Introduction

Feed alone account for up to 70% of the total cost of production (Ubosi et al., 2000; Okorie, 2003). The major constraint in animal production has been the high cost of feeding which is being compounded with the present economic depression and the fact that most of the feed ingredients such as maize, sorghum and soybean are used in preparing rabbits diets face serious competition from man and other animals as food (Ijaya et al., 2002).

Maize (Zea mays) is one of the most important cereal crops grown mainly for human consumption. However, maize has been the chief source of energy in monogastric animals especially poultry and rabbits feeding in Nigeria. Therefore, the demand for maize exceeds the supply as a result of its additional use as component of livestock feeds, baking, and brewing industry (Dada et al., 1998). The need to find alternative ways of providing another source of energy to rabbits is therefore long overdue. Millet (Pennisetum typhoid) is commonly grown in drier areas of Nigeria and tropics. It has very small grain and like sorghum is susceptible to pests like quells birds (Uchegbu et al., 1998). Millet is the dominant food crop in the Sahel zone of Nigeria, and ranks second only to sorghum in the Sudan Savannah Zone (Nwasike et al., 1982). Millet is superior and higher in tryptophan than maize though close to wheat. Lysine is however the most limiting amino acid of the crop (Olomu, 1995). Oyenuga (1988) reported the chemical composition of millet as follows; 88.78% dry matter, 9.02% crude protein, 4.99% ether extract, 0.66% crude fibre, 83.20% nitrogen free extract and 2.13% total ash. NRC (1996) reported that millet has no tannin, but contains 5.7% oil and is higher in protein and mineral content than maize and sorghum. This study was therefore designed to determine the replacement value of millet for maize as a source of energy in the diets of growing rabbits.

Material and Methods

Experimental Site

The experiment was conducted at the Abubakar Tafawa Balewa University Rabbits Research Farm, Bauchi. The University is located at Yelwa along Tafawa Balewa Road; Bauchi State occupied a land area of about 60, 000sq km (approximately 7% of Nigerian’s total land area). The state lies between latitude 90⁰ 30N and 120⁰ 30’N and longitude 8⁰ 42’E and 11⁰ 8’E. The average rainfall ranges from 600mm in the north to 1300mm in the south west part of the state. The rainfall pattern is immoderate and the rain starts from June to September in the northern part and from April to October in the south-western part of the state, and maximum temperature of 35⁰C and minim of 18⁰C (B.S.A.D.P, 1999).

Experimental Animals and their Management

The rabbit house was cleaned and disinfected before the start of the experiment. Similarly, the ages, plastic feeders, and water container were thoroughly washed and disinfected. Forty mongrel rabbits were used for the experiment. The rabbits were individually housed in a long tier cages supported at base with wooden planks about 80cm from the floor level. They were netting and cages were properly five. The rabbits were fed every morning at 7.00am and residue left were collected and weighed before the next feeding.

Measurements Taken

At the beginning of the experiment, rabbits were individually weighed and initial weights were taken and the individual weights were taken at weekly interval for six weeks using weighing scale. The feed and water consumption was also determined by the intake and left over of feeds recorded.

Statistical Analysis

Data obtained were subjected to analysis of variance (NOVA) in a completely randomized design (Steel and Torrie, 1980). Differences between means were separated using Duncan’s Multiple Range Test (DMRT).

Experimental Diets

Five isonitrogenous diets (16% crude protein) were formulated in which maize was replaced with millet at 0, 25, 50, 75 and 100%, such that the two ingredients collectively occupy 50% of the diets. The ingredients composition of the experimental diets is shown in Table 1. The forty weaned mongrel rabbits were randomly assigned to the five dietary treatments with eight rabbits per treatment. The experimental lasted eight weeks excluding two weeks adaptation period.

Table 1: Ingredients composition of experimental diets (%)

Results

Performance of Rabbits Fed Experimental Diets

Data on daily feed intake is presented in Table 2. There were no significant (P>0.05) difference among 0,25,50,75 and100% level of replacement of the diets across all the treatments.

