Maize stover and cobs as a feed resource for ruminants in Tanzania

N A Urio
Department of Animal Science and Production, Sokoine University, Morogoro, Tanzania.

J A Kategile
International Development Research Centre, P.O. Box 62084, Nairobi.

Abstract
Introduction
Composition & nutritive value of maize cobs & stover
Performance of livestock fed on maize stover/maize cobs
References

Abstract

Maize is the most important crop in Tanzania and total grain yields amount to 2 million tons annually, accompanied by the production of residues (stover and cobs) exceeding 4 million tons. Maize stover is largely grazed in situ and maize cobs used as fuel in small scale farms. The nutritive characteristics of both residues were studied through digestibility studies of diets formulated to contain 35 - 70% residues followed by production feeding trials on the most promising diets. It was shown that diets containing proportions of maize stover and maize cobs could support reasonable growth rates and milk yields.

The application of research results on farms is being investigated in a follow up project. It is obvious that the use of maize cobs as a ruminant feed is limited to large scale farms where adequate quantities are produced and grinding mills are available. In the case of maize stover, the major constraints to application of better feeding strategies is bulkiness which renders storage and transportation difficult. Further research is still required to elucidate the specific roughage x energy supplement interactions.

Introduction

Crop residues have been estimated to account for about 25 percent of the total feed energy suitable for ruminant livestock in both developed and developing countries (Kossila 1985). In 1981, maize was considered the leading crop in providing crop residues that could be utilized as a livestock feed (Table 1).

In Tanzania maize is the most important cereal crop grown for human food production (Table 2). Using a ratio of 1:2 between grain and amount of crop-residues produced, suggests that about 4 million tonnes of maize stover and maize cobs are produced annually. In some areas the high potential maize producing areas have high cattle populations as well, while in other areas maize is grown in marginal rainfall areas and does not overlap with high cattle populations.

Both maize stover and maize cobs contribute significantly as ruminant livestock feed particularly during the dry season. Some of the major constraints that limit efficient utilization of maize stover and/or maize cobs are as tabulated below:

Attributes and disadvantages of using maize stover/cobs as livestock feed.

	Maize stover	Maize cobs
1. Present use	Mostly grazed in situ	Used as firewood in small scale farms, wasted on large scale farms
2. Availability as livestock feed	Available	Available on large scale farms only
3. Collection	Has to be collected from the field	Produced at homesteads
4. Transportation	From field to homestead	No need (cobs shelled at homestead or at granary)
5. Storage	Bulky, preferably baled	Medium density
6. Baling/grinding	Applicable but not necessary	Has to be ground and output is good
7. Mixability with other ingredients	Difficult	Easily mixed after grinding

Table 1. Global production of fibrous crop residues from different crops in trillion tonnes, 1981.*

Crop	Amount of crop residue
	(trillion tonnes)
Maize	1.0
Wheat	0.5
Rice	0.5
Pulses, each	0.5
Sorghum	0.3
Barley	0.2
Sugarcane	0.2
Roots and tubers	0.17
Millets and nuts each	0.13
Fruit and berries	0.11
Vegetables	0.08
Oats	0.06
Rye	0.05

* FAO Animal Production and Health Paper 50 FAO Rome -1985.

Table 2. Food Crop production estimate in Tanzania 1984/1985 season ('000 tons)

Region	Food crops
	Maize	Millets	Paddy	Beans	Wheat	Cassava	Banana	Sweet Potatoes
Arusha	127	33	3	13	52	5	12	2
Coast	11	4	32	1	-	88	10	1
Dodoma	23	84	2	1	-	5	-	-
Iringa	367	11	3	45	23	10	-	10
Kagera	68	49	11	82	-	22	268	22
Kigoma	73	10	3	47	3	3	13	3
Kilimanjaro	60	7	12	18	4	3	220	3
Lindi	22	36	21	12	-	135	18	-
Mara	31	44	1	4	-	19	70	19
Mbeya	240	38	48	38	5	18	75	18
Morogoro	110	10	80	4	-	1	3	1
Mtwara	22	39	26	9	-	4	-	4
Mwanza	76	68	37	19	-	78	-	78
Rukwa	160	50	12	25	-	2	1	2
Ruvuma	142	23	21	27	4	125	-	-
Shinyanga	286	267	61	52	-	92	25	92
Singida	23	126	2	1	-	11	-	11
Tabora	166	128	45	23	-	37	-	37
Tanga	60	-	5	17	-	1	58	1
TOTAL	2067	1018	425	438	93	1921	773	304

* Marketing Development Bureau, Dar es Salaam R 4/85.

The practice of in situ grazing is wasteful and inefficient (French 1943). Where the animals have to be fed indoors the bulk factor becomes as important constraint as this increases transportation and storage costs. Grinding of maize cobs on the other hand increases wear and tear on the hammer mills.

