Effect of feeding cassava fruit coat meal on the nutrient digestibility and performance of broilers

E A Iyayi and F K Fayoyin*

Institut für Enährungswissenchaften, Martin-Luther-Universität, Emil-Abderhaldenstr. 26, 06108 Halle, Germany.
^*Department of Animal Science, University of Ibadan, Ibadan, Nigeria.
iyayi@landw.uni-halle.de and eaiyayi@yahoo.com

Abstract

The replacement value of a by-product of cassava harvesting - cassava fruit coat (CFC) meal -  for wheat bran  for broiler production was investigated. CFC was produced by milling dried cassava fruits often discarded after harvesting the roots and stems. The CFC meal was used to replace 25, 50, 75 and 100% wheat bran (w/w) in a basal diet for broilers. Seventy-five one-week old broiler chicks were distributed into 15 pens each holding 5 birds. Each of the 5 experimental diets was allocated at random to 3 pens. At the end of the first 4 weeks (starter phase), the diets were switched to finisher diets for a further 4-week period. Feed and water were supplied ad libitum. Data were recorded and analysed on pen basis. CFC meal had a crude protein of 44 g/kg and crude fibre of 149 g/kg.

All production parameters, other than mortality, deteriorated as the degreed of substitution of wheat bran by CFC was increased. The apparent digestibilities of dry matter and nutrients were significantly (p<0.05) reduced by dietary increase in level of CFC.

It is concluded that CFC  can replace up to 50% of the wheat bran requirement for feeding broilers in the finisher phase, but higher levels markedly reduce performance.

Key words: Broilers, cassava fruit coat meal, performance

Introduction

Feed resources are a major input in poultry production systems in Nigeria. It is estimated that feed accounts for about 60 percent of total production costs in the commercial poultry sector. The Nigerian poultry industry was dealt a severe blow when unfavourable government policies in the 80s caused a dramatic reduction in the poultry population from 40 million birds to 6 million in the mid 90s. However, recent government policies, like the ban on the importation of frozen chickens and the support for the search of local alternatives to replace the imported conventional ones, have given cause to a steady rise in poultry production again. The use of unconventional feed resources could be one way of expanding the feed resource base of poultry production because the unconventional ration is cheaper than grain-based ration. Moreover, various techniques to produce unconventional feed resources in the tropics have been reported, although on a small-scale basis. Most of the research on these feedstuffs (reviewed by Musharaf 1990; Sonaiya 1993) have been based on intensive poultry production units. Agro-industrial by-products (AIBs) have in recent times been the focus of research in animal nutrition especially for monogastric animals. In fact, many feeds which can be fed alternatively at cheaper cost to monogastric livestock are based on the use of AIBs which are usually of no food value to humans. Babatunde (1989) reported that integration of many of these AIBs into animal feeding holds tremendous potentials in alleviating the existing situation of inadequate feed supply in the Nigerian poultry industry.

Nigeria is the leading world producer of cassava, whose roots supply energy to millions of people in the country. Its fruit can also be of value for poultry feeding. Flowering in some cultivars is frequent and regular. After pollination and subsequent fertilization, cassava ovaries develop into young fruits. The mature fruit is a capsule, globular in shape with woody endocarp (fruit coat). The coat splits explosively to release and disperse the seeds when dry (Onwueme and Charles 1994). Cassava fruit coat (CFC) is free of hydrocyanic acid (HCN), the antinutritive factor and toxic component in cassava which is found in the roots, branches and leaves of the plant. Cassava fruit coat is abundant in rural areas where flowering cultivars are grown. Its low fibre content makes it a potential dietary ingredient for rural poultry feeding. The aim of this study was to investigate the effect of replacement of wheat bran (a conventional poultry ingredient) with cassava fruit coat on the nutrient digestibility, growth performance and carcass measures of broilers.

Materials and methods

Cassava fruit coat was obtained from cassava plots at the International Institute for Tropical Agriculture (IITA), Ibadan, Nigeria. The material was milled with the sieve in the milling machine adjusted such that the milled CFC had the same coarse size as the wheat bran used in the study. Seventy-five one week old broiler chicks were randomly distributed into 5 experimental treatments of 3 replicates. Each replicate had 5 birds. The diets were formulated such that the cassava fruit coat meal replaced wheat bran at 25, 50, 75 and 100% levels in the diets at both the starter and finisher phases. The diets were made up with other ingredients such that the birds' requirements for nutrients were met (Tables 1 and 2). The proximate compositions of the diets and CFC meal were analysed by the method of AOAC (1990).

