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Methods of improving the utilization of cereal straw by ruminants. III. A note on the effect of ensiling straw treated with urea
Animal Feed Science and Technology, 9 (1983) 181--183 Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands
181
METHODS OF IMPROVING THE UTILIZATION OF CEREAL STRAW B Y R U M I N A N T S . III. A N O T E O N T H E E F F E C T O F E N S I L I N G S T R A W TREATED WITH UREA
P.B.A. MBATYA* R o w e t t Research Institute, Bucksburn, Aberdeen AB2 9SB (Gt. Britain)
(Received 30 September 1982; accepted for publication 30 March 1983)
ABSTRACT Mbatya, P.B.A., 1983. Methods of improving the utilization of cereal straw by ruminants. III. A note on the effect of ensiling straw treated with urea. Anita. Feed Sci. Technol., 9: 181--183. Straw treated with urea was offered to lambs either freshly prepared (EN0) or after ensiling with urea for 30 days (EN3.~). The lambs also received l0 g dry matter (DM) of shredded, artificially dried grass per day per kg of metabolic liveweight. Ensiling straw significantly increased its intake from 32 to 41 g DM per day per kg of metabolic liveweight, and its DM digestibility from 375 to 450 g per kg.
INTRODUCTION AND OBJECTIVES U r e a is n u t r i t i o n a l l y v a l u e l e s s t o t h e h o s t ( M c D o n a l d , 1 9 5 2 ) , b u t serves as a s u b s t r a t e f o r t h e e n z y m e u r e a s e r e s u l t i n g in e v o l u t i o n o f a m m o n i a in t h e r u m e n , a n d as a s o u r c e o f n i t r o g e n f o r o p t i m i s a t i o n o f m i c r o b i a l f l o r a g r o w t h in t h e d i g e s t i v e t r a c t . U r e a is also h y d r o l y s e d to a m m o n i a b y u r e o l y t i c b a c t e r i a in s t r a w . H o r t o n a n d S t e a c y ( 1 9 7 9 ) , a m o n g o t h e r s , h a v e s h o w n t h a t t r e a t i n g s t r a w w i t h a m m o n i a i n c r e a s e s its i n t a k e a n d digesti b i l i t y . It was a n t i c i p a t e d t h a t if u r e a - t r e a t e d s t r a w was e n s i l e d in c l o s e d c o n tainers, the liberated a m m o n i a could react with the straw and thus increase its i n t a k e a n d d i g e s t i b i l i t y . W i t h this in m i n d , a trial was d e s i g n e d t o investigate t h e e f f e c t o f e n s i l i n g u r e a - t r e a t e d s t r a w . EXPERIMENTAL S p r i n g b a r l e y s t r a w (cv. ' G o l d e n P r o m i s e ' ) ( T a b l e I) was t r e a t e d w i t h u r e a 30 d a y s o r I d a y b e f o r e t h e e x p e r i m e n t s t a r t e d ( t r e a t m e n t s EN30, a n d E N 0 , r e s p e c t i v e l y ) . E i g h t l a m b s ( 3 4 . 9 ± 2 . 9 8 kg) w e r e d i v i d e d i n t o t w o *Present address: University of the West Indies, Department of Livestock Science, St. Augustine, Trinidad.
0377-8401/83/$03.00
~) 1983 Elsevier Science Publishers B.V.
