Studies on ensiled taro (Colocasia esculenta) leaves in
diets of local crossbred pigs in Cambodia were conducted at the
Center for Livestock and Agriculture Development (CelAgrid) and in
two different districts of Pursat and Kandal provinces in Cambodia.
The main objectives were to determine the varieties and cultivation
techniques of taro and its use (Paper I) and to determine the
digestibility and nitrogen balance in pigs given diets with ensiled
taro leaves replacing fish meal (Paper II). The aim was also to
determine feed intake, growth rate, feed conversion ratio and
economic benefits of crossbred pigs fed diets with ensiled taro
leaves replacing fish meal, and with rice bran and sugar palm syrup
as energy sources (Paper III).
The survey was carried out in two provinces, Pursat and Takeo,
representing two major agro-ecological Zones (AEZs) in Cambodia.
Fifty four families from six villages were interviewed. Two
varieties of taro, called locally Chouk and Sla, are commonly
cultivated and Trav Prey (wild taro) also grows naturally. Chouk
and Sla taro are short-term varieties and can be harvested 5-8
months after planting. Taro is considered to be a good vegetable
crop and is planted in the late dry and early rainy season, between
April and July, nearby the houses in the two selected provinces.
The tubers are used for human consumption, while stems and leaves
are only occasionally used for animal feed. The main reasons for
not using them were given as being that they cause itching, and
that farmers lack tradition and knowledge. The average tuber yield
is 4.5-6.0 tons ha-1 while the average petiole and leaf
yield is 5.0-8.5 tons ha-1. Farmers considered the stems
to be the worst in terms of itching, followed by leaves then root.
However the effect can be reduced by boiling, frying, ensiling or
sun drying. Both salt and sugar palm syrup can be used as additives
for ensiling.
The second part of the thesis is a study on digestibility and N
balance in pigs of diets with ensiled taro leaves replacing fish
meal, carried out on the CelAgrid experimental farm. The four
treatments applied to 4 growing pigs in a 4*4 Latin Square
arrangement were levels of ensiled leaves of taro (Colocasia
esculenta) equivalent to 25, 50, 75 and 100% substitution of
the protein from fish meal in a basal diet of sugar palm syrup. The
results show that there were positive curvilinear trends in dry
matter and crude protein intake and in N retention in response to
replacement of fish meal by ensiled taro leaves, with the optimum
proportion being at about 70-75% replacement. Coefficients of DM
apparent digestibility were high on all diets, but those for crude
protein showed a negative curvilinear response with declining
values beyond 25% substitution of the fish meal protein by that
from taro leaf silage. The limiting factor to the utilization of
the taro leaf silage appears to be the lower apparent digestibility
of the protein in the taro leaves and not the amino acid balance of
the protein.
The third study was on the effect of taro (Colocasia
esculenta) leaf silage as replacement for fish meal on the feed
intake and growth performance of crossbreed pigs. Eighteen
crossbred (Large White x Local) male pigs with initial body weight
of 20.9± 0.29 kg were allocated randomly into 3 treatments
replicated 6 times, with one pig in each pen. The treatments were
ensiled leaves of taro replacing 0 (FM), 50 (FM-TS) or 100 (TS) %
of the protein from fish meal in a basal diet of sugar palm syrup
and rice bran. Total dry matter feed intake was lower in TS than in
FM and FM-TS (P<0.01), also when expressed on a live weight
basis (37.8, 41.9 and 33.1 g/kg for FM, FM-TS and TS, respectively)
(P<0.01). Average daily gain was highest for FM-TS (278g),
followed by FM (226g) and TS (119g) (P<0.05). Dry matter feed
conversion and cost of feed per kg gain were highest for TS (8.79
kg/kg gain and 2.24 US$/ kg gain, respectively) and lowest for
FM-TS (4.69 kg/kg gain and 1.09 US$/kg gain, respectively)
(P>0.05). Daily gains and feed conversion were only around 50%
of the genetic potential of the pigs for these traits. Further
research is needed to identify the true constraints to pig growth
when protein from ensiled taro leaves is a major component of the
diet.