The greatest welfare challenges for sheep during grazing are tick-borne fever (TBF), blow-flies, alveld and predators. Production losses on tick infested pastures are substantial, and it is expected that more than 300 000 lambs/sheep are affected by TBF. In sustainable farming, particularly organic farming, the focus on solving these challenges should be on preventive measures. The dependence on drugs implies a risk for developing resistance. It is therefore of general interest to use preventive methods. However, few efficient preventive measures against tick infection and TBF are available. Thus, there is a need for alternative strategies. The focus of the project will be on:
The indirect loss caused by TBF is impaired welfare, growth rat e, meat quality and income. National data will provide information on weight, slaughter quality and losses of animals on tick infested pastures and will be used to identify and quantify indirect losses. Increased knowledge about the extent of indirect los ses to ticks will increase awareness and motivation for implementing preventive measures.
Turn out time on pasture and immunity
Lambs on tick infested pasture and sheep brought to tick infested pasture for the first time are at highest risk. Animals will develop immunity after the first infection. The effect of exposing lambs to tick infection at a very early life stage will be tested in an experiment carried out at five farms involving 300 lambs. The hypothesis is that lambs infected early will handle th e disease better and will not become seriously ill.
There is indication of individual variance in susceptibility against TBF in sheep. Many factors may cause variation in resistance to ticks and TBF between individuals. Exploiting a pos sible genetic variance between breeds and individuals within breed in such resistance will be done by a controlled challenge test and by analysing data on sheep from ram circles in tick infested areas.