Citation of this paper

Effect of cassava pulp substituting maize on the growth performance and haemato-biochemical attributes of broiler chickens

N O Oyewole, S A Akinyele and M H Ogunsipe¹

Department of Science Technology, Federal Polytechnic Ado Ekiti
moogunsipe2009@gmail.com
¹ Animal Production Unit, Department of Agricultural Science, Adeyemi College of Education, Ondo, Nigeria

Abstract

Broiler-chickens were fed for 56 days on diets in which dried cassava pulp replaced maize at levels of 0, 20, 40 and 60%cof the diet.

There were 7% linear decreases in growth rate and feed efficiency as cassava root pulp meal replaced maize at 60% of the diet. The heart and kidneys were enlarged as maize was replaced by cassava pulp.

Keywords: feed conversion, HCN, heart, kidney

Introduction

The search for alternative feed resources in livestock production, particularly for poultry, has been a major concern of animal researchers. Maize remains the first-choice energy source for livestock, while soybean meal is the chief plant protein source, particularly for monogastric animals. The price of these ingredients has increased beyond their economic use in poultry diets. Thus, many small and medium poultry farms in Nigeria are finding it difficult to remain in business.

Maize production in Africa represents about 7.5% of the world production. The largest Africa producer is Nigeria with 11 million tonnes in 2019, followed by South Africa, Egypt and Ethiopia. Africa imports nearly as much maize as it produces with Nigeria importing about 200,000 metric tonnes in 2017 increasing to 400,000 metric tonnes in 2018 and 2019 (Table 1).

Table 1. Maize importation in Nigeria in the last 8 years
Market Year	Imports	Growth Rate

2012	200,000	100.00 %
2013	200,000	0.00 %
2014	150,000	-25.00 %
2015	200,000	33.33 %
2016	650,000	225.00 %
2017	200,000	-69.23 %
2018	400,000	100.00 %
2019	400,000	0.00 %
Source: FAS/USDA 2019

Within the past 20 years or more, Nigeria remains the largest producer of cassava in the world estimated at about 37 million metric tonnes in 2012 out of the total world production of over 280 million metric tonnes (FAO 2013). In 2017, Nigeria produced 59 million tonnes making her the world’s largest producer (approximately 20% of the global production) with a 37% increase in the last decade (IITA 2017). Cassava root upon processing generates a lot of byproducts/wastes which include pulp, peel, seivate, leaves and discarded root tubers. Cassava pulp is the waste generated from cassava root processing for the extraction of starch.

The process of starch granule-cassava pulp separation is achieved by crushing of the cells and separation of the granules from other insoluble matter (adhering dirt and cell-wall material) including the preparatory operations of washing and peeling the roots, rasping them and straining the pulp with the addition of water. The residual pulp which is separated from the starch in the screening process is used as animal feed. This product is considered a byproduct of the cassava starch industry and represents about 10 percent by weight of the cassava roots.

This waste which is often drained as effluent by the factory constitutes an environmental hazard to the factory as well as the host community with consequential effect on human health arising from the repugnant odour from its decomposition. The evacuation of this waste also constitutes additional overhead cost on the factory which affects their revenue. This waste remains not fully exploited in broiler chicken diets.

It is hoped that the use of cassava pulp in broiler chicken diets will help mitigate the environmental concerns and health challenges arising from the dumping and decomposition of the waste. It will also stem the demand for maize as the sole energy source in broiler chicken diets with additional advantage of improving poultry farmers’ income.

Materials and methods

Collection and processing of cassava pulp meal

Cassava pulp used for this study was collected fresh from a local cassava processing factory. The pulp was sun-dried with regular turning for about 5 days on a tarpaulin spread on a concrete floor. The dried pulp was milled using hammer mill and stored in cool dry place prior to use.

The dried cassava pulp was analyzed for proximate composition as described by AOAC (2002). . Cyanide was determined was by the method of Rao et al (1997), tannin was determined according to Makkar and Goodchild (1996) and oxalate by the method of Baker and Silverton (1985).

Experimental design

The experimental design was a completely randomized block with cassava pulp meal substituted for maize at 0 (control), 20, 40 and 60% levels (Table 2).

One hundred and twenty day-old broiler chicks were randomly distributed to each of the 4 diets which were fed ad-libitum for a period of 56 days. Cool water was served at all times. Records of daily feed intake and group weight changes were taken throughout the experimental period.

