The effect of different protein sources and their combination on the performance of growing rabbits in tropical conditions

J N Mbanya, B N Ndoping, J M Mafeni and D W Fomunyam*

IRAD Regional Center Bambui.
PO Box 51, Bamenda. Cameroon.
mbanyajustin@yahoo.com ^IRAD Station Mankon.
PO Box 125, Bamenda, Cameroon*.

Abstract

Seven concentrate feeds were compounded for growing rabbits (n=56) to include one, two or three different sources of protein together with maize (about 35%), wheat bran (about 50%), palm oil (1%), bone meal (0.5%) and common salt (0.5%) . The rabbits were paired and housed in metallic cages and given free access to wilted Guatemala grass (Trypsacum laxum) and 100g/head/day of the concentrate supplement. The dietary treatments consisted of: Cottonseed cake, Soybean cake, Fish meal, Cottonseed cake and soybean cake.

Growth rate was in the range of 10 to 16 g/day and appeared to be highest when fish meal was the sole source of supplementary protein; however, variation was high within treatments and only the difference between fish meal and cottonseed cake was significant. Feed conversion (air-dry feed basis and excluding the grass) was in the range of 4.4 to 5.2 and was not related with growth rate.

Key words: Feed intake, growing rabbits, live weight change, protein sources.

Introduction

Rabbit production in Cameroon is practiced mainly in the rural areas under traditional management systems with forage-based diets as the principal feed resources. The poor and unbalanced quality of grasses is a major constraint, which limits the successful production of rabbits. Cheeke and Raharjo (1988) concluded from a review of rabbit production on tropical feed resources that tropical grasses were unsuitable as the sole feed for rabbits due to their low digestibility (less than 10%). However rabbits can successfully be raised on diets that are low in grains and high in roughage (Cheeke 1986). Growing rabbits can be maintained satisfactorily on diets consisting of 100 to 200g green roughage and 40 to 60g concentrate mixtures for maximum production (Ranjhan 1980).

Adequate supplementation remains a principal hurdle to be overcome for rabbit rearing in Cameroon. Supplementary concentrates are based on mixtures of locally available protein feedstuffs (cottonseed cake, soybean cake, fish meal) and energy (wheat bran, rice brain, maize). Concentrates are presented either as commercial mixtures or homemade feeds. The high cost of commercial feeds and the irregular supply of protein feedstuffs for compounding home-made feeds by farmers confounds with other constraints to complicate the nutritional adequacy of diets for rabbits. Rabbit farmers practice the inclusion of multiple protein-rich feedstuffs as sources of protein in their home-made concentrate feeds. This practice does not only have an increased effect on the cost, but leaves the farmers with limited options in the manipulation of feed formulae in the absence of some of these feedstuffs on the market. The use of soybean meal as the sole source of supplementary protein has been suggested (Rahin et al 1997). Other authors (Roy et al 2002) reported the effects of supplementation with different sources of protein (Soybean meal, gram and til oil cake) on growth and reproductive performance of rabbits.

Information is limited in the literature on the response of growing rabbits to concentrate supplementary feeds containing different sources of protein, and their combinations and, in particular, the economic benefits associated with these dietary supplements for rabbits in tropical environments. This study was therefore designed to compare the effects of supplementing cottonseed cake, soybean cake, fishmeal and their combinations in a concentrate diet on the performance of growing rabbits.

Materials and Methods

Animals and management

The experiment was carried out at the Mankon station of Agricultural Research for Development. Californian New Zealand White crossbred weaned rabbits (30 males and 26 females), aged 6-8 weeks and with initial live weight of 628g (SD 155; range 300-900g) were used in the study during a period of 8 weeks. The rabbits were paired and housed in metallic cages provided with feeders and drinking cups. Housing and other management practices were maintained similar for all treatment groups.

Diets

Seven experimental diets were compounded to include one, two or three different sources of protein (Table 1). The dietary treatments consisted of:

CSC: Cottonseed cake,
SC: Soybean cake,
FM: Fish meal,
CSC-SC: Cottonseed cake and soybean cake;
CSC-FM: Cottonseed cake and fish meal;
SC-FM: Soybean cake and fish meal.
CSC-SC-FM: Cottonseed cake, soybean cake and fish meal

Table 1: Proportions of feed ingredients in experimental diets
	CSC	SC	FM	CSC-SC	CSC-FM	SC-FM	CSC-SC-FM
Composition on as-fed basis, g/kg
Maize	350	350	310	365	355	395	365
Wheat bran	510	535	605	500	520	490	510
Cottonseed cake	115	0	0	80	80	0	60
Soybean cake	0	90	0	30	0	60	20
Fish meal	0	0	60	0	20	30	20
Palm oil	10	10	10	10	10	10	10
Bone meal	10	10	10	10	10	10	10
Table salt	5	5	5	5	5	5	5
Calculated analyses (g/kg as fed basis)
Crude protein	161	162	161	161	161	162	162
Digestible energy (Mcal/kg)	3.00	2.99	2.93	3.00	2.98	3.00	2.99
Dry matter	861	859	839	860	802	860	861
Crude fiber	65	63	64	63	63	58	62
Ether extract	44	41	39	43	43	41	41
Ash	420	520	410	440	430	430	430

The diets were iso-caloric and iso-nitrogenous, and were made in batches and offered at a daily rate of 100 g/animal. In addition each animal was given a daily allowance of 200g of Guatemala grass (Trypscum laxum) to boost the fiber content of the diet. The grass was bundle wrapped and placed in the cage. Water was provided ad-libitum. All feeds were offered in the morning after collection of the left overs.

