R T Fomunyam and F Meffeja
Institute of Animal Research, Mankon Bamenda, Cameroon
Abstract
Introduction
Materials and methods
Results and discussion
References
Sundried cassava leaves were fed to rabbits, and peels to sheep, in an attempt to determine suitable rations that can prevent dry season animal weight losses. Rabbits fed 50, 62.5 and 75% levels of leaves in test diets ate 65.8, 73.5 and 71.8 g/d and gained 17.4, 19.4, 18.2 g/d respectively. There was no difference in growth traits between female and male rabbits.
Sheep fed 0, 35, and 70% of the diet as cassava peels (and respectively 70, 35 and 0% elephant grass), with cottonseed cake as the protein source, gained respectively 45, 107 and 227 g/d; these differences were significant (P<.0.05). These diets show promise as dry season feedstuffs.
A survey of sheep and goat production systems in Cameroon showed that nutrition, especially in the dry season, and the tethering management practice, are the principal constraints to increased meat and milk production from these species. This study attempts to evaluate the use of cassava by-products as feedstuffs for animals in an attempt to avoid weight losses normally observed during this period (mid-November to mid-March).
Cameroon produces an estimated 620 thousand tonnes (t) of cassava (Manihot esculentum Crantz) annually, the by-products of which amount to 37.2 thousand t of leaves, 74.4 thousand t of peels and 528 thousand t of stems. Currently these by-products are used as manure, or fuel in the case of stems. Some leaves are used as human food. Cassava contains the cyanogenic glucosides linamarin [2(B - D - glucopyranosyloxy) isobutyronitrile] and lotaustralin [2(B - D - glucopyranosyloxy) 2-methylbuty-ronitrile] which yield HCN on hydrolysis; apparently grass-eaters are somewhat adapted to dispose of this poison and its metabolic products (Oke 1973, Devendra 1977).
Sonaiya and Omole (1981) demonstrated that growing rabbits successfully utilized a ration containing 40% cassava peel meal. Eshiett, Omole and Ademosun (1981) fed five-week old rabbits on rations containing 0, 15, 30 or 40% cassava root meal and found liveweight performance and carcass quality to be similar on all rations. Adebowale (1981) fed sheep fermented cassava peels at levels of 0, 20, 40 or 60% in the diet over a 6 month period. The 40 and 60% cassava peel rations had lower digestibilities of dry matter, crude fibre and TDN, feed intake, body weight gain and feed efficiency, but had no effects on weights of liver and hides.
In this work the effects of including sun dried cassava leaves with the diet were examined in rabbits and sheep.
Animals: 36 four-week old rabbits, (18 male, 18 female crossbred New Zealand x chinchilla x Californian) were allocated to three groups each of 6 males and 6 females, and fed diets containing 50, 62.5 or 75% cassava leaf (Table 1). Water and feed were given ad libitum with feeding being carried out twice a day. The feed and water were supplied in clay croques and the animals were allowed 12 hours of light. The temperature ranged from 23.2°C to 28.3°C. Ten hour fasted weights were obtained every week and the experiment lasted four weeks. In the second trial, nine rams of initial weight 24.3 kg were fattened on three test diets (Table 2) using a 3 x 3 latin square design over 3 months.
Table 1. Percentage composition of cassava leaf based diets for rabbits
|
Feed Items |
Rations |
||
|
I |
II |
III |
|
|
Cassava leaf |
50.0 |
62.5 |
75.0 |
|
Ground maize |
45.5 |
33.0 |
20.5 |
|
Palm Oil |
3.0 |
3.0 |
3.0 |
|
Minerals/vitamins etc |
1.5 |
1.5 |
1.5 |
|
Calculated analysis |
|||
|
Energy DE (Kcal/kg) |
3454 |
3230 |
3008 |
|
Crude protein % |
16.1 |
16.8 |
16.8 |
|
Crude fibre % |
13 |
14 |
16 |
|
Calcium % |
0.64 |
0.76 |
0.88 |
|
Phosphorus % |
0.46 |
0.48 |
0.51 |
Table 2. Percentage composition of test diets containing graded levels of cassava peels for sheep
|
Feed Items |
Rations |
||
|
I |
II |
III |
|
|
Cassava peels |
0 |
35.5 |
71 |
|
Elephant grass |
71 |
35.5 |
0 |
|
Cottonseed cake |
20 |
20 |
20 |
|
Molasses |
5 |
5 |
5 |
|
Bone meal |
2.5 |
2.5 |
2.5 |
|
Salt |
1.5 |
1.5 |
1.5 |
|
Calculated analysis |
|||
|
Crude protein % |
14.4 |
13.9 |
13.4 |
|
Crude fibre |
23.8 |
16.5 |
9.2 |
|
Calcium % |
1.2 |
1.1 |
1.1 |
|
Phosphorus % |
0.6 |
0.6 |
0.7 |
|
D.E. (Kcal/kg) |
2527.8 |
2573.2 |
2618.7 |
|
HCN (mg/kg) |
0 |
72.2 |
144.4 |
Cassava leaf and peels
Cassava leaf including petioles and cassava peels were obtained from 15 month-old plants and were sundried on black polythene sheets for about 2 - 3 days. Old leaves, seeds and stems were picked out and the rest bagged in jute sacks and stored until ready to be fed. Leaves contained 74 mg HCN/kg leaf and peels contained 203.4 mg/HCN/kg determined by the agentometric method.
