The intake and digestibility of stale bread by
 the domestic rabbit

R Ramchurn and Y Dullull

University of Mauritius, Reduit, Mauritius
devr@uom.ac.mu ; Ramchurnco@intnet.mu

Abstract

Thirty-two crossbred rabbits were randomly allocated to four groups each with eight animals, and kept individually in separate cages. The four dietary treatments were (control) ad libitum commercial rabbit pellets, 75% pellets and stale bread ad libitum, 50% pellets and stale bread ad libitum and only ad libitum stale bread.  No obvious health problem was encountered during the experiment. The parameters measured were feed intake and digestibility (dry matter, organic matter, crude protein, crude fibre and energy).

Average feed intake was the highest with 100% commercial pelleted diet (128 ± 2.04 g DM/day) and lowest on 100% stale bread (58.5 ± 2.45 g DM/day), reflecting a 54% decrease in dry matter intake. The dry matter, organic matter and protein digestibility were higher on stale bread than on commercial pellets. 

Keywords: Rabbits, stale bread, intake, digestibility, energy 

Introduction

The cost of commercial feeds usually accounts for about 70% of total cost of rabbit production and therefore, to reduce the cost of feed, alternative resource feed materials are exploited. The advantage of the rabbit is that it is a herbivorous non-ruminant, and compared to other monogastric animals, it can digest the protein in forage very efficiently (Cheeke 1978). For instance, it can digest 75-80% of alfalfa protein compared to only 50% by pigs (Cheeke et al 1987). The rabbit’s biological characteristics – its short life cycle, its prolificacy and feed conversion capacity – make it, immediately after chickens and turkeys, the best “animal protein machine” (Lebas et al 1986).  Rabbit meat being low in cholesterol has replaced poultry meat in several recipes around the world. Moreover, rabbits have proved to be able to utilise various plant products and by-products such as Leucaena leucocephala (Awotarowa 1992), wheat bran (Ramsamy 1993), Cynodon plectostachyus (Ramchurn et al 2000) and Stenotaphrum dimidiatum (Haukim 1999).

Stale bread is another alternative feed resource. It is readily available and its utilization is a means to avoid wastage of resources. In a survey done in Mexico city, 14.5% of farmers in the sample area reported the use of stale Tortilla (Mexican bread made of maize) as rabbit feed  (Lopez et al 1999). Stale bread can even be successfully fed to dairy cattle in limited amounts. Stale whole-meal bread makes a very good food for the mouse. The reason for allowing the bread to go stale is that some mice apparently react badly to enzymes present in fresh bread which are killed by the aging process (http://www.horns.freeserve.co.uk/mouse3.htm). According to a survey done by Ahseek (2000), stale bread was being fed to rabbits in the backyard system of rabbit production in Mauritius.

Materials and methods

Thirty-two crossbred rabbits were individually caged in a three-tier system. Fresh water was supplied all the time. A completely randomised design was used with eight rabbits in each of the following four treatments: 

CM100: Ad libitum commercial rabbit pellets at rate of 170 g/day (based on value recorded during adaptation period)
CM75: 128 g pellets (75% of control) + stale bread ad libitum 
CM50: 85 g pellets (50% of control) + stale bread ad libitum
SB: Stale bread ad libitum

The experiment lasted for 18 days, during which there was an 8-day adaptation period and a digestibility trial of 10 days. The total collection method was used. Feed intake and faecal output were recorded daily and samples taken for analysis of dry matter, organic matter, crude protein, crude fibre and energy (AOAC 1975).  The dry matter was determined by drying the samples at 70°C for 24 h using a Memmert convection oven, while the organic matter was obtained by burning the samples in a muffle furnace (Carbolite furnace CWF 12/13). Analysis of nitrogen  was done using the Macro-kjeldahl technique. For the energy content determination, an adiabatic bomb calorimeter was used. The data for feed intake, digestibility and energy were analysed by one-way ANOVA with diet and error as the variables. 

Results

The crude protein, crude fibre, calcium, phosphorus and energy contents were higher in the pellets than in stale bread (Table 1). Feed intake decreased as the proportion of stale bread in the diet increased (Table 2). When only stale bread was offered the dry matter intake was only half that recorded on the control diet of commercial pellets. The coefficients of apparent digestibility for dry matter, organic matter and crude protein increased (p<0.05) as the proportion of stale bread in the diet increased (Table 2 and Figure 1). There was little change in the digestibility of crude fibre. 

