Utilization of soybean milk residue, cowpea testa and corn starch residue by weaner rabbits

S M Odeyinka, A S Olosunde and O J Oyedele

Department of Animal Science, Faculty of Agriculture, Obafemi Awolowo University, Ile-Ife, Nigeria
smodeyinka@yahoo.co.uk   or   sodeyink@oauife.edu.ng

Abstract

In a fourteen week trial, fifty-six weaner rabbits comprising of New Zealand White, Chinchilla and California breeds of both sexes, aged 5-6weeks, and weighing 250.6g-596.0g were equally allotted to four experimental diets in a completely randomized design to evaluate and determine the utilization of soybean milk residue, cowpea testa (cowpea seed waste), corn starch residue and maize-groundnut-cake (a control diet) by rabbits.

There were no significant differences in the mean dry matter intakes of animals on the four diets. The mean dry matter intake (48.36g/day/animal) on the control maize-groundnut (CD) diet was lower than mean values of 48.84, 48.80 and 49.5g/day/animal, obtained by feeding soybean milk residue (SMRD), corn starch residue (CSRD) and cowpea testa (CTD) based diets respectively. Differences in the weight gains of animals on the four diets were not significant. Feed conversation ratio was 4.12, 4.08, 4.35 and 4.69 for animals fed CD, SMRD, CSRD and CTD, respectively.

There was no significant difference in hot dressing percentage. The dressing percentage was 52.5, 52.9, 53.3 and 51.3% for animals fed CD, SMRD, CTD and CSRD diets, respectively. The weights of the kidney, stomach, kidney fat, head, heart, lung and skin of rabbits on different diets were not significantly different (P>0.05) while the liver, caecum and small intestine were significantly different (P<0.05).

Weaner rabbits can utilize soybean milk residue, cowpea testa and corn starch residue without adverse effect on their performance. Soybean milk residue, corn starch residue and cowpea testa can replace maize and groundnut cake in the diet of weaner rabbits.

Keywords: corn starch residue, cowpea testa, soybean milk residue, weaner rabbit

Introduction

Inadequate animal protein in the diets of people in developing countries has called for the integration of some non-conventional protein sources into livestock production. Productivity of these livestock will depend to a large extent on their ability to utilize feeds that have no value in human feeding.

Rabbits have a number of characteristics that might be advantageous to smallholder subsistence type integrated farming system. The small body size, short generation interval, rapid growth rate, genetic diversity and high reproductive potentials are characteristics, which make rabbit suitable as meat producing small livestock in developing countries (Arijeniwa et al 2000). The nutrition of rabbit in Nigeria is primarily based on grasses (mainly Panicum maximum) and legumes (mainly Centrosema pubescens and Stylosanthes guianensis).Their growth and availability in the dry season cannot sustain all-year round rabbit production thus necessitating supplementation with cereal grains amongst others. Some studies have been carried out on the replacement or supplementation of cereal grains in rabbit pellet as alternative protein/energy source (Omole and Ajayi 1976) Cereal-based feeds are generally too expensive for use as supplements (Hulman 1988).

Little is known about the potential of cereal by-products and bean residues in rabbit nutrition. Raharjo et al (1986) however noted that cereal by-products have high digestible energy content for rabbits. Hence, this study was undertaken to evaluate the growth performance and carcass characteristics of weaner rabbits fed soybean milk residue, cowpea testa and corn starch residue.
 

Materials and methods

Animals and housing

The experiment was conducted at the Rabbit Unit of the Teaching and Research Farm, Obafemi Awolowo University, Nigeria. Fifty-six weaner rabbits comprising of New Zealand White, Chinchilla and California breeds of both sexes were used in this experiment. The animals were 5-6 weeks old and weighed between 250.6g-596.0g. They were randomly allotted to four treatments in a completely randomized design. The experimental animals were housed two per hutch, and maintained in cages with wire screen floors raised to a height of 90cm from the concrete. Row cages of size 76cm x 62cm x 42cm each were used.

Diets

Four rations were formulated in such a way that soybean milk residue (SMR), cowpea testa (CT) and corn starch residue (CSR) served as sources of nitrogen. The SMR, CT and CSR were made up of 20.5% each to replace 5% of GNC and 15.5% of maize in the control diet. The animals were fed 4% of their body weight on dry matter basis daily. The residues were prepared as described by Odeyinka et al (2003). Each residue was air dried for three days to reduce moisture content and formulated into an experimental diet, fed to the rabbits

Data collection

The animals were subjected to 14-day adaptation period. Growth and digestion trials lasted for 14 weeks. Each animal was weighed before the commencement of the experimental period and weekly throughout the period. The feed leftover was weighed to estimate the previous day's feed taken by each animal.

Carcass evaluation

Five rabbits per treatment were selected for postmortem studies after the completion of the experiment based on similarity in weight and were killed for carcass evaluation. Dislocating its neck, while the skin, head, stomach, kidney, kidney fat, intestine, liver, lungs, and heart were removed before weighing the carcass.

