A repeated drench with soybean oil improves growth and feed conversion of beef cattle fed rice straw supplemented with urea molasses

M J Uddin, K S Huque, S A Chowdhury¹ and Z H Khandaker²

Department of Animal Nutrition, Sylhet Agricultural University, Sylhet, Bangladesh
jasimsau@gmail.com
¹ Bangladesh Livestock Research Institute, Savar, Dhaka
² Department of Animal Nutrition, Bangladesh Agricultural University

Abstract

Twenty three growing bulls about 1-1.5 yrs old and 185±23.6 kg live weight were allocated to 4 treatments (DEF1, DEF2, REF and CTL). The DEF1 treatment was a single drench with 3g of soybean oil per kg live weight;  DEF2 animals were drenched twice (the second drench 30 days after the first one),  cattle on the REF treatment were refaunated 30 days after the initial oil drench, while the CTL treatment was neither renched nor refaunated.

Dry matter (DM) feed converson (FCR) and live weight gain were better for the cattle given a repeated drench with soybean oil than for the control animals. Between the defaunated treatments,  the repeaated defaunation (DEF2) showed better feed utilization and growth rate with lower feed intake than the single defaunation. The higher growth rates were associated with protozoal counts less than 50,000/ml compared with counts of the order of 200,000/ml before oil treatment. It is concluded that oil drenching may be a suitable option for profitable cattle fattening.

Key words: beef production, defaunation, refaunation, rumen protozoa

Introduction

A sensible livestock development strategy needs to match with the feed resources, type of animals and the animal products with the national requirement. It is obvious from the experience over generations in Bangladesh, that an exclusive diet of rice straw, with little or no supplementation, barely supports the nutritional needs of livestock, resulting in stunted growth, impaired reproduction and lactation and reduced working ability. The feeding value of rice straw can be improved with a number of treatment techniques that have been developed (Trach and Thom 2004). However, neither improved feeding techniques such as urea-treated straw or urea-molasses block supplementation are being used by the farmers in Bangladesh.

 In ruminants, protozoa account for 20 to 70% of the ruminal microbial biomass, but their contribution to microbial protein flow at the duodenum is limited to only 20 to 40% (Jouany 1996). Nhan et al (2003) confirmed the advantages of an oil drench in increasing the live weight gain of local Yellow cattle fed on untreated rice straw supplemented with cassava foliage. The oil drench has an anti-protozoal effect which might improve rumen cellulolysis, increase digestibility and intake, and eventually animal growth (Seng et al 2001).

The early procedures used a chemical surfactant for eliminating the protozoa but this was a difficult procedure which often resulted in the death of the animals, and thus had a negative impact at farmer level. Using oil to eliminate the protozoa from the rumen has been shown to improve growth rates,  increasing bacterial population and microbial protein flow from the rumen to lower tract (Leng 1990). Lipids are toxic to rumen ciliate protozoa (Newbold and Chamberlain 1988) and the approach for reducing rumen protozoa with oil drenchng has a positive effect on growth rate of cattle (Nguyen Thi Hong Nhan et al 2001). A single dose oral administration of oil at farmer level resulted in better growth performance of cattle (Nguyen Thi Hong Nhan et al 2003, Seng et al 2001).  

The Government of Bangladesh has taken beef fattening as an action program to generate income for the rural farmers. Thus this research focused on the effects of defaunation on the growth rate of  local cattle.

Methodology

Several methods are available for eliminating protozoa from the rumen, and they are mostly based on the use of chemicals (e.g., copper sulfate and calcium peroxide) that have toxic effects on ruminal protozoa (Jouany 1996). A major drawback of using chemicals to eliminate ruminal protozoa is that they can be toxic to experimental animals and can also alter other aspects of the ruminal microbial ecosystem (Jouany et al 1998), hence it was decided to use soybean oil as a defaunating agent in this program following the research of Nguyen Thi Hong Nhan et al (2001).

Experimental animals and management

Twenty three native Pabna bulls about 1-1.5 yrs old and 185±23.6 kg live weight were selected from the stock herd of Bangladesh Livestock Research Institute for a trial of 120 days duration. They were allocated to 4 treatments (DEF1, DEF2, REF and CTL). The DEF1 treatment was a single oil drench, DEF2 was drenched twice (the second drench 30 days after the first one), the REF treatment was refaunated following the initial defaunation, while the CTL treatment was neither defaunated not refaunated. Animal on each treatment were housed in different sheds to avoid contamination.  All the cattle were fed ad libitum straw supplemented with urea-molasses (3% urea, 20% molasses) plus a  concentrate mixture (wheat bran, gram bran 1: 1)  at 1% of their live weight. A pre-experimental period of 10 days was considered as an adjustment period to adapt the animals with whole experimental feeding system. The urea-molasses supplemented straw (UMS) and the concentrate were given twice daily, in the morning and evening. Feed offered and feed residues were recorded daily. Samples were taken three times per week for determination of  dry matter (DM). Live weights were recorded every 2 weeks. 