Feed intake was calculated as the difference between the feed given and the quantity of feed remaining after removing foreign material. Feed conversion ratio was calculated as feed consumed/live weight gain.

Slaughtering, evisceration and haemato-biochemical determination

After 56 day, 3 birds from each replicate were chosen at random, weighed, starved overnight, weighed again, stunned, sacrificed and bled and the dressed carcasses eviscerated. The organs measured were heart, lung, liver, spleen, kidney, gizzard and the intestinal length. All the organs measured were expressed in g/kg live weight while the dressed carcass and eviscerated weights were expressed as % live weight. Blood was collected into EDTA bottles for haematological determination; other blood samples were collected into sterile bottle without EDTA for serum biochemical determination using commercial kits (Reflectron^® Plus 8C79 (Roche Diagnostic, GombH Mahnheim, Germany).

Statistical analysis

Data collected were subjected to analysis of variance procedure using SAS (2002) version 9.1. Means were compared using the appropriate option of the same statistical software.

Table 2. Gross composition of diets in which maize was substituted by cassava pulp meal
Feed ingredients, kg	Cassava pulp meal, % in the diet
	0	20	40	60	0	20	40	60
	Broiler starters				Broiler finisher

Maize	52.53	42.03	31.53	21.01	55.59	44.47	33.35	24.24
Cassava pulp meal	-	10.50	21.00	31.52	-	11.12	22.24	33.35
Soybean meal	22.50	22.50	22.50	22.50	21.42	21.24	21.24	21.24
Groundnut cake	14.17	14.17	14.17	14.17	11.94	11.94	11.94	11.94
Fish meal	5.00	5.00	5.00	5.00	4.50	4.50	4.50	4.50
Bone meal	2.00	2.00	2.00	2.00	2.50	2.50	2.50	2.50
Oyster shell	0.50	0.50	0.50	0.50	0.60	0.60	0.60	0.60
Premix	0.25	0.25	0.25	0.25	0.20	0.20	0.20	0.20
Lysine	0.11	0.11	0.11	0.11	0.10	0.10	0.10	0.10
DL- Methionine	0.11	0.11	0.11	0.11	0.10	0.10	0.10	0.10
Salt	0.30	0.30	0.30	0.30	0.35	0.35	0.35	0.35
Vegetable oil	2.50	2.50	2.50	2.50	2.70	2.70	2.70	2.70

Results

Chemical composition of diets

Compared with maize, cassava pulp had lower crude protein and ether extract but higher crude fiber and ash content (Table 3).

Table 3. Chemical composition of cassava pulp compared with maize
Proximate composition, g/100g	Cassava pulp	Maize #

Dry matter, %	88.6
Crude protein	3.95	9.4
Crude fibre	20.0	2.5
Ether extract	3.35	4.3
Ash	4.12	1.4
Nitrogen free extract	57.2
Phytochemical components
Cyanide CN^-, mg/kg	23.9
Tannin, g/100g	0.08
Oxalate, mg/kg	269
# http://feedipedia.org/node/556

Performance traits

There were linear trends in performance criteria of the broilers as maize was replaced by cassava pulp (Table 4; Figures 1-3). Feed intake increased, weight gain decreased and feed conversion increased as cassava pulp replaced maize in the diet. At the highest levels of substitution of maize by cassava pulp, the performance indices were reduced by about 7%

Table 4. Performance of broiler chickens fed increasing levels of cassava pulp meal substituting maize
	Cassava pulp meal, % in the diet				SEM	p
	0	20	40	60	SEM	p

Live weight/bird
Initial, g	50.3	50.5	50.5	50.4	0.52	0.91
Final, kg	2.37^a	2.37^a	2.31^b	2.27^b	0.06	<0.04
Daily gain, g	41.4^a	41.4^a	40.3^b	39.6^b	0.04	<0.03
Feed intake, g/d	100	101	102	103	1.99	0.69
Feed conversion	2.42	2.45	2.54	2.60	0.21	0.35
^abcd Means without common superscripts along the same row differ at p< 0.05


Figure 1. Effect of replacing maize with cassava root pulp on feed intake of broilers	Figure 2. Effect of replacing maize with cassava pulp on weight gain of broilers

Figure 3. Effect of replacing maize with cassava pulp on feed conversion of broilers

Carcass attributes

The dressed carcass as percent of live weight was not affected by dietary levels of carcass pulp; however, the eviscerated carcass as percent of live weight showed a negative trend as cassava pulp in the diet was increased (Table 5).The weights of heart and kidney showed an increase relative to live weight as cassava pulp levels in the diet were increased.

