legume forage

Small Ruminant Research ELSEVIER

Small Ruminant Research 13 (1994) 243-249

Growth of male WAD sheep fed cassava waste or dried sorghum brewer' s grains as supplements to tropical grass/legume forage J.A. Adeneye*, E.M. Sunmonu Department of Animal Science, University of lbadan, lbadan, Nigeria

( Accepted 23 August 1993)

Abstract Eighteen 4-5-month-old individually penned West African Dwarf (WAD) rams (mean weight 14 kg) were offered one of three rations for 112 d to determine growth rate on a supplemented Panicum/Centrosema (6 : 1) forage ad libitum and forage/ concentrate ratio of 56:44. Grass and legume contained 11.9 and 23.3% CP and 31.7 and 31.2% crude fibre, respectively. Supplements fed at 2%/BW contained 97% cassava wastes (CW), 97% dried sorghum brewer's grains (DSBG) or 48.5% each of CW and DSBG, and 5.4, 33.2 and 18.1% CP, respectively. Digestibility and nitrogen balance of the rations were determined with three other rams in a 3 X 3 Latin square experiment. Intake and digestibility of DM and energy of the rations were similar. Nitrogen intake, N absorbed and urinary N loss increased directly with dietary DSBG levels (P < 0.01 ). High starch and fibre in CW, lowest N content and intake from 97% CW supplement were implicated in least N digestibility of the supplement. At low N intake, faecal N loss was greater than urinary N excretion, but with increased N, more N was lost in urine than faeces. All animals were in positive N balance. Average daily BWG ranged from 12 to 68 g. DSBG was a better supplement than CW but the mixed supplement was best for highest N retention, average BWG as well as feed, energy and protein conversion efficiencies. It is concluded that DSBG is an energy- and protein-rich feed for ruminants. Its inclusion at 48.5% level with 48.5% CW in a Panicum-Centrosema forage supplement promoted maximum daily gain among WAD rams, while 97% level of either feed in the supplement depressed growth. Key words: Sheep; Growth; Cassava waste; Sorghum brewer's grain

1. Introduction Supplementary concentrate feeding is a common strategy for increased supply of dietary protein for ruminants. Research efforts on the utilization of agroindustrial by-products as ingredients in concentrate diets have been intensified because these products are readily available and relatively cheap. Cassava wastes consist of peels, some pulp removed with the peels as well as the small, broken and rejected *Corresponding author, Elsevier Science B.V. SSDI0921-4488 (93)E0093-8

fibrous tubers. Their quality depends on cassava variety, method of peeling, amount of pulp and tubers, sand contamination and pre-feeding processing methods. In spite of their low crude protein, high fibre and hydrocyanic acid content, cassava peels have been fed to ruminants (Adebowale, 1981; Aregheore, 1982; Ifut, 1987). Their disposal increases otherwise environmental pollution and health hazards. Dried sorghum brewer's grains ( D S B G ) are made locally as follows. After soaking sorghum grains in water for a few minutes, the grains are spread on a platform for 3 - 4 d to germinate. They are then milled,

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J.A. Adeneye, E.M. Sunmonu /Small Ruminant Research 13 (1994) 243-249

mixed with water and the mixture boiled for 2 h in a large container, cooled and sieved. The residue is sundried and constitutes DSBG. The alcoholic liquid, 'burukutu', is popular since it is cheaper than other commercial alcoholic drinks. DSBG is available in limited quantity throughout the year and is relished by ruminants. Information on the utilization of DSBG in the literature is not available. Small ruminant production in tropical rural areas in Nigeria depends largely on the quantity and nutritive value of uncultivated and unsupplemented guinea grass ( Panicum maximum) and centro ( Centrosema pubescens) forages, available for free or zero-grazing. The objective of this experiment was to compare intake, digestibility, growth rate and N retention by sheep fed cassava wastes (CW) and DSBG as supplements to a Panicum-Centrosema basal forage.

