ABSTRACT
Green liver discoloration (GL) in fattening turkeys is suspected to be a multifactorial disease complex with a compromised immune system as the key factor. This study aimed to identify the formal pathogenesis of GL and to investigate possible nutritional influences. A total of 360 Bronze turkey hens out of 10 flocks from 5 fattening farms were necropsied for detection of GL during 2 consecutive trials on 2 examination dates each (70th to 75th and 120th to 127th day of fattening, respectively). At each examination date, hematological and clinical chemistry analyses, as well as determination of vitamin E and selenium concentrations in the liver, were carried out in 6 hens with (if applicable) and 6 hens without GL, representing a total of 130 individuals. Raw nutrient, energy, amino acid, bulk and trace element, and vitamin E and D3 concentrations were analyzed in feed samples for each of the five feeding phases during each trial. The results of the hematological analyses, clinical chemistry analyses, and determination of vitamin E and selenium liver concentrations were statistically evaluated between: (i) individuals with and without GL, and (ii) individuals from flocks with and without turkeys with GL. At both fattening stages, the occurrence of GL was characterized by an inflammatory reaction. A subacute inflammatory reaction was detected in the early fattening stage, indicating a viral cause of the disease. In the late fattening stage, acute inflammation indicated a bacterial cause of the disease. The results of the feed sample analyses of the different flocks were generally quite homogeneous. However, the nutrient and energy content of the feed likely contribute to GL pathogenesis.
ABSTRACT
A recent study revealed that organically raised Bronze turkeys showed a high prevalence of green liver discoloration. This alteration is commonly associated with the Turkey Osteomyelitis Complex and potentially caused by opportunistic bacteria. Therefore, 360 organically fattened Bronze turkeys were examined post-mortem throughout two fattening trials with two examinations each to determine possible infectious risk factors and reduce disease prevalence. Clinical and pathoanatomical examinations were performed on every hen. Histopathological, bacteriological, parasitological, and virological examinations were performed on at least six hens without and, if applicable, six hens with green livers on each examination date. Overall, 9.0% of all hens had a green liver without a correlation with bacterial or parasitological findings but multiple health impairments. The discoloration correlated significantly with the detection of immunosuppressive turkey hemorrhagic enteritis virus at the early stage and macro- and histological joint/bone lesions at the late fattening stage, indicating the presence of two different predisposing pathogeneses. Flocks not being vaccinated against hemorrhagic enteritis but having a virus-positive sample showed the highest prevalence of green liver discoloration and developed worse in various parameters. In conclusion, an adequate vaccination schedule and the prevention of field infections may lead to a decreased risk of performance reduction and improved animal health.
ABSTRACT
Conventional turkey husbandries frequently fail to provide any structural elements or occupational material apart from the feeding and drinking systems. However, these may carry numerous advantages for animal welfare (spatial separation to exercise natural behavior, retreat options, stimulation of locomotion). Hence these are increasingly discussed in conventional turkey husbandry, especially against the background of minimizing injurious pecking. Studies reported in the literature concerning the effects of structural elements or occupational materials are not exactly comparable to one another due to variations in study design. However, the described positive effects predominate across the different evaluations. Nonetheless, when using such elements consideration must be given to several variables. For example, the use and positive effects of perching options depend on the type and dimensions of their structure used as well as on sex, age and breed of the animals. Straw bales represent one option, which then may also serve as occupational material. When hay or straw is offered, appropriately sized grit must also be administered in order to prevent obstipation of the gastrointestinal tract. Different occupational materials should be offered alternately and in sufficient quantities. The outdoor-climate and run area offer climatic and optic stimuli and additional opportunities for exercise. However, various basic requirements must also be considered here. In principle, the commitment and knowledge of the breeder are of crucial importance for all of the animal welfare improvements mentioned. Therefore, regular further training for this group of people is recommended.
