- Email: [email protected]
Nutritive value of leaf protein coagulum and cereals mixtures
Animal Feed Science and Technology, 4 (1979) 91--96
91
© Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands
NUTRITIVE VALUE OF LEAF PROTEIN COAGULUM AND CEREALS MIXTURES
PIOTR HANCZAKOWSKI and MICHAL PETZEL 1 Institute o f Animal Production, Department o f Animal Nutrition, 32-083 Baliee (Poland) 1 Central Laboratory o f Agricultural Industry, Chmielna 2, 20-079 Lublin (Poland)
(First received 29 December 1978; accepted for publication 11 June 1979)
ABSTRACT Hanezakowski, P. and Petzel, M., 1979. Nutritive value of leaf protein coagulum and cereals mixtures. Anita. Feed Sc£ Technol., 4: 91--96. Experiments were performed to compare the composition and nutritive value of mixtures containing leaf protein coagulum from lucerne with cereals (ground barley, ground wheat and wheat bran), with non-processed cereals alone or with the addition of separately-dried leaf protein. The chemical composition of mixtures and amino acid composition of their proteins were determined by conventional methods. The biological value and true digestibility of cereals and mixture proteins were determined on rats by the Thomas-Mitchell balance method. The biological values of mixture proteins were higher, but their digestibility was lower, than those of cereals alone. Generally, better results were obtained when cereals were mixed with separately-dried leaf protein and with barley rather than wheat.
INTRODUCTION Leaf protein may become a valuable source of protein for non-ruminants a f t e r s e p a r a t i n g it f r o m excess o f fibre. T h e p r o c e s s o f e x t r a c t i n g p r o t e i n f r o m f o r a g e was d e s c r i b e d b y Pirie ( 1 9 6 6 ) . T h e p r o c e d u r e involves t h e ext r a c t i o n o f juice f r o m p l a n t m a t e r i a l , h e a t c o a g u l a t i o n o f t h e juice p r o t e i n a n d s e p a r a t i o n a n d d r y i n g o f t h e l e a f - p r o t e i n curd. As t h e price o f e n e r g y c o n t i n u e s t o rise, d r y i n g b e c o m e s v e r y e x p e n s i v e . ~F u r t h e r m o r e , t h e r e is t h e p o s s i b i l i t y o f l e a f p r o t e i n o v e r h e a t i n g . T h e risk o f h e a t d a m a g e m a y b e dim i n i s h e d b y using a m i x t u r e o f w e t p r o t e i n c o a g u l u m w i t h g r o u n d grain, as p r o p o s e d b y F o o t ( 1 9 7 4 ) . S u c h m i x t u r e s c o u l d b e d r i e d at l o w t e m p e r a t u r e s a n d s t o r e d s a t i s f a c t o r i l y as l o n g as t h e i r h u m i d i t y did n o t e x c e e d 16%. T h e p r o d u c t i o n o f l e a f p r o t e i n a n d cereals m i x t u r e s m a y b e n u t r i t i o n a l l y a d v a n t a g e o u s . B e c a u s e o f its high lysine c o n t e n t , l e a f p r o t e i n is a g o o d supp l e m e n t f o r cereals w h i c h are p o o r in this a m i n o acid. T h e s e e x p e r i m e n t s w e r e u n d e r t a k e n t o e x a m i n e t h e n u t r i t i v e value o f m i x t u r e s c o n t a i n i n g l e a f p r o t e i n c o a g u l u m dried w i t h cereals a n d t o c o m p a r e t h e m w i t h n o n - p r o c e s -
92
sed cereals given alone or with separately dried leaf protein coagulum. M A T E R I A L AND METHODS
