Crop residues and agro-industrial byproducts in Zambia: Availability, utilisation and potential value in ruminant nutrition

E M Aregheore ¹ and A M Chimwano

Department of Animal Science
School of Agricultural Sciences
University of Zambia
PO Box 32379, Lusaka, Zambia

¹ Permanent address:
College of Education
PMB 1251, Warri, Bendel State, Nigeria

ABSTRACT

Large quantities of crop residues and agro-industrial byproducts are produced each year in Zambia. The potential value of these materials in animal nutrition is well known, but little information has been published on their actual utilisation as livestock feed or on their availability to smallholder farmers in the country. Where they are available, most of them are used haphazardly because farmers lack storage facilities and knowledge of how to use them effectively in animal diets. Efforts currently being made to help smallholders solve their animal feed problems are focusing on improving methods of harvesting, handling and processing crop residues and byproducts, and on incorporating them into year-round feed budgets. Improved feeding methods could lead to substantial increases in Zambia's livestock population.

RESUME

Les résidus de récolte et les sous-produits agro-industriels en Zambie: production, utilisation et valeur potentielle pour l'alimentation des ruminants

De grandes quantités de résidus de récolte et de sous-produits agro-industriels sont produits chaque année en Zambie. Alors que leur valeur potentielle en tant qu'aliment du bétail est bien documentée, on ne peut en revanche pas en dire autant de leur utilisation réelle et de leur relative disponibilité au niveau des petits paysans. Ceux-ci les utilisent au petit bonheur faute de matériel de conservation et d'une méthode rationnelle d'introduction de ces produits dans l'alimentation du bétail. Aussi les efforts déployés actuellement en Zambie pour aider les petits éleveurs à mieux nourrir leurs animaux visent-ils en priorité, non seulement d'améliorer leurs méthodes de récolte et de traitement des résidus de récolte et des sous-produits agro-industriels, mais également à les amener à prévoir dans leurs budgets les dépenses annuelles d'achat de ces produits. L'amélioration des méthodes d'alimentation du bétail devrait permettre d'accroître de manière substantielle les effectifs des animaux d'élevage dans le pays.

INTRODUCTION

Zambia's ruminant livestock population currently comprises about 2.4 million cattle, more than 600 000 goats and more than 50 000 sheep. Malnutrition is the major constraint on animal production, especially during the seven-month dry period when grazing ruminants lose weight dramatically. However, Zambia produces sufficient feed resources, in the form of crop residues and agro-industrial byproducts, to make it potentially capable of supporting a much larger animal population. The problem is that these resources may not be readily available to smallholder farmers, or are not being used as effectively as they could be. This paper discusses the availability, utilisation and potential value in ruminant nutrition of agro-industrial byproducts and crop residues in Zambia.

CROP RESIDUES AND AGRO-INDUSTRIAL BYPRODUCTS IN ZAMBIA

Production

Zambia produces a wide variety of cereals and other food crops (Table 1). After these crops have been harvested and processed, various residues and byproducts remain - for example, stovers, straws, husks, cobs and brans from cereal crops; and shells, heads, pulp, peels and tops from other crops.

No accurate data have been published on the quantities of crop residues and agro-industrial byproducts produced in Zambia. However, based on government crop production statistics, and using appropriate crop:residue ratios (Munthali and Dzowela, 1987), it is estimated that more than 3.25 million tonnes of crop residues and byproducts could be available each year (Tables 2 and 3).

Value in livestock nutrition

Basic chemical composition and nutritive value data available for most of the crop residues and agro-industrial byproducts produced in Zambia (Chimwano, 1990) show clearly that they could satisfy the nutritional requirements of ruminant livestock.