Table 2: Performance of rabbits fed the experimental diets

^a,b means in the same row with different superscripts are significantly different (* = P<0.05, ***=P<0.001); NS = Not Significant, SEM = standard error of mean, LS = Level of significance

The DFI value ranges from T1 90.62 – T5 94.35. Obtained in this study which was higher than values 56.19-66.28g reported by Agunbiade et al. (2002); Ajayi et al. (2007). Although, it appears that the rabbits consumed more feed as the level of replacement increases. Daily water intake was highly significant (P<0.001) among the treatments means with the higher value recorded in T5 (211.09ml) and lower value in T1 (148.04ml).

No differences (P>0.05) across the treatments means in the initial weight. While there were significant (P<0.05) difference in T2, T4 and T5 in the final weight of the experimental animals but no differences (P>0.05) in T1 and T3. The highest value recorded was in T4 (2075.50 and the least in T1 (1883.94). Daily weight gain was recorded significantly (P<0.05) different in T1 and no (P>0.05) differences across the remaining treatments. The values obtained in this study 15.88-20.50g were higher than value 13.01-15.03g recorded by Jokthan et al. (2003) and 11.13-12.14g by Ajayi et al. (2007). Although, the weight gain were lower than the 25-50g/day reported for temperate rabbits (Deblas and Garvey 1975); Reddy et al., 1977. The differences may be due to breed and environmental factors. Ekpan Yong (1984) and Aduku et al. (1988) used New Zealand white rabbits, while Mongrels rabbits were used for this study. Gillespie (1992) observed that New Zealand white rabbits have faster growth and rate of gain than most other breeds. Cheek (1987) also reported that rabbits of temperate origin have faster rate of gain than their tropical counterparts. The feed conversion ratio was recorded the same (P>0.05) in the mean separation in T1, T2 and T3, T5 but different (P<0.05) in T4. The values were higher than 2.63-4.00 reported by Ayers et al. (1996); Okorie, (2003), but almost similar to that of 5.32-5.63 reported by Eustace et al. (2003). Conversely, this is prior to the value (3.6) reported by Rastogi (1989) for rabbits fed pelleted concentrates, pelleting has been recommended as a way of minimizing selective feeding and consequent wastage of feed (Lang, 1981; Cheeke, 1979).

Carcass Characteristics and Organ Quality of the Experimental Animals

The results on the carcass yield and internal organ characteristics were presented in Table 3.

Table 3: Carcass characteristics and organ quality of rabbits fed the experimental diets

^{a, b} means in the same row with different superscripts are significantly different (*= P<0.05, **=P<0.01,***=P<0.001); NS = Not Significant, SEM = standard error of mean, LS = Level of significance

The results showed no significant (P>0.05) difference across the processing methods for live weight, carcass weight, head, tail, spleen, small intestine, large intestine and stomach. Dressing percentage was recorded significant (P<0.05) difference in T1 and T5, but not significant in the remaining treatments. The values obtained in this study were low 40.76-59.28% than the range of 55.30+0.72-67.45+0.43% reported by Idowo et al. (2006). But comparable to 42.43- 47.61% reported by Abdul et al. (2012). The values range obtained for weight of the heart are similar to the values 0.24-0.26g reported by Onifade and Tewe (1982). The weight of spleen obtained in this study was higher than 0.05-0.07g by Ozung et al. (2011). The stomach weights were comparable to the results of Maryam (2008) who recorded approximately 3.90-6.35g for stomach. Pelt was recorded highly significant (P<0.001) with the highest value in T4 (22.05g) and least value in T1 (8.10g). Liver was also recorded highly significant (P<0.001) higher value in T3 (3.38g) and lower value in T2 (1.05). Lungs was significantly higher too (P<0.001) with the highest grams recorded in T5 (0.70g) and least in T1 (0.28g). Kidney and kidney fat were observed significantly high (P<0.01) across the treatments means.

Economic Analysis of the Formulated Feeds

The economic analysis of replacing maize with millet as a source of energy in the diets of growing rabbits is presented in Table 4.

