Histologically validated scoring system for the assessment of hock burn in broilers.

The assessment of bird-based welfare indicators plays an important role in the evaluation of bird welfare. The aim of the study was to histologically validate a visual scoring system for hock burn in broilers and to detect threshold values of a visual score to define welfare-relevant alterations in terms of mild lesions or ulcers of the hock. We collected 200 hocks of 39- to 42-day-old Ross 308 broilers after the slaughter process. Each hock was scored visually ("macro scores" 0-4) and evaluated histologically ("micro scores" 0-3), with high scores representing more severe lesions. Although we found a tendency for higher micro scores with increasing macro scores, an exact allocation of macro to micro scores was not possible. For example, macro score 1 could represent micro scores 1, 2 and 3, whereas macro scores 3 and 4 always represented micro score 3 (ulcer). The conditional probability of certain micro scores for given macro scores was estimated using a multinomial logistic regression model. Ulcer showed the highest probability at macro score 1, whereas mild lesions were not found to have an estimated highest probability at any macro score. The depth of inflammation of hock burn lesions increased with increasing macro scores up to macro score 3 with an average depth of 1019 µm. Visually more severe and deeper lesions were also histologically rated with higher scores. Thus, considering limitations, the herein validated macroscopic assessment scheme for hock burn allows an estimation of histological alterations in hocks of broilers.RESEARCH HIGHLIGHTS Histological validation of a visual assessment scheme for hock burn in broilers.Tendency for higher micro scores with increasing macro scores.Estimation of histological score via macro score possible with limitations.Histological depth of inflammation increased with an increasing macro score.

[Immunizing against salmonella infections with live and inactivated vaccines]. / Immunisierung gegen Salmonella-Infektionen mit Lebend- und Inaktivat-Vakzinen.

A live attenuated auxotrophic S. typhimurium (S. tm.)-mutant was used by orally administration via drinking water several times during rearing, combined with 1- or 2-times parenteral injection of an autogenous S. enteritidis (S. e.)/S. tm.-oil emulsion vaccine. In a 8-month period, more than 500,000 birds were vaccinated. The vaccine was safe. Challenge test showed protection in the vaccinates and their offspring. The number of isolates in the farms detected by regular monitoring decreased. The protection of the live-culture mutant lasted about only 8 to 10 weeks. A. S. tm.-mutant more potent for chickens will be tested now. We consider vaccinations as one important factor in a salmonella control program, especially for commercial layers and broiler breeders.

[Vaccination against infectious anemia of poultry (CAA)--results of field studies]. / Impfungen gegen die Infektiöse Anämie des Geflügels (CAA)--Ergebnisse von Feldversuchen.

Infectious anemia of poultry is a disease of high economical significance. Connatal infection of chicks with the chicken anemia agent (CAA) via the embryonated egg causes anemia along with severe immunosuppression, thus rendering the chicken susceptible for secondary infections. In order to prevent infection of young chicks, it is necessary to induce immunity against CAA in parent flocks, with the aim to prevent connatal spread of the infection and provide maternal protection for baby chicks. In this publication, the efficacy and use of a live CAA vaccine is reported. From autumn 1986 until summer 1990, 3 experimental vaccine charges were applied in 85 broiler parent flocks with totally 3.1 million chickens. In addition, totally 293,000 broiler breeder and 171,000 layer breeder chicken were vaccinated in 1989/90. The vaccine was administered between the 13th and 19th week of life by drinking water without adverse effect to the birds. Chicken anemia symptoms were observed only at the begin of laying period in two parent flocks. These flocks had been vaccinated in the 17th and 19th week, respectively. The offsprings of all other vaccinated parent flocks remained free of chicken anemia. Day-old chicks derived from vaccinated parent flocks were protected against CAA challenge infection. It is emphasized, that vaccination should be performed within the 13th to 15th week of life, because according to our observations, this will lead to an immediate seroconversion.