Sugar cane products in diets of ducks

Sugar cane juice and "A" molasses were fed as complete replacement of rice byproducts in diets of Cherry Valley Super M ducks during the period from 22 to 60 days of age. Growth rates and feed conversion favoured the control diet followed by cane juice and finally "A" molasses (P<.05). The differences were most marked in the case of feed conversion with 29% and 48% more feed dry matter required on cane juice and "A" molasses diets respectively. For growth rate the differences in performance were less; 12 and 26% poorer for cane juice and "A" molasses, respectively. Carcass yield was slightly less and livers heavier on cane juice compared with the control and molasses more so. The yield of all edible parts did not differ between cane juice and the control but was less on "A" molasses.

KEY WORDS: Ducks, sugar cane juice, "A" molasses, rice byproducts, growth, conversion, Vietnam

Duck production is expanding widely in Vietnam, playing an important role in providing meat and eggs in the daily diet of the people in the Mekong Delta and goods for export (meat, eggs and feathers). The duck population in the MeKong region is the highest in the country because there are profitable conditions for raising ducks. They can be herded the year round and are managed mostly by peasant households being raised usually in the rice fields where during the harvest periods they consume the left-over rice and natural feeds in the rice paddies and canals.

Because duck production is mostly based on the rice crop the prices of duck meat and eggs fluctuate according to the economics of rice production and thus vary in different months of the year. The higher the price of rice the greater the incentive to use other feeds as substitutes in order to maintain duck production at a uniform level.

Sugar cane grows well on the acid soils of the Mekong Delta and is becoming increasingly important in the cropping systems.

Traditionally it is processed in "cottage industries" into "A" sugar providing "A" molasses as a byproduct. This molasses is mostly fermented to alcohol but can also be used as animal feed, especially for pig production (Figueroa and Ly 1990).

In a trial with "A" molasses as partial substitute for rice byproducts in the diet of fattening ducks, there were no significant differences in performance traits between ducks given the control and experimental diets with up to 30% of "A" molasses (Men and Su 1990).

The present trial was set up to test the hypothesis that either "A" molasses or fresh sugar cane could be given as a complete substitute for rice byproducts in the diet of fattening ducks.

The trial was carried out at the Faculty Experiment Farm between March and June 1991. 270 Cherry Valley Super M ducks were used for the experiment over the age period of 22-60 days. The treatments were:

There were 3 replications each of 30 ducks on each treatment. The experimental design was of completely random blocks. The composition of the diets from hatching to 21 days and during the experimental period from 22 to 60 days of age is shown in Table 1.

In addition the ducks were given small amounts of duckweed (Lemna spp), averaging 3.2 g (fresh basis)/duck/day during the brooding stage and 17-19 g/duck/day during the experiment. The duckweed was mixed with the mash (control) or with the protein concentrate (molasses and cane juice diets).

Table 1: Proportions of ingredients (dry matter basis) in the diets of ducks in the brooding stage (1-21 days) and during the experiment (22-60 days)

Ingredients	Brooding	Control	Cane juice				"A"molasses
	1-21d	22-60d	A	B	C	D	A	B	C	D

Broken rice	30	54	28	-	-	-	37	17	6	-
Rice polishing	10	24	10	19	9	-	-	-	-	-
Maize meal	30	-	-	-	-	-	-	-	-	-
Fish meal	16	17	22	23	26	22.8	22	23	24	22.8
Soyabean meal	12	3	8	6	3	5.7	9	8	8	5.7
Bone meal	1	1	1	1	1	0.5	1	1	1	0.5
Premix vit/min	1	1	1	1	1	1	1	1	1	1
Cane juice	-	-	30	50	60	70	-	-	-	-
"A" molasses	-	-	-	-	-	-	30	50	60	70

Prior to feeding, water was added to the mash (control diet) at the rate of 1 part of water: 4 parts of dry feed; in the experimental diets the rates were fresh sugar cane juice to concentrate at 1:3 and "A" molasses and water to concentrate at 1:1:1.5, respectively.

The fresh sugar cane juice used for the experiment was extracted in a 2-roll mill which had a capacity of 100 kg of cane stalk per hour with 50% extraction of juice (50 kg juice from 100 kg of cane stalk). The cane stalks were obtained from the HoaAn Sulphate Acid Soil Research Centre, Phunghiep district and kept during 3-5 days before crushing. The juice used in the experiment had an average brix of 20°.