Table1. Composition of experimental diets for broilers at starter phase
Ingredients, g / kg	CFC0	CFC25	CFC50	CFC75	CFC100
Level of CFC replacement, %	0	25	50	75	100
Maize	400	400	400	400	400
Wheat bran	273	204.75	136.50	68.25	-
Cassava fruit coat meal	-	68.25	136.50	204.75	273
Groundnut cake	150	150	150	150	150
Soy bean meal	100	100	100	100	100
Fish meal	40	40	40	40	40
Bone meal	20	20	20	20	20
Oyster shell	10	10	10	10	10
Premix*	2.5	2.5	2.5	2.5	2.5
Salt	2.5	2.5	2.5	2.5	2.5
Methionine	1.0	1.0	1.0	1.0	1.0
Lysine	1.0	1.0	1.0	1.0	1.0
Total	1000	1000	1000	1000	1000
Analysed chemical composition
Crude protein, g/kg	232	222	216	210	209
Crude fibre, g/kg	56.9	59.7	66.9	67.3	69.8
Fat	52.8	52.3	51.6	42.9	41.6
Ash	160	159	151	129	128
Dry matter	807	855	828	843	850
ME, MJ	10,980	11,013	11,050	11,087	11,124
Micro-mix broiler premix supplied the following per 2.5 kg: Vitamin A: 12, 500,000.00 I.U., Vita mine D3: 2, 500, 000.00 I.U., Vitamin E: 40, 000, 000.00 mg; Vitamin B2 5,500.00 mg; Niacin: 5, 500.00 mg; Vitamin B1 3, 000.00 mg; Calcium Pantothenate: 11, 500.00 mg; Vitamin B6: 500.00 mg; Vitamin B12: 25.00 mg; Folic acid: 1,000.00 mg; Iron: 100, 000.00 mg; Zinc: 80, 000.00 mg; Copper: 8,500.00 mg; Iodine:  1,500.00 mg; Cobalt: 300.00 mg; Selenium: 120.00 mg; Anti-oxidant: 120,000.00 mg

Table 2. Composition of experimental diets for broilers at finisher phase
Ingredients, g / Kg	CFC0	CFC25	CFC50	CFC75	CFC100
Level of CFC replacement, %	0	25	50	75	100
Maize	400	400	400	400	400
Wheat bran	308	231	154	77	-
Cassava fruit coat meal	-	77	154	231	308
Groundnut cake	125	125	125	125	125
Soy bean meal	100	100	100	100	100
Fish meal	30	30	30	30	30
Bone meal	20	20	20	20	20
Oyster shell	10	10	10	10	10
Premix*	2.5	2.5	2.5	2.5	2.5
Salt	2.5	2.5	2.5	2.5	2.5
Methionine	1.0	1.0	1.0	1.0	1.0
Lysine	1.0	1.0	1.0	1.0	1.0
Total	1000	1000	1000	1000	1000
Analysed chemical composition
Crude protein, g/kg	218.30	216.4	215.50	208.80	201.80
Crude fibre, g/kg	65.80	89.60	98.50	101.50	103.60
Fat	51.40	50.70	49.20	40.6	39.20
Ash	101	91.40	89.8	88.70	86.10
Dry matter	860.70	867.40	86.50	869.20	844.4
ME, MJ	10, 856	10, 897	10, 939	10, 980	11, 021
*Micro-mix broiler premix supplied the following per 2.5 kg: Vitamin A: 12, 500,000.00 I.U., Vita mine D3: 2, 500, 000.00 I.U., Vitamin E: 40, 000, 000.00 mg; Vitamin B2 5,500.00 mg; Niacin: 5, 500.00 mg; Vitamin B1 3, 000.00 mg; Calcium Pantothenate: 11, 500.00 mg; Vitamin B6: 500.00 mg; Vitamin B12: 25.00 mg; Folic acid: 1,000.00 mg; Iron: 100, 000.00 mg; Zinc: 80, 000.00 mg; Copper: 8,500.00 mg; Iodine: 1,500.00 mg; Cobalt: 300.00 mg; Selenium: 120.00 mg; Anti-oxidant: 120,000.00 mg

The birds were fed for 4 weeks on the starter diet after which the diets were switched to finisher diets for another 4 weeks. Vaccination and normal routine management were adhered to. Body weights of the birds were taken at weekly intervals and feed intake determined by deducting the remnant from the total quantity supplied the previous day at specific time. At the end of 8 weeks, another set of birds were placed on the diets in metabolic cages where faeces were collected for five days for apparent nutrient digestibility (% retention) estimates. Fresh faeces were weighed and recorded daily, oven-dried, and weighed again for percent dry matter. Proximate composition of the faeces was also carried out by the method of AOAC (1990).