Mixtures were made with barley, wheat and wheat bran ground to 1--2 mm in size, and leaf protein coagulum from lucerne. Lucerne was cut in September (the third growth), ground in a universal mill (RU Bak) and the juice extracted in a screw press (Bentall). The juice was heated b y steam injection to 80°C and the precipitated curd was filtered through a nylon filter. The dry matter of the resulting leaf protein coagulum was a b o u t 20%. Coagulum was divided into t w o parts. One part was mixed with cereals at 1:1.5 w / w ratio, while the second part was air-dried at temperatures lower than 50 ° C. The leaf protein and cereals mixtures were dried b y means of a pneumatic conveyor at 40 ° C. Control mixtures of cereals and separately dried leaf protein were prepared. Each of their components supplied these mixtures with the same a m o u n t of protein as in the corresponding cereals/wet coagulum mixtures. The gross composition of cereals and mixtures was determined b y standard methods (Skulmowski, 1974). Amino acid analyses were performed b y the m e t h o d of Spackmann (1963) with the Carlo Erba amino acid analyser. The lysine availability was estimated b y Carpenter's m e t h o d (1960) modified with high voltage electrophoresis (Rys et al., 1967). Methionine (total and available) was determined microbiologically {Ford, 1964) and carotene according to Gstirner (1965). The biological value and true digestibility of proteins were determined by the Thomas--Mitchell balance method. Eight male albino rats, each weighing TABLE I
The chemical composition (%) of cereals and their mixtures with leaf protein coagulum Specification
Dry matter
Crude protein
Ether extract
Fibre
Ash
N-free extractives
Ground wheat Ground wheat mixed with wet LP coagulum Wheat bran Wheat bran mixed with wet LP coagulum Ground barley Ground barley mixed with wet LP coagulum Dried LP coagulum
88.7
11.2
2.0
0.9
1.8
72.8
1.6
92.0 91.4
14.3 15.1
2.4 3,7
0.8 5.3
2.3 3.4
72.2 63.9
52.8 1.7
92.4 91.0
19.8 11.9
3.8 2.6
5.0 3.9
3.4 2.1
60.4 70.5
66.0 0.7
91.6 93.7
14.2 43.5
3.4 9.2
3.9 1.0
3.2 4.1
66.9 35.9
54.3 520.5
Carotene (mg/kg)
a = Available.
His Arg Asp Thre Ser Glu Pro Gly Ala Val Ileu Leu Tyr Phe Lys Lys a Met Met a
Amino acid
2.2 4.6 4.8 2.9 4.9 33.8 9.1 4.4 3.8 4.6 3.2 6.6 2.9 4.6 2.7 2.5 2.0 1.6
Ground wheat
2.2 5.0 5.8 2.9 4.3 27.4 8.0 4.4 3.8 4.5 3.2 6.4 2.8 4.4 3.2 2.8 1.9 1.4
Ground wheat mixed with wet LP coagulum 2.7 5.7 5.7 2.5 2.8 23.0 8.2 4.4 3.1 4.7 3.3 6.1 2.4 4.1 3.7 3.4 2.1 1.5
Wheat bran
2.8 5.4 7.4 3.2 3,0 19.4 7.7 4.0 5.0 5.0 3.9 6.9 2.5 4.8 4.2 3.8 1.9 1.2
Wheat bran mixed with wet LP coagulum 2.3 4.2 5.8 2.7 2.5 25.0 12.9 3.8 4.0 4.7 3.6 6.6 1.9 5.4 3.3 3.0 2.0 1.3
Ground barley
2.3 4.4 6.8 3.2 2.8 20.2 10.0 3.5 4.9 5.3 3.9 6.8 2.1 5.2 3.8 3.5 2.0 1.2
2.8 4.9 9.3 3.8 2.8 10.3 5.O 5.2 5.7 5.7 4.9 7.6 3.7 6.1 5.1 4.7 1.9 1.1
Ground barley m i x e d Dried with wet LP coagulum coagulum
Amino acid composition o f cereals and their mixtures with wet leaf protein coagulum (g per 16 g N)
TABLE II
05
94 TABLE III Nutritive value of proteins of cereals and their mixtures with leaf protein coagulum Specification
Biological value (% +_SE)
True digestibility (% +- SE)
Net protein lization*
Ground wheat Ground wheat mixed with wet LP coagulum Ground wheat mixed with dried LP coagulum Wheat bran Wheat bran mixed with wet LP coagulum Wheat bran mixed with dried LP coagulum Ground barley Ground barley mixed with wet LP coagulum Ground barley mixed with dried LP coagulum Dried LP coagulum
57 + 1.7
89 -+ 1.1
51
58 -+ 1.8
87 -+ 1.1
51
60 + 2.1 61 + 1.7
88 + 1.2 92 + 0.9
53 56
62 + 2.1
84 + 1.3
52
65 + 1.6 62 + 1.9
85 +- 1.2 86 -+ 0.9
55 53
66 + 2.1
85 +- 1.0
56
68 -+ 1.8 56 -+ 2.9
85 + 1.4 80 -+ 1.8
58 49