Experimental design

The treatments were randomized in a 2x7 factorial arrangement (two sexes and seven diets). Animals were blocked by sex and initial live weight and randomly allocated to the treatment diets within blocks . Animals on each treatment diet were allocated to cages in a manner to ensure equitable treatment distribution within the house.

Measurements

Feeds offered and the left-overs were recorded daily for each treatment to determine intake. Live weight change and feed intake were recorded weekly until the end of the trial. Feed conversion was determined by dividing the unit of feed intake by that of live weight gain. The nutrient content of the diets was predicted from data in animal feed composition tables (McDonald et al 1973).

Statistical analyses

All data were assembled using Excel 2000 in Windows 98. The data on live weight gain, the mean values of data for feed intake for each pair of animals, and the data on costs and returns were analyzed using the general linear model (GLM) procedure in the SAS program (SAS 1996) to test significant effects of diet, sex and their interactions. Contrast comparison was applied (SAS 1996) to test the significant effects of inclusion of one, two or three protein sources in the diet. The Duncan multiple range test was used to rank means of treatments.

Results

Live weight gain

Growth rate appeared to be highest when fish meal was the sole source of supplementary protein , however, variation was high within treatments and only the difference between fish meal and cottonseed cake was significant (Figure 1 and Annex 1).

Figure 1: Relationship between source of protein supplement and growth rate of rabbits

Feed intake and conversion

Feed intake appeared to be highest on the fish meal as sole protein supplement but there was no obvious pattern with the other protein supplements (Figure 2 and Annex 1). As a result there was no logical relationship between protein source and feed conversion (Figure 3).

Figure 2: Relationship between source of protein supplement and feed intake of growing rabbits

Figure 3: Relationship between source of protein supplement and feed conversion rate of growing rabbits

Discussion

The results of this experiment are somewhat inconclusive in that the growth rate, which varied from 10.2 to 16 g/day, was not related with the feed conversion rate (range from 4.4 to 5.2; R² = 0.01). The highest growth rate on the fish meal supplement would appear to be the logical consequence of the superior amino acid balance of this protein source, compared with cottonseed cake and soybean cake (McDonald et al 1973), but surprisingly this was not reflected in a better feed conversion.

There appeared to be an advantage in growth rate from including fish meal with soybean cake or cottonseed cake, compared with the vegetable sources as sole protein supplements, but the high variability among treatments precluded these effects reaching a level of significance.

Acknowlegements

This research was funded by IRAD Mankon Station management. The authors are grateful to Mrs Abudu Philisia , veterinary assistant, Mr Anye Samuel and Mr Gea, both livestock attendants, for care of the animals throughout the duration of the study.

References

Cheeke P R 1986: Potentials of rabbits production in tropical and subtropical agricultural systems. J. Anim. Sci. 63: 1581-1586.

Cheeke P R and Raharjo C 1988: Evaluacions de forrajes tropicales y subpcoductos agricdes como alimento pava conejos. In: Sistemas Intensivos para la Produccion. Animal y de Energia Renovable con Recursos Tropicales (Editors: T.R Preston and M. Rosales) CIPAV: Cali Tomo II pp 33-42.

McDonald P, Edwards R A and Greenhalgh J F D 1973: Protein concentrates. In: Animal Nutrition. Second Edition. 398-418.

Rahim A, Reza A and Shahjalal 1997: Comparative study of soybean meal and whole gram on growth and reproductive performances of rabbits. Bangladesh J. Anim Sci. 26:89-97

Ranjhan 1980: Animal Nutrition in the Tropics. Vkas Publishing house Pvt. Ltd. Sahibabab. Ghaziabad. P: 335.

Roy J, Sultana N, khondoker Z, Reza A and Hossain S M 2002: Effect of different sources of protein on growth and reproductive performance of rabbits. Pakistan Journal of Nutrition 1 (6): 279-281.

SAS 1996: Statistical Analysis System. SAS system for Windows version 6.12. SAS Institute Inc. Cary NC 27513, USA.

Received 18 November 2004; Accepted 12 January 2005; Published 1 March 2005

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Annex 1: Performance data of growing rabbits fed different sources of protein.

CSC

CSC-SC

CSC-FM

SC-FM

CSC-SC-FM

Wt gain g/day

10.2^a

2.3

11.7^a

2.0

16.0^a

1.9

14.2^a

1.9

13.9^a

2.0

14.1^a

1.9

12.5^a

2.3

Feed conversion

4.6^a

2.4

4.4^a

2.2

4.8^a

2.1

4.7^a

2.0

4.7^a

2.2

5.1^a

2.0

5.2^a

2.4

T. F intake g se

3437^c

155

3581^c

127

4045^a

131

3637^abc

127

3278^c

127

3669^ab

127

3967^abc

155

D.F.intake (g)

61.4^bc

2.8

63.9^ab

2.2

72.2^a

2.3

64.9^abc

2.2

58.5^c

2.2

65.5^abc

2.2

70.8^ab

2.8

abcd = means with different superscript letters within rows are different at p<0.05

*p< 0.05

NS = not significant (p>0.05)

se = standard error of mean

T. F. intake = total feed intake

D. F. intake = daily feed intake