2. Materials and m e t h o d s

Growth trial Eighteen West African Dwarf (WAD) rams, 4-5 months old and 14 kg mean body weight (BW) were dewormed and sprayed against ectoparasites 1 week before the trial commenced. They were divided into three groups of six animals each. All animals were individually fed a basal forage at 2.4% of BW and had free access to clean water and salt lick. Each group was randomly assigned to one of three supplements fed at 2% of BW. The forage and supplements were fed in separate feed troughs once daily at 08:00 h in a forage/ concentrate ratio of 56 : 44 for I 12 d. The forage consisted of 8-week-old regrowths of guinea grass (Panicum maximum) and centro (Centrosema pubescens) freshly harvested and chopped manually to 10-15 cm lengths, mixed in a ratio of 6:1 (Panicum/Centro) and fed ad libitum at 110% of the forage intake of the previous day. The supplements contained 97% CW, 97% DSBG and 48.5% each of CW and DSBG. Each supplement was fortified with 1% oystershell, 1% common salt and 1% mineral-vitamin mixture. Daily measurements were made of feeds offered, refusals and intakes. After 24 h feeding, 31 and 5% of the forage and supplement DM offered, respectively, were rejected. The initial and weekly BW of each animal taken before feeding and watering were recorded and con-

centrate diets adjusted according to animal BW in the preceeding week. Representative samples of fresh feeds and feed refusals were taken weekly and handled as described for fresh faeces.

Balance trial The digestibility and N balance of the rations fed at the same levels as in the growth trial were studied in a 3 x 3 Latin square design with three other rams that were placed in individual metabolism cages that had feeding, watering and separate total faecal and urine collection facilities. Each 28-d feeding period was preceded by a l-week adaptation period. During the last 7 d of each feeding period, feed intake and refusals, total faeces and urine voided by each animal were determined as described by Oyenuga ( 1961 ). Total fresh faeces of each animal were weighed and 10% representative samples taken daily for analysis. A sub-sample for DM determination was dried at 105110°C to constant weight in a forced draught oven. Subsamples for analysis of crude protein (CP), ether extract (EE), crude fibre (CF) and total ash by AOAC (1984) procedures were dried at 70°C for 3 d, milled in a Christy-Norris hammer mill fitted with a 2-mm sieve, the 7 d milled samples bulked together and stored in air-tight bottles until analysis. Gross energy in feed, feed refusals and faecal samples was evaluated in a Gallenkamp ballistic bomb calorimeter. Urine of each animal was collected daily in a small plastic bucket that contained 5 ml of 10% mercuric chloride solution to prevent N loss. Volume and weight of urine were determined and 10% of daily output taken and stored at - 5°C in a deep freezer. At the end of the collection period, the samples for each animal were bulked and stored in the freezer until analysis. N in representative bulked urine was determined by the micro-Kjeldahl method.

Statistical analysis Analysis of variance of the data was by the methods of Steel and Tome (1980). Differences between means were assessed by Duncan's (1955) multiple range test.

3. Results and discussion

Chemical composition of the grass and centro agreed with published values (Devendra and McLeroy, 1982)

J.A. Adeneye, E.M. Sunmonu/ Small Ruminant Research 13 (1994) 243-249

Grass contained twice as much CP and CF than CW and was of medium quality. Centro, a legume forage, contained twice the CP content of Panicum. DSBG was highest in CP content (34.1%) and ether extract (6.3%) but lowest in total ash which probably accounted for its highest gross energy content (Table 1 ). Its large-scale use for ruminant feeding is desirable since its 12.4% CF content might limit its wide use in poultry rations. While the total ash content of the feeds may partly be due to soil contamination during harvesting and sundrying, legumes are rich sources of minerals and this accounts for part of the high ash content of centro. The CP, EE, CF and total ash content of CW-DSBG supplement were 181.2, 39.4, 145.8 and 61.8 g kg ] DM, respectively. 3.1. Voluntary intake

The least total DM was consumed from the ration that contained 97% CW as supplement. The lower CP and energy, higher CF and residual HCN (not determined) content of CW might be responsible. CW contributed 527 g kg J total DM intake from the ration. This might have reduced the total DM intake. Adebowale ( 1981 ) and Van Eys et al. (1987) have found that optimum cassava level in small ruminant rations was 40% since higher levels reduced animal performance. Rams consumed 8.8 and 5.7% more DM from CWDSBG supplement and its total ration, respectively, compared with sole CW supplement due probably to additional protein supply from the DSBG component. In cattle, DM intake similarly increased as dietary protein content and intake increased (Poos et al., 1979; Cressman et al., 1980; Cowan et al., 1981 ). DM intake from CW was 27.1% of total DM intake from CWDSBG ration. The CW level might not have adversely affected the voluntary intake of rams on the ration. Further work is needed to determine the optimum CWDSBG combination that would supplement forage for maximum performances of sheep. DM intake from grass, concentrate and total ration was depressed when forage was supplemented with DSBG alone rather than the CW-DSBG mixture. Inadequate energy content and intake from the ration was apparently responsible. The metabolizable energy content calculated from the estimated digestible energy (DE) of rations containing CW, DSBG and CW-