182 TABLE I Diet ingredients and composition Ingredient
(%)
(kg)
Straw Urea Water Composition {g/kg DM) Crude protein Ash
100.00 1.00 25.00
79.4 0.8 19.8
7.30 3.81
g r o u p s a c c o r d i n g to liveweight, and a l l o c a t e d to t h e t w o s t r a w diets. S t r a w a n d w a t e r w e r e o f f e r e d ad l i b i t u m . All the l a m b s were s u p p l e m e n t e d with 10 g D M / h e a d / d a y p e r u n i t m e t a b o l i c liveweight (kgW °.~s) o f s h r e d d e d , artifically dried ryegrass ( 1 5 0 g C P / k g DM). T h e l a m b s were p e n n e d individually d u r i n g the 1 0 - d a y p r e l i m i n a r y p e r i o d , a n d t h e n in m e t a b o l i s m cages. F e e d i n t a k e a n d faecal o u t p u t w e r e r e c o r d e d for 7 days. RESULTS T h e l a m b s w e r e h e a l t h y a n d h a d g o o d a p p e t i t e s . T h e ensiled s t r a w s t o r e d v e r y well (i.e. t h e r e was n o m o u l d growth}. T h e r e was o n l y a f a i n t smell o f a m m o n i a f r o m the straw. T h e ensiled s t r a w (EN3o) h a d a s o f t e r consistency t h a n t h e freshly p r e p a r e d s t r a w (EN0). L a m b s o n t h e EN0 s t r a w d i e t s e l e c t e d against t h e s t r a w stalks, b u t t h o s e o n diet EN30 did n o t . Ensiling i n c r e a s e d t h e i n t a k e a n d digestibility o f the s t r a w significantly (Table II). TABLE II Dry matter intake and digestibility (means of four animals) Straw
Straw intake (g day-' ) (g/day/kgW °'Ts )
EN0 EN3o SED Significance
450 579 32.9 (P < 0.1 )
32 41 1.8 (P < 0.05)
Digestibility of DM (g kg-' ) 375 450 13.8 (P ~. 0.05)
SED = Standard error of difference. DISCUSSION A high c o n c e n t r a t i o n o f a m m o n i a is usually r e q u i r e d t o i m p r o v e t h e i n t a k e a n d digestibility o f cereal s t r a w ( H o r t o n a n d S t e a c y , 1 9 7 9 ; L a w l o r a n d O ' S h e a , 1 9 7 9 ; A b i d i n a n d K e m p t o n , 1 9 8 1 ; B o r h a m i a n d Sundst~l,
183 1 9 8 2 ) . In this e x p e r i m e n t t h e a m m o n i a l i b e r a t e d was barely d e t e c t a b l e . It is possible t h a t the r a t e o f u r e a a p p l i c a t i o n (Table I) was t o o l o w , b e c a u s e M b a t y a ( 1 9 8 0 ) d e t e c t e d m o r e a m m o n i a w h e n 2.3 kg u r e a was u s e d t o t r e a t 1 0 0 kg o f b a r l e y straw. I t is, t h e r e f o r e , u n l i k e l y t h a t a m m o n i a was r e s p o n sible f o r t h e significant increase in t h e DM i n t a k e a n d DM digestibility o f straw. I t is possible, h o w e v e r , t h a t t h e ensfled s t r a w m i g h t h a v e b e e n p r e d i g e s t e d ( d u r i n g ensilage) b y bacteria, o r it m i g h t h a v e u n d e r g o n e a s t r u c t u r a l change. Since EN30 was ensiled in closed c o n t a i n e r s , t h e w a t e r m i g h t h a v e c a u s e d t h e p l a n t cell walls t o swell, in a m a n n e r similar t o t h a t demonstrated by Watson (1941) after treating straw with 1.5%.caustic s o l u t i o n f o r 24 h, a n d b e c o m e m o r e p e n e t r a b l e t o cellulolytic m i c r o b e s a n d digestive juices in t h e a l i m e n t a r y t r u c t t h a n EN0" This is a likely p r o p o s i t i o n b e c a u s e o f t h e s o f t e r c o n s i s t a n c y o f EN30 which c o n t r i b u t e d t o t h e higher DM i n t a k e . CONCLUSION Ensiling u r e a - t r e a t e d s t r a w can be o f partical significance as t h e s t r a w can be ensiled in t h e s u m m e r f o r w i n t e r f e e d i n g in t e m p e r a t e c o u n t r i e s or d u r i n g the d r y season in t r o p i c a l c o u n t r i e s . This w o u l d increase t h e utilization of poor-quality roughages and improve the body condition o f r u m i n a n t s which t e n d s to d e t e r i o r a t e in w i n t e r and d r y seasons. M o r e r e s e a r c h is, h o w e v e r , r e q u i r e d in this area. ACKNOWLEDGEMENT Special t h a n k s to m e m b e r s o f t h e R o w e t t R e s e a r c h I n s t i t u t e especially Mr. R.I. S m a r t , P e t e r D e w e y and all the s t o c k m e n , a n d Mrs. A. M o r l a n d a n d Mrs. M. R o s e f o r t y p i n g this p a p e r .
