Field trials with an ovine salmonella vaccine

Abstract

Extract

Since 1949 when salmonellosis in adult sheep was first confirmed in New Zealand, this disease has been a continuing threat to the health of sheep in Hawke's Bay. Until recently, it has been controlled mainly by management methods which consisted of spreading the flock of sheep over as large an area as possible when deaths were occurring. Wherethe stocking rate can be reduced to less than three per acre (Beckett, 1967), this method is reasonably successful, but it has many drawbacks when considered in relation to efficient farm management. Pastures which are overgrown in autumn give a lowered production in the following spring, and ewes which become over fat in the autumn are more disposed to metabolic troubles and vaginal prolapse in late pregnancy. Also, in the January to May period when salmonellosis is most likely to be a problem, facial eczema is very often a threat in Hawke's Bay so that sheep should ideally be confined through this period rather than be spread out on pastures which are potentially dangerous.