Immediately after collection, the samples were refrigerated and sent to the laboratory, processed to obtain sera, aliquoted and stored at ?20 C until analysis. pestivirus infections, for which the presence of antibodies in the animals was associated with reduced final weight at the end of the fattening period. Abstract The presence of respiratory viruses and pestiviruses in sheep has been widely Rabbit Polyclonal to Cytochrome P450 2C8 exhibited, and their ability to cause injury and predispose to respiratory processes have been confirmed experimentally. A longitudinal observational study was performed to determine the seroprevalence of bovine parainfluenza computer virus type 3 (BPIV-3), bovine respiratory syncytial computer virus (BRSV), bovine herpesvirus type 1 (BHV-1) and pestiviruses in 120 lambs at the beginning and the end of the AZ304 fattening period. During this time, the animals were clinically monitored, their growth was recorded, and post-mortem examinations were performed in order to identify the presence of pneumonic lesions in the animals. Seroconversion to all viruses tested except BHV-1 was detected at the end of the period. Initially, BPIV-3 antibodies were the most frequently found, while the most common seroconversion through the analysed period occurred to BRSV. Only 10.8% of the lambs showed no detectable levels of antibodies against any of the tested viruses at the end of the survey. In addition, no statistical differences were found in the presentation of respiratory clinical indicators, pneumonic lesions nor in the production performance between lambs that seroconverted and those which did not, except in the case of pestiviruses. The seroconversion to pestiviruses was associated with a reduction in the final weight of the lambs. spp. and . However, the involvement of viral brokers in this disease has not AZ304 AZ304 been clarified in lambs. It is well known the role of respiratory viruses such as bovine parainfluenza computer virus type 3 (BPIV-3), bovine respiratory syncytial computer virus (BRSV), bovine herpesvirus type 1 (BHV-1) and pestiviruses in the development of bovine respiratory disease (BRD). In sheep and lambs, evidence of natural contamination by these viruses has been reported by several authors in different geographic locations [2,3,4,5]. In addition, experimental infections performed in different lamb models have confirmed the ability of respiratory viruses to cause disease in ovines [6,7,8,9,10,11]. Similarly, despite respiratory lesions not being the main feature of pestivirus infections, lung damage has been noted under certain conditions in cattle [12,13,14] but also in sheep in the case of experimental infections with border disease computer virus (BDV) . Likewise, other pestiviruses different than BDV, such as bovine viral diarrhoea computer virus (BVDV) have also demonstrated being able to infect lambs . The susceptibility to some of these viruses seems to be age-dependent, decreasing progressively as the age of the lamb increases [15,16]. Furthermore, under experimental conditions, the consequences derived from these infections in lambs tend to be mild unless they are combined with a bacterial infection, especially by Pasteurellaceae [11,15,16,17]. The most common clinical signs associated with respiratory viruses are nasal discharge, tachypnoea and fever . However, transient immune AZ304 suppression has been described as one of the main pathogenic effects associated with these viral infections in cattle [18,19,20], also reported in ovines [5,21]. The aim of this study was to elucidate the importance of these viruses in feedlot lambs under natural conditions through the observation of the evolution of seroconversions during the fattening period. Health and production data from this period were also analysed, evaluating the influence of the viral infections on these parameters that have a relevant economic impact. 2. Materials and Methods A longitudinal observational study was conducted in a lamb feedlot located in Aragn (North-Eastern Spain). One hundred and twenty Rasa Aragonesa clinically healthy fattening male lambs without clinical indicators of disease were randomly selected throughout all seasons in two years, distributed in 8 groups of 15 animals each. Lambs were recruited at weaning age (40C50 days aged) with 12C15 kg of live weight. All the studied animals were individually identified and tagged at the farm of origin. On arrival at the feedlot, the lambs were classified and stocked in groups mixed with other animals at a maximum density of 1 1.67 lambs/m2, and after six weeks of fattening (82C92 days old), they were sent to the slaughterhouse. Blood samples without anticoagulant were taken by jugular venipuncture from all the lambs at two different moments: around the farm of birth, just before the transport to the feedlot, and at the end of the.