Composition & nutritive value of maize cobs & stover

Several studies were conducted at Morogoro, Tanzania with the overall objective of assessing the nutritive value of maize crop residues with a view of developing feeding packages for farmers. Results involving alkali treatment have been omitted since the technology can no longer be justified because of the prohibitive costs of alkalis. Data on chemical composition, derived from work carried out at Morogoro and Kabete, in Tanzania and Kenya respectively, are given in Table 3, and Table 4 presents the formulation and digestibility of several diets based on maize cobs and stover.

Table 3. Chemical composition of maize cobs and stover (% DM)

	Maize stover Hybrid 631/32 (Musimba 1980)	Maize stover Ilonga composite (Biwi 1986)	Maize stover Ilonga composite (Urio 1981)	Maize cobs Ilonga composite (Urio 1981)
Dry matter (DM)%	93.4	-	90.6	88.1
Ash	12.1	8.1	6.0	3.9
CP	2.3	3.5	2.4	2.2
CF	45.3	39.4	-	-
EE	1.8	0.6	-	-
NFE	38.4	48.4	-	-
NDF	-	80.7	-	-
Ca	-	0.32	-	-
P	-	0.28	-	-
GE, MJ/kg DM	-	16.6	16.3	17.3

The results indicate that maize stover and/or maize cobs can successfully be incorporated in ruminant rations and that such rations have relatively high digestibilities.

With rations 1 and 2 (Table 4) the replacement of cottonseed cake by urea as a source of protein did not affect digestibility, although Kategile (1978) observed a slight depression in voluntary feed intake when urea was used at 0.5 percent with no further effect when urea was increased above 0.5 percent. There was no significant difference in digestibility between diets 3 and 4 when urea was used as a source of protein in place of cottonseed cake. Other sources of protein such as leucaena can be used effectively with maize stover as shown in diet 5. The comparatively low digestibility coefficient noted with diet 6 is probably due to the fact that digestibility was determined at ad libitum level of intake and that the roughage constituted a much higher percentage of the ration.

Table 4. Digestibility coefficients of diets based on maize stover/cobs

Ingredients (percent of ration)	Diets
	1	2	3	4	5	6
Maize stover	-	-	-	-	38.3	78.8
Maize cobs	59.8	67.0	45.0	35.0	-	-
Leucaena	-	-	-	-	16.1	-
Molasses	19.0	20.0	24.0	24.0	-	3.6
Cassava	-	-	15.0	-	18.5	-
Maize bran	-	-	-	-	17.3	5.9
Urea	1.0	3.0	3.0	-	1.2	-
Cottonseed cake	18.0	8.0	10.0	37.5	7.4	10.6
Bone meal/Maclik*	2.0	2.0	2.5	2.5	1.2	1.1
Salt	0.2	-	0.5	0.5	-	-
Digestibility coefficients (In vivo)
DM	61.3	61.1	68.8	69.8	64.7	56.5
OM	59.9	62.6	69.3	72.3	67.8	59.7
CP	-	-	81.5	83.5	71.7	-
CF	70.2	-	66.8	68.3	69.6	-
NDF	-	52.9	-	-	-	-
EE	-	-	78.4	78.9	-	-
NFE	-	-	71.1	71.1	-	-
DM intake g/kgW0.75	60.5	43.7	28.5	28.0	93.6	61.1
	Kategile		Mangazeni		Biwi	Urio
	(1978)		(1982)		(1986)	(1981)

* Maclick - Coopers Ltd. Kenya.

Both maize stover and maize cobs are high in lignocellulose content and would probably require a source of readily available carbohydrate for optimum utilization. Preliminary studies (Table 5) have shown that cassava combines well with both stover and cobs, but more so with stover (Kategile 1981), producing substantial increases in dry matter digestibility. Further work is required on the utilization of available sources of readily available carbohydrate in the production of rations with these maize residues.

Table 5. The effects of sources of readily available carbohydrates on digestibility coefficients.*

Ingredient %	Diets
	1	2	3	4
Maize cobs	58.0	58.0	-	-
Maize stover	-	-	58.0	58.0
Molasses	20.0	-	20.0	-
Cassava	-	20.0	-	20.0
Sunflower/cottonseed cake	20.0	20.0	20.0	20.0
Bone meal/salt	2.0	2.0	2.0	2.0
Digestibility coefficients
DM	62.6	68.7	55.3	74.0
OM	68.9	69.7	58.4	76.8
CP	53.1	43.9	79.1	67.2
EE	79.2	80.7	68.8	84.4
CF	64.1	61.3	46.9	70.0
NFE	70.2	79.0	59.8	80.5
DM intake g/W0.75	44.5	45.2	43.9	44.3

* Kategile (1981)

Performance of livestock fed on maize stover/maize cobs

After obtaining results on the potential of maize stover/cobs as a livestock feed, complete rations were formulated and tested using various classes of livestock (Table 6). The rations promoted reasonable rates of production even at high levels of residue inclusion. Diets 1, 4, 5 and 6 constituted complete rations while diets 2 and 3 were used as supplementary rations for grazing steers.

