.J., Graham, R.P., Walker, H.C. and Kohler, G.O., 1974. Chemicals with pressure treated cobs. J. Anita. Sci., 39: 243. Kristensen, V.F.~ 1975. Chemicad and physical treatment of straw. A Seminar in EEC Programme of Coordination of Research on Beef Production. In: Improving the Nutritional Efficiency o f Beef Production. J.C. Tayler and J.M. Wilkinson (Editors), pp. 2 6 3 - 2 7 6 . Leaver, J.D., Campling, R.C. and Holmes, W., 1969. The effect of level of feeding on the digestibility of diets for sheep and cattle. Anita. Prod., 1 1 : 1 1 - - 1 8 . Maeng, W.J., Mowat, D.N. and Bilanski, W.K., 1971. Digestibility of sodium hydroxidetreated straw fed alone or in combination with alfalfa silage. Can. J. Anita. Sci., 51: 743--747. Mattson, L.A. and Lagerstrom, G,, 1976. Boliden-metoden for lutning och naringsberikning av halm. Foder Journalen, (3--4) pp. 77--87. Milne, J.A. and Campling, R.C., 1972. Intake and digestibility b y sheep of artificially dried forages in several physical forms. J. Agric. Sci., Cambridge, 78; 79--86. Ololade, B.G. and Mowat, D.N.,'1975. Influence of wholeplant barley reconstituted with sodium hydroxide on digestibility, tureen fluid and plasma metabolism of sheep. J. Anim. Sci., 40: 351--357. Phoenix, S.L., Bilanski, W.K. and Mowat, D.N., 1974, In vitro digestibility of barley straw treated with sodium hydroxide at elevated temperatures. Trans. Am. Soc. Agric. Eng., 17"- 780--782. Pigden~ W.J. a n d Bender~ F., 1972. Utilisation o f Iignoceilulose by ruminants. WorId Anita, Rev., 4: 7--10. Pigden, W.J. and Heaney, D.P., 1969. Lignocellulose in ruminant nutrition.' Cellulases. and their Applications. Adv. Chem. Ser.~ 95: 245--261. Randel, P.F., 1972. A comparison of the digestibility of two complete rations containing either raw or alkali-treated sugarcane bagasse. J. Agric. Univ, P.R., 52: 18--25.
Rexen~ F., Stigsen, P. and Kristensen, V.F., 1975. The effect of a new alkali technique on the nutritive value of straws. Ninth Conf. Feed Manufacturers, University of Nottingham, pp. 65--82. Saxena, S.K., Otterby, D.E., Donker, J.D. and Good, A.L., 1971. Effects of feeding alkali-treated oat straw supplemented with soybean meal or non-protein nitrogen o n growth of lambs and o n certain blood and rumen liquor parameters. J. Anita. Sci., 33: 485--490. Singh, M. and Jackson, M.G., 1971. The effect of different levels of sodium hydroxide spray treatment of wheat straw on consumption and digestibility b y cattle. J. Agric. Sci., Cambridge, 77 : 5--10. Thomsen, K.V., Rexen, F. and Kristensen~ V.F., 1973. Experiments with NaOH treatment o f straw. Ugeskrift for Agronomer og Hortonomer, No. 25, pp. 1--15. Todorov, N.A., 1975. Recent developments in animal nutrition research in Eastern Europe. J. Anim. Sci., 40: 1284--1299. Urio, N.A., 1978. Improvement of low quality roughages by alkali treatment under Tanzanian conditions. M. Sco Thesis, University of Dar es Salaam° Van Soest, P.J., 1963. Use of detergents in the analysis of fibrous feeds. 11. A rapid method for the determination of fibre and lignin. J. Assoc° Off. Agric. Chem., 46: 829--835. Van Soest, P.J. and Wine, R.H., 1967. Use of detergents in the analysis of fibrous feeds. IV. Determination of plant cell wall constituents. J. Assoc. Off. Agric. Chem., 56: 50--55. Waiss, .a_C., Guggolz, J., Kohler, G.O., Walker, H.G. and Garrett, W.N., 1972. Improving digestibility of straws for ruminant feed by aqueous ammonia. J. Anita. Sci., 35: 109--112. Wilson, ILK. and Pigden, W.J., 1964. Effect of sodium hydroxide treatment on the utilization o f wheat straw and poplar wood by rumen microorganisms. Can. J. Anita. Sci., 44: 122--123. Woodman, H.E. and Evans, R.E., 1947. The nutritive value of fodder cellulose from wheat straw. J° Agric. Sci., Cambridge, 37: 202--210.