Figure 1:  Apparent digestibility coefficients in rabbits fed different proportions
of commercial pellets and stale bread

Discussion

The high values for digestibility of dry matter and protein in the stale bread may have been as a result of the baking process (http://www.chem.swin.edu.au/ma/cereal.html) and of allowing it to age. In mice it has been reported that stale bread is more digestible than fresh bread (http://www.horns.freeserve.co.uk/mouse3.htm). Similar findings have been recorded by Jackel et al (1952) in humans. 

The most striking finding was the reduction in intake as the proportion of stale bread increased (diets CP75, CP50 and SB). This can be explained partly by the fact that rabbits adjust their feed intake according to the energy concentration of the feed. The digestible energy of the feed which consisted only of stale bread was 14.9 MJ/kg DM compared with 10.1 for the commercial pellets. Nevertheless, the compensation was only evident in diets CP75 and CP50.  On the diet consisting only of stale bread the digestible energy intake was only 67% of that for the control diet.  The imbalances of protein, calcium and phosphorus, relative to energy in the stale bread, are the most likely explanation of the low energy intake when only this feed was supplied.

Conclusions 

The digestibility of stale bread was high reflecting the basic ingredients used in preparing this commodity, and with no apparent negative effect of it being stale when fed to rabbits. It appears that stale price can be used in rabbit diets at levels of up to 50% of the expected dry matter intake, however, this needs to be confirmed in feeding trials over the normal production cycle. 

Acknowledgements 

The authors wish to acknowledge the co-operation of Miss B Ramasawmy, Farm Manager of the University Farm. 

References 

Ahseek N 2000 The performance of the domestic rabbit under different management systems in Mauritius. B.Sc Final year dissertation, University of Mauritius, Reduit.

AOAC 1975 Official methods of analysis. 12th edition. Association of Official Agricultural Chemists. Washington DC, USA 

Awotarowa A 1992 A study of the utilisation of Leucaena leucocephala by the domestic rabbit. B.Sc Final year dissertation, University of Mauritius, Reduit. 

Cheeke P R 1978 Alfalfa as a feedstuff for rabbits. Journal of Applied Rabbit Res., 1 (1):6-8. 

Cheeke P R, Patton N M, Lukefahr S D and Mcnitt I J 1987 Rabbit production. 6^th edition. The interstate Printer and Publisher. Inc. 

Dullull Z B 1998 The utilisation of star grass (Cynodon plectostachyus) by the domestic rabbit (Oryctolagus cuniculus). B.Sc Final year dissertation, University of Mauritius, Reduit. 

Haukim M Y 1999 Potential use of Stenotaphrum dimidiatum as a feed resource for domestic rabbit. B.Sc Final year dissertation, University of Mauritius, Reduit. 

Jackel S S, Schaeder W E, and Schultz A S 1952 Susceptibility to hydrolysis by beta-amylase of soluble and insoluble fractions of the crumb of conventional and bacterial alpha amylase supplemented white bread. Cereal chemistry 29:190. 

Lebas C P, Rouvier R and Rochambeau D 1986 The rabbit – husbandry, health and production. Publishing division, FAO of the United Nations. 

Lopez M, Losada H, Sandoval S, Bennett R, Arias L, Rangel J, Soriano R and Cortés J 1999 The influence of urban tourism on backyard agriculture: the rabbit as a new guest in the southeast of the Metropolitan area of Mexico City. Livestock Research for Rural Development  (11) 3: http://www.cipav.org.co/lrrd/lrrd11/3/los113.htm 

Ramchurn R, Dullull Z B, Ruggoo A and Raggoo J  2000 Effects of feeding star grass (Cynodon plectostachyus) on growth and digestibility of nutrients in the domestic rabbit. Livestock Research for Rural Development 12 (2) 2000 

Ramsamy S 1993 The utilisation of Wheat Bran (Triticum vulgare) by the domestic rabbit. B.Sc Final year dissertation, University of Mauritius, Reduit.

Received 28 March 2001

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