* N P u = B V x TD 100 a b o u t 80 g, were used in o n e e x p e r i m e n t a l g r o u p . T h e a d a p t a t i o n p e r i o d lasted 5 d a y s a n d t h e balance p e r i o d 6 days ( N e h r i n g a n d Haesler, 1 9 5 4 ) . E a c h rat received 1 5 0 m g N a n d 10 g d r y m a t t e r per d a y t h r o u g h o u t t h e t w o periods. T h e e x p e r i m e n t a l feeds were t h e o n l y s o u r c e o f p r o t e i n in t h e diet. Diets also c o n t a i n e d : s o y a b e a n oil (6%), m i n e r a l m i x t u r e (4%) a n d v i t a m i n m i x t u r e (2%), t h e c o m p o s i t i o n o f b o t h m i x t u r e s b e i n g a c c o r d i n g t o E g g u m ( 1 9 7 3 ) . In o r d e r t o c o m p l e t e t h e diet c o m p o s i t i o n , w h e a t starch was a d d e d . Diet No. 10, b a s e d o n dried leaf p r o t e i n c o a g u l u m , was s u p p l e m e n t e d w i t h sucrose (10%) a n d ceUulose (4%). /J
RESULTS AND DISCUSSION T h e m i x t u r e s h a d a m o i s t u r e c o n t e n t o f less t h a n 10% a n d were s t o r e d satisfactorily u n d e r n o r m a l c o n d i t i o n s f o r a b o u t o n e year. T h e leaf p r o t e i n c o a g u l u m p r o v i d e d f r o m 16% o f t h e t o t a l p r o t e i n in its m i x t u r e w i t h barley, t o n e a r l y 24% in t h e w h e a t b r a n p r e p a r a t i o n . These l o w values o f leaf p r o t e i n were d u e t o t h e l o w d r y m a t t e r c o n t e n t o f fresh c o a g u l u m . I t is possible t o increase this c o n t e n t b y a d d i t i o n a l pressing o f c o a g u l u m . H o w e v e r , this w o u l d c o m p l i c a t e t h e process a n d m a k e it m o r e expensive. T h e a d d i t i o n o f c o a g u l u m caused a small increase in t h e e t h e r e x t r a c t and ash c o n t e n t s o f t h e m i x t u r e s (Table I) as a result o f t h e i r high c o n t e n t s in t h e leaf p r o t e i n p r e p a r a t i o n . T h e c a r o t e n e c o n t e n t o f t h e m i x t u r e s was m u c h
95 :L i : :
-
higher than of cereals alone. The leaf protein concentrates, especially from lucerne and grasses, are k n o w n as good sources of this provitamin (Arckoll, 1973). There were no significant differences in amino acid composition between cereals and their mixtures with leaf protein coagulum (Table II). All preparations were poor in methionine, especially in its availability. In all mixtures, the lysine c o n t e n t was higher than in cereals alone. Because of the higher protein c o n t e n t in the mixtures, the differences in lysine c o n t e n t in 100 g whole feed should be more distinct than in 100 g pure protein. Drying at low temperatures did n o t seem to lower lysine availability. The biological value of mixture proteins was slightly higher than t h a t of cereals and of leaf protein alone (Table III). This t e n d e n c y could be the result of their higher lysine content. The positive effect of supplementary amino acids in cereals and leaf extracts was suggested by Woodham (1971) and experimentally determined by Kawatra et al. (1974). This effect is probably limited by low methionine c o n t e n t in both proteins. Another reason for the higher biological value o f mixed proteins could be their higher contents o f carotene, a provitamin which can influence protein metabolism. As was stated by Singh (1971, unpublished), carotene contained in leaf protein concentrates was well utilized by rats and caused better animal body weight gain than carotene in its synthetic form. On the other hand, in our experiments t h e