Effect of paddy rice on growth performance of rabbits fed water spinach as the sole forage or combined with leaves of water hyacinth

Bui Phan Thu Hang, Vo Lam and T R Preston*

Angiang University, Faculty of Agriculture and Natural Resources, Vietnam
bpthang@agu.edu.vn
* Finca Ecológica, AA48 Socorro, Santander, Colombia

Abstract

Weaned crossbred rabbits (n=30) were allocated to a 2*5 factorial design, to compare: (i) water spinach (WS) as the only foliage, or offered at 50% of observed intake in treatment WS with ad libitum water hyacinth  leaves (WHL);  and (ii) levels of paddy rice (PR) of  0, 5, 10, 20 or 35 g/day.   

There were linear increases in growth rate on WS and WHL treatments as the offer level of paddy rice was increased up to 20 g/day, with no further increase at the 35 g/day level . At all levels of paddy rice the growth rates on water spinach as the sole forage were almost double those when the water spinach was restricted and water hyacinth leaves were fed ad libitum.  There were improvements in feed conversion as the level of paddy rice was increased, and poorer results when water hyacinth leaves replaced 50% of the water spinach.

Key words: carbohydrate, feed conversion, non-nutritional factors

Introduction

Much of the recent research with rabbits in the region has been with diets based on forages such as water spinach and sweet potato vines.  (http://www.mekarn.org/prorab/content.htm). These feeds are high in protein and it would be expected that supplementation  with sources of highly digestible carbohydrate would have beneficial effects on growth rate and feed conversion. In practice, the results have been variable, with no response to broken rice (Hongthong Phimmasan et al 2004), banana fruit, sweet potato root or sugar cane stalk (Sen Sorphea 2008). More consistent results have been obtained with paddy rice as the supplement (Sangkhom Inthapanya and Preston 2009; Nguyen Huu Tam et al 2008).

As paddy rice is the source of rice grain for human consumption, it is important to determine the optimum amount needed to support economic growth in rabbits.

Materials and Methods

Location and climate of the area

The experiment was done in the animal farm of Angiang University, Chauphu district, Longxuyen city, Vietnam.  

Experimental design

Thirty weaned crossbred rabbits (New Zealand x local female) 8 weeks of age were allocated to a 2*5 factorial in a complete randomized design with 3 replications. One rabbit housed in a wire mesh and wood cage, was the experimental unit. The experiment lasted for 8 weeks. The factors were:

Levels of paddy rice

·         0, 5, 10, 20 and 35 g/day

Type of forage

·         Water spinach (WS) as the sole foliage or water spinach and leaves of water hyacinth (WHL) (in this treatment, water spinach was restricted  to 50% of the amount consumed by rabbits fed only water spinach and no paddy rice)

Feeding and management

Water spinach and leaves of water hyacinth were hung in bunches above the feed trough for the rabbits to choose freely. Paddy rice was fed in the troughs. Fresh quantities of the feeds were offered three times daily (at 08:00 h, 14:00 h and 18:00 h). Fresh water was always available. The feed refusals and spillage were collected and weighed daily in the morning before feeding to calculate the feed intake. The animals were vaccinated to prevent hemorrhagic diarrhea.

Measurements

The rabbits were weighed at 14 day intervals. Feeds offered and refusals were analysed for DM, N and ash according to AOAC (1990).

Statistical analysis

The data from the experiment were subjected to analysis of variance using the General Linear Model (GLM) procedure of Minitab Software Release version 15 (Minitab 2007). Sources of variation were: forage source, paddy rice and interaction forage*paddy rice.  

Results and Discussion

The contents of DM, OM and CP (N*6.25) in water hyacinth leaves were higher than in water spinach (Table 2).

The paddy rice was consumed completely at all offer levels (Table 2). When water spinach was the only forage source, its intake declined so that total DM intake was the same at all levels of paddy rice.  On the mixed foliages, the effect of increasing the offer level of paddy rice was to depress the intake of water hyacinth leaves while intake of water spinach remained constant, with all the offer level being consumed.