Table 5. Carcass evaluation (% live weight) and organ description (g/kg live weight) of broiler chickens fed increasing levels of cassava pulp meal substituting maize
	Cassava pulp, % in the diet				SEM	p
	0	20	40	60	SEM	p

Carcass attributes
Dressed % of LW	86.3	85.2	84.6	84.6	0.81	0.29
Eviscerated % of LW	76.2^a	76.9^a	75.2^a	73.9^b	0.72	0.02
Relative organ weights, g/kg LW
Heart	3.78^b	4.16^a	4.22^a	4.19^a	0.39	<0.03
Lung	5.83	5.83	5.85	5.89	0.19	0.14
Liver	18.0^b	18.1^b	18.2^b	18.5^a	0.44	<0.04
Spleen	1.16	1.17	1.17	1.16	0.18	0.11
Kidney	4.32^b	4.42^b	4.42^b	4.63^a	0.31	<0.02
Gizzard	18.8	19.7	19.8	20.4	0.62	0.39
Intestinal length, mm	2094	2204	2233	2230	6.03	0.31
^ab Means without common superscripts along the same row are different at P< 0.05

Haemato-biochemical attributes

Among the haemato-biochemical variables only aspartate transaminase was related to increasing cassava pulp in the diet (Table 6).

Table 6. Haemato-biochemical of broiler chickens fed increasing levels of cassava pulp meal substituting maize
	Cassava root pulp, % in the diet				SEM	p
	0	20	40	60	SEM	p

Haematological indices
Packed cell volume, %	33.1	32.1	32.1	32.3	0.36	0.54
Red blood cell counts, 10⁹/ml	3.50	3.44	3.35	3.49	0.21	0.15
Hb, g/dL	10.9	10.4	10.2	10.6	0.26	0.31
Serum chemistry
Total serum protein, g/dL	3.87	3.85	3.79	3.85	0.11	0.42
Cholesterol, mg/dL	132	132	131	132	1.21	0.63
ALT, u/l	1.74	1.75	1.76	1.76	0.12	0.87
AST, u/l	238^b	247^ab	255^a	256^a	4.06	<0.03
^ab Means without common superscripts along the same row differ at p< 0.05

Discussion

The negative trends in performance traits, with increasing levels of cassava pulp replacing maize, were relatively small (about 7% lower weight gain and poorer feed conversion at the maximum (60%) degree of replacement of maize by cassava pulp) and probably reflected the increased levels of fiber in cassava pulp compared with maize (Table 3). The detoxification of the cyanogenic precursors in the cassava pulp (Table 3) would have a metabolic cost to the birds as reflected in enlargement of the heart and kidneys with increasing levels of cassava pulp in the diet. The detoxification of HCN requires sulphur either from methionine-cystine or elemental sulphur in the diet.

In any event, the small negative response (7%) due to cassava pulp replacement of maize should be viewed against: (i) the relative costs (maize is more expensive than cassava); and (ii) cassava pulp, as a by-product of starch manufacture, may have a negative cost if it is otherwise wasted, causing pollution. From the environment standpoint, much of the maize used in Africa is imported and its production in, and transport from, importing countries is associated with a loss of biodiversity and major emissions of greenhouse gases. Replacing imported maize by locally produced cassava can thus be interpreted as a contribution to the global strategy for reducing greenhouse gas emissions and loss of biodiversity.

Conclusions

Including cassava root pulp at 60% of a broiler diet, replacing maize, led to:

7% linear decrease in growth rate and feed efficiency
The enlargement of the heart and kidneys

References

AOAC 2002 Association of Analytical Chemist. Official Method of Analysis. 18^th edition. Washington DC., USA www.aoac.org

Baker F J and Silverton R E 1985 Introduction to Medical Laboratory Technology, 6^th Ed., Butterworth, England, pp: 304-346

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IITA 2019 International Institute for Tropical Agriculture www.iita.org

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