diets were supplemented with vitamin A (in the vitamin mixture) and it cannot be stated categorically t h a t relatively small amounts o f carotene contained in the mixtures could increase their nutritive value. The addition of coagulum seemed to reduce protein digestibility. The decreased digestibility had a detrimental effect on the final results of the experiments, i.e. net protein utilization. This was most evident in the case of wheat bran. In all cases, mixtures with dried leaf protein were better than those with wet coagulum. Generally speaking, better results were obtained when mixing leaf protein with barley than with wheat. These differences cannot be explained on the basis of differences in amino acid composition or in carotene contents. They m a y be one of the reasons w h y we obtained better results from giving leaf protein to pigs (Glaps and Korniewicz, 1975} fed on barley-based diets than in the case of chicks (Hanczakowski et al., 1976) which were fed on other cereals, mostly wheat or maize. CONCLUSIONS
The results presented above suggest t h a t leaf protein concentrates from lucerne m a y be a good supplement for cereals, especially for barley. It seems t h a t mixing cereals with dry leaf protein is better than drying wet coagulum together with cereals.
96 REFERENCES Arckoll, D.B., 1973. The preservation and storage of leaf protein preparations. J. Sci. F o o d Agric., 24: 437--445. Carpenter, K.J., 1960. The estimation of the available lysine in animal protein foods. Biochem. J., 77: 604--610. Eggum, B.O., 1973. A study of certain factors influencing protein utilization in rats and pigs. Beret. Forsoegs-lab., K~benhavn, No. 406. F o o t , A.S., 1974. Lucerne juice for pigs. Pig Farming, 22 (9): 71. Ford, J.E., 1964. A microbiological method of assessing the nutritive value of proteins. Br. J. Nutr., 18: 449--460. Glaps, J. and Korniewicz, A., 1975. Zastosowanie koncentratow bialkowych z soku roslin zielonych w tuczu trzody chlewnej. Rocz. Nauk, Zootech., 2: 221--239. Gstirner, F., 1965. Chemisch-physykalische Vitaminbestimungsmethoden. F. Enke Verl., Stuttgart, p. 45. Hanczakowski, P., Rys, R. and Barabasz, J., 1976. Zastosowanie koncentratow z lucerny w zywieniu kurczat. Acta Agrar. Silvestria Ser. Zootech., 16: 21--32. Kawatra, B.L., Garcha, J.S. and Wagle, D.S., 1974. Effect of supplementation of leaf protein extracted from berseem (Trifolium alexandrinum) to wheat flour diet. J. F o o d Sci. Technol., 11: 241--242. Nehring, K. and Haesler, E., 1954. Untersuchungen uber die Biologische Wertigkeit yon Eiweissfutterstoffen. Arch, Tierern~ihr., 5: 110--126. Pirie, N.W., 1966. Leaf protein as a human food. Science, 152: 1701--1705. Rys, R., Krasnodebska, I. and Ernest, T., 1967. Oznaczanie lizyny przyswajalnej przy p o m o c y elektroforezy wysokonapieciowej. Rocz. Nauk Roln., 90-B-2: 237--243. Singh, N., (unpublished), Cit.: Pirie, A., 1971. Carotene content of leaf protein preparations and their use as sources of vitamin A. In: N.W. Pirie, (Editor), Leaf Protein: Its Agronomy, Preparation, Quality and Use. Blackwell, Oxford, Edinburgh, pp. 138 142. Skulmowski, J., 1974. Metody okreslania Skladu Pasz i Ich Jakosci. PWRiL, Warszawa, 184 pp. Spackmann, D.H., 1963. Accelerated system for the automatic analysis of amino acids. Fed. Proc., 22: 244. Woodham, A.A., 1971. The use of animal tests for the evaluation of leaf protein concentrates. In: N.W. Pirie (Editor), Leaf Protein: Its Agronomy, Preparation, Quality and Use. Blackwell, Oxford, Edinburgh, pp. 115--130.
