A study of associated fresh forages for feeding growing crossbred rabbits the Mekong delta of Vietnam
 

Nguyen Van Thu & Nguyen Thi Kim Dong

Cantho University, Cantho City, Vietnam

 nvthu@ctu.edu.vn

Abstract                                             

This study aimed to evaluate effects of levels of fresh spophocarpus scandén (SS) replacing fresh para grass (Brachiaria mutica,); And sweet potato vine and water spinach associated with Mom grass (Hymenache acutigluma) or Cuc (Wedelia spp) in the diets on feed and nutrient utilization, growth performance and economic return of crossbred rabbits. Two experiments were carried out in the experimental farm at Cantho University. Both experiments were complete randomized designs with five treatments and three replicates. Two female rabbits (Exp 1) and two male ones at 60 days of age (Exp 2) were allocated in one experimental unit. In the Exp 1 the treatments were levels of 0, 20, 40, 60 and 80% (DM basis) of spophocarpus scandén replacing para grass in the diets. In the Exp 2, six diets including water spinach (WS), Sweet potato vine (SP), WS + Mom grass, WS+Cuc, SP+Mom grass and SP+Cuc were used as treatments. The combination of two kinds of feeds was at a ratio of 1:1 (DM basis).

 The results of Exp 1 showed that DM intake was significantly different (P<0.01) among diets. Crude protein intake of rabbits significantly (P<0.01) increased with the higher levels of para grass replaced by SS. The daily weight gain of the rabbits were higher in the diets with SS replacement, however only the daily weight gain of the SS40 treatment was significantly higher than the SS0 one. The profit was improved with the increased replacement of SS. The nutrient digestibility (dry matter and crude protein) and nitrogen retention of rabbits were also significantly (P<0.01) improved when increasing the levels of SS replacement. In Exp 2 there was no significant difference (P>0.05) of DM and crude protein intakes among the diets, but a significant difference (P<0.001) of NDF intake was found. The daily weight gain was significantly higher in the WS diet, however, the higher benefits of SP+M and SP+C diets were found. The carcass and meat quality were not significantly different among the treatments. The conclusion of the study was that using of Spophocarpus scandén to replace para grass improved nutrient utilization, daily weight gain and profits. Water spinach, sweet potato vine, Mom grass (Saciolopsis indica) and Cuc (Wedelia spp) could be used for feeding the growing rabbit. Water spinach and sweet potato vine associated Mom grass or Cuc at ratio of 1:1 could be economically used and increase economic return.

Keywords: para grass, spophocarpus scandén, Saciolopsis indica, water spinach, sweet potato vine, growing rabbit, feed utilization, daily weight gain, economic return.    

Introduction

 Due to the bird flu, rabbit meat production has been more developed recently in Vietnam in order to meet the meat demand of human food. Rabbit production is good for commercial farm income and also a tool of the poor producers for erasing starvation and alleviating poverty. Crossbred rabbits (Local and improved pure breeds) are popularly raised in the Mekong delta because of a good adaptation to the local climate and feeds. Organic rabbit farming based on locally available feeds resources, particularly natural grasses, legume leaves and wild vegetables have very important role for production in villages such as sweet potato vine, water spinach, Mom grass, Cuc, etc. However, the appropriate usages of these feeds in rabbit diets are still limited due to a lack of feeding techniques produced. There are also several kinds of available protein-rich forages in the Mekong Delta such as tropical kudzu, clovers, water spinach leaves, etc, which have been very good plant protein sources for rabbits (Nguyen Van Thu and Nguyen Thi Kim Dong, 2005). They provides adequate protein and other essential nutrients for rabbits, while para grass (Brachiaria mutica) from natural pastures is a good fiber feed source for rabbits (Nguyen Thi Kim Dong et al., 2007^a and Le Nguyen Huyen Trang, 2006). However, studies on them for crossbred rabbits have been not yet implemented. Consequently their results have been not available for the producers. Therefore, the objectives of study are to evaluate effects of using the association of spophocarpus scandén, sweet potato vine, water spinach, Mom grass (Hymenache acutigluma) and Cuc (Wedelia spp) in the diets on feed and nutrient utilization, growth performance and economic return of growing crossbred rabbits. The results of the study could be disseminated to producers for practice.

