Climate change temperature rises could lead to lambing losses, researchers say

According to the research which appeared in online journal Nature Food, 2.1 million potential lambs are already lost annually due to heat stress alone, which is estimated to increase to 2.5 million if temperatures rise by just one degree and 3.3 million if temperatures rise by three degrees.

The study, entitled Heat stress from current and predicted increases in temperature impairs lambing rates and birth weights in the Australian sheep flock was carried out by the University of Adelaide, South Australian Research and Development Institute and the South Australian government with funding from Meat & Livestock Australia.

Heat stress affects reproduction in multiple ways, reducing fertility in both ewes and rams as well as having an effect during pregnancy by impairing fetal development, decreasing the proportion of lambs born alive, increasing postnatal mortalities and affecting milk production.

The researchers found that heat stress experienced by flocks in recent climate conditions was modelled to decrease the numbers of lambs born by 9 per cent, with a one degree temperature rise expected to bump that up to 11pc, while a three degree rise would increase it to 14pc.

The losses caused by the three degree rises would amount to $166 million.

Researchers also estimate lamb survival would take a major hit.

Modelling indicates that ewe exposure to heat stress during pregnancy reduces the number of lambs weaned per ewe by 2.5pc in a historical temperature scenario, rising to 3.1pc and 4pc with one degree and three degree temperature rises.

The three degree temperature scenario would equate to a financial loss of $278 million.

Queensland was anticipated to be the state most impacted by heat stress related lambing losses, followed by New South Wales and Western Australia.

Researchers have suggested that the findings are "of global relevance" and that further work is needed to develop strategies to reduce heat exposure such as effective shade provision or improve heat tolerance using nutrition and genetic selection.

The study points out that recent modelling suggests climate change will result in 18pc of the global sheep population being exposed to extreme heat events before the end of the century.