91
© Elsevier Scientific Publishing Company, Amsterdam -- Printed in The Netherlands
NUTRITIVE VALUE OF LEAF PROTEIN COAGULUM AND CEREALS MIXTURES
PIOTR HANCZAKOWSKI and MICHAL PETZEL 1 Institute o f Animal Production, Department o f Animal Nutrition, 32-083 Baliee (Poland) 1 Central Laboratory o f Agricultural Industry, Chmielna 2, 20-079 Lublin (Poland)
(First received 29 December 1978; accepted for publication 11 June 1979)
ABSTRACT Hanezakowski, P. and Petzel, M., 1979. Nutritive value of leaf protein coagulum and cereals mixtures. Anita. Feed Sc£ Technol., 4: 91--96. Experiments were performed to compare the composition and nutritive value of mixtures containing leaf protein coagulum from lucerne with cereals (ground barley, ground wheat and wheat bran), with non-processed cereals alone or with the addition of separately-dried leaf protein. The chemical composition of mixtures and amino acid composition of their proteins were determined by conventional methods. The biological value and true digestibility of cereals and mixture proteins were determined on rats by the Thomas-Mitchell balance method. The biological values of mixture proteins were higher, but their digestibility was lower, than those of cereals alone. Generally, better results were obtained when cereals were mixed with separately-dried leaf protein and with barley rather than wheat.
INTRODUCTION Leaf protein may become a valuable source of protein for non-ruminants a f t e r s e p a r a t i n g it f r o m excess o f fibre. T h e p r o c e s s o f e x t r a c t i n g p r o t e i n f r o m f o r a g e was d e s c r i b e d b y Pirie ( 1 9 6 6 ) . T h e p r o c e d u r e involves t h e ext r a c t i o n o f juice f r o m p l a n t m a t e r i a l , h e a t c o a g u l a t i o n o f t h e juice p r o t e i n a n d s e p a r a t i o n a n d d r y i n g o f t h e l e a f - p r o t e i n curd. As t h e price o f e n e r g y c o n t i n u e s t o rise, d r y i n g b e c o m e s v e r y e x p e n s i v e . ~F u r t h e r m o r e , t h e r e is t h e p o s s i b i l i t y o f l e a f p r o t e i n o v e r h e a t i n g . T h e risk o f h e a t d a m a g e m a y b e dim i n i s h e d b y using a m i x t u r e o f w e t p r o t e i n c o a g u l u m w i t h g r o u n d grain, as p r o p o s e d b y F o o t ( 1 9 7 4 ) . S u c h m i x t u r e s c o u l d b e d r i e d at l o w t e m p e r a t u r e s a n d s t o r e d s a t i s f a c t o r i l y as l o n g as t h e i r h u m i d i t y did n o t e x c e e d 16%. T h e p r o d u c t i o n o f l e a f p r o t e i n a n d cereals m i x t u r e s m a y b e n u t r i t i o n a l l y a d v a n t a g e o u s . B e c a u s e o f its high lysine c o n t e n t , l e a f p r o t e i n is a g o o d supp l e m e n t f o r cereals w h i c h are p o o r in this a m i n o acid. T h e s e e x p e r i m e n t s w e r e u n d e r t a k e n t o e x a m i n e t h e n u t r i t i v e value o f m i x t u r e s c o n t a i n i n g l e a f p r o t e i n c o a g u l u m dried w i t h cereals a n d t o c o m p a r e t h e m w i t h n o n - p r o c e s -
92
sed cereals given alone or with separately dried leaf protein coagulum. M A T E R I A L AND METHODS
