Pregnancy scanning in extensive sheep flocks

Summary

This Producer Demonstration Site (PDS) is designed to demonstrate that pregnancy scanning for foetal number and foetal age together with wet and drying ewes at marking can be used to both optimise the management of breeding ewes as well as identify and retain ewes with proven reproductive performance and increase the national reproduction rate in extensive sheep flocks with an extended joining period.

Objectives

By June 2023, in the western division (Hay) of New South Wales:

1. Benchmark the reproductive performance of breeding ewe flocks (n=6) and identify the environment and management constraints to net reproduction rate (NRR, lambs weaned/ewes joined) at the beginning of the demonstration.

2. Demonstrate the use of pregnancy scanning as a management tool to improve NRR by up to 10% through:

   i. identify and differentially manage single and twin bearing ewes

   ii. identify and cull twice dry ewes (maidens and adults) from the breeding flock

   iii. identify early- and late- ewes to draft into mobs for differential management

   iv. wetting and drying ewes at marking and use simple ear notches (or coloured tags) to identify high/poor performing ewes

   v. improved lambing management for those flocks with extended joining periods.

3. To have the six core group members trained in condition scoring sheep and understand the key factors limiting the reproductive performance of their sheep flocks and the key management interventions available to overcome them:

   i. the impact of length of joining on the ability to implement pregnancy scanning and improve lambing and weaning management

   ii. using pregnancy scanning to identify ewes for differential nutritional management, allocation of lambing paddocks and optimised lambing mob size

   iii. wet and dry ewes at marking to quantify ewe reproductive performance and inform ewe selection and culling decisions

   iv. the potential of eID to collect and use data for informed decision marking

4. To have half of the observer producers understand the range of factors that can impact on the reproductive performance of their flocks and recognise the key management interventions that could be used to improve the reproductive performance of their flocks.

5. That 75 % of core producers and 30 % of observer producers will routinely adopt the key practices demonstrated by this project.

Progress

The Pregnancy scanning in extensive sheep flocks Producer Demonstration Site (PDS) sought to increase the adoption of pregnancy scanning in extensive sheep enterprises by demonstrating that pregnancy scanning for multiples together with wet and drying ewes can be used to optimise breeding ewe management, identify productive ewes to retain in the breeding flock and increase net reproduction rate (NRR).  

Four properties participated in a benchmarking process and an on-farm comparison of their ‘standard’ breeding ewe management with differential management based on pregnancy scanning information during 2022 and 2023.  

Despite extremely challenging seasonal conditions, three of the four sheep enterprises completed the PDS comparison. However, the seasonal conditions hindered their ability to apply differential management to the trial mob in late 2022 and early 2023 and the targeted 10% improvement in NRR was not achieved by all the Core Producers in monitored breeding cycles. Nevertheless, the marking and weaning rates achieved by the producers in the PDS monitored mobs were significantly higher (by 14 to 100%) than the past five-year performance of each property.  

This PDS has demonstrated the value of pregnancy scanning for extensive sheep enterprises.