245

DSBG was 2.28, 2.34 and 2.36 Mcal k g - ~DM, respectively. A high protein content in DSBG is only beneficial with high energy content since both energy and protein levels of diets control voluntary intake and energy consumed (NRC, 1985). DSBG appeared to be a better forage supplement than CW since it promoted 2.9% greater total DM intake from the ration. Its higher CP and EE but lower CF content (Table 1) appeared more beneficial to sheep. On a metabolic size basis, the daily total DM intake from the rations was in accord with values of 69.772.5 g previously recorded for the breed (Adeneye and Oyenuga, 1976; Adebowale and Ademosun, 1985), and of 60 g (or 30 g k g - ~BW) for Javanese sheep fed napier grass, concentrates and cassava meal separately (Van Eys et al., 1987). The results emphasized the advantage to supplement these forages with concentrates for improved nutrition of tropical sheep breeds. Irrespective of the rations, rams consumed 446.3 g forage DM in every kg of total DM intake. Furthermore, total DM intake from CW, DSBG and CW-DSBG rations was 32.70, 31.86 and 33.92 g k g - ~BW, respectively, the average (32.83 g kg-~ BW) being higher than 30 g kg-~ BW recommended by Devendra and McLeroy (1982). CP intake from the rations varied significantly (P < 0.01 ) and reflected DSBG levels in the diets. Animals on sole DSBG supplement derived 6.3- and 1.7times the protein supply from CW and CW-DSBG supplements, respectively. The CW, DSBG and CWDSBG concentrates supplied 32.7, 75.7 and 63.6% of total CP intake from the rations, respectively. Adegbola et al. (1977) reported that CP intake similarly increased as increasing levels of high-protein groundnut meal replaced cassava flour in WAD sheep ration but the values obtained, 3.06-9.69 g d a y - ~k g - l WO.75, were lower than in the present report. When Cynodon nlemfuensis hay was supplemented with a 2 : 1 ratio of cassava/groundnut diet, CP intake was 63.50 g d a y or 4.85 g d a y - ~k g - ~W °75 (Adegbola, 1988). In the present report, each kg of DM consumed from CW, DSBG and CW-DSBG rations contained 89.51,238.24 and 159.13 g CP, respectively. The actual and metabolic size-based digestible DM and DE intakes reflected DM intake, while the trends for CP and digestible CP (DCP) intakes were similar. DCP content of the DM consumed increased directly

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J.A. Adeneye, E.M. Sunmonu / Small Ruminant Research 13 (1994) 243-249

Table 1 Chemical compositionof feeds Component ( %)

DM CP (% DM) Ether extract ( % DM) Crude fibre ( % DM) NFE ( % DM) Total ash (% DM) GE (kcal/g)

Guinea grass

23.24 11.89 2.46 31.72 41.15 12.78 3.94

Centrosema

23.33 23.27 2.58 31.20 33.71 9.24 4.25

Cassava wastes (CW)

Dried sorghum brewer's grains (DSBG)

Supplement ~ 97% CW

97% DSBG

48.5% CW plus 48.5% DSBG

91.50 5.50 0.93 16.39 70.37 6.81 4.00

90.75 34.12 6.30 12.41 41.75 5.42 4.77

91.60 5.41 0.78 15.80 71.34 6.68 4.02

90.82 33.20 6.22 12.36 42.83 5.39 4.75

97.50 18.12 3.94 14.58 57.18 6.18 4.37

~Each supplementalso contained 1% oystershell, 1% commonsalt and 1% mineral-vitaminmixtureof the followingcomposition:Vit. A, 8 millionIU; vit. D3, 1.5 millionIU; Vit. E, 3000 IU; Vit. K~, 3 g; Vit. B2, 2.5 g; nicotinicacid, 8 g; calciumD-pantothenate,3 g; Vit. B6, 0.3 g; Vit. Bj2, 8 mg; manganese, 10 g; iron, 5 g: zinc,4.5 g; copper, 0.2 g; iodine,0.15 g; cobalt, 0.02 g; selenium,0.01 g.

with dietary DSBG levels. However, DE content of DM consumed peaked in CW-DSBG ration and confirmed that a lower energy content in DSBG ration was probably responsible for the lower DM intake of DSBG ration, relative to CW-DSBG ration.