REFERENCES Abidin, Z. and Kempton, T.J., 1981. Effects of treatment of barley straw with anhydrous ammonia and supplementation with heat-treated protein meals on feed intake and liveweight performance of growing lambs. Anim. Feed Sci. Teehnol., 6: 145--155. Borhami. B.E.A. and Sundst61, F., 1982. Studies on ammonia-treated straw. I. The effect of type and level of ammonia, moisture content and treatment time on the digestibility in vitro and ezyme soluble organic matter of oat straw. Anim. Feed Sci. Technol., 7: 45--51. Horton, G.M.J. and Steacy, G.M., 1979. Effect of anhydrous ammonia treatment on the intake and digestibility of cereal straws by steers. J. Anim. Sci., 48: 1239--1249. Lawlor, M.J. and O'Shea, J., 1979 The effect of ammoniation on the intake and nutritive value of straw. Anita. Feed Sci. Technol., 4: 169--175. •Mbatya, P.B.A., 1980. High quality forage as a supplement to ruminants offered barley straw. Ph.D. Thesis, University of Aberdeen. McDonald, I.W. 1952. The role of ammonia in ruminal digestion of protein. Biochem. J., 51: 86--90. Watson, S.J., 1941. Increasing the feeding value of cereal straws. J.R. Agrie. Soc., 101: 37--43.
181
METHODS OF IMPROVING THE UTILIZATION OF CEREAL STRAW B Y R U M I N A N T S . III. A N O T E O N T H E E F F E C T O F E N S I L I N G S T R A W TREATED WITH UREA
P.B.A. MBATYA* R o w e t t Research Institute, Bucksburn, Aberdeen AB2 9SB (Gt. Britain)
(Received 30 September 1982; accepted for publication 30 March 1983)
ABSTRACT Mbatya, P.B.A., 1983. Methods of improving the utilization of cereal straw by ruminants. III. A note on the effect of ensiling straw treated with urea. Anita. Feed Sci. Technol., 9: 181--183. Straw treated with urea was offered to lambs either freshly prepared (EN0) or after ensiling with urea for 30 days (EN3.~). The lambs also received l0 g dry matter (DM) of shredded, artificially dried grass per day per kg of metabolic liveweight. Ensiling straw significantly increased its intake from 32 to 41 g DM per day per kg of metabolic liveweight, and its DM digestibility from 375 to 450 g per kg.
