Effects of dietary replacement of maize with malted or unmalted sorghum on the performance of weaner rabbits

M Abubakar, U D Doma, D J U Kalla, M B Ngele and C L D Augustine^*

Animal Production Programme, Abubakar Tafawa Balewa University, PMB 0248, Bauchi, Nigeria
mabubakarkobi@yahoo.co.uk
^*VeterinaryHospital, Ministry of Agriculture and Natural Resources, Jos, Plateau State, Nigeria                           

Abstract

A feeding trial was conducted using twenty-one, 8 to 9 weeks old weaner rabbits allotted to three groups of seven animals each in a completely randomized design. The study which lasted for six weeks was undertaken to investigate the effects of dietary replacement of maize as a source of energy with malted or un-malted sorghum on the performance of the animals.

The rabbits fed malted sorghum based diet had a similar dry matter intake to those on the maize based diet, but significantly higher than those on the unmalted sorghum based diet. All the animals gained weight, at rates similar across the treatments, indicating that the intake of energy and proteins were well above maintenance requirements. The best feed efficiency was recorded for rabbits fed on the malted sorghum based diet. The financial analysis revealed that feed cost per kg body weight gain was lowest for animals on the malted and unmalted sorghum based diets.

It is concluded that malted or unmalted sorghum could effectively replace maize as a source of energy in diets for weaner rabbits without any adverse effects on performance and with reduced cost of feed per kg body weight gain.

Keywords: maize, performance, rabbits, sorghum

Introduction

Rabbit production has a considerable potential in the developing countries for the supply of the much needed animal protein due to the low capital investment and space requirements, short generation interval, rapid growth rate, high reproductive potential and ability to utilize the abundant forages and fibrous agricultural by- products (Cheeke 1986; Biobaku 1994; Joseph et al 1997).

In spite of these advantages, rabbit production has not received the desired attention in the tropics. Productivity is usually 50% or less of what is typical in the temperate countries (Cheeke 1986).While high temperature (causing heat stress and discomfort) may have contributed to the low productivity (Cheeke 1992), however, inadequate and high cost of feed ingredients brought about mainly by the stiff competition between people and monogastric animals such as the rabbit and poultry for grains, which is the major constraint (Agunbiade et al 2002). Maize grain is the major source of energy in rabbit feeds in  Nigeria, usually accounting for over 40% of the diets (Adegbola and Okonkwo 2002; Bamgbose et al 2004).

Maize is slightly higher in energy content compared to sorghum (Oyenuga 1978). On the other hand, sorghum contains more crude protein than maize (11.00 vs 9.56%) (Oyenuga 1978; Malau-Aduli et al 2003). Sorghum is cheaper than maize and abundantly available in most parts of Northern Nigeria. A measure of sorghum will cost almost half the price of the same quantity of maize. The projected production targets of maize and sorghum in the country for the year 2010 were put at 13,388,000 and 5,977,000 tonnes, respectively (Shaib et al 1997). However, in Bauchi State sorghum was always ahead of maize in terms of output. The figures for 2000 were 362,000 and 238,000 tonnes for sorghum and maize respectively (Anonymous 2003).

A lot of research work has been conducted in Nigeria in an effort to substitute maize with cheaper and readily available ingredients in order to reduce cost and over-dependence on the feedstuff for rabbit feeding. Thus, cassava peel meal (Agunbiade et al 2002), cassava leaf meal (Adegbola and Okwonko 2002), Bread waste meal (Dairo and Ojekale 2004), Jackbean meal (Udedibie et al 2005) and rumen content (Dairo et al 2005) have replaced maize in rabbit diets with moderate results among many other similar studies. However, there is a paucity of information on the utilization of sorghum in rabbit diets in the country.

On the other hand, various processing methods have been employed to improve the nutritional value of cereal grains, one of which is malting. Malting involves steeping grains in water for about 4-10 days. The sprouting grain known as malt is then removed and dried for days by periodically turning it to provide good aeration (Brian and Allen 1961). Malting increases the protein, soluble sugars and lysine and reduces the tannin contents of sorghum (Barrett and Larkin 1974; Wu and Wall 1980; Kubiezek et al 1984; FAO 1995).

This study was therefore designed to investigate the effects of dietary replacement of maize as source of energy with malted or unmalted sorghum on the performance of growing rabbits.

Materials and Methods

Twenty-one New Zealand White rabbits, 8 to 9 weeks of age, with average initial weight of 946g were randomly allotted to three groups of seven animals each, in a completely randomized design. The rabbits were kept in individual cages with facilities for feed and water. Three iso-nitrogenous (16% crude protein) diets were formulated in which maize was substituted with either malted or unmalted sorghum, which were incorporated into the feeds by mixing together the various ingredients. Proximate components of maize, unmalted and malted sorghum were determined according to AOAC (1995) methods as shown in Table 1. Composition of the experimental diets and calculated nutrient contents are presented in Table 2.

