Biological Systems: Open Access

The animal protein for human consumption in Nigeria (from cattle, pigs, poultry, sheep and goats.) has not been able to bridge the gap between demand and supply. Despite the numerous advantages associated with the consumption of animal protein, the minimum intake recommended by FAO (1992) has not been met. This is mostly because the price of meat has gone beyond the means of most Nigerians.

The domestic rabbit (Oryctolagus cunniculus) is an important non ruminant herbivore for meat production. Rabbit meat is a source of healthful food as it is low in cholesterol but high in protein 22 g/1000 [1]. Rabbit can also utilize the available proteins in celulose rich plants whereas, it is not economical to feed these to chickens and turkeys, the only animals with higher energy and protein efficiency. Since there is high demand for additional source of food world wide the exploitation of plant seeds of low economic importance would be a step toward better resource utilization Telek et al. [2] which is in line with the strategy to achieve sustainable animal production system by matching them with locally available feed sources [3].

The continued increase in cost of conventional feeding ingredients especially grains, cakes and meals and the effective competitions from both poultry industry and human population are the major constrains for progressive growth of the rabbitary in developing countries. One of the method that have been utilized for some time now in alleviating this problem is the replacement of percentage grains and cakes in the diet of monogastric animals especially rabbits. However, the present trend in the annual increase in the cost of these products have necessitated the need to use unconventional feeding stuffs for rabbitory that are free of competition from other industries.

Seed collection and preparation

The seeds of Delonix regia were obtained from College of Agriculture and Science, Mando Kaduna State, Nigeria. The pods were soaked in a pool of water for 3 days for the seeds to split open after sun drying. The seeds collected were divided into six batches; one batch was left raw, while other batches were cooked for various durations, namely, 0, 15, 30, 45, 60, 75 and 90 minutes, respectively. Timing commenced immediately after adding the seeds in boiling water. The boiled seeds were drained off the water and sun dried for 4 days. The raw and boiled seeds were milled in a hammer mill and stored in screwcapped container until required for feed formulation.

Proximate analysis

Moisture content : Five grams of the sample was weighed into preweighed aluminum drying dish. The sample was dried to a constant weight in an oven at 105°C for 4 h [4]. The moisture content was then determined as follows:

m₀ = Weight of aluminum dish

m₁ = Weight of fresh sample + dish

m₂ = Weight of dried sample + dish

Ash content: Five grams of the sample was weighed into a porcelain crucible, previously ignited and weighed. Organic matter was charred by igniting the material on a hot plate in the fume cupboard. The crucible was placed in the muffle furnace and maintained at 60°C for 6 h. It was then cooled in a desiccator and weighed out immediately. The percentage ash was determined using the following formula:

Crude fat: Five grams of the sample was put in the thimbles and plugged with cotton wool. The thimbles were dried and inserted into a Soxlet system HT2. The extraction cups were dried and weighed, 25 ml of petroleum ether was added to each cup. The cup was inserted in the soxhtec, and the sample was extracted for 15 min in a boiling position and 45 min in a rising position. The percentage fat in the sample was calculated as follows:

W₁ = weight of sample

W₂ = weight of empty cup

W₃ = weight of cup with extracted oil

Crude fibre: The trichloroacetic acid method of Joslyn [5] and Adeniji et al. [6] was used. The sample was defatted with petroleum ether. Five grams of the defatted sample was weighed into a 600 ml beaker and 100 ml trichloroacetic acid was added. The sample was boiled and refluxed for 4 min. The cooled sample was filtered with a filter paper, Whatman No. 4.

The residue was washed with distilled water and methylated spirit. The filter paper together with the sample were transferred to porcelain crucible and dried in an oven overnight at 100°C. The sample was cooled in a desiccator and weighed. It was then ashed in a muffle furnace at 600°C tor 6 h and weighed again after cooling. The loss in weight during incineration was equivalent to the amount of crude fiber.

Sample weight:

Weight A = weight of sample after drying

Weight B = weight of sample after ashing

Crude protein : For determination of crude protein, a Kjedahl nitrogen method was used. One gram of the sample was introduced into the 800 ml digestion flask. Kjedahl catalyst (5 Selenium tablets) was added to the sample. 20 ml of concentrated sulphuric acid was added to each sample and fixed to the digestion flask until a clear solution was obtained. The cooling digest was transferred into 100 ml volumetric flask and made up to the mark with distilled water.

The distillation apparatus was set up and rinsed for 10 min after boiling; 20 ml of 4% Boric acid was pipetted into cornical flasks, 5 drops of Methyl red was added to each flask as indicator and the digest was diluted with 75 ml distilled water. 10 ml of the digest was made alkaline with 20 ml of 20% NaOH and distilled. The steam exit of the distillator was closed and the change in colour of boric acid solution to green was noted. The mixture was distilled for 15 min [4]. The boric acid along with distillate was then titrated against 0.1N hydrochloric acid and, consequently, the total nitrogen was calculated as indicated below:

Total nitrogen = Normality = 0.1 N

% Crude protein — % Total Nitrogen x 6.25

Carbohydrate: This was obtained by subtracting the sum or the percentage moisture, ash, crude fiber, fats and protein from 100.