INTRODUCTION AND OBJECTIVES U r e a is n u t r i t i o n a l l y v a l u e l e s s t o t h e h o s t ( M c D o n a l d , 1 9 5 2 ) , b u t serves as a s u b s t r a t e f o r t h e e n z y m e u r e a s e r e s u l t i n g in e v o l u t i o n o f a m m o n i a in t h e r u m e n , a n d as a s o u r c e o f n i t r o g e n f o r o p t i m i s a t i o n o f m i c r o b i a l f l o r a g r o w t h in t h e d i g e s t i v e t r a c t . U r e a is also h y d r o l y s e d to a m m o n i a b y u r e o l y t i c b a c t e r i a in s t r a w . H o r t o n a n d S t e a c y ( 1 9 7 9 ) , a m o n g o t h e r s , h a v e s h o w n t h a t t r e a t i n g s t r a w w i t h a m m o n i a i n c r e a s e s its i n t a k e a n d digesti b i l i t y . It was a n t i c i p a t e d t h a t if u r e a - t r e a t e d s t r a w was e n s i l e d in c l o s e d c o n tainers, the liberated a m m o n i a could react with the straw and thus increase its i n t a k e a n d d i g e s t i b i l i t y . W i t h this in m i n d , a trial was d e s i g n e d t o investigate t h e e f f e c t o f e n s i l i n g u r e a - t r e a t e d s t r a w . EXPERIMENTAL S p r i n g b a r l e y s t r a w (cv. ' G o l d e n P r o m i s e ' ) ( T a b l e I) was t r e a t e d w i t h u r e a 30 d a y s o r I d a y b e f o r e t h e e x p e r i m e n t s t a r t e d ( t r e a t m e n t s EN30, a n d E N 0 , r e s p e c t i v e l y ) . E i g h t l a m b s ( 3 4 . 9 ± 2 . 9 8 kg) w e r e d i v i d e d i n t o t w o *Present address: University of the West Indies, Department of Livestock Science, St. Augustine, Trinidad.
0377-8401/83/$03.00
~) 1983 Elsevier Science Publishers B.V.
182 TABLE I Diet ingredients and composition Ingredient
(%)
(kg)
Straw Urea Water Composition {g/kg DM) Crude protein Ash
100.00 1.00 25.00
79.4 0.8 19.8
7.30 3.81
g r o u p s a c c o r d i n g to liveweight, and a l l o c a t e d to t h e t w o s t r a w diets. S t r a w a n d w a t e r w e r e o f f e r e d ad l i b i t u m . All the l a m b s were s u p p l e m e n t e d with 10 g D M / h e a d / d a y p e r u n i t m e t a b o l i c liveweight (kgW °.~s) o f s h r e d d e d , artifically dried ryegrass ( 1 5 0 g C P / k g DM). T h e l a m b s were p e n n e d individually d u r i n g the 1 0 - d a y p r e l i m i n a r y p e r i o d , a n d t h e n in m e t a b o l i s m cages. F e e d i n t a k e a n d faecal o u t p u t w e r e r e c o r d e d for 7 days. RESULTS T h e l a m b s w e r e h e a l t h y a n d h a d g o o d a p p e t i t e s . T h e ensiled s t r a w s t o r e d v e r y well (i.e. t h e r e was n o m o u l d growth}. T h e r e was o n l y a f a i n t smell o f a m m o n i a f r o m the straw. T h e ensiled s t r a w (EN3o) h a d a s o f t e r consistency t h a n t h e freshly p r e p a r e d s t r a w (EN0). L a m b s o n t h e EN0 s t r a w d i e t s e l e c t e d against t h e s t r a w stalks, b u t t h o s e o n diet EN30 did n o t . Ensiling i n c r e a s e d t h e i n t a k e a n d digestibility o f the s t r a w significantly (Table II). TABLE II Dry matter intake and digestibility (means of four animals) Straw
Straw intake (g day-' ) (g/day/kgW °'Ts )
EN0 EN3o SED Significance
450 579 32.9 (P < 0.1 )
32 41 1.8 (P < 0.05)
Digestibility of DM (g kg-' ) 375 450 13.8 (P ~. 0.05)
SED = Standard error of difference. DISCUSSION A high c o n c e n t r a t i o n o f a m m o n i a is usually r e q u i r e d t o i m p r o v e t h e i n t a k e a n d digestibility o f cereal s t r a w ( H o r t o n a n d S t e a c y , 1 9 7 9 ; L a w l o r a n d O ' S h e a , 1 9 7 9 ; A b i d i n a n d K e m p t o n , 1 9 8 1 ; B o r h a m i a n d Sundst~l,
