"A" molasses in diets for growing ducks
Bui Xuan Men and Vuong Van Su
Faculty of Animal Husbandry and Veterinary
Medicine, University of Cantho, Cantho, Hauglang, Vietnam
Summary
"A" molasses was substituted for broken rice and
rice polishings at 15 or 30% in the diets of growing ducks
between the ages of 22 and 60 days. Daily liveweight gains and
feed conversion were satisfactory on the molasses diets, and not
significantly different from the control group.
Key words: "A" molasses, ducks, rice byproducts,
growth
Introduction
Ducks are an important source of animal protein in Vietnam,
particularly in the Mekong delta, where over ten million are
reared annually for both egg and meat production. The majority of
these birds are local breed types, which traditionally are kept
as scavengers, with supplementary feed being supplied when
available in the form of seasonal crop residues and by-products.
Levels of performance are normally low, but could be
significantly improved by using fast growing hybrids and
providing them with balanced diets, preferably still based on
cheap, locally available by-products. Rice bran and polishings,
derived from the country's staple food grain, are the traditional
feed supplements for all classes of livestock.
Sugar cane, the second most important crop in Vietnam, also
produces valuable byproducts in the form of molasses. Small
scale, artisan methods for extracting sucrose from the heated
juice, are still widely used, the most popular involving a single
centrifuging which gives rise to a crystalline white sugar (
"A" sugar) and an enriched "A" molasses. The
latter product, which has a higher content of sugars than the
"final" or "C" molasses produced by
industrial methods, has potential as a substitute for cereal
grains and grain byproducts in diets for monogastric animals
(Preston 1987). In preliminary trials in Cuba, Pérez and San
Sebastián (1970) reported better growth rates for ducks fed
"A" molasses than for those fed "C" (Final)
molasses.
Materials and methods
Housing and birds:
The experiment was carried out at the University of Cantho
research farm in the Mekong delta, between February and July,
1990. A total of 270 Cherry Valley hybrids were used, with three
dietary treatments and three replicates of 30 birds per
treatment. The ducklings were given a commercial type starter
diet between hatching and 21 days of age, and were then allocated
at random to one of the experimental diets. Groups of 30,
consisting of approximately equal numbers of males and females,
were housed together in pens constructed from bamboo, with
thatched roofs and rice straw covered packed earth floors, with
an average density of five ducks per square metre. During the
daytime the birds also had access to outside sand yards (one duck
per square metre), and for approximately 6 hours per day to a
fresh water swimming area (five ducks per square metre).
Diets and feeding:
The composition and chemical analysis of the diets are shown
in table 1. The "A"" molasses used in the
experiment was collected from a small sugar refining factory in
the area, and is the residue after the heated syrup from sugar
cane juice is centrifuged to separate the crystalline sugar. The
sample used in this experiment had the following analysed
chemical composition: °Brix (a measure of dissolved solids) 78;
dry matter 66.5%; crude protein 1.71%; ether extract 0.91%; crude
fibre 0.37%; ash 3.37% and calculated ME (poultry) 9.43 MJ per
kg. The "A" molasses replaced a mixture of broken rice
and rice bran, and was thoroughly mixed with the dry meal.
The ducks were fed ad libitum, with fresh feed being
offered at three hours intervals throughout the day, mixed with
water in a ratio of 4:1 meal to water. In addition they were
given a mixture of green water plants (Azolla, water spinach and
duck-weed) at a rate of approximately one part green material per
6 parts of dry feed. The birds were slaughtered at 60 days of
age, eviscerated and plucked, and the carcass weight recorded.
Results and discussion
Growth performance and carcass parameters are presented in
Table 2.
| Table 2: Effect
of "A" molasses partially substituted for
broken rice and rice bran on the performance of growing
ducks between 22 and 60 days of age. |
 |
| |
Control |
15% molasses |
30% molasses |
SE (Prob)± |
|
| Liveweight
(g) |
|
|
|
|
| Initial |
568 |
568 |
568 |
|
| Final |
2090 |
2120 |
2028 |
|
| Daily gain |
40.0 |
40.8 |
38.4 |
0.98 (0.32) |
| |
|
|
|
|
| Feed intake
(g/day) |
|
|
|
|
| Meal |
181 |
179 |
178 |
|
| Green feeds |
31 |
31 |
31 |
|
| |
|
|
|
|
| FCR (kg
mash/kg gain) |
4.48 |
4.39 |
4.64 |
0.12 (0.39) |
| |
|
|
|
|
| Dressing % (%
of liveweight) |
76.8 |
78.6 |
76.7 |
|
|
Feed intakes and daily gains were satisfactory when "A"
molasses was included in the diets, and similar to those of ducks
on the control diet. There were no apparent health problems
attributable to the molasses and the excreta were of normal
consistency.
It is concluded that up to a level of 15% of the diet for
growing ducks "A" molasses can be substituted on a
weight basis for rice bran and broken rice. The decision as to
when to use it will depend on its price relative to that of the
cereal byproducts. The opportunity price of "A"
molasses is determined by its relative availability (eg: in the
sugar cane harvest season) and its value as a substrate for
alcohol (rum) manufacture.
Acknowledgements
Grateful acknowledgement is made to SAREC and to FAO
(TCP/VIE/8954) for technical and financial support for this work.
References
Pérez R and San Sebastian J R 1970
Liquid molasses-based diets for ducks. Revista Cubana de Ciencia
Agrícola 4:205-207
Preston T R 1987 Pigs and poultry in the
tropics. Utilization of local feed resources. Technical Centre
for Agricultural and Rural Cooperation:Ede-Wageningen,
Netherlands pp25
(Received 15 October 1990)