Defaunation and refaunation

Removal of protozoa in treatments (DEF1, DEF2 and REF)  was performed by drenching the animals with 3g of soybean oil per kg live weight.  After 15 days DEF2 cattle were given a second oil drench  and at the same time the REF animals were refaunated by feeding 500 ml of fresh rumen liquor collected from rumen-cannulated bulls. Prior to, and after 7 days of oil treatment and at the termination (120th days) of the experiment, rumen liquor was collected through a stomach tube from all animals 1.5-2 hours after the morning feed. Immediately after collection of the rumen sample, the pH was measured and the sample stored at 5ºC for counting of protozoa. For the protozoa counting, the samples were at kept room temperature before diluting (1:1) with formalin and the protozoa then counted under a microscope. For the measurement of NH₃, the rumen samples were acidified with 3-4 drops of concentrated sulfuric acid (99% purity) and then stored in a deep freezer until laboratory analysis.

Results

Growth and feed conversion

DM intake was reduced, growth rate appeared to be increased (p=0.099), and DM feed conversion was improved, in the cattle given a repeated oil drench (DEF2) as compared with the control (CTL)treatment (Table 1; Figure 1). These effects were less marked for the single oil drench treatment. The growth performance of the refaunated (REF) animals was similar to that on the control treatment.

Figure 1. Effect of a single or repeated oil drench on cattle fed rice straw supplemented with molasses-urea and wheat bran

Before oil treatment, protozoal numbers on all the treatments were similar, but 7 days after the first oil drench, the protozoal population was decreased to levels much lower than in control animals (Table 2). After the second oil drench (DEF2 treatment), protozoal numbers in these animlas remained low, but they tended to increase in those animals drenched only once (DEF1), while in the refaunated animals (REF) numbers of protozoa were almost back to the levels before the oil drench. After 120 days (end of the trial), protozoal numbers in DEF1 and DEF2 had increased but were still lower than in the control and refaunated treatments.

The pH in the rumen was not changed by the oil drench (Table 3).

Discussion

The increase in growth rate following defaunation is in agreement with many reports in the literature of the positive effects of defaunation in roughage-based diets (eg: Demeyer et al I982; Leng 1982; Trach and Thom 2004; Seng et al 2001; Nguyen Thi Hong Nhan et al 2001, 2003, 2007, 2008). The decrease in the protozoal population as as a result of the oil drench, and the subsequent gradual restoration of protozoal numbers is in accordance with the findings of Seng et al (2001). The  better feed conversion, and the tendency for a higher growth rate in DEF2, compared with DEF1 animals, implies that there may be advantages in repeated oil drenching. There appear to be no reports of this method being used in a practical feeding situation. This procedure merits further research.

Conclusions

• Utilization of feed (FCR) and live weight gain appeared to be improved by 30% in cattle given a repeated drench with soybean oil compared with control animals. The higher growth rates were associated with protozoal counts less than 50,000/ml compared with counts of the order of 200,000/ml before oil treatment.
  
  
• It is concluded that oil drenching may be a suitable option for profitable fattening of cattle on diets based on rice straw.

References

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Jouany J P 1996 Effect of rumen protozoa on nitrogen utilization by ruminants. Journal of Nutrition 126:1335S–1346S.

Jouany J P, Demeyer D I and Grain J 1998 Effect of defaunating the rumen. Animal Feed Science Technology 21:229–265.

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Leng R A1982 Dynamics of protozoa in the rumen of sheep. British Journal of Nutrition 56:917-935

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Nguyen Thi Hong Nhan, Nguyen Van Hon, Nguyen Trong Ngu, Nguyen Tien Von, Preston T R and Leng R A 2001 Practical Application of Defaunation of Cattle on Farms in Vietnam: Response of Young Cattle fed Rice Straw and Grass to a Single Drench of Groundnut Oil). Asian-Australian Journal of Animal Sciences (14) 4: 485-490.

Nguyen Thi Hong Nhan, Nguyen Van Hon, Nguyen Trong Ngu, Nguyen Thi Thu Hong, Preston T R and Leng R A 2003 Effect of drenching with cooking oil on performance of local "Yellow" cattle fed rice straw and cassava foliage.Livestock Research for Rural Development 15 (7). http://www.lrrd.org/lrrd15/7/nhan157.htm

Nguyen Thi Hong Nhan, Nguyen Trong Ngu, Vo Van Son, Preston T R and Leng R A 2007 Effects of oil drench on growth rate of cattle fattened on grass, supplemented with molasses, rice bran or rice straw. Livestock Research for Rural Development 19 (9). http://www.lrrd.org/lrrd19/9/nhan19133.htm

Nguyen Thi Hong Nhan,  Nguyen Trong Ngu, T R Preston and R A Leng 2008 Effects of drenching soybean oil and fish oil on intake, digestibility and performance of cattle fattening in the Mekong Delta, Vietnam. Livestock Research for Rural Development 20 (7) http://www.lrrd.org/lrrd20/7/nhan20113.htm

Seng M, Preston T R, Leng R A and Meulen U 2001 Effect of a single drench of cooking oil on the rumen ecosystem and performance of young local "yellow cattle" fed rice straw and cassava foliage.Livestock Research for Rural Development 13 (4). http://www.lrrd.org/lrrd13/4/seng134.htm

Trach N X and Thom M T 2004 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. Livestock Research for Rural Development. Volume 16, Article # 53 from http://www.lrrd.org/lrrd16/7/trac16053.htm

Received 18 September 2014; Accepted 4 January 2015; Published 4 February 2015

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