The small intestine and caecum (without the appendix) were measured while lying on a wet, coated plywood draining board, so as to avoid any artificial stretching. The stomach, small intestine and caecum were opened and the contents removed under a gentle flow of water, and then allowed to drain for sometime before weighing. Water or blood that may have adhered to the liver and kidney was removed with filter paper. The kidney fat (being a reasonable estimate of overall fatness) was also weighed.

Chemical and data analyses

The composition of the experimental diet is shown in Table 1.

Experimental diets and faeces were analyzed for proximate composition using the methods of AOAC (1990). All data obtained were statistically analyzed with the general linear model of SAS (1998) and the Duncan multiple range tests were used to detect significant differences among means.
 

Results and discussion

The chemical composition of the diets (Table 2) was satisfactory enough to meet the requirements of all stages of rabbits fed solely or compounded for rabbits ration (NRC 1977 and Lebas 1988).

Dry matter intake and weight gain

The dry matter intake g/day of the rabbits on different diets was not significantly different (P>0.05) (Table 3).

The mean dry matter intakes (g/day) of the weaner rabbits fed the experimental diets are shown in Table 3. The mean dry matter feed intakes was 48.36, 48.84, 49.56 and 48.80g for rabbits fed CD SMRD, CSRD and CTD diets respectively. There was no significant difference (P>0.05) between the mean dry matter intakes.

The mean daily weight gains (g/day) of the weaner rabbits fed the experimental diets are shown in Table 3. The mean daily weight gains were 11.75, 11.98, 11.40 and 10.40g/day/animal for rabbits fed supplementary CD, SMRD, CSRD and CTD respectively. There was no significant difference (P>0.05) between the mean daily weight gains. Animals in all the treatments were in a positive weight balance. The highest daily weight gain was recorded for weaner rabbits fed the SMRD (11.98g per day), which was statistically similar (P>0.05) to what was obtained with those on other diets. CTD diet promoted the highest feed conversion ratio 4.96 (table 3) compared with SMRD, CSRD and CD diets though not statistically significant. The results agreed with the growth performance of rabbits reported from some tropical countries (Lukefahr and Cheeke 1990; Muir and Massaete 1996, Akinfala et al 2003 and Iyayi and Odueso 2003) but lower than those reported by Sarwatt et al 2003, Hongthong et al 2004, Tran Hoang Chat et al 2005 and Pok Samkol et al 2006 who fed water spinach (Ipomoea aquatica) to rabbits. They were however higher than the weight gains by rabbits fed Stylosanthes guianensis (Hongthong et al 2004).

The animals on SMRD had the highest apparent digestibility for all the parameters and the difference was significantly different from the other diets (P<0.05) (Table 4).

The results were similar to the one obtained for apparent digestibility (Raharjo et al (1986) for woody legumes but higher than that of non- woody legumes such a Centrocema pubescens that is commonly fed to rabbits in Nigeria but lower than that of rabbits on Ipomea aquatica (Hongthong et al 2004).

Carcass evaluation

Table 5 shows the means of the parameters used in determining the carcass characteristics of weaner rabbits fed CD, SMRD, CSRD and CTD diets.

Animals fed SMRD had higher mean dressing percentage, which was not significantly different from those of the rabbits, fed CSRD, CTD and CD (Table 5). The mean dressing percentage was 52.5, 52.9, 53.3 and 51.3% for animals fed DC, SMRD, CTD and CSRD diets, respectively. The kidney, stomach, kidney fat, head, heart, lung and skin observed were not significantly different (P>0.05). The liver, caecum and small intestine were significantly different (P<0.05). The mean values obtained for lung weight was 53.4, 46.6, 44.9 and 42.3g for animals fed CD, SMRD, CSRD and CTD diets, respectively; caecum was 1.5, 1.0, 0.6 and 0.6g for animals fed CSRD, CD, SMRD and CTD diets, respectively; small intestine was 0.7, 0.6, 0.5 and 0.4g for animals fed CSRD, SMRD, CTD and CD diets, respectively (P<0.05). The experimental diets had no influence on the remaining external and internal organs measured. The results agree with previous studies on rabbits` carcass characteristics (Iyayi and Odueso 2003 and Amaefule et al 2005).

Economic analysis

The costs of maize and groundnut cake as feed ingredients for the composition of weaner rabbits diet is higher than that of soybean milk residue, corn starch residue and cowpea testa. N54 per Kg, N48 per Kg, N10 per Kg, N20 per Kg and N20 per Kg for maize, groundnut cake, cowpea testa, corn starch residue and soybean milk residue respectively [1 U.S dollar ($) = 130 Nigerian naira (N)].

The residues used in this study were cheaper than conventional concentrates for rabbits and are not edible to man. Alawa et al (1990) advocated that to make rabbit rearing more viable as a small -scale business, there must be the development of alternative feeding materials that will be relatively cheap when compared with commercial feeds or conventional feedstuffs.
 

Conclusions

• Weaner rabbits can utilize soybean milk residue diet, corn starch residue diet and cowpea testa diet without any adverse effect on their growth performance and carcass characteristics.

• Comparing the results of the study with those of rabbits fed on Ipomoea aquatica, it is evident that future research should be directed towards the use of "protein-rich tropical foliages" and not starch-rich concentrates.
   

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