Table 3 shows that sex differences and ration effects were not statistically significant as far as rabbits fed graded levels of cassava leaves were concerned. However, female rabbits tended to eat less feed (66.0 g/d vs 71.2 g/d) and grew slightly faster (18.8 g/d vs 18.0 g/d). Female rabbits are generally heavier than male rabbits. There was a tendency for higher feed intakes and higher weight gains with higher levels of cassava leaf in the diet. There were no differences between sexes or rations in efficiency of feed utilization, and no rabbits died nor were any cases of diarrhoea observed.
Table 3. Feed intake and weight gains of rabbits fed cassava leaf-based diets
|
Sex |
Leaf level |
Daily Dry Matter Intake (g/rabbit) |
Daily weight gain (g/rabbit) |
Feed/gain |
|
|
Female
|
50 |
72.2 |
16.8 |
4.0 |
|
|
62.5 |
68.2 |
18.7 |
4.1 |
||
|
75.0 |
71.6 |
21.1 |
4.6 |
||
|
Male
|
50.0 |
57.8 |
17.9 |
6.4 |
|
|
62.5 |
78.2 |
20.8 |
4.2 |
||
|
75.0 |
63.2 |
15.2 |
3.8 |
||
|
S.E.M. |
|
23.14 |
15.13 |
5.16 |
|
|
Sex means |
|||||
|
|
Female |
|
66.0 |
18.8 |
4.2 |
|
|
Male |
|
71.2 |
18.0 |
4.8 |
|
|
S.E.M. |
|
18.04 |
12.62 |
6.83 |
|
Ration means |
|
|
|
|
|
|
|
50 |
65.8 |
17.4 |
4.2 |
|
|
62.5 |
73.5 |
19.4 |
4.1 |
||
|
75.0 |
71.8 |
18.2 |
4.2 |
||
|
S.E.M. |
20.31 |
18.01 |
5.12 |
||
Harris et al (1981) fed several tropical forages to weanling rabbits and observed daily weight gains of 33 g/rabbit and a feed/gain of 3.38 for rabbits fed cassava leaf-based diets. These workers observed no mortalities nor diarrhoea cases with these diets, but diarrhoea did occur in rabbits fed low saponin alfalfa, winged bean and Stylosanthes guianensis.
The low weight gains observed in this trial may be due to the fact that the feed was not pelleted and was scattered. Harris, Cheeke and Patton (1983) showed that feeding non-pelleted diets resulted in much feed being scattered. Nevertheless, cassava leaf based diets for rabbits show promise, and will reduce competition for other protein sources such as oil seed cakes as well as supplying the fibre required for rabbit growth.
In the second trial (Table 4) the sheep fed diets with cassava peel grew significantly better (P<0.05) than those fed the elephant grass diet (227 g/d vs 45.2 g/d). The differences could be attributed to higher intakes of digestible dry matter. The cassava peels also contributed additional soluble carbohydrate (8%) as peels were removed from tubers in pencil sharpening format.
Table 4. Weight gains and feed intake of sheep fed graded levels of cassava peels
|
Characteristics |
Level of peel |
||
|
0% |
35% |
70% |
|
|
Dry matter intake (kg/day/sheep) |
0.87 |
1.36 |
1.06 |
|
Daily weight gain (g/sheep) |
45.20a |
106.70b |
227.14c |
|
Dry matter digestibility (%) |
50.91 |
79.02 |
88.13 |
|
Crude protein digestibility (%) |
56.12 |
76.23 |
74.27 |
a, b and c. Within rows means not bearing the same superscript are significantly different (P<0.05).
Adebowale (1981) fed fermented cassava peel to sheep and observed depressed weight gains as the level of peel increased in the diet. It is possible that fermented cassava peels depressed rumen function, while in the present work, sundried cassava did not. The diets were palatable and no sheep died nor showed any adverse effects.
Cassava peels show great potential in sheep and goat production in Cameroon not only in preventing dry season weight losses but also in supporting growth. The technology of feed-stuff preparation is simple, not labour intensive and easily applicable to farmer situations.
Adebowale E.A. (1981). The maize replacement value of fermented Cassava peels (Manihot utillissima Pohl) in rations for sheep. Tropical Animal Production 6:66-72.
Devendra C. (1981). Cassava as a feed source for ruminants. In Cassava as animal feed. Proceedings of a workshop held at the University of Guelph. Ed. Nestel and Graham.
Eshiett N.O., Omole T.A. and Ademosun A.A. (1981). The effect of feeding Cassava root meal on the performance, carcass characteristics, serum and urinary thiocyanate concentration of fryer rabbits. Ife J. of Agriculture. (In press).
Harris D.J., Cheeke P.R. Telek L. and Patton N.M. (1981). Utilization of alfalfa and tropical forages by weanling rabbits. Journal of Applied Rabbit Research 4:4-9.
Harris D.J., Cheeke P.R. and Patton N.M. (1983). Feed preferences studies with rabbits fed fourteen different fresh greens. Journal of Applied Rabbit Research. 6:120-124.
Oke O.L. (1973). The mode of cyanide detoxification. In "Chronic Cassava Toxicity" Neste B. and MacIntyre R. ed. London, England.
Sonaiya E.B. and Omole T.A. (1981). Cassava peels in rabbit diets. Nutrition Reports International (In press).
