L.PDS.2017 - PDS: Maximising Dorper Reproductive Performance

Summary

Sheep producers in the far west coast region of South Australia, had identified decreasing reproduction rates in their self-replacing Dorper flocks. This Producer Demonstration Site (PDS) project was designed to demonstrate that the adoption of best practice management can improve the conception rate, lambing percentage, weaning rate and production efficiency of Dorper (& White Dorper) flocks in mixed farming systems.

Individual ewe performance was monitored for three years in two demonstration flocks, one joining biannually and one joining annually. In addition, four training workshops were conducted.

Monitoring of the biannually joined flock clearly demonstrated the relationship between condition score and conception rate and weaning rate. It became apparent that this was not a sustainable joining strategy for this producer’s production environment and labour model.

The adoption of improved management practices in the annually joined flock including: monitoring of ewe condition score; pregnancy scanning; differential management of single and twin bearing ewes; culling scanned empty ewes; ram soundness checking prior to joining; and timely weaning resulted in an increase in conception rate in the monitored group of ewes from 125% to 159%. Over this period, the whole of flock marking percentage increased from 99% in year one to 137% in year three. Contributing to the final year result was improved seasonal conditions and treatment of some ewes with Ovastim®.

Objectives

By January 2023, on three prime lamb properties in the far west Eyre Peninsula region of South Australia:

1. Establish base line productivity measures in all participating flocks (nine), but with a particular focus on the three demonstration sites (one flock with biannual mating, one with annual mating and one with continuous mating).
2. Demonstrate that the adoption of best management practice (including lambing twin bearing ewes in small mobs) can improve the conception rate, lambing percentage, weaning rate and production efficiency (kilogram of lamb turned-off annually per ewe and per hectare) of Dorper (& White Dorper) flocks by 10% in mixed farming systems.
3. Undertake a cost benefit analysis of the use of eID to monitor individual reproductive performance and inform culling decisions.
4. Undertake a range of training and extension programs with commercial shedding sheep producers on condition scoring, pre-joining management of rams and feed budgeting etc so that:
   a) 80% of core producers and 40% of observer producers will have adopted best practice management for Dorper reproduction.
   b) 100% of core producers and 60% of observer producers will have improved their knowledge and skills in relation to the reproductive performance of Dorpers.
5. Changes in marking and weaning percentages following the adoption of a Campyloba.

Key findings

The results from the monitoring of the biannually joined flock show that, even though the Dorper is considered a hardy breed that can remain productive on a poorer diet, conception rates and marking rates are still heavily influenced by the condition score (CS) of the ewes. Lower condition score animals, less than CS three, will have reduced conception rates and weaning rates.With the annually joined flock, the value of managing ewes differentially based on their foetus number was demonstrated.

In addition, the adoption of an earlier weaning strategy enabled the ewes to be in better CS for mating.Other practices adopted in this flock which, combined with the aforementioned, contributed to an observed 38% increase in marking percentages included; lambing twin bearing ewes in smaller mobs, supplementary feeding of twin bearing ewes, removing passenger ewes and assessing ewe and ram fitness to join.The increase in marking percentage demonstrated in this flock was equivalent to an increase in gross margin for the enterprise of $16/DSE.Cost benefit analysis of individual strategies or management practice change was not possible, as multiple changes to management were being made at one time and it was impossible to attribute the proportion of change to any one practice.

25 producers and stock agents attended at least one face-to-face project activity with seven attending every activity. In addition, update newsletters were shared with interested producers from outside the project group and it is intended that the findings will be shared through the rural press, breed societies and service provider groups.100% of the remaining two core producers have adopted or intend to adopt the measured best management practices including pregnancy scanning, condition scoring, wet/dry at weaning, separate management of twin & single bearing ewes, use of campylobacter vaccination, ram checks prior to joining and eID.

Benefits to industry

This project was able to demonstrate that it is possible to achieve good reproduction rates in this challenging production environment if attention is paid to the management of the flock. Adoption of the recommended ‘best practice’ management strategies could result in an increase in lambing percentages of as much as 30%.

MLA action

MLA continues to deliver the Producer Demonstration Site (PDS) program, supporting livestock producers working in peer-to-peer groups to pursue new skills, knowledge and management practices applicable to their own commercial livestock production system.

Future research

The shedding sheep industry could benefit from further research that continues to clarify the relationship between condition score, weight and reproduction efficiency for these breeds. This could include gaining further understanding of the limitations of over fat ewes; whether they are over fat because they don’t conceive or whether they don’t conceive because they are over fat.

Further analysis of lamb survival rates from birth to marking in shedding breeds, and the factors impacting this, would also be beneficial.

There is an opportunity to incorporate messaging specifically targeted at shedding sheep producers in any industry extension/adoption programs, with the aim to increase shedding sheep producers’ understanding of the importance of monitoring ewe weight and condition score, and the value proposition from being able to differentially manage twin bearing ewes.

Messaging should also include the importance of assessing fitness to join of both rams and ewes and the value of feed budgeting, including understanding the nutritional value of different feedstuffs and the nutritional requirements of different classes of stock.