183 1 9 8 2 ) . In this e x p e r i m e n t t h e a m m o n i a l i b e r a t e d was barely d e t e c t a b l e . It is possible t h a t the r a t e o f u r e a a p p l i c a t i o n (Table I) was t o o l o w , b e c a u s e M b a t y a ( 1 9 8 0 ) d e t e c t e d m o r e a m m o n i a w h e n 2.3 kg u r e a was u s e d t o t r e a t 1 0 0 kg o f b a r l e y straw. I t is, t h e r e f o r e , u n l i k e l y t h a t a m m o n i a was r e s p o n sible f o r t h e significant increase in t h e DM i n t a k e a n d DM digestibility o f straw. I t is possible, h o w e v e r , t h a t t h e ensfled s t r a w m i g h t h a v e b e e n p r e d i g e s t e d ( d u r i n g ensilage) b y bacteria, o r it m i g h t h a v e u n d e r g o n e a s t r u c t u r a l change. Since EN30 was ensiled in closed c o n t a i n e r s , t h e w a t e r m i g h t h a v e c a u s e d t h e p l a n t cell walls t o swell, in a m a n n e r similar t o t h a t demonstrated by Watson (1941) after treating straw with 1.5%.caustic s o l u t i o n f o r 24 h, a n d b e c o m e m o r e p e n e t r a b l e t o cellulolytic m i c r o b e s a n d digestive juices in t h e a l i m e n t a r y t r u c t t h a n EN0" This is a likely p r o p o s i t i o n b e c a u s e o f t h e s o f t e r c o n s i s t a n c y o f EN30 which c o n t r i b u t e d t o t h e higher DM i n t a k e . CONCLUSION Ensiling u r e a - t r e a t e d s t r a w can be o f partical significance as t h e s t r a w can be ensiled in t h e s u m m e r f o r w i n t e r f e e d i n g in t e m p e r a t e c o u n t r i e s or d u r i n g the d r y season in t r o p i c a l c o u n t r i e s . This w o u l d increase t h e utilization of poor-quality roughages and improve the body condition o f r u m i n a n t s which t e n d s to d e t e r i o r a t e in w i n t e r and d r y seasons. M o r e r e s e a r c h is, h o w e v e r , r e q u i r e d in this area. ACKNOWLEDGEMENT Special t h a n k s to m e m b e r s o f t h e R o w e t t R e s e a r c h I n s t i t u t e especially Mr. R.I. S m a r t , P e t e r D e w e y and all the s t o c k m e n , a n d Mrs. A. M o r l a n d a n d Mrs. M. R o s e f o r t y p i n g this p a p e r .
REFERENCES Abidin, Z. and Kempton, T.J., 1981. Effects of treatment of barley straw with anhydrous ammonia and supplementation with heat-treated protein meals on feed intake and liveweight performance of growing lambs. Anim. Feed Sci. Teehnol., 6: 145--155. Borhami. B.E.A. and Sundst61, F., 1982. Studies on ammonia-treated straw. I. The effect of type and level of ammonia, moisture content and treatment time on the digestibility in vitro and ezyme soluble organic matter of oat straw. Anim. Feed Sci. Technol., 7: 45--51. Horton, G.M.J. and Steacy, G.M., 1979. Effect of anhydrous ammonia treatment on the intake and digestibility of cereal straws by steers. J. Anim. Sci., 48: 1239--1249. Lawlor, M.J. and O'Shea, J., 1979 The effect of ammoniation on the intake and nutritive value of straw. Anita. Feed Sci. Technol., 4: 169--175. •Mbatya, P.B.A., 1980. High quality forage as a supplement to ruminants offered barley straw. Ph.D. Thesis, University of Aberdeen. McDonald, I.W. 1952. The role of ammonia in ruminal digestion of protein. Biochem. J., 51: 86--90. Watson, S.J., 1941. Increasing the feeding value of cereal straws. J.R. Agrie. Soc., 101: 37--43.