Milk production losses in Latxa dairy sheep associated with small ruminant lentivirus infection

• Published in: Preventive veterinary medicine 2020-03, Vol.176, p.104886-104886, Article 104886
• Main Authors: Juste, Ramon A., Villoria, Monica, Leginagoikoa, Iratxe, Ugarte, Eva, Minguijon, Esmeralda
• Format: Article
• Language: English
• Subjects: Latxa; Milk production; Production losses; Sheep; Small ruminant lentivirus; Visna/Maedi virus
• ISSN: 0167-5877; 1873-1716
• DOI: 10.1016/j.prevetmed.2020.104886

•Production losses associated to SRLV infection is a controversial subject.•This study showed that SRLV infection is associated with an average loss of milk production of about 6.7 % per lactation.•The highest negative effect of SRLV infection occurs at ewe production peak between second and fourth lactation.•Lifelong losses in milk and lambs might have a cost of nearly 50€ ewe/year.•Production losses prevention would widely offset the costs of a control program. Visna/Maedi is a disease of sheep caused by small ruminant lentivirus (SRLV) infection that is widespread throughout the world and that has been recognized to be present in the Basque Country (Spain) since the early 1980′s. Nearly seven decades of studies have improved the knowledge on its clinical signs and epidemiology. However, its slow progressive nature, subclinical most of the time, makes difficult to assess its real impact on productive traits, a question of critical importance to balance out the economic costs it causes and the benefits of designing and deploying an eradication program. Development of a dairy breeding program since the 90 s in the local Latxa sheep population has provided data on milk productivity in several flocks where SRLV infection prevalence has been continuously monitored. This study analyses retrospectively the association between SRLV prevalence and production variables during ten yearly lactations in three Latxa dairy flocks with medium-high SRLV seroprevalence. Our results indicate that average standard lactation of seropositive sheep was 6.7 % lower than controls. The largest differences (p