Table 4: Economic analysis of replacing maize with millet as source of energy in the diets of growing rabbits

The total feed intake recorded was 3.84, 3.86, 3.83, 3.81 and 3.96 for T1, T2, T3, T4 and T5 respectively. The total feed intake 3.96kg was observed high on the rabbits fed T5 while T4 recorded the least 3.81. T1 had the highest feed cost (N 53.40) while T4 recorded the least (N 33.80) cost decreases with increase in level of replacement. And for the total feed cost, it was recorded with highest value in T1 (N 205.10) and lowest value in T4 (N 128.80) this indicate that the levels at 2, 3, 4 and 5 are more economical in supporting growth than the 1(control). T4 had highest total weight gain (3.44kg) and T1 with the least value (2.62kg). Feed cost (N /kg gain) was estimated high in T1 (N78.28/kg) and low in T4 (N 37.44/kg gain).

Conclusion

The results obtained from this study showed that substituting maize for millet as source of energy in the diets of growing rabbits has the potential of improving growth performance. It could be concluded that rabbit’s diet can be incorporated with millet (Pennisetum typhoid) at varying levels without any adverse effects on growth performance, carcass and internal organ indices of weaner rabbits. Therefore, for the economic advantage in millet as a diets for energy source farmers should be encourage to embark on the cultivation of the crop.