The above results indicate that maize stover/cobs is a potentially valuable feed resource for ruminants, whose efficient utilization can result in appreciable production improvement in various livestock classes. Dry seasons in Tanzania as well as in many other tropical countries are marked with periods of feed shortages resulting in general retardation in animal growth and production. Maize stover/cobs contribute significantly in reducing the dry season feed stress. This contribution could probably be increased if the following improvements could be made:

1. Improving handling and transportation of maize stover by reducing bulkiness and transport costs by baling or other processes to minimize wastages.

2. Studying optimum ration formulations both as a means of improving feed quality as well as formulating a least cost ration.

3. Where technology allows, grinding of maize cobs provides opportunity of utilizing a feed resource which is otherwise wasted, and ground maize cobs could form a major component in basal rations for steers for which feedlots could easily be established near large scale maize farms.

Table 6. Performance of livestock fed on maize stover/cobs based diets

Ingredients (percent of ration)	Diets
	1	2*	3*	4	5	6
Maize cobs	60.8	45.0	35.5	50.8	-	-
Maize stover	-	-	-	-	78.8	38.3
Molasses	19.0	24.0	24.0	8.4	3.6	-
Cassava	-	15.0	-	-	-	18.5
Urea	1.0	3.0	-	-	-	1.2
Maize bran	-	-	-	13.8	5.9	17.3
Leucaena	-	-	-	-	-	16.1
Cotton/sunflower seed cake	17.0	10.0	37.0	24.6	10.6	7.4
Bone meal	2.0	2.5	2.5	2.4	1.1	1.2
Salt	0.2	0.5	0.5	-	-	-
ANIMAL PERFORMANCE
Species	Heifers	Steers	Steers	Goats	Sheep	Lactating cows
Numbers	6	10	10	6	6	6
Initial weight (kg)	170.1	251.3	251.2	15.2	30.3	-
Final weight (kg)	195.3	297.2	299.5	18.5	38.5	-
Daily gain g/day	412	511	533	33.2	80.7	-
Daily milk yield kg/day	-	-	-	-	-	7.6
DM intake g/kgW0.75	104	-	-	45.6	61.1	93.6
Feed DM/kg gain	13.2	-	-	13.0	11.7	-
	Kategile		Mangazeni	Urio	Urio	Biwi
	1979		1982	1981	1981	1986

* Supplementary rations for grazing steers, others are complete diets.

References

Biwi K.M. 1986. The effect of feeding sodium hydroxide 'dip' treated and untreated maize stover to lactating dairy cattle. M.Sc. Thesis, Sokoine University of Agriculture, Morogoro.

French M.H. 1943. Feeding values of stover from maize, millet and bulrush millet. East African Agricultural Journal 9: 88 - 89.

Kategile J.A. 1978. Improvement of the nutritive value of maize cobs using sodium hydroxide. Ph.D. Thesis. University of Dar es Salaam.

Kategile J.A. 1979. Performance of heifers fed on diets based on NaOH-treated maize cobs and the effect of supplementary urea and source of carbohydrates. Animal Feed Science and Technology 4: 97 - 107.

Kategile J.A. 1981. Digestibility of low quality roughages supplemented with concentrates. In the utilization of low quality roughages in Africa; proceedings of workshop held in Arusha, Tanzania. Edited by Kategile J.A., Said A.N. and Sundstol F. AUN Agricultural Development Report No 1 Aas NLH-Norway.

Kossila V.L. 1985. Global review of the potential use of crop residues as animal feed. In FAO Animal Production and Health Paper 50, 1 - 13. FAO Rome.

Mangezeni S. 1982. Performance of steers fed on supplementary diets based on NaOH-treated maize cobs and urea. M.Sc. Thesis, University of Dar es Salaam.

Marketing Development Bureau 1985. Price Policy Recommendations for the 1985 Agricultural Price Review. Vol. 1, Maize, Rice and Wheat. Marketing Development Bureau, Dar es Salaam, 1985 R 4/85.

Musimba N.K.R. 1980. Digestibility and nutritive value of maize stover, rice straw, wheat straw and oat straw treated with sodium hydroxide (NaOH) and Magadi soda. M.Sc. Thesis, University of Nairobi.

Urio N.A. 1981. Alkali treatment of roughages and energy utilization of treated roughages fed to sheep and goats. Ph.D. Thesis, University of Dar es Salaam.