Materials and methods

The study included two experiments:

The experiment 1 aimed to measure the effects of the replacement of Para grass by Spophocarpus scandén on dietary nutrient digestibility, growth rate and economic analysis of crossbred rabbits. Thirty growing female rabbits (New Zealand x local breed) at 60 days of age (mean live weight of 799g) were allocated in a complete randomized design with 5 treatments and 3 replications (two rabbits in an experimental unit). The treatments were the replacement of para grass (Brachiaria mutica) by spophocarpus scandén at levels of 0, 20, 40, 60 and 80% (DM basis), while the concentrate supplementation was the same in all treatments of 15g /day/rabbit. At 105 days of age the feeds offered, refusals and urine were collected for nutrient digestibility and nitrogen retention measurement.

In the experiment 2, thirty six growing male rabbits of 60 days of age were allocated in a Complete randomized design with 6 treatments and 3 replications to evaluate effects of different local forages including water spinach, sweet potato vine, Mom grass (Hymenache acutigluma) and Cuc (Wedelia spp) in the diets on feed utilization, growth rate, carcass quality and profit. The treatments (diets) are presented in table 1.

The feeds and refusals were taken for analyses of DM, OM, CP, EE, NDF, ADF, and Ash following procedure of AOAC (1990) and Van Soest et al (1991). At the beginning of the experiment two rabbits per experimental unit were weighed individually weekly. Daily feed intakes, growth rate, and feed conversion ratios were measured and calculated. The economic analysis was also done among the treatments in both two experiments. For the measurements of nutrient digestibility and nitrogen retention, feeds and refusals were daily measured. Urine was also collected for nitrogen analysis to calculate the nitrogen retention.  DM, CP, EE, NDF and ADF digestibility were employed according to Mc Donald (2002). In the experiment 2, after finishing the rabbits were slaughtered for evaluating carcass and meat quality.  

  The data from both experiments were analyzed by analysis of variance using the ANOVA of General Linear Model, while Tukey test was used to compare the means of treatments of Minitab Reference Manual Release 13.20 (Minitab, 2000). Economic analyses were done using current prices in Vietnamese Dong (VND) to compare differences of income and the feed cost in different treatments.

Results and discussion

 Exp 1

 Chemical composition of feeds is in Table 2

In Table 2, the DM of Para grass was 19,1% and higher than Spophocarpus scandén of 14%. DM of para grass reported by Nguyen Thi Xuan Linh (2005) was of 16,4% and Danh Mo  (2003)  of 18,4%. The higher figures of DM of para grass in the experiment could be caused by cutting during the dry season. The CP content of Spophocarpus scandén was of 23.1%, while it was 9.92% in para grass. NDF content of Spophocarpus scandén was lower than para grass (41.8%  vs. 61.6%).

In table 3 showed that DM intake of rabbit was lower in the treatments, which increased the SS replacement. The DM intake of SS80 was significantly lower than the SS0 and SS20 diets due to the lower DM of the SS compared to the PG. These results were consistent of that reported by Nguyen Thi Xuan Linh (2005) and Dao Hung (2006). The CP intake proportionally increased in the diets to the increase of the SS replacement and they are significantly different among the treatments (P<0.01), while opposite pattern occurred for the NDF  intake, due to the lower NDF content in the SS.       

Daily weight gain, feed conversion ratio and economic return of the rabbits in Exp 1 are stated in Table 4.