References

1. AOAC (1990). Association of Official Analytical Chemists. Official Methods of Analysis. (15^th Edition), Washington DC. Pp 803-845.
2. Adamu, T.Z. and Haruna, H. (2002). Effects of dietary sources of fibre on feed intake, growth performance nutrient digestibility and carcass characteristics of growing rabbits. Journal of sust.Trop.Agric. Res., 4:67-67.
3. Abdella, H. M., Shalash, S. M., Boulos, N.Z. and Selim, A.B. (1988). Effects on growing rabbits of feeding different levels of Crude Protein. Journal of Applied Rabbit Research, 11(5):252-254.
4. Abdul, S.B., Jokthan, G.E; Hassan, M.R; Adamu, H. Y; Yashim, S.M and Ikari, E (2012).
5. Effects of inclusion level of carrot (Daucus carrot) leaf meal on performance of growing rabbits. World Journal of life and Medical Research. 2; 2:65.
6. Abdel-Salem, F. E; EI – Abdady, M. R., Aboul – Seoud, A. A., Omar, E. M. and Khafagi, S. Z.I (1972). Effects of Dietary Crude Protein levels on Growing Rabbits. Agric. Res. Rev., 50. 129 -149.
7. Amaza, F. (1992). Carcass and organ weight measurement of growing rabbits fed three levels of protein and energy diets. Nigerian Journal nutrition Science, 3:2: 104 -144.
8. Awosanya, B., Joseph, J. K., Apata, D. F and Ayoola, M. A. (1999). Performance, blood chemistry and carcass quality attributes of rabbits. Int. Trop J. Anim. Sci., 2: 89-96.
9. Abdulrazak, S.A and Fujittara, T. (1999). Animal Nutrition; a Laboratory Manual. Kashiwagi Printing Company, Japan Pp 32-39.
10. Amata, I. A and Bratte, L. (2008). The effects of partial replacement of soybean meal with Gliricidia leaf meal on the performance and organs weights of weaner rabbits in the tropics. Asian Journal of Animal and Veterinary Advance, 3: 169-173.
11. Butter, O. O and Ellies, L.G. (2001). Reduction of digestability of enzymes protein by tannin in rabbits. Journal of plant and foods 4. 49-55.
12. Biobaku, W. O. (1998). Growth response of rabbits fed graded level of ground nut shell: effects on weight and enzymes activity. Journal of pure and Applied Science 1 (1) 44-50.
13. Clark, H. E; Eva, M.E and Scott, P.P. (2002). The performance of growing rabbits fed ration containing rumen content. Proceedings of 7^th annual conference of Animal Science association of Nigeria. Abeokuta. Pp131-134.
14. Cheeke, P.R (1987). Rabbits feeding and nutrition. Academic Press Inc. Orlando. Florida U.S.A.
15. De Blas, J.C (1981). Effects of diet on feed intake and growth of rabbits from weaning to slaughter of different ages and weights. Journal of Animal Science, 52: 1225- 1231.
16. De Blas, J.C., Garcia, J. and Carabano, R. (1999). Role of fibre in rabbit’s diets. A review. Ann Zootech. 48: 3-9.
17. De Blast, J.C., and Garvey, J.P (1975). A note on the retention energy and nitrogen in rabbits. Animal Production 21: 345-347.
18. Duncan, D.B (1995). Multiple Range and Multiple F-test. Biometrics. 11: 1-42.
19. Ekpenyong, T.E (1984). Effects of feeding Poultry mash on growth performance of weaner rabbits. Journal of Applied Rabbit Research 7: 144-146.
20. Forbes, J.M. (1995). Voluntary feed intake and diet selection in Farm Animals. CAB Intl. Wallingford, U.K., Pp. 7 – 8.
21. Gidenne, T. (1992). Effects of fibre level, particle size and adaptation period on digestibility and rate of passage as measured at the ileum and in the faeces in the adult rabbit. Br. J. Nutr. 67:133.
22. Gillespie, J. H. (1992). Modern livestock and Poultry Production. 4^th ed. Delmar Publisher U.S.A.
23. Hamzat, R. A; Adejimi, O.O; Babatunde, B.B and Adejumu, M. O. (2007). Evaluation of cocoa shell as a feed ingredient for rabbits. African crop Science Conference proceedings Vol. 8 Pp583 – 584.
24. Idowu, O. M. O., O. M. Idowu, Jegede, A.V., Alabi, E.E. Adenugba. A. O and Bamgbose A. M. (2006). Performance and carcass characteristics of weaner rabbits fed diets containing cassava root peel and cassava sievate. Tropical Journal of Animal Science 9 (1):81 – 87.
25. McDonald, P and Edword, R. A. (1988). Animal nutrition 5^th edition. Longman Group. Hong kong.Pp180 – 220.
26. Mufwa, B. J; Yakubu, B; Kibon, A. and Zaklag, D.U.(2011). Haematological and Biochemical indices of growing rabbits fed graded levels of brewers dried grains. Journal of Agrc and Vet Sci. 3: 13 – 19.
27. Maryam, B. (2008). Effects of Muskwari sorghum cultivar on carcass yield and internal weight organ of weaner rabbits. M.sc thesis Department of Animal Sci. and Range Mgt. federal University of Tech. Yola, Nigeria.
28. Okoye, F. C. (2001). Substitution of Moringa Oleifera for Vitamin supplement in weaner rabbits meal. Journal of Animal nutrition.9 (3) 72-79.
29. Onyimonyi, A. E. and Onukwufor, J. O. (2003). Effects of toasted Bambara nut waste on performance of growing pullets. Proc. Of the 28^th Conferernce of NSAP 28: 234 -239.
30. Owen, J.E. (1981). Rabbit’s meat for the developing Countries. Wld. Anim. Rev., 39: 2 – 11.
31. Reed, J. D. (2001). Condensed Tannins, A factors limiting the using of cassava forage. Journal of Science food Agrc.33:213-217.
32. Reedy, N. V; Rao, D. and Chen, C.P. (2001). Comperative performance of rabbits and broilers. Nutri. Rep. Int. 17(3) 144-150.
33. Stein, S. and Walshaw, S. (1996). Rabbits. In: Laber-Laid, K., Swindle, M.M. and Flecknell, P. (ed). Handbook of rodent and rabbit medicine. Pergamon press, England, Pp183.
34. Stewart M. (1991). Animal physiology. The Open University, U.S.A., Pp 132 – 133.
35. Yahaya, S. (2006). Feed preference and growth performance of rabbits fed pelled vs unpelled diet. Journal Applied Rabbits Research. 7:27-33.
36. Yakubu, A., Adua, M.M and Adamude, H. (2008). Welfare and haematological indices of weaner rabbits as affected by stocking density. 9^th world rabbit Congress- June 10-13, Verona, Italy.