The metabolisable energy (ME, kcal/kg) of maize, unmalted and malted sorghum were estimated using the methods of Pauzenga (1985) as follows:

ME=35 X CP% + 81.8 X EE% + 35.5 X NFE%

Each rabbit was provided with 100g of the diet at 0700h and left over were collected and weighed before the next morning feeding. Clean, cool water was provided ad lib. The rabbits were weighed on weekly basis and feeding lasted for six weeks. All data were subjected to one-way analysis of variance and significant differences between means were separated by least significant difference method (Steel and Torrie 1980).

Results and Discussion

Data on feed intake, live weight changes and feed efficiency are presented in Table 3.

Economics of replacing maize with malted or unmalted sorghum in rabbit diets is shown in Table 4.

The daily dry matter intake (DMI) of rabbits on the maize and malted sorghum-based diets was significantly (P<0.05) higher than those on the unmalted sorghum-based diet. The DMI of the diets (50.70 to 60.67g/ day) were similar to those of Adegbola and Okonkwo (2002) (53.00 to 66.85g/ day) reported for rabbits fed diets containing 24.4 to 61.0 % maize and varying levels of cassava leaf meal and 53.50 to 65.46g/day reported by Doma et al (1999) for rabbits fed diets containing 25.30 to 50.70% maize and 20 and 40% varying levels of cowpea shell and maize cobs. However, the DMI values obtained are higher than the 47.40 to 50.10 g/day reported by Udedibie et al (2005) for rabbits fed varying levels of cracked and cooked Jackbean and Jackbean soaked in water prior to cooking in diets containing 32.50 to 55.00 % maize and having 3.52 to 4.52 % crude fibre contents. The fibre level of feed has been found to effect intake and digestibility in rabbits (Adegbola and Osuji 1985) and DMI was found to increase significantly as the dietary fibre was increased (Abou-Shour and Barakat 1986). Feeds in the present study have a higher crude fibre content compared to those of Udedibie et al. Hence, the higher DMI observed.

All the animals gained weight, which are similar across the treatments, indicating that the intake of energy and proteins were well above maintenance requirements. Rabbits can perform better on weight gain basis when provided with at least 16% crude protein (Fasanya and Ijaiya 2002). Also, rabbits require a level of crude fibre in excess of 9% for normal growth and healthy life (Champe and Maurice 1983) as obtained in the diets of the present study (13.1 to 13.9 %).The result of the average daily gain (ADG) obtained is comparable to the 18.40 to 20.30g reported by Agunbiade et al (2002) for rabbits fed diets containing 0 to 50 % maize and varying levels of dried cassava peel meal. However, the result is lower than the 42.76 to 45.36g/ day reported by Dairo et al (2005) for rabbits fed 22.84 to 39.75 % maize and varying levels of rumen content and blood-rumen content mixture in diets. This could be attributed to the higher DMI of 72.55 to 81.64g/ day observed in the latter study and the types of protein (Plant vs Animal) used in the two studies. The value for efficiency of feed utilization was significantly (P<0.05) lower for rabbits on the sorghum-based diets, indicating that the diets were more utilized than the maize-based diet.

The cost of feed per kg body weight gain was lower in the malted and unmalted sorghum diets, indicating that at 100% replacement level, malted or unmalted sorghum is superior and cheaper source of energy and more economical than maize. The decrease in cost of feed per kg body weight gain was as a result of the lower cost of sorghum compared to maize since ADG observed were similar across the treatments. Decrease in feed cost per Kg gain with dietary replacement of costly ingredients with cheaper ones has been reported (Igwebuike et al 1998). Cost savings of #18.80 and #24.19 were recorded for the unmalted and malted sorghum respectively.

Conclusions

• The results of this study revealed that malted or unmalted sorghum is a superior and cheaper source of energy and more economical than maize.
  
  
• 100% replacement of maize with malted or unmalted sorghum as source of energy in diets for weaner rabbits had no adverse effects on performance.
  
  
• The results also showed that malted or unmalted sorghum gave the best performance in terms of feed efficiency and reduced cost of feed per kg body weight gains was ensured
  
  
• It is therefore recommended that maize should be replaced with malted or unmalted sorghum as source of energy in diets for weaner rabbits for enhanced performance and decreased cost of feed, thereby reducing the stiff competition between man and monogastric animals for maize as a source of food in the country.

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Received 2 January 2006; Accepted 6 March 2006; Published 11 May 2006

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