Effect of taro (Colocasia esculenta)foliage on the performance of growing common ducks

Abstract: Two on-farm experiments were carried out in An Giang Province, Vietnam, to investigate the effect of diets of rice bran with taro (Colocasia esculenta) foliage on the growth performance of common ducks. The first experiment was on chopped fresh taro leaves supplemented to a basal diet, which included rice bran, broken rice and soybean meal, to determine the intake level, the growth performance and carcass traits of crossbred common ducks. In total 168 ducks (crosses of an exotic and indigenous breed) were used in a completely randomized design (CRD) with 7 dietary treatments and 3 replicates. The ducks were offered chopped fresh taro leaves ad libitum, supplemented with five levels (3, 4, 5, 6 and 7% of live weight [LW] as dry matter [DM]) of a basal diet with a premix added. There were two other treatments, the basal diet without premix fed at 3% of LW, with free-access to taro leaves, and the basal diet with premix, fed at the equivalent of 7% of LW, with no taro leaves provided. Each experimental unit included 8 ducks, balanced for sex. The total DM intake was highest on the treatment in which the ducks were fed 7% of LW of the basal diet supplemented by fresh taro leaves ad libitum (110g/day), and lowest in the treatment with 3% of LW of the basal diet and taro leaves ad libitum (84.4g/day). The average daily gain (ADG) among treatments was significantly different (P<0.05), and was poorest in the treatment 3% of basal diet-taro leaves ad libitum. There was no effect on ADG and feed conversion ratio (FCR) of including a mineral-vitamin premix when Taro leaves were also fed. The second experiment was conducted to evaluate the effect of taro silage (made from leaves and stem of Colocasia esculenta) and rice bran on the growth performance of common ducks. In total 80 common ducks were used, with ten treatments, two replicates and four ducks (balanced for sex) per replicate. The dietary treatments were arranged as a 5'2 completely random factorial design, with ingredient ratio (5) and feeding system (2) as factors. The basal diet was high protein rice bran supplemented by five levels of taro silage (20, 30, 40, 50, and 60%), fed to the ducks in mixed or separate form. The calcium oxalate content was reduced 2.45 times in the silage product compared to the concentration in fresh taro leaf (0.31 vs 0.76% DM basis, respectively). Ducks gained better when they were fed rice bran and taro silage in the “mixed system”, and the ADG was significantly different from that in the “separate system” (P<0.05). The ADG was the same over a range of ratios of rice bran and taro silage, from 80:20 to 40:60, and was 8% higher when the feeds were given as a mixture rather than separately. Calcium oxalate in taro leaf-stem silage was lower than in fresh taro leaves. There was a positive effect on carcass quality (lower abdominal fat) from supplementing rice bran with taro silage. For smallholder farmers in the Mekong delta there can be significant economic benefits from fattening common ducks using resources (rice bran and taro foliage) that are widely available in the region and of lower cost than commercial feeds.