Livestock Research for Rural Development

1997, Volume 9, Number 3

A study of feed degradability and rumen environment of swamp buffaloes

Nguyen van Thu

Faculty of Agriculture, Cantho University, Vietnam

Abstract

Two experiments were carried out on four fistulated swamp buffaloes to evaluate local feed resources using the in sacco method to study degradability and effects of the rumen environment. Promising feeds included: water plants (duckweed, azolla, Eleocharis dulcis, Blyxa Javenicey, and Sacciolepis indica), natural grasses (Bbrachiaria mutica and Panicum repens), legume tree leaves (Sesbania sesban, Sesbania grandiflora, and Leucaena leucocephala), crop residues and agro-industrial by-products (rice straw, sugarcane tops, maize stover and pine apple peel) and protein and energy-rich supplements (coconut and ground nut cake, rice bran, broken rice and maize).

The rumen environment study was a Latin square arrangement with four different diets: rice straw (RS), rice straw and molasses-urea cake (MUC), rice straw, MUC and grass (0.5% body weight), and rice straw and grass (0.5%DM of body weight). The results in the above order of diets were: ruminal NH3-N, 9.17, 13.7, 12.3, 10.2 mg/100ml (SE=1.19, P=0.032); bacteria population, 0.84, 1.01, 1.07, 0.98*109 (SE=0.03, P=0.002); protozoa population 2.49, 3.03, 3.38, 2.84*105 (SE=0.12, P=0.002). Feed intake was 96.0, 99.0, 113 and 109 g DM/W0.75 (SE=2.10, P=0.001), respectively. There was an indication of improvement in feed degradability when the rice straw was supplemented with molasses-urea cake and grass.

It is concluded that there is an abundance of local feeds available for buffalo production in the Mekong delta and that supplementation of rice straw with molasses-urea cake and grass has beneficial effects on the rumen environment of swamp buffaloes.

Key words: Swamp buffaloes, local feed resources, rice straw, molasses-urea cake, grass, ruminal ammonia, bacteria, protozoa, feed degradation.

 

Introduction

Swamp buffaloes have played an very important role of providing draught power and beef for people in the Mekong delta of Vietnam. Farmers have benefited much from swamp buffalo production, but feeding systems are traditional and there are few studies aimed at improving the performance of buffaloes and how to enhance profit for farmers who keep these animals.

In recent years the buffalo population has seriously decreased due to the limitation on grazing land areas and the increased use of tractors. In many cases farmers sold buffaloes to buy tractors for work, then they had to sell tractors to buy buffaloes for work again (Ogle et al 1994). By the end of the dry season, in many areas buffaloes have only rice straw to eat. Then their working performance and health is poor. In many serious cases, they have been sold for slaughter.

A multi-nutritional supplement - molasses-urea cake (MUC) - produced at Cantho University - improved the swamp buffalo performance in working, growth rate and milk production (Nguyen Van Thu 1996). The aim of this study was to produce some basic data on the nutritive value of local feed resources for swamp buffalo and to study the effect of small amounts of low-cost supplements such as molasses-urea cake and grass on the rumen ecosystem.

Materials and methods

In the first experiment, four buffaloes with permanent rumen fistulas, two years of age, were used to investigate feed selection, composition and relative rumen degradation rate of natural grasses, water plants, agro-industrial by-products, and energy and protein supplements available in the Mekong delta. The samples of feeds were oven-dried and ground through a 2-3mm screen. The procedure for measuring degradability was that descibed by Orskov et al (1980) and Orskov and Shand (1997). Bags were removed from the rumen at 6, 12, 24, 36, 48, 72 and 96 hours.

In the second experiment four dietary treatments were compared in a 4*4 Latin square arrangement using the same animals as in the first experiment. The diets were: rice straw (RS); rice straw and molasses-urea cake (MUC) fed at 350 g/day, rice straw plus fresh grass at 0.5% of body weight (dry basis) (RSG) and the combination of rice straw, molasses-urea cake and grass (RSMG). Rumen fluid was collected at 06:30 hours prior to feeding. pH was measured with a glass electrode and ammonia by steam distillation. Protozoa were counted in a 0.2 mm deep chamber under 100*magnification. Numbers of bacteria were counted in a Neubauer chamber under 1200*magnification following the procedure decribed by Hernander (1989). The rumen degradation rates of reference feed samples (rice straw, sugar cane bagasse, banana leaves and leaves and stems of Sesbania grandiflora) were determined using the in sacco method. The samples were oven-dried and then cut into 2-3 mm pieces. Feed intake was recorded.

Results and discussion

Of the feed resources tested (Table 1), the water plant Blyxa Javenicey had the highest value (60%) for 24 hour degradability. Two other water plants - duckweed and Saciolepis indica - had degradabilities of 56 and 50%, respectively.

Azolla was very poor with a 24 hour degradability of only 29%. The two grasses were similar to duckweed (about 50% degradable at 24 hours).

There were marked improvements in degradability for incubation periods of 72 hours with all the tested feeds reaching values between 70 and 80%. It is generally considered that rumen turnover time is slower in buffaloes than in cattle thus 72 hour values may be a more appropriate indicator of potential fermentability of feeds in the former species.

In the second experiment the results showed that there was a significant increase in ruminal pH when the molasses-urea cake was fed. Ammonia concentration, and populations of protozoa and bacteria populations, were higher on all supplemented diets compared with unsupplemented rice straw. Feed intake was increased by supplementation with grass but not with the molasses-urea cake (Table 2).

None of the supplementation treatments affected the rumen degradabilities of the reference feeds (Table 3). These findings with swamp buffalo are different from what has been recorded for cattle fed rice straw and supplements. Bui Xuan An et al (1992 ) reported a 16% increase in rumen degradability of rice straw in nylon bags (48 hour incubation) in cattle when their rice straw diet was supplemented with a molasses-urea block. Similar findings were reported by Wanapat et at (1991) when Brahman cattle fed rice straw were supplemented with a feed block. Kabatange and Shayo (1991) showed increases in rumen degradability of a fibrous feed (maize stover) in cattle when a maize stover basal diet was supplemented with leucaena hay. Addition of grass to the diet of sisal waste fed to sheep also increased fibre degradability in nylon bags (Guttierrez et al 1984).


It appears that swamp buffaloes may have lower requirements for rumen ammonia than cattle (rskov E R 1997, personal communication) which could explain the lack of effect of the supplements on feed degradability despite the fact that most criteria of an effective rumen ecosystem were improved by molasses-urea supplementation (Table 2).

Conclusions and recomendations

Local feed resources available for swamp buffalo production in the Mekong delta were abundant. Supplementation of a rice straw basal diet with a molasses-urea cake and small amounts of natural grass (0.5% of liveweight, DM basis) improved the rumen environment of swamp buffaloes but there were no benefits on rumen degradabilities of rice straw, sesbania leaves or banana leaves.

Swamp buffaloes fed on rice straw may respond differently to supplementation compared with cattle which is a topic meriting further research.

Acknowledgements

The research described here was financed in part by the International Foundation for Science (IFS) whose support is gratefully acknowledged (Grant B2296-1)

References

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Received 1 March 1997

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