3.2. Growth rate

Average daily gain ( A D G ) in weight was depressed when CW instead of DSBG or CW-DSBG ration was fed. This showed that the high proportion of CW supplement adversely affected the growth rate of sheep. In a locality where DSBG is not available or its cost is not affordable, forage supplementation with sole CW, especially during the dry season would not only prevent weight loss but also encourage about 12 g ADG. Since a higher 31 g ADG was obtained with sole DSBG supplementation, this would be an advantage especially where CW is not available. However, when forage was supplemented with equal proportions of CW and DSBG, the highest ADG (68 g) was achieved. This value fell within the range of 49-82.5 g ADG, previously reported for the breed (Adeneye and Oyenuga, 1976; Adebowale and Ademosun, 1985). Feed conversion ratios are in Table 2. CW-DSBG ration was most efficiently converted to weight gain. Rams on CW rather than DSBG ration needed more DM and energy (about 2.5-times) to achieve a unit increase in BW. Contrarily, the protein in CW ration

was more efficiently converted to BW gain than that in DSBG ration, but not significantly so.

3.3. N balance

Results of digestibility and N balance trials are in Table 3. N intake, absorbed N and urinary N increased substantially ( P < 0.01 ) as concentrate protein content increased as a consequence of increasing dietary DSBG levels. This is supported by previous reports (Poos et al., 1979; Cressman et al., 1980). Faecal N loss of CWDSBG ration was the least, similar to that of CW ration and only 56% of that for sole DSBG supplemented ration. When faecal N was expressed as a percentage of N intake, the means decreased from 39% in CW ration to 22% in CW-DSBG ration. Exclusion and reduction of CW in DSBG and CW-DSBG rations, respectively, and consequent increase in dietary CP content apparently accounted for reduction in percentage of N intake lost in the faeces. The percentage of N consumed that was excreted in the urine increased directly ( P < 0.01 ) with N intake and dietary N concentration. Two-thirds of the N absorbed from DSBG ration were excreted in the urine compared with about 40% from CW or CW-DSBG ration. This was a probable reflection of inadequate available energy in DSBG ration relative to the high amount of ruminal ammonia that probably resulted from N digestion in DSBG ration, agreeing with the

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Table 2 Voluntary intake, weight gain and conversion efficiencies of sheep fed rations containing cassava wastes or dried sorghum brewer's grains as forage supplements Intake (g day ~)

Forage plus CW supplement ÷

Forage plus DSBG supplement + +

Forage plus CW-DSBG supplement + + +

SEM

DM Guinea grass Centrosema Concentrate Total g kg-~ W°75 g kg-~ W

219.69 27.89 294.12a 541.71 66.10 32.70

217.80 27.65 312.18b 557.63 65.39 31.86

225.50 27.22 320.00b 572.72 68.88 33.92

2.04 0.58 2.34 6.42 1.36 1.14

CP Guinea grass Centrosema Concentrate Total g kg- i W07~ gkg i DM

26.12 6.49 15.88a 48.49a 5.91a 89.51

25.90 6.43 100.52b 132.85b 15.53b 238.24

26.81 6.33 57.98c 91.13c 10.94c 159.13

1.02 0.36 2.86 3.62 1.64

DDM g kg ~W °7~

352.60a 42.92

363.46a 42.48

385.94b 46.34

2.82 1.90

DCP g kg- 1 WO75 g kg ~DM

29.63a 3.61a 54.67

97.61 b 11.41b 175.04

70.94c 8.52c 123.87

2.14 1.02

1506.53a 183.46a 2.78

1590.59b 185.90a 2.85

1647.15c 197.76b 2.88

12.64 3.86 0.06

11.90a

30.95b

67.86c

2.96

45.52a 4.07a 126.60a

18.02b 4.29a 51.39b

8.44c 1.34b 24.27c

2.38 1.12 5.86

DE (kcal day ~) kcal kg i WO75 Mcal kg - ~DM Average daily gain (g) Conversion ratio (intake gain ~) DM CP DE

Means followed by unlike letters differ (P < 0.05 ). +97% cassava waste supplement. ÷ ÷ 97% dried sorghum brewer's grains supplement. + + + 48.5% cassava wastes plus 48.5% dried sorghum brewer's grains supplement. reports o f P o o s et al. ( 1 9 7 9 ) , C r e s s m a n et al. ( 1 9 8 0 ) a n d C o w a n et al. ( 1 9 8 1 ) . N r e t e n t i o n i n c r e a s e d significantly ( P < 0 . 0 1 ) . Approximately one-quarter, one-third and half of N i n t a k e f r o m D S B G , C W a n d C W - D S B G rations, respectively, w e r e retained. A b o u t 6 0 % o f t h e N a b s o r b e d f r o m C W or C W - D S B G r a t i o n was r e t a i n e d c o m p a r e d w i t h 3 3 % f r o m D S B G ration. A p p a r e n t d i g e s t i b i l i t y coefficients o f D M a n d gross energy of rations were not significantly affected by

