Browsing by Subject "Organic turkey farming"

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Effects of different dietary energy and essential amino acid levels on growing turkeys under organic farming conditions
(2025) Kirn, Anna Isabella; Rodehutscord, Markus
An adequate supply of dietary apparent metabolizable energy (AMEN) and essential amino acids (EAA) is crucial for turkeys to reach their genetic growth potential. However, optimizing diets in organic turkey production is challenging due to regulatory restrictions under EU Regulation 2018/848, which often lead to increased crude protein levels, potentially compromising animal health and environmental sustainability. To address this, targeted feeding strategies can be applied, leveraging compensatory growth through an initial qualitative feed restriction followed by a re-alimentation phase. Previous research showed that a consistent 10% reduction in AMEN combined with an initial EAA reduction of up to 20% (relative to commercial breeder guidelines), gradually restored to 90-100% during refeeding, effectively triggered compensatory growth, resulting in full catch-up growth. Nevertheless, as nutrient intake also affects welfare indicators such as plumage condition and injury prevalence, a balance between growth and welfare is essential. The present thesis aimed to evaluate whether dietary EAA levels could be further reduced by up to 30%, maintaining a constant 10% AMEN reduction, in male and female turkeys of two genotypes (slow-growing Auburn and fast-growing B.U.T. 6) across various housing systems (indoor, indoor with silage, and mobile housing with free-range). The study focused on evaluating growth, slaughter performance, and welfare indicators. Additionally, the potential of a newly introduced scoring system for wing feather structure and depigmentation was examined as a sensitive indicator of dietary EAA supply status. In the first study, 600 male day-old chicks from two genotypes (B.U.T. 6 and Auburn) were allocated to three feeding strategies differing in EAA levels across five 4-week phases: F1 (80/90/90/90/90%), F2 (80/80/90/100/90%), and F3 (70/80/90/100/90%). After rearing in indoor housing until week 8, the turkeys were transferred to one of three housing systems (indoor, indoor with silage, and mobile with free-range; weeks 9–20). Results showed that up to 30% initial EAA reduction followed by gradual re-alimentation triggered compensatory growth without affecting final body weight, total feed intake, or valuable cuts. No genotype by feeding interaction was observed. However, compensatory feed intake increased the feed conversion ratio and nutrient intake per kilogram of weight gain. While there was no housing by feeding interaction, housing significantly affected performance. Mobile housing with free-range and silage supplementation improved the feed conversion ratio and reduced abdominal fat. Additionally, mobile housing increased breast meat yield. Notably, a significant genotype by housing interaction suggested that B.U.T. 6 may demonstrate superior adaptability to the nutritional and environmental variability of the housing systems compared to Auburn. Building on this, the second study tested a similar approach in 432 female turkeys across three feeding strategies (F1: 80/90/90/90%, F2: 80/80/90/90%, F3: 70/80/90/90%) over four four-week phases. After being reared indoors until week 8, birds were assigned to indoor or mobile housing with free-range access (weeks 9-16). While a 20% EAA reduction maintained growth and slaughter performance, a 30% reduction led to significant decreases in final body weight, slaughter weight, and dressing percentage. A significant genotype by feeding interaction suggested that B.U.T. 6 was more sensitive to the 30% reduction than Auburn. Mobile housing improved breast meat yield and reduced abdominal fat but increased feed conversion ratio, likely due to winter fattening conditions. The third study examined the effects of dietary AMEN and EAA reductions on injuries, plumage damage, and the potential of a newly introduced scoring system for wing feather structure and depigmentation as an indicator of dietary EAA supply status. A total of 216 non-beak-trimmed female turkeys from the second study, housed indoors and subjected to the same feeding strategies, were evaluated. The most restrictive feeding strategy (30% EAA reduction) increased the prevalence of skin injuries, plumage damage, alterations in feather structure, and depigmentation. In contrast, the 20% EAA reduction preserved welfare and performance outcomes. Importantly, wing feather structure and pigmentation showed graded responses to varying EAA levels, supporting their potential as sensitive indicators of dietary EAA status in turkeys. In conclusion, this thesis demonstrated that reducing EAA levels by 20%, followed by a re-alimentation phase, alongside a 10% AMEN reduction, can be successfully applied in organic turkey production. This approach maintained final growth performance, slaughter performance, and welfare in male and female Auburn and B.U.T. 6 turkeys by effectively leveraging compensatory growth. Wing feather structure and pigmentation scoring proved to be a sensitive indicator of EAA supply status. External feed sources such as silage and free-range foraging contributed nutritionally, while mobile housing enhanced breast muscle yield and reduced abdominal fat. Overall, turkey growth and performance under organic conditions resulted from complex interactions between endogenous factors (sex, genotype, age) and exogenous factors (housing, environment, feeding), highlighting the need for integrated and adaptive management approaches.