Mixtures were made with barley, wheat and wheat bran ground to 1--2 mm in size, and leaf protein coagulum from lucerne. Lucerne was cut in September (the third growth), ground in a universal mill (RU Bak) and the juice extracted in a screw press (Bentall). The juice was heated b y steam injection to 80°C and the precipitated curd was filtered through a nylon filter. The dry matter of the resulting leaf protein coagulum was a b o u t 20%. Coagulum was divided into t w o parts. One part was mixed with cereals at 1:1.5 w / w ratio, while the second part was air-dried at temperatures lower than 50 ° C. The leaf protein and cereals mixtures were dried b y means of a pneumatic conveyor at 40 ° C. Control mixtures of cereals and separately dried leaf protein were prepared. Each of their components supplied these mixtures with the same a m o u n t of protein as in the corresponding cereals/wet coagulum mixtures. The gross composition of cereals and mixtures was determined b y standard methods (Skulmowski, 1974). Amino acid analyses were performed b y the m e t h o d of Spackmann (1963) with the Carlo Erba amino acid analyser. The lysine availability was estimated b y Carpenter's m e t h o d (1960) modified with high voltage electrophoresis (Rys et al., 1967). Methionine (total and available) was determined microbiologically {Ford, 1964) and carotene according to Gstirner (1965). The biological value and true digestibility of proteins were determined by the Thomas--Mitchell balance method. Eight male albino rats, each weighing TABLE I
The chemical composition (%) of cereals and their mixtures with leaf protein coagulum Specification
Dry matter
Crude protein
Ether extract
Fibre
Ash
N-free extractives
Ground wheat Ground wheat mixed with wet LP coagulum Wheat bran Wheat bran mixed with wet LP coagulum Ground barley Ground barley mixed with wet LP coagulum Dried LP coagulum
88.7
11.2
2.0
0.9
1.8
72.8
1.6
92.0 91.4
14.3 15.1
2.4 3,7
0.8 5.3
2.3 3.4
72.2 63.9
52.8 1.7
92.4 91.0
19.8 11.9
3.8 2.6
5.0 3.9
3.4 2.1
60.4 70.5
66.0 0.7
91.6 93.7
14.2 43.5
3.4 9.2
3.9 1.0
3.2 4.1
66.9 35.9
54.3 520.5
Carotene (mg/kg)
a = Available.
His Arg Asp Thre Ser Glu Pro Gly Ala Val Ileu Leu Tyr Phe Lys Lys a Met Met a
Amino acid
2.2 4.6 4.8 2.9 4.9 33.8 9.1 4.4 3.8 4.6 3.2 6.6 2.9 4.6 2.7 2.5 2.0 1.6
Ground wheat
2.2 5.0 5.8 2.9 4.3 27.4 8.0 4.4 3.8 4.5 3.2 6.4 2.8 4.4 3.2 2.8 1.9 1.4
Ground wheat mixed with wet LP coagulum 2.7 5.7 5.7 2.5 2.8 23.0 8.2 4.4 3.1 4.7 3.3 6.1 2.4 4.1 3.7 3.4 2.1 1.5
Wheat bran
2.8 5.4 7.4 3.2 3,0 19.4 7.7 4.0 5.0 5.0 3.9 6.9 2.5 4.8 4.2 3.8 1.9 1.2
Wheat bran mixed with wet LP coagulum 2.3 4.2 5.8 2.7 2.5 25.0 12.9 3.8 4.0 4.7 3.6 6.6 1.9 5.4 3.3 3.0 2.0 1.3
Ground barley
2.3 4.4 6.8 3.2 2.8 20.2 10.0 3.5 4.9 5.3 3.9 6.8 2.1 5.2 3.8 3.5 2.0 1.2
2.8 4.9 9.3 3.8 2.8 10.3 5.O 5.2 5.7 5.7 4.9 7.6 3.7 6.1 5.1 4.7 1.9 1.1
Ground barley m i x e d Dried with wet LP coagulum coagulum
Amino acid composition o f cereals and their mixtures with wet leaf protein coagulum (g per 16 g N)
TABLE II
05
94 TABLE III Nutritive value of proteins of cereals and their mixtures with leaf protein coagulum Specification
Biological value (% +_SE)
True digestibility (% +- SE)
Net protein lization*
Ground wheat Ground wheat mixed with wet LP coagulum Ground wheat mixed with dried LP coagulum Wheat bran Wheat bran mixed with wet LP coagulum Wheat bran mixed with dried LP coagulum Ground barley Ground barley mixed with wet LP coagulum Ground barley mixed with dried LP coagulum Dried LP coagulum
57 + 1.7
89 -+ 1.1
51
58 -+ 1.8
87 -+ 1.1
51
60 + 2.1 61 + 1.7
88 + 1.2 92 + 0.9
53 56
62 + 2.1
84 + 1.3
52
65 + 1.6 62 + 1.9
85 +- 1.2 86 -+ 0.9
55 53
66 + 2.1
85 +- 1.0
56
68 -+ 1.8 56 -+ 2.9
85 + 1.4 80 -+ 1.8
58 49
