Wednesday, July 6, 2022

Abortion common

It’s official: Abortion occurs on most New Zealand deer farms. This is according to preliminary findings of a research project investigating foetal loss. During 2012, the first year of the project, abortions were observed in 73% of yearling herds with loss rates ranging from 1% to 17%, and 63% of MA herds, ranging from 1% to 4% during the middle stages of pregnancy.

A total of 24,700 hinds from 55 farms nationwide were scanned in early pregnancy and 12,100 of these scanned again toward the end of the middle third of pregnancy.

The first scan pregnancy rates for yearling and adult hinds were 87% and 93% respectively. The mid-pregnancy abortion rate – actual losses observed between the two scans – averaged 2.8% in yearlings and 1.24% in MA hinds. The estimated rate for the whole of pregnancy, assuming losses occur evenly throughout pregnancy, could be as high as 6.7% in yearling hinds and 3% in MA hinds.

Project leader Professor Peter Wilson, of Massey University, emphasises that these estimates are “speculative” and need validation. In some herds parasites were found both in aborting foetuses and in the uteri of non-pregnant hinds. These could have caused foetal death before the normal time for first scanning.

“That means early abortion may also be contributing to lower scanning percentage in yearlings,” he said. “Also, there are almost always unexplained losses between second scanning and weaning, suggesting some later losses later in pregnancy.”

Blood and tissue samples, management, environmental and other relevant information needed for better understanding of abortion patterns have also been collected. The second year of the three-year project will involve repeat scanning of some of the farms to see how repeatable abortions are year-by-year, investigation of abortions earlier than normal scanning times, sampling of additional farms to improve the robustness of estimation of the occurrence of abortion, and further collection of samples and data for investigation of causes.

The project, initiated by the Deer Reproductive Efficiency Group, is a collaborative effort between the Massey University Deer Research Group and AgResearch. PhD candidate and vet Kandarp Patel is collecting and analysing much of the research.

Related story: Tackling foetal wastage in deer

More articles on this topic