Proceedings Buffalo Workshop December 2001

Supplementing cassava root meal and cassava processed leaves to diets based on natural grasses, maize stover and rice straw for fattening young swamp buffaloes

Dao Lan Nhi, Mai Van Sanh and Le Viet Ly

National Institute of Animal Husbandry, Hanoi

Abstract

Two experiments were conducted to evaluate the effects of different levels of cassava root meal and processed cassava leaves supplemented to the diets based on maize stover or natural grasses and rice straw on performance of growing-fattening male buffaloes. In each experiment, 20 male buffaloes 19-21 months of age and body weight of 110-130 kg was divided into 4 groups of 5 each with a randomized block design. In Expt. I, buffaloes were fed maize stover, rice straw and supplemented mixture of cassava root meal (CRM) and cassava leaf meal (CLM) (ratio 1:1) with the levels of 0.8, 1.6, 2.4 and 3.2 kg. In Expt. II, buffaloes were fed natural grasses, rice straw and supplemented 0.5 kg cassava root meal plus 1.4, 2.8, 4.2, 5.6 kg cassava leaf silage (CLS).

Increased the levels of cassava root meal and cassava leaf meal or cassava leaf silage resulted in increased dry matter (DM) intake and body weight gain. At the level of 2.4 kg mixture of CRM and CLM or 0.5 kg CRM and 5.6 kg CLS, buffaloes gained 500-600 g/day, feed consumption was 10.5-11.0 kg DM. The profit per fattening head was 230-249 thousand VND during 3 months. Cassava leaf can be used as supplemented feed for growing fattening buffaloes in dry form or silage.

Key words: Buffaloes, fattening, cassava, leaves, root

Introduction

The major feeds for buffalo are natural grasses and crop residues as maize stover and rice straw which are low in protein and energy. Supplementation of high protein and energy feeds is necessary for the growing-finishing buffalo to maximize the potential of meat production. In Vietnam, cassava is one of the important crops for farmers in mountainous provinces. Cassava leaf has high crude protein concentration (from 16.7 to 39.8%, Allen 1984). However, there were not much interest to use fresh cassava leaves in animal feeding. Buitrago (1990) stated that the great limitation of using cassava leaf as animal feed is its content of cyanogenic glucosides. The most common procedures for reducing the concentration of these substances are sun-drying and ensiling (Wanapat,1997; Pham Sy Tiep 1999; Duong Thanh Liem et al 2000). The yield of cassava leaves was 2.5-3.0 tonnes (containing 500-600 kg dry matter and 110-130 kg crude protein per ha prior to root harvesting (Bui Van Chinh et al 1992).

The objective of the experiments was to study the effects of different levels of cassava root meal and processed cassava leaves supplementing to diets based on natural grasses and crop residues on performance of growing-finishing male buffaloes.

Materials and methods

Location:

The experiments were carried out at the Centre for Livestock Research and Development in the mountainous region of Thai nguyen province.

Experimental design:

Forty male swamp buffaloes (19-21 months of age) with live weight of 110-130 kg were allocated into two experiments. In each experiment, 20 buffaloes were blocked and divided into 4 groups (5 per each group) with a randomized block design according to body weight and age of animals.

Processing cassava leaves:

The fresh cassava leaves were collected before harvesting. For cassava leaf meal, the cassava leaves were dried under sunlight and ground by machine. For ensiling, cassava leaves were mixed with 10% cassava root meal and salt (1 kg salt for 1 tonne of cassava leaves), put in plastic bags and incubated for 45-50 days before feeding.

Table 1. The experimental design
	Treat. 1	Treat. 2	Treat. 3	Treat. 4
Exp. 1. CLM
Fresh maize stover (kg)	10-12	10-12	10-12	10-12
Rice straw*	Ad lib.	Ad lib.	Ad lib.	ad lib.
Cassava root meal (kg)	0.4	0.8	1.2	1.6
Cassava leaf meal (kg)	0.4	0.8	1.2	1.6
Exp. 2. CLS
Natural grasses (kg)	12-15	12-15	12-15	12-15
Rice straw*	Ad lib.	Ad lib.	Ad lib.	ad lib.
Cassava root meal (kg)	0.5	0.5	0.5	0.5
Cassava leaf silage (kg)	1.4	2.8	4.2	5.6
CLM: Cassava leaf meal; CLS: Cassava leaf silage

Animal feeding and management:

Maize stover or natural grasses and rice straw were given at 7:00; 11:00; 15:00 and 18:00 h. Cassava root meal and processed cassava leaves (meal or silage) were given at 7:00 and 15:00 h. Buffaloes were kept and fed individually indoor with exercise dailly for a few hours outside. Water was available in the trough which was cleaned every day.

Data collection procedure:

Refusals were weighed daily in the morning before supplying new feeds. Body weight was determined every month (weighed in the morning before feeding and drinking). Feed composition was analyzed twice a month by the procedure of Vietnam (1986).

Experimental duration:

The feeding period was 3 months (excluding the feed adaptation time of 10 days)

Statistical analysis:

Data were analyzed by ANOVA, using the General Linear Model in the Minitab programme release 12.21 (1998).

Results and discussion

Chemical composition of feeds

Composition of the diet ingredients was in accordance with expectations (Table 2). The values of HCN were 14.6 mg/kg in cassava leaf silage and 18.7 mg/kg in cassava leaf meal. These data were lower than those of previous reports by Bui Van Chinh et al (1992) and Wanapat et al (1997).

