Returns increase in a PRRS-positive farm in the middle of a census increase plus a change of management in the batch farrowing system, from 3 weeks to 1.
articles about returns in Clinical casesSections
The farm reports a problem of low prolificacy (mean annual live births of 11.91) and low fertility in summer, with a marked increase in acyclic returns.
There is an unusual increase of the returns-to-oestrus at 31-39 days. The majority are due to sows previously negative to the pregnancy ultrasound testing, and the returns-to-oestrus happened before 42 days.