Effect of L-Dopa in Replacing Dl-Methionine on the Performance of Broiler Chickens

The L-Dopa found in mucuna seed, when present with other antinutritional factors, has been implicated on nutritional disorders of monogastric animals. It is also reputed to influence muscular development. However, information on its effect on methionine utilisation is scanty. Therefore, the effect of L-Dopa on growth performance and its replacement for DL-methionine in broiler chickens was investigated.

In a 42-day trial, between August and September 2014, two hundred and forty one-day old chicks were allotted to six diets which contained a diet with 0 % L-Dopa + 0 % DL-methionine and other five diets containing L-Dopa replacing DL-methionine at 0, 25, 50, 75 and 100 %. All treatments had 4 replicates with 10 birds per replicate in a completely randomized design. Feed Intake (FI), Final Weight (FW), Body Weight Gain (BWG), Feed Conversion Ratio (FCR), Serum Methionine (SM), Methionine Adenosyltransferase (MAT), Breast Meat Protein (BMP), liver enzymes, haematological parameters and serum biochemical indices were determined following standard procedure. Data were analysed using descriptive statistics and ANOVA at P = .05.

The result revealed that the FI, FW and BWG of birds fed diets containing 0%L-Dopa+100% methionine (3491.2 g, 2148.8 g and 2108.5 g) and 50 % L-Dopa + 50 % methionine (3556.1 g, 2137.6 g and 2097.3 g) were similar but significantly better than other diets. The FCR (1.86) of broilers fed 0 % L-Dopa +0 % methionine diet was better than other diets. It was also observed that the MAT (0.45 ng/ml) of broilers fed diet containing 50 % L-Dopa + 50 % methionine was higher than that of other diets but similar to MAT of birds on 75 % L-Dopa + 25 % Methionine. Haematology, SM, BMP and liver enzymes were not significantly affected across treatments.

L-Dopa extract, at levels tested, had no detrimental effect on broilers and can replace synthetic DL-methionine up to 50 %. Therefore, 0.2 % inclusion of L-Dopa is recommended in diets of broiler chickens for improved performance and utilisation of available methionine.