Improving the lifetime performance of ewes

A research project to develop best practice for managing replacement ewes and understand the impact of the rearing phase on a ewe’s lifetime performance, has now reached its third year. The AHDB Beef & Lamb-funded project, Challenge Sheep, is set to take seven years in total, with 11 farmers committed to recording data for the duration of the project.

Covering both sheep bred as ewe lambs, and as shearlings, the project is tracking 7,000 replacements from a range of English sheep farms up and down the country who are monitoring data via electronic identification (EID) – weights, body condition score, lambing data and lamb performance.

While the project is a way off seeing end results, the Challenge Sheep farmers have already identified fundamental outcomes from the data, which they are using to implement changes in their management to improve overall flock performance. At a recent project meeting, the participating farmers were asked to identify what they considered to be key intervention points for ewe lambs and shearlings.

Areas identified by Challenge Sheep Farmers as key actions to take at crucial intervention points:

1. Identifying and managing thin ewes
2. Every breeding ewe must be over 60% mature liveweight at tupping
3. Managing young ewes in separate groups until at least their first lambing
4. Selecting ewe replacements based on genetics and health status
5. Don’t be shy of culling ewes for poor performance at any stage

Identifying and managing thin ewes

Findings from the project show that regular body condition scoring (BCS) and accurately weighing ewes throughout the year, especially at tupping, scanning, lambing, eight-weeks post lambing and at weaning, can help quickly identify thin ewes enabling management to be adjusted accordingly. In particular, dietary inadequacies at these key timepoints can be realised and addressed. Achieving target BCS at key stages of the production cycle will improve ewe fertility and productivity as well as lamb survival and growth rates from birth to weaning.

Every breeding ewe must be over 60% mature liveweight at tupping

Research shows that thin ewes are generally less fertile than those at target BCS and weight. In addition, ewe lambs are generally less fertile than mature ewes. It is therefore essential that ewe lambs reach at least 60% of their target mature bodyweight by tupping (even if not breeding until the following year) to improve chances of conception and to enable their lamb’s nutritional requirements to be met during development. Weight and BCS of ewe lambs should also be monitored post-tupping to ensure they continue to grow as expected.

It is essential that worm control is also considered in the management of thin ewes, alongside nutrition. Faecal egg counts (FECs) can help determine the need to treat and can be used when reviewing animal health plans with the farm’s vet.

Managing young ewes separately

It is commonly known that a ewe’s requirements for energy and protein varies significantly depending on age, stage of the production cycle, BCS and litter size. However, the Challenge Sheep farmers have identified that it is therefore beneficial to manage shearlings as a separate group to ewe lambs throughout the lambing season, even if they are lambing for the first time. Additionally, shearlings should be managed separately from mature ewes right up until their second lambing. Post-scanning, these age groups can be subdivided further by litter size so that feeding can be tailored to the number of lambs they are carrying. Particular attention needs to be given to young ewe nutrition, including shearlings, with priority given to those bearing twins.

Selecting ewe replacements based on genetics and health status

Amey Brassington, Animal Health and Welfare Scientist who is the technical lead on the Challenge Sheep project explains: “Ewe selection based on genetics and health status can vastly improve the performance and profitability of your flock. Maternal breeding strategies for replacement ewes are complex, and a breeding ewe’s ideal genetic makeup will depend on multiple traits, including, but not exclusively, fertility, number of lambs born, lambing ease, maternal behaviour, maternal ability, as well as temperament and disease resistance. Selective breeding can improve many of these traits by exploiting within-breed differences.

“Genetic improvement by selective breeding has a permanent effect on the ewe’s (and the lamb’s) lifetime performance and improvements can continue to be made as long as there is genetic variation.

The main causes of ewe death should be included in the farm’s health plan, with monitoring points and appropriate treatments or activity listed with suggested timings, e.g. vaccination programme or

BCS assessment. This will help when selecting replacements. Do not compromise on health status – your flocks health status is only as good as the worst replacements you purchase.”

Culling poor performing ewes

Studies have shown that on average, flocks replace 20–25% of their ewes every year, depending on their culling policy and ewe mortality. Underperforming ewes consume feed, take up space, and require additional labour, while generating less profit than their counterparts.

The Challenge Sheep farmers have proved that consistently using data to identify and remove underperforming ewes from the flock is one way to improve overall performance and help make sheep production more profitable, sustainable and viable.

Reasons to cull include:

• Poor performance – barren/unproductive, poor body condition, poor mothering ability
• Structural integrity – too old or broken-mouthed, poor teat conformation
• Disease – abortion, mastitis, lameness, prolapse

It is worth interrogating culling records to see if trends are developing or if there are common causes that could be avoided.