All data were subjected to one-way analysis of variance (ANOVA); means that were significant were separated by the Duncan multiple range test. Regression analysis was run using the general linear model (SAS 1997).

Results

The protein content of CFC was very low and the usefulness of it for poultry feeding therefore lies on its use as an energy source.

Table 3. Performance of broilers on experimental diets (0-8 weeks)
Parameters	CFC0	CFC25	CFC50	CFC75	CFC100	SEM	P	Reg Equation
Level of CFC replacement, %	0	25	50	75	100
Feed intake, g/ d	161	166	160	154	148	36	NS	Y= 157.78 -1.07x
Weight gain, g / d	66a	68a	67a	54b	48b	17	<0.001	Y= 474.62-1.167x
Feed conversion	2.43a	2.43a	2.38a	2.84b	3.07b	0.16	<0.05	Y= 2.426 + 0.005x
Feed efficiency	0.41a	0.41a	0.42a	0.36b	0.33b	0.02	<0.05	Y= 0.414 – 0.001x
Mortality, %	3.02	2.67	2.67	2.67	1.33	-	-	-
Note: Values with different letters on same row are significantly (p<0.05) different

All production parameters, other than mortality, deteriorated as the degreed of substitution of wheat bran by CFC was increased (Table 3). The apparent digestibilities of dry matter and nutrients (Table 4) were significantly (p<0.05) reduced by dietary increase in level of CFC.

Table 4. Nutrient digestibility (% retention) in broilers fed experimental diets
Parameters	CFC0	CFC25	CFC50	CFC75	CFC100	SEM	P	Reg Equation
Level of CFC replacement, %	0	25	50	75	100
Dry matter	74a	69a	69a	62b	45c	5.93	<0.05	Y=76.302-0.251x
Crude protein	81a	81a	83a	66b	51c	2.56	<0.01	Y=84.793-0.287x
Crude fibre	84a	80a	80a	72b	59c	3.64	<0.01	Y=86.500-0.227x
Ash	77a	72a	72a	66b	51c	4.51	<0.05	Y=79.607-0.239x
Crude fat	89a	88a	88a	81b	75b	2.19	<0.01	Y=91.114-0.141x
Nitrogen free extracts	68a	61a	61a	58b	38c	6.01	<0.05	Y=69.655-0.252x
Note: Values with different letters on same row are significantly (p<0.05) different

Discussion

Cherry (1983) reported that the extent to which an animal will increase its feed consumption is dependent on the fibre source, the lignification of the feed and the chemical variation in the fibre itself. Even though the CFC was milled to the same size as the wheat bran, the physical texture of the CFC, which was reported by Onwueme and Charles (1994) to be woody, could have caused a reduced intake by the birds (Abdelsalamie et al 1991). The reduction in weight gain observed in this study is supported by earlier reports of Summer and Leeson (1986) and Fahey et al (1990) that growth rate of birds is reduced with increased dietary fibre level. Furthermore, reports of Linderman et al (1986) and Gous et al (1990) showed that feed volume increased with increasing levels of dietary inclusion of fibre. Under this condition the nutrient density is reduced. The birds that were on the high CFC based diets could not satisfactorily consume the requisite nutrients for growth.

The results of apparent digestibility agree with the reports of Ibrahim and El-Zubeir (1991) and Lourdes et al (1999). The decreased apparent nutrient digestibility can be attributed to shorter resident time of the more fibrous diets in the intestines of the birds (Cabotaje et al 1992). 

Conclusions

• It is concluded that CFC  can replace up to 50% of the wheat bran requirement for feeding broilers to the finisher phase, but higher levels markedly reduce performance.

Acknowledgement

The authors are grateful to Dr A. G. O. Dixon and Mr Paul Ilona of the Cassava Breeding Unit, IITA, Ibadan, Nigeria for providing the cassava fruit coat.

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