The behaviour, growth rate, feed intake, health and slaughter quality of group-housed veal calves fed automatically with milk replacer were compared with those of veal calves kept in individual crates and bucket-fed the same milk replacer. The growth rate and feed intakes of the group-housed calves were lower than those of the calves in individual crates. Their feed conversion rates were similar and there were no significant differences in carcase conformation. The meat of the group-housed calves was paler in colour. The feeding behaviour of the group-housed calves was studied to see whether sick animals could be identified at an early stage but behaviour alone provided an inadequate detection system. Intensive health controls in one of the trials showed that infectious respiratory and digestive diseases may be a greater problem in group-housed veal calves than in veal calves kept in crates.

The cause of arterial hypoxia during natural infection with bovine respiratory syncytial virus was studied in seven calves (three to nine months of age) originating from five herds with respiratory tract disease and serological evidence of infection with the virus. Blood gas values were measured during ambient air breathing and during 100 per cent oxygen breathing. The percentages of contribution to the arterial hypoxia from alveolar hypoventilation, mismatching of ventilation and perfusion, and right-to-left shunting were calculated from the measured parameters. Calculated percentages of total venous admixture varied from 14 per cent of cardiac output in relatively mild cases to 48 per cent in the worst affected animal. This venous admixture had been caused mainly by right-to-left shunting of blood, while mismatching of ventilation and perfusion became important in the more severely affected animals. Alveolar hypoventilation was only important in the worst affected animal.

IntroductionThe pig industry nowadays faces more complex diseases than ever before, such as Porcine Multi Systemic Wasting Syndrome and Porcine Respiratory Disease Complex. These disease entities are often caused by multiple infections combined with suboptimal conditions in the field of environment, management, biosecurity climatic conditions and more. Successful preventive plans include the identification of infectious and non infectious factors and preventive interventions based on this. Regarding PMWS, Madec formulated a list of 20 management measures and this was already quite successful in reducing the impact of that syndrome. A poor understanding of the risk factors for infectious diseases often results in the unnecessarily prolonged use of preventive and curative antibiotic treatments, which is not good for human food safety and also allows the development and selection of more antibiotic-resistant bacteria (1). ResPig is a digital diagnostic and monitoring program for veterinarians including regular cross-sectional serological investigations for the presence of PRRSV, PCV2, Actinobacillus pleuropneumoniae (App), Mycoplasma hyopneumoniae (M hyo), Influenza and Haemophilus parasuis. It includes also an objective scoring system for possible risk factors (environment, management, housing, biosecurity) for respiratory diseases and an economic module to estimate the financial loses due to infectious diseases and the financial effects of advised interventions. The program helps the veterinarian to take the necessary steps towards a structured approach to respiratory problems with restrictive use of antibiotics. Because of the high number of participating farms and the uniform sampling protocols, it is possible to analyze the disease situation on a cluster of farms. Analysis of the ResPig databank provides information on possible relationships between the serological test results and the technical-and slaughterhouse performance parameters of finishers. When antibiotic use will be registered in ResPig it must also be possible tot determine relations between infectious diseases, management, biosecurity, housing and antibiotic use.