Use of Cassava as Animal Feed

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Effects of roughage source on rumen microbes, feed intake and digestibility in swamp buffaloes
 

C Yuangklang, S Wora-anu, M Wanapat, N Nontaso^* and C Wachirapakorn

 Department of Animal Science, Faculty of Agriculture,  
^* Department of Microbiology, Faculty of Science, 
Khon Kaen University, Khon Kaen 40002, Thailand

Abstract

Four, 4-7 year-old rumen-fistulated swamp buffaloes were randomly assigned to a 4x4 Latin square design to receive the following treatments: RS= untreated rice straw; UTS = urea treated (5%) rice straw; RH = ruzi grass hay and CH = cassava hay. Each period lasted for 2 weeks during which feed intakes were measured. A the end of the period, rumen fluid samples were collected and analyzed. 

Digestion coefficients of dry matter and organic matter, and dry matter intakes were highest for the urea-treated rice straw and cassava hay treatments.

Key words: Roughages, rumen microbes,  feed intake,  digestibility,  buffaloes

Introduction

Roughages play a major role as feed for ruminants in the tropics. Seasonal patterns affect the availability and quality of these roughages, particularly during the dry season (Wanapat 1999). Efficient utilization of roughages depends on the availability of nutrients needed by both rumen microbes and by the animal with the ultimate aim of maximizing feed intake and performance (Preston and Leng 1987).

The following study aimed at comparing the effect of different sources of forage on the rumen ecosystem, feed intake and digestibility in swamp buffaloes. Cassava hay is a new feed resource (Wanapat et al 1997) which appears to have high potential as a protein-rich supplement in the tropics.

Materials and Methods

Four rumen-fistulated swamp buffaloes,  4-7 years old, were randomly assigned to four dietary treatments according to a 4x4 Latin Square design with periods of 14 days on each of the following diets: 

• RS = untreated rice straw;
• UTS= urea-treated (5%) rice straw;
• RH = ruzi grass hay (Brachiaria ruziziences),
• CH = cassava hay. 

All the buffaloes were drenched with an anthelmintic and injected with vitamins A, D and E prior to commencing the experiment. They were kept in individual stalls.

Urea-treated rice straw was prepared by pouring a urea solution (5 kg of urea in 100 kg of water) over a stack of straw and covering with a plastic sheet for 10 days before feeding to the animals. Cassava foliage was harvested 3 months after planting, and was chopped and then sun-dried for 1-2 days to obtain cassava hay. All the roughages were offered ad libitum with fresh feed offered in the morning and afternoon.

Feed intakes were measured daily during each two-week experimental trial. Samples of rumen fluid were collected at the end of each period and immediately analyzed for pH and temperature and prepared for measurement  of total microscopic and viable bacterial count, protozoa, fungi zoospores, and types of bacteria (Galyean 1989; Hungate 1969).  Rectal samples of feces were  taken at the end of each period and analyzed for acid-insoluble-ash (AIA) as an internal indicator to estimate digestibility of DM and OM (Van Keulen and Young 1977). Feeds were analyzed for DM, ash, nitrogen, NDF and ADF by standard methods (AOAC 1985; Goering and Van Soest 1970). All data were statistically analyzed by the GLM option of ANOVA  (SAS 1987) and treatment means compared by Duncan’s New Multiple Range test.

Results and Discussion

There were major differences in the nature and content of the crude protein component of the different forages (Table 1). In terms of requirements for rumen fermentable nitrogen the rice straw and ruzi grass hay are likely to be highly imbalanced.  In contrast, the cassava hay provided more fermentable nitrogen than needed by rumen micro-organisms. 

 There were no major differences between diets in the rumen populations of bacteria, protozoa and fungi, all of which appeared to be in the normal range (Table 2).  Surprisingly, rumen pH appeared to be lowest on the urea-treated rice straw. 

Table 2. Effect of roughage source on rumen pH, temperature and microbes
	RS	UTS	RH	CH	SEM
Rumen pH	6.6a	6.2b	6.5 a	6.7 a	0.07
Rumen temperature, oC	38.0 a	38.5 ab	39.0b	38.0 a	0.10
Total microscopic direct counts
Bacteria, x 10-10 cells/ml	8.4 ab	9.2 a	7.2 b	8.1 ab	0.33
Protozoa, x 10-5 cells/ml	3.9 ab	4.4 a	3.7 ab	2.7 b	0.90
Fungal zoospores, x 10-5 cells/ml	24.2 a	24.6 a	19.1 b	20.5 b	0.84
Grouping of bacteria
Total viable bacteria, x10-9CFU/ml	4.1 a	4.6 a	2.5 b	4.5 a	0.64
Celluloytic bacteria, x 10-8 CFU/ml	5.9 a	8.4 b	3.5 C	3.9C	0.54
Proteolytic bacteria, x 10-6 CFU/ml	12.3 a	22.3 b	8.8 a	9.8 a	1.80
Amylolytic bacteria, x 10-7 CFU/ml	1.7	1.9	1.1	1.5	2.43
abc Values in the same row with different superscripts differ (P<0.05) RS = Rice straw, UTS= Urea-treated rice straw, RH= Ruzi hay, CH = Cassava hay

Feed DM intakes and apparent digestibility coefficients were higher (p<0.05) for urea-treated rice straw and for cassava hay than for rice straw and ruzi grass hay (Table 3). These results probably reflect the differences in the supply of fermentable nitrogen from these two feeds. 

 
References

AOAC  1985  Official  Methods of Analysis. Association of Official Analytical Chemists. Washington, D C

Galyean  M  1989  Laboratory procedures in animal nutrition research. Department of Animal  and Life Science. New Mexico State University, USA

 Goering  H K  and  Van Soest  P J 1970  Forage fiber analysis (apparatus, reagents, procedures and some applications). Agric. Handbook. N. 397. ARS, USDA, Washington, DC 

Hungate  R E  1969  A roll tube method for cultivation of strict anaerobes. In: Methods in Microbiology , edited by J R  Norris and D W  Ribbons. New York. Academic Press. 313:117.

Preston T R and Leng R A 1987 Matching ruminant production systems with available resources in the tropics and sub-tropics, 245p. Penambul Books Armidale, NSW, Australia

SAS  1987  SAS/STAT Guide for Personal Computers, Version 6, Cary, NC:SAS Inc.

Van Keulen  J  and Young B A 1977  Evaluation of acid insoluble ash as a neutral marker in ruminant digestibility studies. Journal Animal  Science  44:282.

Wanapat  M  1999  Feeding of Ruminants in the Tropics Based on Local Feed Resources. Khon Kaen Publishing Comp. Ltd., Khon Kaen, Thailand, 236 pp.

Wanapat  M,  Pimpa O, Petlum A and  Boontao U 1997  Cassava hay: A new strategic feed for ruminants during the dry season. Livestock Research for Rural Development, 9(2): http://www.cipav.org.co/lrrd/lrrd9/2/metha92

Wanapat  M, Pimpa  O , Sripuek W, Puramongkol T,  Petlum A, Boontao U, Wachirapakorn C and Sommart  K 2000  Cassava hay: an important on-farm feed for ruminants. In Proc. International Workshop on Tannins in Livestock and Human Nutrition (Editor: J D  Brooker), ACIAR Proc. No. 92, p. 71-74.

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