The "A" molasses was taken from the artisan factory at HoaAn village. "A" molasses is the part remaining after the concentrated cane syrup is centrifuged to separate the white crystalline "A" sugar. The samples of molasses taken before each feeding had an average brix of 79.6°, and total reducing sugars 64% and non-sugar organic matter of 1.4%.

The "A" molasses was diluted with water at the rate of 1 part of molasses: 3 parts of water, to give a solution with an average brix of 24°.

The ducks were offered fresh feed 5 - 6 times daily in the brooding stage and 3 times daily during the experiment. Feeding was ad libitum in amounts that corresponded to the proportions indicated in Table 1.

The ducks were housed in a shed divided into pens. Each pen accommodated 30 ducks with 5 m² floor area, 30 m² running yard and 8 m² water surface for swimming. The pens had access to water on the bank of a canal and fenced with bamboo and reed where the ducks were able to swim about 1-2 hours daily depending on the tide in the canal. Feeders and drinkers used during the experiment were round plastic basins (40 cm diameter, 10 cm depth). Natural light was used in day time and electric bulbs (4 w/m² of floor) at night for ducks from hatching to 60 days. The temperatures during the experiment averaged 30°C.

Growth rates and feed conversion favoured the control diet followed by cane juice and finally "A"molasses (P<.05). The differences were most marked in the case of feed conversion with 29% and 48% more feed dry matter required on cane juice and "A" molasses diets respectively. For growth rate the differences in performance were less; 12 and 26% poorer for cane juice and "A" molasses, respectively.

Table 2: Performance of ducks fed with complete replacement of rice byproducts by cane juice and "A" molasses

Item	Control	Cane juice	"A" molasses

Liveweight (g)
Initial	717	716	708
Final	2756	2513	2213
Daily gain	52.3a*	46.0b	38.6c
Feed intake (g/d)
Mash/concentrate	162	80	80
Duckweed	17	19	19
Cane juice		435.5
"A" molasses			106.1
Feed conversion (DM basis)	2.72a	3.51b	4.03c

Carcass parameters are shown in Table 3. Carcass yield was slightly less and livers heavier on cane juice compared with the control and molasses more so. The yield of all edible parts did not differ between cane juice and the control but was less on "A" molasses. The caecum appeared to be bigger and the small intestines longer on the diets containing sugar.

Table 3: Slaughter yield of the experimented ducks fed with complete replacement of rice byproducts by cane juice and "A" molasses

Item	Control	Cane juice	"A" molasses

Liveweight (g)	2493	2353	2123
Carcass weight (g)	1931	1785	1543
Carcass yield (%LW)	77.4	75.8	72.6
Heart (g)	15.3	17.1	15.8
Liver (g)	43.3	53.2	57.4
Gizzard (g)	54.0	60.5	58.2
All edible parts (%LW)	88.6	88.9	87.4

Body measurements (cm)
Length	24.1	22.8	20.6
Heart girth	31.0	30.1	28.0
Chest depth	9.1	8.8	8.1
Brisket length	14.1	13.6	12.8
Caecum length	32.8	37.6	37.6
Small intestine length	168.3	196.6	202.6

From the results of this trial it is concluded that sugar cane juice and "A" molasses can be used to substitute completely rice byproducts in the diets of fattening ducks with no adverse effects on health, but with slight reduction in growth rate and more so in feed conversion, the differences being more marked for "A" molasses than for cane juice. These results are broadly similar to those reported for pigs fed sugar cane juice and high-test molasses, where the tendency is for similar or slightly poorer growth rate and consistently inferior fed conversion (Mena 1981, 1989; Figueroa and Ly 1990; Sarria et al 1990; Van and Men 1992).

Figueroa Vilda y Ly J 1990 Alimentación porcina no convencional. Colección GEPLACEA, Serie DIVERSIFICACION: México pp215

Men B X and Su V V 1990 "A" molasses in diets for growing ducks. Livestock Research for Rural Development Volume 2 Number 3:54-57

Mena A 1981 Sugar cane juice as an energy source for fattening pigs. Tropical Animal Production 6:338-344

Mena A 1989 La producción de cerdos con base en la caña de azúcar. Sistemas Intensivos para la producción animal y de energía renovable con recursos tropicales (Editores: Susana Lopez, T R Preston y Mauricio Rosales). CIPAV: Cali

Sarria Patricia, Solano A y Preston T R 1990 Utilización de jugo de caña y cachaza panelera en la alimentación de cerdos. Livestock Research for Rural Development Volume 2, Number 2:92-99

Van B H and Men L T 1992 Feeding of sugar cane juice and "A" molasses to fattening pigs. Livestock Research for Rural Development Volume 4, Number 3 (In press)