* N P u = B V x TD 100 a b o u t 80 g, were used in o n e e x p e r i m e n t a l g r o u p . T h e a d a p t a t i o n p e r i o d lasted 5 d a y s a n d t h e balance p e r i o d 6 days ( N e h r i n g a n d Haesler, 1 9 5 4 ) . E a c h rat received 1 5 0 m g N a n d 10 g d r y m a t t e r per d a y t h r o u g h o u t t h e t w o periods. T h e e x p e r i m e n t a l feeds were t h e o n l y s o u r c e o f p r o t e i n in t h e diet. Diets also c o n t a i n e d : s o y a b e a n oil (6%), m i n e r a l m i x t u r e (4%) a n d v i t a m i n m i x t u r e (2%), t h e c o m p o s i t i o n o f b o t h m i x t u r e s b e i n g a c c o r d i n g t o E g g u m ( 1 9 7 3 ) . In o r d e r t o c o m p l e t e t h e diet c o m p o s i t i o n , w h e a t starch was a d d e d . Diet No. 10, b a s e d o n dried leaf p r o t e i n c o a g u l u m , was s u p p l e m e n t e d w i t h sucrose (10%) a n d ceUulose (4%). /J
RESULTS AND DISCUSSION T h e m i x t u r e s h a d a m o i s t u r e c o n t e n t o f less t h a n 10% a n d were s t o r e d satisfactorily u n d e r n o r m a l c o n d i t i o n s f o r a b o u t o n e year. T h e leaf p r o t e i n c o a g u l u m p r o v i d e d f r o m 16% o f t h e t o t a l p r o t e i n in its m i x t u r e w i t h barley, t o n e a r l y 24% in t h e w h e a t b r a n p r e p a r a t i o n . These l o w values o f leaf p r o t e i n were d u e t o t h e l o w d r y m a t t e r c o n t e n t o f fresh c o a g u l u m . I t is possible t o increase this c o n t e n t b y a d d i t i o n a l pressing o f c o a g u l u m . H o w e v e r , this w o u l d c o m p l i c a t e t h e process a n d m a k e it m o r e expensive. T h e a d d i t i o n o f c o a g u l u m caused a small increase in t h e e t h e r e x t r a c t and ash c o n t e n t s o f t h e m i x t u r e s (Table I) as a result o f t h e i r high c o n t e n t s in t h e leaf p r o t e i n p r e p a r a t i o n . T h e c a r o t e n e c o n t e n t o f t h e m i x t u r e s was m u c h
95 :L i : :
-
higher than of cereals alone. The leaf protein concentrates, especially from lucerne and grasses, are k n o w n as good sources of this provitamin (Arckoll, 1973). There were no significant differences in amino acid composition between cereals and their mixtures with leaf protein coagulum (Table II). All preparations were poor in methionine, especially in its availability. In all mixtures, the lysine c o n t e n t was higher than in cereals alone. Because of the higher protein c o n t e n t in the mixtures, the differences in lysine c o n t e n t in 100 g whole feed should be more distinct than in 100 g pure protein. Drying at low temperatures did n o t seem to lower lysine availability. The biological value of mixture proteins was slightly higher than t h a t of cereals and of leaf protein alone (Table III). This t e n d e n c y could be the result of their higher lysine content. The positive effect of supplementary amino acids in cereals and leaf extracts was suggested by Woodham (1971) and experimentally determined by Kawatra et al. (1974). This effect is probably limited by low methionine c o n t e n t in both proteins. Another reason for the higher biological value o f mixed proteins could be their higher contents o f carotene, a provitamin which can influence protein metabolism. As was stated by Singh (1971, unpublished), carotene contained in leaf protein concentrates was well utilized by rats and caused better animal body weight gain than carotene in its synthetic form. On the other hand, in our experiments t h e diets were supplemented with