Daily weight gains of the rabbits were higher in the diets with SS replacement, however the daily weight gain of the SS40 treatment was significantly higher than the SS0 one. The daily weight gain of rabbits in the experiment 1 was similar to results in the crossbred rabbits reported by Dao Hung (2006) from 14.5-19.0g and Nguyen Van Thu and Nguyen Thi Kim Dong (2005) from 12.9-19.0g. The feed conversion ratio of the SS40, SS60 and SS80 was significantly lower than that of SS0 and the results were consistent with those reported by Dao Hung (2006) of 4,27. The economic analysis showed that the SS40 diet gave the best benefit from the experiment.

Nutrient digestibility and nitrogen retention of rabbits are shown in Table 5.

The digestibility of DM, OM and CP were improved with the increase of Spophocarpus scandén leaves in the diets. The DMD were significantly higher for the SS60 and SS80 diets, while the lowest DMD was for the SS0 diet (42.1%). These results were consistent with figures reported by Dao Hung (2006 ) from 46.1- 66.7%. and Nguyen Thi Xuan Linh (2005) from 41.7-73.0% which included para grass and sweet potato leaves in the diets. The increasing OMD pattern was similar to that of the DMD. There was an increase of CPD corresponding to the increased Spophocarpus scandén in the diets with a significantly higher CPD for the SS80 diet (84.4%) compared to that of the SS0 one. The result was also consistent with that (82.0-83.0%) reported by Nguyen Van Thu and Nguyen Thi Kim Dong (2005). The digestibility of NDF in different diets was not significantly different, however there was proportionally an improvement of NDFD numerically (from 35.3 to 40.9%) with the increase of Spophocarpus scandén leaves in the diets. Similar patterns of nitrogen intake and retention were obtained in diets, however, they were significantly different (P<0.01) among the treatments with the highest values of the SS80 diet (2.99 and 2.42 g/kg W^0,75, respectively ). This indicated that there was better utilization of plant foliated protein in rabbits when increasing legume leaves in the diets.

Exp 2

 The chemical composition of green feeds and paddy rice fed to rabbits in the Exp 2 is shown in Table 6.

Mom grass had the highest DM content (15.7%) compared to Cuc, water spinach and sweet potato vine (12.1, 9.63 and 8.56%, respectively). These figures were similar to reports by Nguyen Hai Phu (2004), Danh Mo (2004) and Dao Hung (2006). Crude protein content was higher for sweet potato vine and water spinach. Those figures were slightly lower than that of Nguyen Thi Xuan Linh (2005) and Danh Mo (2004) due to the effects of rainy season for Exp 2. The NDF content was high in Mom grass (66.3%), while that was similar in the others. The ADF content of Mom grass and Cuc was higher than those of sweet potato vine and water spinach. Paddy rice supplemented had DM and CP content of 87.4 and 6.68%, respectively.

Feed and nutrient intakes of rabbits in Exp 2 are presented in Table 7.

The DM intake (g/rabbit/day) was not significantly different among different diets, however, the lower figures were for the WS  and SP diets, due to the low DM content of the SP and WS. These results were consistent with report of Nguyen Van Thu and Nguyen Thi Kim Dong (2005) being from 51.4-61.5 gDM/rabbit/day in a study with SP replacing para grass in growing rabbit diets. In general DM intake of rabbits in the present experiment was good with the values ranged from 60.7 to 65.0g/day/rabbit. The OM and CP intakes were not significantly different among the treatments, however, the CP intake of the WS and SP diets was numerically higher than the rest of diets. The NDF intake of the WS+M and SP+M diets were significantly higher than other because of higher NDF content of the Mom grass.

 Daily weight gain, feed conversion ratio and economic analysis are shown in Table 8.

