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| Mini-project Research
protocol |
MSc in Tropical Livestock Systems (2005-2007) |
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| Mini-project Research
protocol |
MSc in Tropical Livestock Systems (2005-2007) |
| Contents |
Pig farming plays an important role in Laos in small farming systems as a source of protein, as a valuable fertilizer for paddy and vegetable plots, and as a means of family capital accumulation. Pigs are normally raised in a free-range system supplemented by rice bran and other household waste products.(http://clubs.uow.edu.au/clubs_websites/oxfam/Why%20Pigs.pdf).Sweet potato (Ipomoea batatas L. (Lam)) is the common crop in Laos after rice and maize, and has high biomass yields of both tubers and vines. Traditionally, sweet potato is used as human food when rice was not sufficient, although at present it is commonly used as feed for farm livestock, especially pigs. The tubers have a high carbohydrate content while the leaves are rich in protein, and both tubers and vines can be used as animal feed (Woolfe 1992). The vines include the leaf and stem, with a crude protein content in the leaves of 260-330 g/kg DM compared with 100-140 g/kg DM in the stems (Woolfe 1992; Ishida et al 2000; An et al 2003). It has been shown that the leaves make up approximately half of the sweet potato vines biomass (Woolfe 1992; An et al 2003). Thus, if the leaves could be separated from the stems a considerable improvement with respect to the dietary protein and amino acid supply would be expected (An et al 2003).
Water spinach (Ipomoea aquatica) is a water plant. It is
cultivated for human food and used for pigs and other animals in
Laos. It does not appear to contain anti-nutritional compounds and
has been used successfully for growing pigs as the only source of
supplementary protein in a diet based on broken rice (Ly 2002).
Prak Kea et al (2003) reported that fresh water spinach can
provide up to 20% of the dietary protein for growing pigs, when it is
supplemented with broken rice. In addition, Chhay Ty and Preston
(2005) reported that fresh water spinach was more palatable than
the cassava leaves as reflected in higher total DM intake and the
proportion of the diet (47%) provided by the leaves. The digestibility
of dry matter, organic matter, N and crude fiber were higher in
the diet with water spinach than in the diet with cassava
leaves.
Feed intake and digestibility in pigs will be better when water spinach is added to the diet of rice bran and cassava root meal and sweet potato leaves.
To study intake and digestibility in growing pigs
fed different levels of sweet potato foliage and water
spinach as supplement to a mixture of rice bran and cassava root meal
The experiment will be conducted at the Livestock Research Center of the National Agriculture and Forestry Institute (NAFRI), Nam Xuang about 44 km from Vientiane city, Lao PDR from September to October 2005.
The daily dry matter (DM) allowance will be calculated at 4% of the body weight. The cassava root meal and rice bran (50:50 mixture) will be restricted to 2% (DM basis) of live weight, the sweet potato leaves mixed with water spinach will be fed ad libitum (120% of observed intake). Fresh sweet potato leave and water spinach will be harvested everyday in the Livestock Research Center. The sweet potato leaves and water spinach will be chopped into small pieces and offered immediately.
There are three treatments:
WS0: mixture of rice bran and cassava root meal supplemented with sweet potato leaves
WS25: mixture of rice bran and cassava root meal supplemented
with water spinach and sweet potato leaves (25:75 DM
basis).
WS50: mixture of rice bran and cassava root meal supplemented
with water spinach and sweet potato leaves (50:50 DM
basis).
The experiment will be done according to a 3*3 Latin Square arrangement of the 3 dietary treatments with 3 local male pigs of average live weight 13.3 kg. The animals will be housed in metabolism cages (80 x 80cm) during the whole trial (30 days). Each experimental period consists of 10 days; 5 days to adapt to the diets followed by another 5 days for collection of faeces and urine, and recording of feed offered and feed refusals. The arrangement of the treatments is in Table 1.
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Table 1. Experimental layout |
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|
Periods/pigs |
1 |
2 |
3 |
|
1 |
WSO |
WS25 |
WS50 |
|
2 |
WS25 |
WS50 |
WS0 |
|
3 |
WS50 |
WS0 |
WS25 |
The cassava root meal and rice bran (50:50 mixture) are fed at
2% of live weight (DM basis). The sweet potato leaves and water
spinach will be fed ad libitum (120% of observed intake). The leaves plus stems
of the water spinach and sweet potato leaves will be chopped into small pieces,
separate from the other ingredients
of the diet. The feed will be given in 3
meals daily (7.30, 11.30 and 16.30h). Water will be permanently
supplied through drinking nipples.
Animals are weighed at the beginning of each period. Feed offered,
feed refusals, faeces and urine will be collected every day during the last 5
days of each period. 10% is taken as a representative sample and frozen in plastic bags until analysis.
The samples from every treatment at the
end of each period (feed offered, feed refusals, and faeces) will be
mixed thoroughly by hand and then homogenized in a coffee grinder,
prior to taking representative samples that will be analyzed for
DM, N, water soluble DM and N. Urine will be collected in a plastic bucket
to which sulphuric acid will be added to maintain the pH below 4.0. The volume
of urine will be measured every day and a 10% sample kept in the refrigerator
until the end of each period, the samples then bulked and analyzed for N.
Chemical analyses of the feed ingredients, faeces and urine will
be undertaken following the methods of AOAC (1990) for N. The DM
content will be determined using the microwave method of Undersander
et al (1993). Water soluble DM and N will be determined by the
methods described by Ly and Preston (1997).
The data will be subjected to analysis of variance according to
the general linear model of the Minitab software (Minitab release
13.31, 2000). Sources of variation will be pigs, periods,
treatments and error.
An L V, Lindberg B E F, Lindberg J E 2003 Effect of
harvesting interval and defoliation on yield and chemical
composition of leaves, stems and tubers of sweet potato (Ipomoea
batatas L (Lam.)) plant parts. Field Crops Res. 82,
49-58.
AOAC 1990 Official Methods of Analysis. Association of
Official Analytical Chemists. 15th Edition (K Helrick editor).
Arlington pp 1230.
Chhay Ty and Preston T R 2005 Effect of water spinach and
fresh cassava leaves on intake, digestibility and N retention in
growing pigs; Workshop-seminar
"Making better use of local feed resources" MEKARN-CTU,
Cantho, 23-25 May, 2005. Retrieved September 11, 2005, from http://www.mekarn.org/ctu05/chha
.htm.
http://clubs.uow.edu.au/clubs_websites/oxfam/Why%20Pigs.pdf
Ishida H, Suzuno H, Sugiyama N, Innami S, Tadokoro T and
Meakawa A 2000 Nutritive value on chemical components of
leaves, stalks and stems of sweet potato (Ipomoea batatas
Poir). Food Chem. 68, 359-367.
Ly J 2002 The effect of methionine on digestion indices
and N balance of young Mong Cai pigs fed high levels of ensiled
cassava leaves. Livestock Research for Rural Development. (14) 2:
http://www.cikpav.org.co/lrrd/lrrd14/6/Ly146.htm
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
MINITAB 2000 Minitab reference Manual release
13.31.
Prak Kea, Preston T R and Ly J 2003 Feed intake,
digestibility and N retention of a diet of water spinach
supplemented with palm oil and / or broken rice and dried fish for
growing pigs. Livestock Research for Rural Development (15)
8 Retrieved , from http://www.cipav.org.co/lrrd/lrrd15/8/kea158.htm
Undersander D, Mertens D R and Theix N 1993 Forage
analysis procedures. National Forage Testing Association. Omaha pp
154.
Woolfe J A 1992 Sweet Potato: An Untapped Food Resource.
Cambridge University Press, Cambridge.