Effects of dietary energy and essential amino acid reduction on injuries, plumage damage, and plumage pigmentation of female slow- (Auburn) and fast-growing (B.U.T. 6) Turkey strains under organic feeding conditions

Abstract

The objective of this study was to investigate the effects of reduced dietary AMEN and essential amino acid (EAA) concentrations on injuries, plumage damage, and plumage pigmentation in two female turkey strains. 216 day-old, non-beak-trimmed Auburn and B.U.T. 6 turkeys were assigned to three feeding groups and studied over four 4-week phases. Diets were formulated per phase with a 10 % isoenergetic AMEN reduction compared to breeder recommendations. Feeding groups differed in EAA levels, with methionine and lysine relative to breeder recommendations as follows: F1 (80/90/90/90 %), F2 (80/80/90/90 %), and F3 (70/80/90/90 %). Injuries, plumage damage, and plumage pigmentation were evaluated using a scoring system and a longitudinal visual assessment. Data, including growth performance, were collected during rearing (weeks 4 and 8) and fattening (weeks 12 and 16), at the end of each phase. B.U.T. 6 turkeys showed a higher prevalence of plumage damage, feather structure alterations, and skin injuries compared to Auburn turkeys (P < 0.001). A reduction in EAA by up to 30 % (F3) resulted in increased skin injuries, plumage damage, alterations in wing feather structure, and depigmentation (P ≤ 0.010). An interaction between genotype and feeding was observed (P = 0.048), with the increase in animals showing altered feather structure in F2 and F3 compared to F1 being more pronounced in Auburn than in B.U.T. 6. While pecking injuries and plumage damage increased with age (P ≤ 0.019), feather structure alterations and depigmentation decreased with age (P < 0.001) and higher EAA supply levels, suggesting these alterations are reversible. This study highlights the crucial role of dietary EAA in maintaining plumage and skin condition in female turkeys. Reducing EAA levels by up to 30 % resulted in more pronounced effects, with wing feathers proving to be a useful longitudinal tool to assess amino acid status in turkeys. However, reducing EAA levels by 20 % during rearing maintained final growth performance without adverse effects on injuries, plumage, or pigmentation, but EAA reduction should be carefully monitored in practice.