Nutritive potentials of four conventional forages fed to growing grass-cutter (Thryonomys swinderianus)

 O O Obi, A J Omole, F O Ajasin* and O O Tewe** 

Obafemi Awolowo University, Ile Ife, Nigeria, Institute of Agricultural Research and Training, Moor Plantation, Ibadan, Nigeria

* Federal College of Animal Health and Production Technology, Institute of Agricultural Research and Training, Ibadan, Nigeria

** University of Ibadan, Nigeria

omoleboye@yahoo.com

Abstract 

This study examined the nutritive potentials of four conventional forages fed to growing grass-cutters. A total of thirty-six growing grass-cutters were randomly allotted to 4 dietary treatments in a completely randomized design. Animals in treatment 1 were fed elephant grass stem (EG) while in treatment 2, 3 and 4, they were fed guinea grass (GG), pineapple top (PT) and sugarcane growing point (ST) respectively. Feed intake, weight gains were measured while feed conversion ratio and nutrients’ digestibilities were calculated.

The results revealed that the weight gains were better in grass-cutter fed with elephant grass stem and ST (P<0.05) but the feed intakes were relatively the same for all the treatments (P>0.05). Feed conversion ratios, crude protein, fibre and ether extract digestibilities were not significantly different from one another (P>0.05).

Farmers would be encouraged to feed grass-cutters with any of the aforementioned conventional feeds.

Keywords: Elephant grass stem, feed conversion ratio, guinea grass, pineapple top, sugarcane growing point

Introduction 

In Ghana, it has been reported that grass-cutter contributes to both local and export earnings and dominates the bush meat trade (GEPC 1995). Grass-cutter farming in Nigeria has been gaining a lot of popularity because of its low capital input. The meat is a delicacy and there is no taboo against the rearing and consumption of grass-cutter meat. The meat qualities of the grass-cutter compared favourably with those of domesticated livestock species. The mature live-weight is 5 – 8kg with an average dressing percentage of 65% (Baptist and Mensah1986; Adeola 1992). The meat has a low cholesterol and a low fat contents (Fayenuwo et al 2003).One of the major factors that affect livestock production is the cost of feeding which constitutes about 70 – 80% cost of production (Omole et al 2007). Grass-cutters can utilize high fibrous feeds like the rabbit. Both can utilize cellulose or fibre fraction of the feed more than poultry (NRC 1991; Adeola 1992; Asibey and Addo 2000). The caecum, a specialized organ located at the of the junction of small and large intestine contains a lot of bacteria that enable the grass-cutter to survive on low calorie and high fibre diet (Fayenuwo et al 2003). The conventional feeds fed  to grass-cutter include cassava tuber, guinea grass, elephant grass and sugar-cane stems, pineapple top, sweet potato, etc. (Ayodele 1988) Documentation of the performance of grass-cutter fed these aforementioned will serve as reference point for further research work in nutrition. This study was therefore designed to determine the growth performance and nutrients’ digestibilities of growing grass-cutters fed elephant grass, guinea grass, sugar-cane growing point and pineapple top.

Materials and methods 

Experimental site

The experiment was conducted at the grass-cutter unit of the Institute of Agricultural Research and Training, moor plantation, Ibadan, which is located on Longitude 03°51E, Latitude 07°23N and Altitude 650”.It lies in the humid zone of the rainforest belt 0703.25 of Southwestern Nigeria with mean annual rainfall of 1220 mm and mean temperature of 26°C. The study lasted for 12 weeks with an initial 2 weeks for acclimatization.

Housing

The grass-cutters were reared in a wooden cage of 12 compartments.  Each compartment had a dimension of 0.35 x 0.35m.  The legs of the cage were put inside a container containing used engine oil in order to prevent invasion of soldier ants. 

Experimental procedures

Before the commencement of the experiment the cage was thoroughly disinfected with morigard (Lysol) disinfectant and also washed severally with diazintol (Lysol) following the dilution rates specified by the manufacturers and allowed to dry. The growing grass-cutters were treated on prophylactic dose before the experiment for the control against bacterial and coccidial infections.

Experimental animals

Thirty six growing grass-cutter of both sexes of mean weight 653.89±2.5g were used for the experiment.

Experimental design

A completely randomized design was used for the trial.  The trial consisted of 4 treatments (T1 – T4) with each treatment being replicated 3 times with 3 growing grass-cutters per replicate.  Grass-cutters in treatment 1 (T1) were fed elephant grass stem (EG) while grass-cutters in treatment 2, treatment 3 and treatment 4 were fed guinea grass GG, pineapple top (PT), and sugarcane growing point (ST) respectively. Both ST and elephant grass stem were cut into smaller pieces of about 7cm length. The feeds and water were served inside feeding and water trough made of clay. The quantity of each feedstuff supplied every morning and the left-over from the previous day were weighed and recorded. The feedstuffs given were rinsed thoroughly with water to remove dirt before feeding it to the grass-cutter.

