Livestock Research for Rural Development 2 (3) 1990

Citation of this paper

"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


"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


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).

Table 1: Composition and chemical analysis of the experimental diets.

------------------------ Grower (22-60 days) ------------------------

  (0-21 days) Control 15% molasses 30% molasses
Ingredients (%):        
Broken rice 40.0 52.0 44.2 31.5
Rice bran 18.0 24.0 13.6 8.4
Maize meal 10.0 - - -
"A" molasses - - 15.0 30.0
Fish meal 18.0 15.0 17.0 19.6
Soyabean meal 7.0 - - -
Groundnut cake 5.0 7.0 8.5 9.1
Bone meal 1.0 1.0 0.68 0.35
Min./vit. premix 1.0 1.0 1.02 1.05
Analysed composition (%):        
Crude protein 20.0 17.6 17.4 17.4
Ca 1.48 1.09 1.09 1.12
P (total) 0.67 0.57 0.57 0.58
ME, MJ/kg (calculated) 11.7 11.2 11.1 10.8

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.


Grateful acknowledgement is made to SAREC and to FAO (TCP/VIE/8954) for technical and financial support for this work.


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)