Mini-project Research protocol  

MSc in Tropical Livestock Systems (2005-2007)
Contents

Citation of this paper

Comparison of nutritive value (CP, water extractable DM and N, and NDF) of young and old leaves from mulberry, Trichanthera, Erythrina and cassava trees

Comparison of nutritive value of young and old leaves from Mulberry, Trichanthera, Erythrina, Gliricidia, Cassava, and Sweet potato


Kongmanila Daovy

National University of Laos (NUOL)
Vientiane, Lao PDR
dkongmanila@yahoo.com



Introduction

Livestock are most important for supplying meat and milk for human,consumption, income for farmers and manure for cropping. The traditional feeding system for livestock is based on locally available feed resources such as natural pasture, rice straw, rice bran, sweet potato vine, cassava root meal, some kinds of tree fodder and agro-industrial by-products with the use of commercial feed as a supplement. Simbaya (2002) reported that these feed resources that are available for animals are usuallly fibrous and devoid of most essential nutrients including protein, energy, minerals and vitamins.

There are many kinds of tree fodder, legumes and crops which are important protein resources, for instance Mulberry, Trichanthera, Cassava, and Sweet potato. Normally, green plants are used as traditional feeds in diets for animals but a little is known about their nutritive value and especially protein availability. However, Ngo Thuy Bao Tran (2003) reported that the young leaves at the top of trees have higher nutritive value than those at the bottom of the tree. In this connection, major differences in the in vivo digestibility of young and old cassava leaves were reported by Chhay Ty et al (2003). Dry matter content in the leaves was lower but N, water-soluble DM and N were higher in the leaves taken from the top of young cassava plants compared with the bottom leaves from cassava at about 5 months of age.

Hypothesis

Young leaves at the top of the chosen trees will have higher nutritive value than those at the bottom of the trees.

Objectives

To determine the nutritive value of young and old leaves from

 

Materials and methods

Location
The leaves will be collected from trees located around the Livestock Research Center, in Nam Xaung. The experiment will be conducted in the laboratory of Livestock Research Centre, NAFRI, Lao PDR about 40 km from Vientiane Capital from 13 September to 15 October, 2005.
 
Experiment design

The experiment will be designed as a split-plot factorial arrangement (2 x 6) with three replications. Each replication will consist of 12 kinds of leaves (2 positions in the tree * six types of tree leaves)

Treatments

Six tree leaves will be compared as show below:

    

Mulburry (Morus indica)

Trichanthera (Trichanthera gigantea)

Erythrina (Erythina variegata)

Gliricidia (Gliricidia sepium)

Cassava (Manihot esculenta)

Sweet potato (Ipomoea batatas L.)

 

Each of the tree leaves will be used in two treatments equivalent to young (top) and old (bottom) leaves Individual treatments are: Mulberry top (Mt), Mulberry bottom (Mb), Trichanthera top (Tt), Trichanthera bottom (Tb), Erythrina top (Et), Erythrina bottom (Eb), Gliricidia top (Gt), Gliricidia bottom (Gb), Cassava top (Ct), Cassava bottom (Cb), Sweet potato top (St) and Sweet potato bottom (Sb).

Sample collection

Samples will be taken of leaves from the top and bottom of the following trees: Mulberry (Morus indica), Trichanthera (Trichanthera gigantea), Erythrina (Erythina variegata), Gliricidia (Gliricidia sepium), Cassava (Manihot esculenta) and Sweet potatoes (Ipomoea batatas L.). It will be assumed the leaves at the top of the trees are the young leaves and the leaves at the bottoms are the old leaves. Plant samples will be collected in the morning and immediately put into plastic bags to avoid moisture losses and carried to the laboratory in the same day.

Procedure of water soluble dry matter and N

The samples will be dried in a fixed temperature oven (60°C) for 24 hours and then in a micro-wave oven (Undersander et al 1993) to make sure the samples will completely dry to constant weight. They will be then ground in a coffee mill. A sample (about 1 g) of the dry ground material will be put into weighed nylon bags, size 50 x 150 mm, with a pore size of 45 to 55µ. The bags containing the samples will be tied and put into the washing machine with 3 liters of water per bag. Washing takes place for 90 minutes with 15 minutes in each cycle. After washing, the bags will be dried and weighed and N determined on the dry residues (Ly and Preston 1997).

The formula for the calculation of the water soluble DM is:      

% Water soluble (DM) = 100*( DM - DR)/DM

 Where DM is the weight of the dry original sample and DR is the weight of the dry residues.

The formula for the calculation of the water soluble N is:

 

            % Water soluble (N) = 100*(NS - NR)/NS

 

Where NS and NR are the nitrogen content determined in the original sample and in the residue obtained after washing. The nitrogen content is usually expressed in percent in dry basis, in both cases (Chhay Ty and Julio Ly 2001).

Chemical analysis

Young and old leaves will be analyzed for dry matter (DM), organic matter (OM), crude protein (CP) according to the AOAC (1990). Neutral detergent fiber (NDF) will be determined using the procedure of Goering and Van Soest (1970).  and water-soluble DM and N which were determined by the methods described by Ly and Preston (1997).

Statistic analysis
 

The data will be analyze by Analysis of variance (ANOVA) using the General Linear Model (GLM) procedure of the Minitab software (version 13.3). Sources of variation will be: trees, position in tree, interaction of position*tree and error.

References

AOAC 1990 Official methods of analysis. Association of Official Analytical Chemists, Arlington, Virginia, 15th edition, 1298 pp.

 Chhay Ty,  Preston T R and Ly J 2003  The use of ensiled cassava leaves in diets for growing pigs. 2. The influence of type of palm oil and cassava leaf maturity on digestibility and N balance for growing pigs.  Livestock Research for Rural Development (15) 8 Retrieved September 29, 2003, from http://www.cipav.org.co/lrrd/lrrd15/8/chha158.htm

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

 Goering H and  Van Soest P 1970 Forage fiber analysis. Agriculture hand book No. 379. United State Department of Agriculture, Washington D.C., USA.

 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

Ngo Thuy Bao Tran 2003 Effect of age of leaves from forage trees on nutritive value. Retrieved September12, 2005, from MEKARN Mini-projects. http://www.mekarn.org/msc2003-05/miniprojects/web page/tran.htm 

Simbaya J 2002 Potential of tree fodder/shrub legumes as feed resources for dry season supplementation

of smallholder ruminant animals. National Institute for Scientific and Industrial Research,  Livestock and Pest Research Centre, Chilanga, Zambia. P.69-76.

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