Parameters measured

The initial weights of the growing grass-cutters were taken at the beginning of the feeding trial and subsequently at an interval of one week with a top loading weighing balance. Measurements of apparent feed intake were taken on a daily basis by deducting the left-over feed from feed offered with the use of top loading weighing balance. Feed conversion ratio was also calculated as the ratio of feed intake to weight gain

Digestibility trial

The digestibility trial was carried out at the end of 12 weeks. Four animals per treatment and housed individually. Faeces and urine were collected daily, in foil trays placed under the cage of each animal. The daily collection for each grass-cutter was weighed and stored inside a refrigerator. This was done for seven days at the end of which, the faecal collections were bulked and a sample was taken per grass-cutter for proximate analysis. The urine was also bulked and a sample taken for nitrogen analysis

Chemical analysis of the feeds and faeces

Proximate analyses of the feeds and faeces were carried out according to the method outlined by AOA C (1990).

Statistical analysis

The data were subjected to statistical analysis of variance (ANOVA) and significant differences between the means were separated by using Duncan’s Multiple Range Test (SAS 1999).

Results and discussion 

The results of the chemical composition the feeds showed that the moisture content of elephant grass stem and ST was higher than that GG and PT. The percent crude protein also followed this same trend. The crude fibre was low in elephant grass stem and ST compared to GG and PT (Table 1).

Feed consumption is always affected by level of crude fibre of the diet. The higher the crude fibre of the feed, the lower the feed consumed (Arthur  1975). The initial weight of the grass-cutters was relatively the same so as to reduce error in the feeding trial and to obtain unbiased results. Significant differences (P<0.05) were observed in the mean total weight gain of the grass-cutters. The highest weight gain was recorded for grass-cutters fed ST though this was not significantly different from that of elephant grass stem (Table 2). The mean total feed intake was significantly (P<0.05) influenced by the feed given as observed in Table 2. It was observed that the feed intake recorded in growing grass-cutter fed ST was relatively higher than others.

The lowest feed intake was recorded in grass-cutter fed GG. The high feed intake recorded in ST could be due to sweet and succulent nature of sugar-cane stem. It has been reported that grass-cutters preferred succulent and sweet feed (Fayenuwo et al  2003). The low percent crude fibre of ST compared to GG and PT  also influenced its high

The better weight gains recorded in ST and elephant grass stem over GG and PT could have been due to increased feed intake as a result of low fibre content, sweet and succulent nature of ST and elephant grass stem as mentioned above. The efficiency of feed utilization which is the ratio of feed intake to weight gain as shown in Table 2 was relatively the same. The values range between 4.88 and 5.03, numerically, the order of preference is ST > EG > PT > GG.  The results of nutrients’ digestibilities as shown in Table 3 indicates that no significant differences was observed in the dry matter digestibility across the treatments and the values ranged between 65.5 and 68.4% (P>0.05). The crude protein, crude fibre, ether extract and ash digestibility followed the same trend with that of dry matter digestibility.

Numerically, the order was ST > EG > PT > GG. The better the nutrients digestibility, the better is the feed utilization (MacDonald et al 1987). The better performance reported in grass-cutter fed ST and elephant grass stem could be as a result of improved nutrients digestibility (Tables 2 and 3) compared to PT and GG.

Conclusions

• It could be concluded that sugarcane growing point and elephant grass stem would support better growth of grass-cutters   than pineapple top and guinea grass, however, the efficiency of feed utilization and nutrients digestibility were relatively the same.

• Based on these results, any of the aforementioned feeds could be given to grass-cutters but there is need for determination of nutrients requirements for different stages of production of grass-cutter in the tropics.

References 

Adeola M O 1992 Importance of wild animals and their parts in the culture' religious festivals, and traditional medicine, of Nigeria. Environmental Conservation 19: 125-134

Arthur E C 1975 Feed and Feeding. Animal Nutrition Textbook. Williams and Robins Publisher, New York, pp. 112 – 118, 205 – 213

Asibey E O A and Addo P G 2000 The grasscutter, a promising animal for meat production. In: African perspectives. Practices and policies supporting sustainable development (Turnham D editor) Scandinavian Seminar College, Denmark, in association with Weaver Press, Harare, Zimbabwe.

AOAC (Association of Official  Analytical Chemist) 1990  Official Methods of Analysis, 13^th Edition, Washington, D. C.

Ayodele I A 1988 Essentials of grass-cutter domestication and production. Africa Link 65, 65pp.

Baptist R and Mensah G A 1986 Benin and West Africa: the cane rat, farm animal of the future? World Animal Review 60: 2-6

Fayenuwo J O, Akande,M, Taiwo A A, Adebayo A O, Saka J O and Oyekan P O 2003  Guidelines for grasscutter rearing . Institute of Agriculture. Research and Training  Publications. 38 pp

GEPC (Ghana Export Promotion council) 1995  Report on Comparison of export performance of non-traditional products for the period January to December 1993 and 1994

McDonald P, Edwards R A and J F D Greenhalgh 1987 Animal Nutrition (4th edition). Longman Group Limited.

National Research Council 1991 Microlivestock: Little Known Small Animals with a Promising Economic Future (National Academy Press, Washington DC).

Omole A Jm,  Ajasin F O, Oluokun  J A and Tiamiyu  A K 2007  Rabbit farming without Tears. Greenchoice  Agriculture Publications pp 22-34

SAS 1999  S.A.S. User’s Guide. Statistical Analysis System Institute, Inc.Cary,  N.C.

Received 16 June 2008; Accepted 15 July 2008; Published 6 November 2008

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