Effects of supplementing a basal diet of water spinach (Ipomoea aquatica) with vegetable wastes on rabbit performance
 

Nguyen Huu Tam, Vo Thanh Tuan, Vo Lam, Bui Phan Thu Hang and T R  Preston*

Angiang University, Faculty of Agriculture and Natural Resources, Vietnam
bpthang@agu.edu.vn
^*UTA (Colombia), Socorro, Santander, Colombia

Abstract

Thirty-two weaned crossbred rabbits (New Zealand x local female) with an initial weight between 900 and 1100 g and 6 and 7 weeks of age were used to evaluate the potential of the market wastes of Brassica species and of a supplement of paddy rice on feed intake and live weight change. The basal diet was fresh water spinach offered at 10% of live weight (DM basis). The design was a 2*4 factorial the factors being: (i) With or Without paddy rice; (ii) Supplements of Cabbage, Chinese cabbage, Cauliflower or no supplement. The vegetable supplements were offered ad libitum. Paddy rice was given at 50 g/day. Rabbits had higher feed intake and live weight gain when: they were supplemented with: (i) paddy rice;   and (ii) when they had access to cabbage, cauliflower and Chinese cabbage as well as water spinach.

Key words: Brassica species, growth,, live weight gain, paddy rice
 

Introduction

Rabbits are herbivores and can be fed by grasses and vegetables produced in farmers’ home gardens (Nguyen Quang Suc et al 1996). Water spinach (Ipomoea aquatica) has high biomass yield and is rich in crude protein content (280 g/kg DM), with low crude fibre (120 g/kgDM)  (Ly Thi Luyen 2003; Ho Bunyeth 2003) and has proved to be a valuable basal diet for rabbits (Hongthong Phimmmasan et al 2004). Vegetable wastes from the markets (Brassica species, such as cauliflower, cabbage and Chinese cabbage) are also potential feeds for rabbits

The objective of this study was to evaluate the potential of the market wastes of Brassica species in rabbit feeding.
 

Materials and methods

The experiment was done at the experimental farm of Angiang University, Chauphu district, Longxuyen city, Vietnam. Thirty-two weaned crossbred rabbits (New Zealand x local female) with an initial weight of 900 - 1100 g and ages between 6 and 7 weeks were used.

The experiment was a 2*4 factorial in a complete randomized design with 4 replications. The basal diet was fresh water spinach offered at 10% of live weight (DM basis). The factors were:

Source of supplementary forage: CA: Cabbage; CC: Chinese cabbage; CL: Cauliflower; WS: only water spinach

Supplementation with paddy rice: WR: With paddy rice; NR: Without paddy rice

Water spinach was hung in bunches above the feed trough. Leaves of cauliflower, cabbage and Chinese cabbage were fed in troughs. Feed offered for each rabbit was weighed every morning and the animals were fed with 50% of their daily ration in the morning and 50% in the afternoon. Fresh water was freely available.  

The experiment lasted for 8 weeks. The animals were weighed at the start of the experiment and then weekly, on the same day of the week and before feeding in the morning. Water spinach was included in all the diets and offered at the level of 100 g (DM)/kg body weight. The supplementary forages were fed ad libitum. Paddy rice was supplemented at 50 g/day.

Feeds and refusals were analysed for DM, CP and ash according to AOAC (1990). The data of the experiment were subjected to  analysis of variance using the General Linear Model (GLM) procedure of Minitab Software Release version 13.1 (2000).

Results and discussion

The DM contents of cabbage, cauliflower, chinese cabbage and water spinach were low, but their CP content was high (Table 1.)

.

DM and crude protein intakes and rates of live weight gain were increased when leaves of cauliflower, cabbage or Chinese cabbage were offered in addition to the basal diet of water spinach (Tables 2 and 3). The supplement of paddy rice also supported higher DM intakes and live weight gains, even though CP intake was decreased.

There is no obvious explanation for the stimulating effect on feed intake and growth rate when the water spinach basal diet was supplemented with leaves of cauliflower, cabbage or Chinese cabbage, other than the access to a greater variety of feeds. The positive effect on DM intake and growth of the paddy rice supplement is even more difficult to explain.  A higher energy density does not seem to be the explanation as in several experiments with water spinach basal diets, there have been no responses to supplements of even higher energy density such as broken rice (see: Hongthong Phimmmasan et al 2004;  Pok Samkol et al 2006).  Leng (2006) considered that the rabbit was poorly adapted to digest starch in view of the short small intestine and the rapid transit time. Supplements rich in fibre have given positive results with rabbits fed diets based on water spinach (Khuc Thi Hue and Preston 2006; Doan Thi Gang et al 2006) thus there may have been some benefit in this respect from the fibrous husk of the paddy rice.

Conclusions 

• Feed intakes and growth rates of rabbits fed a basal diet of water spinach were increased when they also had access to leaves of cauliflower, cabbage or Chinese cabbage. A supplement of paddy rice also stimulated feed intake and growth rate.

Acknowledgements

The authors are grateful to the MEKARN project, financed by the Sida-SAREC agency. The authors would like to thank the Department of Animal Husbandry and Veterinary, Faculty of Agriculture and Natural Resources of An Giang University for infrastructure support.

References

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