Daily weight gain was significantly different among the treatments (P<0.05) with the highest value of the WS diet. while the significantly lower values were for SP+M and SP+C diets. The results of daily weight gain of crossbred rabbits fed local green foliages in present experiment ranged from 14.2 to 17.7g. They are consistent with those (from 11.0 to 19.0g) of other reports in Vietnam by Nguyen Thi Xuan Linh (2005) Dao Hung (2006). Nguyen Van Thu and Nguyen Thi Kim Dong (2005) and Nguyen Thi Kim Dong et al. (2007^b). Le Thi Ha et al. (1996) stated that the weight gain of the pure New Zealand rabbits fed grasses and concentrate and legume leaves were 15.5g and 20.6g per day. The values were also within the range reported by (Samkol et al.. 2006). They were slightly lower than those found by Phimmasan et al. (2004) and Khuc Thi Hue and Preston (2006). Feed conversion ratio of the rabbits was from 3.35 to 4.50 and the WS and SP diets was significantly lower than the rest of diets. The obtained values for feed conversion ratio were at acceptable levels and consistent with the results being from 4.9 to 6.0 and 7.0 indicated by Akinfala et al. (2003) and Suc et al. (2000). respectively. The economic analysis showed that the profit got from the WS+M. SP+M and SP+C diets were higher than the rest of diets due to acceptable growth rate and lower cost of feed. despite growth rate and feed conversion ratio of the WS and SP diets were better. Thus fresh forage sources available could be used as staple feeds in the rabbit diets to get better benefits for farmers.

Carcass values and chemical composition of rabbit meat are shown in Table 9.

The criteria of carcass. lean meat. offals and meat quality were not significant affected by the different diets. Nguyen Van Thu and Nguyen Thi Kim Dong (2005) in a study of sweet potato vine replacing para grass in the diets reported that the carcass and lean meat percentage of growing crossbred rabbits were from 41.6 to 47.1% and from 67.8 to 79.2. respectively. Crude protein content of rabbit meat in the present experiment was from 18.7 to 19.5%. while this was 22.5% reported by Nguyen Chu Chuong (2003). The difference could be caused by feed sources and supplements. In the current experiment paddy rice was supplemented with a average level of 15g/day/rabbit. while other experiments on pure improved breeds concentrates were mostly used for supplementing.

Conclusions

 The conclusion of the study was that the use of Spophocarpus scandén to replace para grass in the growing rabbit diets improved crude protein intake, daily weight gain and profit with a consideration of 40% replacement. Fresh forages such as water spinach. sweet potato vine. Mom grass (Hymenache acutigluma) and Cuc (Wedelia spp) could be used for feeding the growing rabbit. Water spinach and sweet potato vine associated Mom grass or Cuc in the diet at the ratio of 1:1 could be economically fed and increase economic return.
 

References

 Akinfala E O. Matanmi O & Aderibigbe AO 2003: Preliminary studies on the response of weaned rabbits to whole cassava plant meal basal diets in the humid tropics. Livestock Research for Rural Development, Vol. 15 (4): http://www.cipav.org.co/Irrd/Ịrrd/4/akĩn.htm.

 AOAC 1990: Official methods of analysis (15^th edition). Washington. DC, Volume 1: 69-90.

Chat T H. Dung N T. Binh D V and Preston T R 2005:  Water spinach (Ipomoea aquatica) as replacement for guinea grass for growing and lactating rabbits. Livestock Research for Rural Development, Vol. 17.

 Danh Mo 2003: A study of improving in vitro forage digestibility measurement by using rumen fluid as nutrient source replacing chemicals for microbes in swamp buffaloes (Vietnamese). MSc thesis, Faculty of Agriculture and Applied Biosciences, Cantho University, Vietnam.

 Dao Hung 2005: Breed characteristics and productivity; and effect of crude protein levels on growth rate, feed intake, nutrient digestibility and nitrogen retention of crossbred rabbits (Vietnamese). MSc thesis, Faculty of Agriculture and Applied Biosciences, Cantho University, Vietnam.

 Khuc Thi Hue and T R Preston 2006: Effect of different sources of supplementary fibre on growth of rabbits fed a basalk diet of fresh water spinach (Ipomoea aquatica). Livestock Research for Rural Development,Vol. 18 (3).

 Le Nguyen Huyen Trang 2006 Effect of sweet potato and water spinach as protein sources on the meat performance and digestibility of crossbred rabbits (Vietnamese). Under Graduated Thesis, Faculty of Agriculture & Applied Biology, Cantho University.

