Mini-project Research protocol  

MSc in Tropical Livestock Systems (2005-2007)
Contents

Citation of this paper

Effect on feed intake and digestibility in goats of different ways of preserving cassava foliage given as a supplement to guinea grass

Effect on feed intake and digestibility in goats of different ways of preserving cassava foliage given as a supplement to Mulato grass


Ho Thanh Tham

Cantho University, Vietnam
httham@ctu.edu.vn

Introduction

Cassava (Manihot esculenta) foliage is mainly available as a crop residue after harvesting the roots. Several researchers have claimed that cultivating cassava for forage purpose could be a productive practice in improving nutritional values for livestock (Preston 2001). Cassava tops are rich in protein, carotene and minerals, and for this reason it is considered a potential source of animal feed in tropical countries (Gohl 1993; Preston and Leng 1987).

In the recent years, many studies have been carried out in Vietnam and in Thailand on cassava top processing, in which dried cassava, ensiled cassava leaves were made from fresh cassava leaves and used as a supplement in diets for small ruminants and cattle. Research in Cambodia showed that intake was higher when cassava foliage was ensiled compared with fresh or sun-dried foliage (Ho Bunyeth and Preston 2005). Although the HCN content of fresh cassava tops was very high, there appear to be no problems of toxicity with feeding of cassava leaves to goats when it is given in fresh, dried or ensiled form as described by Ho Bunyeth and Preston (2005). Bui Van Chinh (1990) also found that ensiling and drying cassava leaves can significantly reduce their HCN content.

Hypothesis

Feed intake and digestibility in goats fed Mulato grass (Brachiaria híbrido, cv.) will be improved when given supplements of cassava foliage fed in three different ways (cassava hay, silage, and fresh).

Objectives

The objective of this experiment is to learn about the effects on feed intake and digestibility of different ways of preserving cassava foliages given as supplement to Mulato grass for growing goats. Emphasis is put on comparing fresh, ensiled and sun-dried leaves as there appear to be no reports comparing these different ways of processing the leaves for growing goats.


Materials and methods

Location

The experiment will be carried out at the Livestock Research Center (LRC) in Nam Xuang village, Vientiane city, Lao PRD, about 40 km from Vientiane.The duration of this experiment is about 30 days, from 12th September to 12th October, 2005.

Treatments and design

There are three treatments in a 3*3 Latin Square design with 3 goats and 3 periods of 10 days (the first 5 days for adaptation and second 5 days for data and sample collection). The treatments were designed as following:

Period/Treatment

Goat 1

Goat 2

Goat 3

1

CH

CS

CF

2

CS

CF

CH

3

CF

CH

CS

where

Experimental animals and feed

Three local crossbred goats will be used in this experiment with average body weight about 15 kg. They are housed in wooden cages designed for separate collection of urine and feaces. Mulato grass is cut from the field daily and fed after chopping into 2-3 cm lengths at 1 % of body weight (DM basis). The fresh, ensiled and sun-dried cassava leaves are offered ad libitum at 120% of observed intake.

Measurements

Animals are weighed at the beginning of every period. Feeds offered and refused, urine and faeces are recorded daily during the last 5 days of each period and 10% of the faeces are kept in plastic bags in the refrigerator. 10% of the urine is stored until the end of each period. Thereafter, at the end of 5 days all samples will be bulked, mixed and representative amounts taken for analysis

Chemical analysis

Sample of feeds offered, refused and faeces are analysed for N by the method of AOAC (1990). DM is determined by microwave radiation (Undersander et al 1993) and water soluble DM and N by the method of Ly and Preston (1997). Samples of fresh cassava, cassava hay and  cassava silage will be taken for analysis of HCN content (Chhay Ty and Ly 2001).

Statistical analysis

The data are analysed using the GLM option of the Minitab software (Minitab release 13.3, 2000). Sources of variation will be treatments, animals, periods and error.


References

AOAC 1990 Official methods of analysis. Association of official analytical chemists. 15th edition (K. Helrick editor) Arlington p.1230.

Bui Van Chinh 1990 Study on ensiling cassava leaves and tops. Proceedings of the National Workshop on the Development of Animal Production in Mountainous Areas of North Vietnam, pp. 4-7.

Chhay Ty and Ly J 2001 Manual of laboratory. Centre for Livestock and Agriculture Development. UTA-Cambodia. 19p.

Ho Bunyeth and Preston T R 2005 The effect of ensiling or sun-drying cassava leaves on feed intake, digestibility and N retention of goats fed a basal diet of Para grass (Brachiaria mutica). MSc thesis. Swedish University of Agricultural Sciences, Uppsala. http://www.mekarn.org/msc2003-05/theses05/content/bunyethcont.htm

Gohl B 1993 Tropical Feeds (in Vietnamese). Hanoi, pp. 318-320.

Ly J and Preston T R 1997 An approach to the estimation of washing losses in leaves of tropical trees. Livestock Research for Rural Development 9(3): http://www.cipav.org.co/lrrd/lrrd13/1/ly131.htm

Preston T R and Leng R A 1987 Matching ruminant production systems with available resources in the tropics and sub-tropics. Penambul Books Armidale , Queensland 4380, Australia, pp. 117-118.

Preston T R 2001 Potential of cassava in integrated farming systems. In: T.R Preston, B. Ogle and M. Wanapat (eds). International Workshop on Current Research and Development on Use of Cassava as Animal Feed. Khon Kaen University, Thailand. July/23-24, 2001. p: 5-12. http://www.mekarn.org/procKK/pres.htm.

Undersander D, Mertens D R and Thiex N 1993 Forage analysis procedures. National Forage Testing Association. Omaha, p. 154.