Table 1. Provincial distribution of crops in Zambia

Province	Crops
Central	Maize, sweet potato, soybean, groundnut, cotton, watermelon, sunflower, wheat, tobacco
Copperbelt	Maize, sunflower, soybean, beans, groundnut, wheat, oilseeds
Eastern	Maize, soybean, sunflower, orange, sweet potato, cassava, cotton, groundnut, pigeon pea, sorghum
Luapula	Cassava, rice, maize, sunflower, sweet potato, millet beans, banana, groundnut, oilseeds
Lusaka	Maize, soybean, sunflower, sorghum, tobacco, sweet potato, pigeon pea, rice, cotton, wheat, watermelon, orange
Northern	Rice, maize, cassava, sunflower, millet, sweet potatoe, banana, cotton, beaus, soybean, coffee
Northwestern	Maize, pineapple, sweet potato, soybean, sunflower, millet, orange, cassava, faba bean, sorghum, coffee, groundnut, rice
Southern	Maize, soybean, sunflower, tobacco, sugarcane, cotton, banana, millet, oranges
Western	Maize, sorghum, rice, millet, groundnut, faba bean, cassava

Table 2. Annual production of crop residues

Province	Annual production (thousands of tonnes)
	Maize stover	Sorghum stover	Millet stover	Rice straw	Wheat straw	Groundnut straw	Soy/ sweetbean straw	Sunflower heads
Central	586.7	11	1.4	-	1.8	1.4	2.4	8.1
Copperbelt	72.7	18	-	0.1	1.5	0.7	0.8	0.1
Eastern	641.5	9	0.5	1.4	-	9.1	1.0	7.5
Luapula	22.9	0.5	0.1	0.7	-	0.4	0.4	0.1
Lusaka	119.5	6	-	-	5.9	0.4	5.2	1.6
Northern	182.5	0.5	8	5.2	-	1.6	4.6	0.1
Northwestern	20.5	7.2	1.2	0.8	-	0.3	4.7	0.1
Southern	536.0	20.1	0.5	-	1.8	3.8	3.7	7.6
Western	40.8	17.1	11.7	3	-	0.4	-	-
Total	2223.1	90.0	23.4	11.2	11.0	18.1	22.8	25.2

Based on government crop production statistics and stover to grain ratios of 2 1 for maize, sorghum and millet, and straw to grain ratios of 1:1 for rice, wheat, groundnut and soybean (Munthali and Dzowela, 1987)

Table 3. Annual production of agro-industrial byproducts

Province	Annual production (thousands of tonnes)
	Maize bran	Rice bran	Wheat bran	Soybean cake	Cottonseed cake	Sunflower cake
Central	94.6	-	0.3	1.2	77.4	2.5
Copperbelt	11.7	0.1	0.4	0.3	0.8	-
Eastern	103.5	0.1	-	0.2	50.7	2.3
Luapula	3.7	0.7	-	-	0.2	-
Lusaka	19.3	-	1.4	2.4	29.1	0.5
Northern	29.4	0.5	-	0.2	0.4	-
Northwestern	3.3	0.1	-	0.1	0.1	-
Southern	86.5	-	0.5	1.8	233.3	2.3
Western	6.6	0.3	-	-	2.1	-
Total	358.6	1.8	2.5	6.2	484.1	7.6

Based on government crop production statistics end grain to bran/cake ratios of 3.1:1 for maize; 10:1 for rice; 4:1 for wheat; 2:1 for groundnut; and 3.3:1 for cottonseed (Munthali and Dzowela, 1987)

Many of these materials have been studied in detail. For example, orange pulp and peels, byproducts of the citrus industry, are known to be good sources of energy for cattle, small ruminants and even monogastrics (Ammerman et al, 1963; Devendra, 1973). Peels, hulls and pulp of other crops, such as cassava, groundnut, sunflower, soybean, potato, pineapple, banana and watermelon, have also been shown to be of value in livestock nutrition (Ting and Deszyck, 1961; Bhattacharya and Harb, 1973; Devendra, 1973; Cantner, 1987; Balock et al, 1988). Malt screening, brewers' grains and Chibuku (local brew) wastes, tonnes of which are produced annually by Zambia's two breweries (at Lusaka and Ndola), are high in protein and of medium energy, and their value in livestock nutrition is well documented (Adebowale and Ademosun, 1981; Ugye et al, 1988; Aregheore et al, 1990). The use of molasses as a carbohydrate and an energy source has been extensively studied (Reyley, 1961; Shindende, 1990). And milling byproducts such as bran, wheatlings and screenings are important byproducts which, along with oilseed cakes from soybean, groundnut, cotton and sunflower, could form important raw materials in the production of livestock feed in Zambia.