Blood samples were collected at the 8th week from the jugular veins of the rabbits into a set of Bijou bottles, containing Ethylene dimetamine tetra acetic (EDTA) [7,8] immediately after collection. The blood samples were taken to the laboratory for analysis.

The Packed Cell Volume (PCV) values of the blood were determined according to the micro-haematocrit method of Benjamin (1978) with slight modification Oladele [9] in timing of the centrifuge. Blood containing EDTA was aspirated into a set of plain capillary tubes. The blood sample was centrifuged at 9,500rpm for 15 minutes and PCV read directly from the graphic reader in percentage.

The values of haemoglobin for the rabbits were estimated by dividing the PCV value by 3 Maxwell et al. [10], Makinde and Olowookurun [11].

The total proteins in the blood of rabbits were determined using hand refractometric method of Benjamin [7]. Data collected were subjected to analysis of variance (ANOVA) Duncan’s Multiple Ranges was used to separate the significant means both contained in SSPSS for Windows 2003

The result of the proximate composition of Delonix regia seed diets are presented in Table 1. Dry matter ranges from 90.48-93.35g while protein is from 18.29-19.02%. Dry matter intake in animal nutrition is very important as it ensures the intake of large quantity of nutrients when compared to high moisture feeds. Significant difference (P>0.05) exist in the dry matter, protein, ether extract, ash and free nitrogen extract when the seeds were cooked at different durations. However, there was no significant difference (P>0.05) in the fibre contents. Crude fibre is useful for maintaining bulk mortality and increase intestinal peristalsis by surface extension of the food in the intestinal track [12].

Table 1: Diets Compositions and Calculated Analysis of Delonix regia Seed Meals Diets.

This is also necessary for food digestion. The result shows that the crude fibre contents of the seeds are within the ranges recommended by Anugwa in 1998 and therefore suitable as materials for monogastric animals.

Table 2 is the effect of cooking Delonix regia seeds at 100°C for various durations. Significant difference exists between seeds cooked at different duration of time. The best cooking time for Delonix regia seed was 60 minutes. At 60 minutes cooking, it had the best feed efficiency, the highest feed consumed and there was no mortality reported. The higher ether extract value indicates a higher fat content.

Table 2: Proximate Composition of Experimental Diets of Delonix regia Seeds Meal Cooked at 100°C for Varying Duration (in minutes).

The crude protein values were well above NRC recommended values for monogastric animals [13]. Studies Aletor and Aladetimi [14], Sobayo et al. [15] have shown that high protein in diets of rabbits could produce some undesirable physiological and biological alterations which may manifest in the haematological characteristics of animal when fed such diets. The test diets shows protein content of Delonix regia seeds. Table 3 shows the haematological parameters of rabbits fed Delonix regia seed diets. It is well established that changes in haematological and biochemical parameters reflect the physiological status of animal [16]. Packed Cell Volume (PCV) values obtained in this study were not significantly (P>0.05) influenced by dietary treatments.

Table 3: Haematological Parameters of Rabbits Fed Delonix regia Seed Cooked at 100°C for Varying Duration.

The Packed Cell Volume (PCV) obtained fell within the range of 31.0-48.6% reported by Mitruka and Rawnsley [17], 33-50% ASAN (2006) and 33-50% reported by Medi Rabbit [18]. The PCV is the fraction or portion occupied by the red blood cell Bush (1991). Haemoglobin levels were within the reported range of 9.9-19.3% reported by Turfey (1995). This normal range of haemoglobin suggests an efficient oxygen transport system. The higher PCV and Hb of rabbits in all the treatments were apparently, due to better nourishment of these diets on the rabbits. This result is in agreement with the findings of Hackbarth et al. [19], who demonstrated that PCV and Hb concentrations indicate the nutritional status of the diets.

The White Blood Cell count was also observed to be within values of 2.0 – 15.0x10ml reported by Medirabbit [18]. This is an indication that defensive system of the rabbits was not affected. The non-significant (P>0.05) higher values of neutrophils content in all the treatments indicate similar environmental conditions of stress on the rabbits. This shows that their resistance to infection was stable. The rare occurrence of monocytes suggests that Delonix regia seeds did not cause inflamatory reactions in the blood system of the rabbits. So also, the absence of eosinophils shows that there was no allergic condition when Delonix regia seeds are consumed. The values obtained compared favourably with those obtained Hewlett et al. [20], RAR [21] and Amata [13]. Thus, Delonix regia seeds may be included in the diet of rabbits without compromising the health status of the rabbits.

The results from the feeding trials indicate normal haemoglobin and higher PCV values of rabbits in all treatments, thus showing the nutritional status of the seeds. The rare occurrence of monocytes and the absence of eosinophils shows that the seeds did not cause any inflammatory and allergic reactions respectively. It can therefore be included on rabbit diets without compromising the health status of the rabbits.