vitamin A (in the vitamin mixture) and it cannot be stated categorically t h a t relatively small amounts o f carotene contained in the mixtures could increase their nutritive value. The addition of coagulum seemed to reduce protein digestibility. The decreased digestibility had a detrimental effect on the final results of the experiments, i.e. net protein utilization. This was most evident in the case of wheat bran. In all cases, mixtures with dried leaf protein were better than those with wet coagulum. Generally speaking, better results were obtained when mixing leaf protein with barley than with wheat. These differences cannot be explained on the basis of differences in amino acid composition or in carotene contents. They m a y be one of the reasons w h y we obtained better results from giving leaf protein to pigs (Glaps and Korniewicz, 1975} fed on barley-based diets than in the case of chicks (Hanczakowski et al., 1976) which were fed on other cereals, mostly wheat or maize. CONCLUSIONS
The results presented above suggest t h a t leaf protein concentrates from lucerne m a y be a good supplement for cereals, especially for barley. It seems t h a t mixing cereals with dry leaf protein is better than drying wet coagulum together with cereals.
96 REFERENCES Arckoll, D.B., 1973. The preservation and storage of leaf protein preparations. J. Sci. F o o d Agric., 24: 437--445. Carpenter, K.J., 1960. The estimation of the available lysine in animal protein foods. Biochem. J., 77: 604--610. Eggum, B.O., 1973. A study of certain factors influencing protein utilization in rats and pigs. Beret. Forsoegs-lab., K~benhavn, No. 406. F o o t , A.S., 1974. Lucerne juice for pigs. Pig Farming, 22 (9): 71. Ford, J.E., 1964. A microbiological method of assessing the nutritive value of proteins. Br. J. Nutr., 18: 449--460. Glaps, J. and Korniewicz, A., 1975. Zastosowanie koncentratow bialkowych z soku roslin zielonych w tuczu trzody chlewnej. Rocz. Nauk, Zootech., 2: 221--239. Gstirner, F., 1965. Chemisch-physykalische Vitaminbestimungsmethoden. F. Enke Verl., Stuttgart, p. 45. Hanczakowski, P., Rys, R. and Barabasz, J., 1976. Zastosowanie koncentratow z lucerny w zywieniu kurczat. Acta Agrar. Silvestria Ser. Zootech., 16: 21--32. Kawatra, B.L., Garcha, J.S. and Wagle, D.S., 1974. Effect of supplementation of leaf protein extracted from berseem (Trifolium alexandrinum) to wheat flour diet. J. F o o d Sci. Technol., 11: 241--242. Nehring, K. and Haesler, E., 1954. Untersuchungen uber die Biologische Wertigkeit yon Eiweissfutterstoffen. Arch, Tierern~ihr., 5: 110--126. Pirie, N.W., 1966. Leaf protein as a human food. Science, 152: 1701--1705. Rys, R., Krasnodebska, I. and Ernest, T., 1967. Oznaczanie lizyny przyswajalnej przy p o m o c y elektroforezy wysokonapieciowej. Rocz. Nauk Roln., 90-B-2: 237--243. Singh, N., (unpublished), Cit.: Pirie, A., 1971. Carotene content of leaf protein preparations and their use as sources of vitamin A. In: N.W. Pirie, (Editor), Leaf Protein: Its Agronomy, Preparation, Quality and Use. Blackwell, Oxford, Edinburgh, pp. 138 142. Skulmowski, J., 1974. Metody okreslania Skladu Pasz i Ich Jakosci. PWRiL, Warszawa, 184 pp. Spackmann, D.H., 1963. Accelerated system for the automatic analysis of amino acids. Fed. Proc., 22: 244. Woodham, A.A., 1971. The use of animal tests for the evaluation of leaf protein concentrates. In: N.W. Pirie (Editor), Leaf Protein: Its Agronomy, Preparation, Quality and Use. Blackwell, Oxford, Edinburgh, pp. 115--130.