UTILISATION OF CROP RESIDUES AND AGRO-INDUSTRIAL BYPRODUCTS

Little information is available on the extent to which smallholder farmers in Zambia use crop residues and agro-industrial byproducts as livestock feed. It is very likely, however, that these resources are under-utilised. Even when they are utilised, farmers may not be able to incorporate them effectively year-round livestock feeding programmes because they lack suitable storage facilities and technical know-how on treatment and processing methods and on formulating feed rations.

The few crop residues known to be used for livestock nutrition in Zambia are brans, stovers and straws of wheat, maize, sorghum and millet. But these are not used in the most efficient manner; smallholder farmers usually feed them to their stock in situ during harvest seasons.

Most of the valuable agro-industrial byproducts produced in Zambia are not used for livestock production at all, and are simply wasted. The problem is mainly one of availability; food manufacturing and processing industries are generally located in urban centres along the railway lines, and so their byproducts are not readily available to smallholder farmers in the rural areas of the country.

IMPROVING LIVESTOCK PRODUCTION IN ZAMBIA

Ruminant livestock production in Zambia could be increased substantially if more efficient feeding methods could be introduced. Adequate feed resources are potentially available, and so the challenge before animal nutritionists is how to improve their utilisation and hence help smallholder farmers solve their feed problems. Current research is focusing on:

· improving methods of harvesting, handling and storing crop residues so as to reduce wastage

· developing treatment methods that could increase the availability of nutrients

· introducing supplementation techniques to correct nutrient deficiencies

· determining seasonal availability and nutritional values of residues and byproducts with a view to formulating adequate year- round feeding systems

REFERENCES

Adebowale E A and Ademosun AA. 1981. The carcass characteristics and chemical composition of organs and muscles of sheep and goats fed brewers' dried grains-based ration. Tropical Animal Production 6:133-137.

Ammerman C B. Arrington L R. McCall J T. Wing J E and Davis G K. 1963. Nutritive value of dried citrus pulp for steers. Journal of Animal Science 20:398 (Abstract).

Balock G M, Soomro F M, Isani G B and Carpenter J R. 1988. Utilization of banana plant silage as a source of roughage for dairy cows. Journal of Dairy Science 71 (suppl 1): 132 (Abstract).

Bhattacharya A N and Harb M. 1973. Dried citrus pulp as a grain replacement for Awasi lambs. Journal of Animal Science 36:1175-1180.

Cantner E W. 1987. The utilization of agricultural waste products in animal nutrition. Animal Research and Development 26:56-70.

Chimwano A M. 1990. Zambia's farm livestock feedstuffs: Their nutrient content and nutritive value. University of Zambia, Lusaka, Zambia. 12 pp.

Devendra C. 1973. Effect of level of inclusion of citrus meal on the digestibility of concentrate diet for sheep in Trinidad. Tropical Agriculture (Trinidad) 50:221-224.

Munthali J T and Dzowela B H. 1987. Inventory of livestock feeds in Malawi. In: Kategile J A, Said A N and Dzowela B H (eds), Animal feed resources for small-scale livestock producers Proceedings of the second PANESA workshop, held in Nairobi, Kenya, 11-15 November 1985. IDRC-MR165e. IDRC (International Development Research Centre), Nairobi, Kenya. pp. 61-69.

Reyley H B. 1961. Urea-molasses supplementation in dairy cattle. Journal of Animal Nutrition 6:71-82.

Shindende D. 1990. Intake and response of grazing goats to supplements of urea-molasses blocks containing varying amount of cement. Special project report, Department of Animal Science, University of Zambia, Lusaka, Zambia. 19 pp.

Ting S V and Deszyck E J. 1961. The carbohydrates in the peel of oranges and grapefruits. Journal of Food Science 26:146-152.

Ugye B H. Anugwa F I O and Nwosu C C. 1988. Effects of varying levels of dietary dried brewers' grains on performance and carcass characteristics of growing pigs. Bulletin of Animal Health and Production in Africa 36:3137.