i n c r e a s i n g dietary N i n t a k e ( P > 0 . 0 5 ) . N d i g e s t i b i l i t y o f C W r a t i o n w a s the least, d u e p r o b a b l y to the h i g h a m o u n t o f starch in the C W s u p p l e m e n t as s u g g e s t e d b y K u r i l o v ( 1 9 8 2 ) or to the h i g h e s t C F c o n t e n t o f the s u p p l e m e n t ( T a b l e 1 ) in a g r e e m e n t w i t h M a r t z a n d B e l y e a ( 1 9 8 3 ) . N d i g e s t i b i l i t y i m p r o v e d significantly (P<0.01) as N i n t a k e i n c r e a s e d to 18.57 g d a y -~ ( C W - D S B G r a t i o n ) as in o t h e r reports ( P o o s et al., 1979; C r e s s m a n et al., 1 9 8 0 ) . A t the h i g h e s t N i n t a k e f r o m f o r a g e a n d D S B G alone, N digestibility w a s

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J,A, Adeneye, E.M. Sunmonu / Small Ruminant Research 13 (1994) 243-249

Table 3 Digestibility coefficients and nitrogen utilization by sheep fed rations containing cassava wastes or dried sorghum brewer's grains as forage supplements

N intake Faecal N

Absorbed N

Urinary N

Retained N

(g day ~) (g day ~kg ~W~L75) (g day " ~) (g day-~ kg t W,75) ( % of intake) (g day i ) (gday I kg I WC~75) ( % of intake) (g day ~) (gday ~kg ~W ~75) ( % of intake) ( % of absorbed) (g day ~) (gday ~kg ~W °75) ( % of intake) ( % of absorbed)

DM digestibility (%) N digestibility ( % ) Energy digestibility ( % )

Forage plus CW supplement ~

Forage plus DSBG supplement + ~

Forage plus CW-DSBG supplement + + +

SEM

11.17a 1.35a 4.37a 0.53a 39.12a 6.80a 0.82a 60.88a 2.82a 0.34a 25.25a 41.47a 3.98a 0.48a 35.63a 58.53a 65.10 60.88a 65.20

27.33b 3.24b 7.16b 0.85b 26.20b 20.17b 2.39b 73.80b 13.48b 1,60b 49,32b 66,83b 6,69b 0.79b 24.48b 33.17b 65,20 73.80b 64.90

18.57c 2.20c 4.08a 0,48a 21,97c 14,49c 1,72c 78,03b 5,68c 0.67c 30.59c 39.20c 8.8 lc 1,04c 47,44c 60,80a 67.40 78.03c 67.70

0,86 0.06 0.62 0.05 1.72 1.22 0.28 3.96 1.84 0.08 1.62 2.83 0.94 0.48 2.06 2.98 1.73 5.20 1.56

Means followed by unlike letters differ (P < 0,01 ). +97% cassava wastes supplement. + + 97% dried sorghum brewer's grains supplement. + ÷ +48.5% cassava wastes plus 48.5% dried sorghum brewer's grains supplement.

reduced by 4% units ( P < 0 . 0 5 ) . The significant increase in faecal N loss when DSBG instead of CWDSBG ration was fed was apparently responsible,, in accord with Kurilov (1982). However, N digestibility of DSBG ration was still significantly ( P < 0 . 0 1 ) higher than that of CW ration, probably because of the lower CF content of DSBG supplement (Table 1).

4. Conclusion CW is an energy-rich, low-protein feed, while DSBG is an energy- and protein-rich by-product of sorghum fermentation. Forage supplementation with sole CW, DSBG or their mixture at 48.5% level each had no significant effect (P > 0.05) on intake and digestibility of DM and energy by sheep. Intake, digestibility, faecal and urinary excretion, and retention of N, growth rate as well as feed and energy conversion efficiencies of sheep were remarkably higher (P < 0.01 ) with DSBG

than CW supplementation. The reverse was true for the protein conversion ratio. However, the mixed rather than the sole supplement supported highest ADG and efficiencies of feed, protein and energy conversion to gain due probably to improved nutrient balance. WAD rams offered 48.5% each of CW and DSBG as forage supplement would reach market weight earlier than those fed 97% CW or DSBG supplement. Since DSBG is inedible to man and its fibre content fairly high for large-scale poultry feeding, competition for its utilization will be low and restricted to ruminant feeding. Being a waste product, it will also reduce feed cost, environmental pollution and health hazard.

5. Acknowledgement This project was funded by the Senate Research Grants Committee of the University of Ibadan.

J.A. Adeneye, E.M. Sunmonu / Small Ruminant Research 13 (1994) 243-249

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