 On both foliages, there were curvilinear increases in growth rate as the offer level of paddy rice was increased up to 20 g/day, with no further increase at the 35 g/day level (Table 3; Figure 1). At all levels of paddy rice the growth rates on water spinach as the sole forage were almost double those when the forage comprised both water spinach and water hyacinth leaves.  The effects of the treatments on feed conversion rate reflected the effects on growth rate with improvements in feed conversion as the level of paddy rice was increased.

Chhay Ty et al (2007) reported similar negative effects on growth rate and feed conversion in pigs when water spinach was replaced by water hyacinth  leaves. Poor results in growing cattle fed water hyacinth leaves were attributed to the presence of anti-nutritional compounds (Sophal et al 2010).  Mortality in rabbits that were fed water hyacinth leaves as the sole diet was observed by the senior author of this paper  (Bui Phan Thu Hang 2010, unpublished data).

Figure 1. Effect of levels of paddy rice on growth rate of rabbits fed water spinach or a combination of water spinach and water hyacinth leaves

Conclusions

• There were linear increases in growth rate, on water spinach as the sole forage or combined with water hyacinth leaves, as the offer level of paddy rice was increased up to the level of 20 g/day.

• At all levels of paddy rice the growth rates on water spinach as the sole forage were almost double those when the water spinach was restricted and water hyacinth leaves were fed ad libitum.  

• There were improvements in feed conversion as the level of paddy rice was increased, and poorer results when water hyacinth leaves replaced 50% of the water spinach.

Acknowledgements

The authors are very grateful to the Swedish International Development Agency (Sida) through the regional MEKARN Project, for the financial support of this study.

References

AOAC 1990 Official Methods of Analysis, 15th edition. Association of the Official Analytical Chemists. Washington D.C

Chhay T, Borin K and Preston T R 2007:  Effect of mixtures of water spinach and fresh water hyacinth leaves on growth performance of pigs fed a basal diet of rice bran and cassava root meal. Livestock Research for Rural Development. Volume 19, Article #194. http://www.lrrd.org/lrrd19/12/chha19194.htm

Hongthong Phimmasan, Siton Kongvongsay, Chhay Ty and Preston, T R 2004 Water spinach (Ipomoea aquatica) and Stylo 184 (Stylosanthes guianensis CIAT 184) as basal diet for growing rabbits. Livestock Research for Rural Development. Vol. 16, Art. # 34. Retrieved from http://www.lrrd.org/lrrd16/5/hong16034.htm

Minitab 2007 Minitab Reference Manual, Release 15 for Windows. Minitab Inc, USA.

Nguyen Huu Tam, Vo Thanh Tuan, Vo Lam, Bui Phan Thu Hang and Preston T R 2009 Effects on growth of rabbits of supplementing a basal diet of water spinach (Ipomoea aquatica) with vegetable wastes and paddy rice. Livestock Research for Rural Development. Volume 21, Article #174. http://www.lrrd.org/lrrd21/10/hang21174.htm

Sangkhom Inthapanya and Preston T R 2009 Effect of supplementation with sweet potato root and paddy rice on growth performance of local rabbits fed water spinach (Ipomoea aquatic) and paper mulberry (Broussonetia papyrifera) as basal diets. Livestock Research for Rural Development. Volume 21, Article # 176. Retrieved , from http://www.lrrd.org/lrrd21/10/sang21176.htm

Sen Sorphea 2008 Sources of carbohydrates for growing rabbits. Miniproject, Mekarn MSc 2008-10  http://mekarn.org/msc2008-10/miniprojects/minpro/sensoph.htm

Sophal C, Borin K and Preston T R 2010 Effects of supplements of water hyacinth and cassava hay on the performance of local “Yellow” cattle fed a basal diet of rice straw. Livestock Research for Rural Development. Volume 22, Article #166. http://www.lrrd.org/lrrd22/9/soph22166.htm

Received 1 February 2013; Accepted 9 February 2013; Published 1 March 2013

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