Livestock Research for Rural Development 16 (7) 2004

Citation of this paper

Responses of growing beef cattle to a feeding regime combining road side grazing and rice straw feeding supplemented with urea and brewers' grains following an oil drench

Nguyen Xuan Trach and Mai Thi Thom

Hanoi Agricultural University, Vietnam
nxtrach@hau1.edu.vn

Abstract

A participatory feeding trial on growing crossbred cattle (Lai Sin) was organized to test a pilot feeding regime based on road side grazing and rice straw supplemented with urea and brewers' grains following an oil drench. Twenty cattle raising farmers in the countryside of Hanoi were selected for the participatory feeding trial in the winter-spring period. Half of the farmers grew their cattle as normally practiced to form the control group. The other ten farmers fed their cattle with rice straw ad libitum plus 4 hour roadside grazing/day supplemented with 2 kg fresh brewers' grains/head/day. The experimental cattle were drenched with cooking oil at a rate of 5ml/kg live-weight. The trial lasted for 3 months after a 15-day adaptation period.

Results showed that the experimental cattle consumed more rice straw (1.85 vs 1.17 kg DM/head/day) and grew faster (408 vs 245 g/head/day). As a result, the introduced feeding regime using brewers' grains and an oil drench resulted in more financial profit to the farmer than the system normally practiced.

Key words: Brewers' grains, cattle, grass, growth, oil, rice straw, urea


Introduction

Rice straw is abundant in Vietnam but still underutilized as feed for ruminants. Rice straw is characterized by high levels of cell wall lignification and unbalanced nutrients. In principle, it is possible to improve the feeding value of rice straw with a number of treatment techniques which have been developed (see review by Nguyen Xuan Trach 1998).  In addition to delignification, straw supplementation with limiting nutrients such as nitrogen (N), minerals, vitamins and readily fermentable carbohydrates is needed to improve its utilization by rumen bacteria (Chenost and Kayouli 1997). However, as shown by Nguyen Xuan Trach (2004), under the smallholder's circumstances, the application of straw treatment techniques is constrained by a number of socio-economic and psychological factors. Straw supplementation with locally available sources of the limiting nutrients may be more applicable for small scale farmers in trying to improve utilization of rice straw as feed for cattle.

Wet brewers' grains (WBG) have been shown to be a very good source of protein, fermentable fiber and growth factors to stimulate cellulolytic bacteria, thus improving straw utilization (Nguyen Xuan Trach 2000). A small amount of green grass has also been shown to stimulate rumen cellulolysis of straw owing to its supply of easily fermentable fiber for cellulolytic bacteria (Preston 1995). Moreover, in Central Vietnam farmers have had a custom to drench their cattle with one liter of groundnut oil at the start of fattening them on rice straw and roadside grass. Recently, studies by Nguyen Thi Hong Nhan et al (2001, 2003) and Mom Seng et al (2001) have shown that the oil eliminated protozoa from the rumen and, as a result, the cattle grew faster.

In the light of the above findings, the present study was conducted to test a pilot feeding scheme in which growing cattle were fed on rice straw supplemented with urea and wet brewers' grains in combination with road-side grass grazing following an oil drench at the beginning. The feeding regime was developed based on a hypothesis that combination of the known effects of the supplements and oil drench can make rice straw better utilized by growing beef cattle.
 

Materials and Methods

Twenty cattle-raising farmers in Bac Ninh (north east of Hanoi) were selected for a participatory feeding trial undertaken in the winter-spring period of 2002-2003. Half of the farmers grew their cattle as normally practiced (rice straw fed ad libitum plus 4 hour roadside grazing a day ) to form the control group. The other ten farmers fed their cattle with 1% urea-sprayed rice straw ad libitum plus 4 hour roadside grazing a day supplemented with 2 kg wet brewers' grains/head/day. The experimental cattle were weighed at the start and drenched with groundnut oil at a rate of 5ml/kg live-weight. The trial lasted for 3 months after a 15-day adaptation period. All the animals were weighed at the beginning, after each month and at the end of the trial. Records were kept by farmers of the straw and brewers' grains that were fed.

During the trial, the straw to be fed was weighed at every feeding. Residues were collected and weighed before the morning feed every day during the whole feeding trial period. Dry matter intake (DMI) of straw was determined based on the daily amounts of straw fed, residues and their dry matter (DM) contents as determined at the laboratory. Samples of natural grass and wet brewers' grains were taken three times in the middle of each experimental month for analysis of dry matter (DM), nitrogen (N), and total ash following Official Methods of AOAC (Cunniff 1997). In addition, neutral detergent fiber (NDF), and acid detergent fiber (ADF) of straw, natural grass and wet brewers' grains were determined according to Van Soest and Robertson (1985).