Table 2. Chemical composition of feeds (* percent in dry matter)
Feed	DM(%)	CP*	EE*	CF*	NEF*	HCN mg/kg
Cassava leaf meal	91.5	21.1	4.5	13.9	39.7	18.7
Cassava leaf silage	33.4	16.5	4.6	16.8	12.0	14.6
Cassava root meal	92.8	1.2	2.4	4.3	77.1	-
Natural grasses	22.0	8.8	1.5	6.9	16.7	-
Maize stover	28.4	4.1	1.2	4.5	6.7	-
Rice straw	89.2	4.6	1.8	30.5	29.8	-

Feed intake and body weight gain of buffaloes in Experiment I

The buffaloes in all treatments readily consumed most feeds supplied, indicated no toxic and palatability problems, except the buffaloes in treatment 4, they consumed only 2.6 kg/day of mixed cassava leaf and root meal (Table 3).

Dry matter intake increased following the increase of CRM and cassava processed leaves. The dry matter intakes (kg/day) were different significantly (P<0.05) between 1 and 2 and 3 but no difference between treatments 3 and 4. Higher supplemented level of 3.2 kg did not significantly give any intake and growth (0.600 kg/day) of buffaloes.

Table 3. Daily feed intake and body weight gain of buffaloes fed maize stover, rice straw and supplemented CRM/CLM
	Supplemental levels (kg/day)
CRM/CLM	*0.4/0.4*	*0.8/0.8*	*1.2/1.2*	*1.3/1.3*
Total DM intake (kg)	5.5^a	5.9^b	6.3^c	6.4^c
% Body weight	2.67	2.82	2.93	2.94
CRM and CLM intake (kg)	0.67	1.08	1.67	2.17
Maize stover intake (kg)	3.08	2.97	3.00	3.25
Rice straw intake (kg)	1.75	1.85	1.60	0.98
Total crude protein (g)	351^a	437^b	518^c	545^c
Metabolisable energy (MJ)	42.0^a	48.9^b	54.9^c	56.4^c
Initial weight (kg)	194	196	197	195
Final weight (kg)	220	235	250	249
Total gain (kg)	25.7	38.8	52.6	54.0
Live weight gain (kg/day)	0.285^a	0.431^b	0.585^c	0.600^c
Feed conversion (kg DM/kg of gain)	19.2	13.7	10.7	10.6
^abc Different superscript within rows indicates significant diferences

Feed intake and body weight gain of buffaloes in Experiment II

There was a trend towards increase of body weight gain (kg/day) follow the increased levels of supplement. Dry matter intake increased following the increace of cassava leaf silage. The dry matter intake (kg/day) were different significantly (P<0.05) between treatment 1 and 3 and 4. Body weight gain also increased following the increase of cassava leaf silage.

Table 4. Daily feed intake and body weight gain of buffaloes fed natural grasses, rice straw and supplemented CRM/CLS
	CRM/CLS (kg/day)
	*0.5/1.4*	*0.5/2.8*	*0.5/4.2*	*0.5/5.6*
Total DM intake (kg/day)	5.3^a	5.6^ab	5.8^b	6.1^c
% Body weight	2.78	2.84	2.80	2.90
CRM and ECL intake	0.69	1.17	1.45	2.10
Natural grasses intake	2.86	2.95	3.05	2.98
Rice straw intake	1.75	1.47	1.30	1.05
Total crude protein (g/day)	433^a	498^ab	535^b	563^c
Metabolisable energy (MJ/day)	43.0^a	46.9^ab	49.7^b	54.0^c
Initial weight (kg)	193.4	195.8	192.1	196.9
Final weight (kg)	223.5	230.4	235.7	247.0
Total weight gain (kg)	20.5	34.6	43.6	50.1
Live weight gain (g/day)	0.334^a	0.384^b	0.483^c	0.557^c
Conversion (kg DM/kg of gain)	15.5	14.4	11.8	10.9
^abc Different superscript within rows indicates significant diferences

The mean daily gain was highest (0.550-0.600 kg/day) and the best feed conversion (about 11 kg DM/kg weight gain) in the treatments with 30-35 % of CRM and cassava leaves in total DM intake. These results were in agreement with the study of Wanapat and Wachirapakorn (1990) who reported that the daily gain was 542-551 g and feed conversion rate was 10.6-10.7 kg DM/kg weight gain of the feedlot buffaloes fed on ure-treated rice straw based diet with supplement of concentrate.

Economic efficiency

Table 5. Estimation of cost/benefit from feeding growing-finishing buffalo (1,000 VND/head)
	CRM/CLM (kg/day)				CRM/ECL (kg/day)
Supplemental levels	0.4/0.4	0.8/0.8	1.2/1.2	1.6/1.6	0.5/1.4	0.5/2.8	0.5/4.2	0.5/5.6
Initial value	1654	1671	1678	1662	1643	1664	1632	1673
Total feed cost	177	245	312	320	170	206	237	271
Other costs	30	30	30	30	30	30	30	30
Total	1861	1946	2020	2012	1843	1900	1899	1974
Final value	1992	2119	2250	2246	2012	2074	2121	2223
Net profit	131	173	230	234	169	175	222	249

Fattening young buffalo diet with 10-12 kg of maize stover or 12-15 kg of natural grass and rice straw offered ad libitum and supplemented with 0.5-1.2 kg of cassava root meal plus 1.2 kg of cassava leaf meal or 5.6 kg of ensiled cassava leaves can get the profit of 230-249 thousand VND/head after 3 months.

Conclusions

Supplementing a basal diet including maize stover or natural grasses and rice straw with cassava root meal and processed cassava leaves (drying or ensiled) at the rate of 30-35 % (DM basis), the young male buffalo gained 0.550-0.600 kg/day and feed conversion of 10.5-11.0 kg DM/kg live weight gain.

The net profit for fattening young male buffalo with these diets was 230-249 thousand VND/head after 3 months.

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