Growth performance and plumage development of young turkeys fed on diets with graded levels of sulfur-containing amino acids

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The aim of this study was to determine whether increased dietary Met concentrations affect feather growth and plumage development in young turkeys raised under standard conditions. The experimental material comprised 1020 one-day-old female Hybrid Converter turkeys randomly assigned to 5 dietary treatments with 12 replicates per group and 17 birds per replicate. In two feeding phases (weeks 1 – 4 and 5 – 8), the methionine (Met) content of diets was 4.49/3.96, 4.96/4.37, 5.95/5.05, 6.38/5.65 and 7.06/5.74 g/kg, respectively. Met accounted for 50% to 60% of total SAA . At 28 and 56 days of age, the quality of feathers collected from the dorsal and thigh regions was evaluated in 14 female turkeys selected from three groups – with the low, moderate and high dietary level of Met. The number of feathers at 5 growth stages was determined. No significant differences in growth performance of turkeys were observed in the first experimental period, whereas in the second feeding phase diets with 5.05 g/kg or higher Met content increased BWG ( P =0.001), compared to birds fed on diets with lower Met levels. No differences in plumage characteristics were noted between turkeys fed on diets containing 4.49/3.96 and 5.95/5.05 g/kg Met. In the first month, an increase in dietary Met to 7.06 g/kg contributed to a distinct ( P =0.075) decrease in the number of feathers and a significant increase ( P =0.007) in the percentage of pinfeathers, with no significant decrease in the number of feathers at the remaining growth stages. Smaller differences in plumage development were noted in the second experimental period. The results indicate that increased dietary Met concentration (from 4.49–4.96 to 5.95 g/kg or more and from 3.96–4.37 g/kg to 5.05 g/kg or more in the first and second month of the rearing period, respectively) improved growth performance in the second experimental period, but it did not increase the number of feathers and did not accelerate plumage development and maturation.