Economic analysis was made using partial budget analysis based on increased costs and increased returns of the treated group as compared with the control group.

Experiment data were analyzed according to a one-way ANOVA model (SAS 1996).
 

Results and discussion

Feed intake and growth rate

Chemical composition of feeds used in the feeding trial is given in Table 1. In the present study, it was not possible to measure the amounts of natural grass consumed by the two groups, which were assumed to be the same because they had the same hours of grazing. However, as shown in Table 2, straw DM intake was significantly different between groups (P<0.01). The treated group consumed 59% more straw DM than the control one. This may be explained by positive effects of the N/protein supplements (wet brewers' grains and urea) on straw digestibility (Nguyen Xuan Trach 2000). Actually, straw intake fell dramatically after oil administration, but returned to normal in two weeks. The depression may be due to the reduction of rumen microbial population as affected by the oil treatment (Mom Seng et al 2001; Nguyen Thi Hong Nhan et al 2003).

Table 1: Composition of feeds used in the feeding trial

 

DM (%)

Chemical composition (% DM)

CP

NDF

ADF

Ash

Natural grass

20.5

12.6

56.4

28.6

20.5

Rice straw

89.2

5.05

80.1

52.7

14.1

Wet brewers’ grains

22.5

27.8

54.7

26.9

4.14

 

Table 2: Effects of supplementation combined with an oil drench on growth and straw intake in young crossbred cattle (10 animals per treatment)

 

Control

Supplemented

Age (months)

10 to 12

10 to12

Initial weight (kg/head)

138

135

Final weight (kg/head)

160a

172b

Total gain (kg/head)

22.1a

36.7b

Average daily gain (g/head/day)

245a

408b

Straw DM intake (kg/head/day)

1.47a

1.85b

ab Means without common superscript in the same row are different at P<0.05.

The growth rate of the cattle was increased significantly by the supplementary feeding regime (Table 2). The average daily gain (ADG) of the treated group was 67% higher than that of the control. This is in agreement with reports of Nguyen Thi Hong Nhan et al (2001, 2003) and Mom Seng et al (2001) who supplemented growing cattle fed rice straw with grass or cassava foliage after a single cooking oil drench. Other studies have shown increases in digestibility and dry matter intake as a result of improved rumen function when low quality roughages are supplemented with green forage and/or a protein source like brewers' grains (Bird et al 1994; Leng 1997;  Nguyen Xuan Trach 2000). In addition, according to Nguyen Thi Hong Nhan et al (2001, 2003) and Mom Seng et al (2001), the oil drench has a defaunation effect which may improve rumen cellulolysis thus increasing straw digestibility and intake, and eventually animal growth. Although the defaunation effect on feed utilization in the rumen is still subject to debate, the positive results of the present trial support the custom to drench cattle with groundnut oil at the start of fattening them on rice straw and roadside grass as practiced by farmers in Central Vietnam. The addition of urea and brewers' grains to the system resulted in additional positive effects on growth of cattle as shown in the present study.

Economic benefits

Based on changes in inputs and output due to the application of the feeding regime and unit prices of the inputs and output at the time of experiment (Table 3), a partial analysis on changes in costs and returns of the experimental group as compared with those of the control was made (Table 4).The results indicate that although additional investment was needed in the new feeding regime, as compared with the conventional practice, the farmers could make a profit equivalent to 55% of the additional investment after 3 months thanks to the increase in growth rate of their animals.

Table 3: Unit prices of the feeds used and the product sold in the feeding trial

Item

Unit price

Rice straw

250 VND/kg

Brewers’ grains

600 VND/kg

Urea

2 800 VND/kg

Cooking oil

12 500 VND/liter

Beef cattle

15 000 VND/kg live-weight


Table 4: Partial budget analysis of the feeding trial (changes in costs and returns of the experimental group as compared with those of the control)

 

 

(VND/head/month)

I. Increased costs

 

47 500

      In which,

Brewers’ grains

36 000

 

Urea

2 300

 

Oil

4 220

 

Increased straw intake

4 950

II. Increased returns

 

73 500

       In which,

Increased live-weight gain

73 500

III. Profit (II-I)

 

26 000

IV. Increased returns/Increased costs (III/I)

1.55/1

N.B. 15 000 VND is equivalent to 1 USD

Conclusions

Feeding growing crossbred cattle (Lai Sin) based road-side grass and urea-sprayed rice straw supplemented with brewers' grains following a single dose of groundnut oil (5 ml/kg live-weight) at the beginning improved feed intake, growth rate and economic profitability.
 

Acknowledgements

This research was supported by the International Foundation for Sciences (IFS), Stockholm, Sweden, through a grant to the first author.
 

References

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Received 26 May 2004: Accepted 16 June 2004

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