 Le Thi Ha, Nguyen Quang Suc, Đinh Van Binh, Le Thi Bien and TR Preston 1996: Replacing concentrates with molasses blocks and protein rich tree leaves for production and growth of rabbits. Livestock Research for Rural Development, Vol. 8 (3): 39-43.

 Mc Donald P, Edwards R A,Greehalgh J F D and Morgan C A 2002: Digestibility evaluation of foods. In Animal Nutrition,6^th Edition, Longman Scientific and Technical, New York. Pp: 245-255.

 Minitab 2000: Minitab reference manual release 13.20. Minitab Inc.

 Nguyen Chu Chương 2003: Questions and Answers on rabbit husbandry. Agriculture Publishing house. Pp. 43 – 45.

 Nguyen Hai Phu 2004: Growth characteristics and nutritional values of Mom (Hymenache acutigluma) and para grass (Brachiaria mutica) growed at SOHA farm. BSc thesis, Faculty of Agriculture and Applied Biosciences. Pp. 3.

 Nguyen Thi Kim Dong, Nguyen Van Thu and Thomas R. Preston 2007^a: Effect of dietary protein supply on reproductive performance of crossbred rabbits. MEKARN Proccedings of Workshop on Forages for Pigs and Rabbits, Phnom Penh, Cambodia, 22-24 August 2006, Agricultural Publishing house – Hanoi. P 176-182.

 Nguyen Thi Kim Dong, Nguyen Van Thu, Brian Ogle and Thomas R. Preston 2007^b: Effect of supplement level of water spinach leaves in diets based on para grass on intake, nutrient utilization, growth rate and economic returns of crossbred rabbits in Mekong delta, Vietnam. MEKARN Proccedings of Workshop on Forages for Pigs and Rabbits, Phnom Penh, Cambodia, 22-24 August 2006, Agricultural Publishing house – Hanoi. P 176-182.

 Nguyen Thi Xuan Linh 2005: Effect of sweet potato vines replacing para grass (Brachiaria mutica) on feed and nutrient digestibility and nitrogen retention of growing crossbred rabbits. BSc thesis, Faculty of Agriculture and Applied Biosciences. Pp. 4-12. 17.

 Nguyen Van Thu and Nguyen Thi Kim Dong 2005: Effect of replacement of diffferent levels of para grass by sweet potato vines on feed utilization, growth rate and carcass quality of crossbred rabbits in the Mekong delta of Vietnam. In proceedings of Integrating Livestock-crop systems to meet the challlenges of globalisation, Ed. Rowlinson. P.. Wachirapakorn. C.. Pakdee. P.. and Wanapat. M.  Vol 2: T51.

Phimmmasan H, Kongvongxay S, Chahay T and Preston T R 2004: Water spinach (Ipomoea aquatica) and Stylo 184 (Stylosanthes guianensis CIAT 184) as basal diets for growing rabbits. Livestock Research for Rural Development. Vol. 16 (5).

Samkol P, Preston T R and Ly J 2006: Digestibility indices and N balance in growing rabbits fed basal diet of water spinach (Ipomoea aquatica) supplemented with broken rice. Livestock Research for Rural Development. Vol. 18 (2).

Suc N Q, Luyen L T & Binh D V 2000: Feeding system for tropical rabbit production emphasizing root and bananas. Proceedings National Workshop-Seminar Sustainable Livestock Production on Local Feed Resources (Editors: T R Preston and RB Ogle), Ho Chi Minh City. Vietnam. http://www.mekarn.org/sarpro/suctuber.htm.

 Van Soest P J. Robertson J B and Lewis B A 1991: Symposium: Carbohydrate methodology, metabolism and nutritional implications in dairy cattle: methods for dietary fiber, and non-starch polysaccharides in relation to animal nutrition, J. Dairy Sci. 74: 3585-3597.

Go to top