Getting to grips with ewe body condition

Each year, the Teagasc e-profit monitor highlights that output per ewe is the key driver of productivity and, ultimately, profitability for a flock. Increasing ewe productivity is a key area of focus of the Teagasc sheep BETTER farm programme.

Aside from changes in breeding policy, improved management prior to and during the breeding season had a major effect on subsequent flock performance.

The target condition score for lowland ewes is 3.5 at joining, but this is not achieved in many cases.

The management of ewes during the next two to three months will be a major determinant of the level of ewe output achieved next season.

The next few months also coincides with a period when feed supply and quality will decline so, in many cases, the next few weeks represents the best opportunity to begin to address ewe condition.

This article will focus on results emerging from data collected from the BETTER farms, highlighting the effects of ewe condition at joining and a number of the management changes made in flocks to achieve improvements.

Condition score is an assessment of ‘‘fatness’’ or more appropriately the level of muscle and adipose tissue deposited on an animal.

The scale we use categorises ewes into scores from zero to five (emaciated to overfat). Each unit of condition is equivalent to about 12% to 15% of body weight. Condition is assessed by handling the ewe along the top and side of the back bone in the loin area immediately behind the last rib and above the kidneys. Here, you can assess the following:

The majority of ewes in Irish flocks will fall between a condition score of two and four. These scores are described in the illustration above.

Ewe condition at joining has an effect on productivity. Each season, individual ewe condition is assessed and recorded for the flocks in the BETTER farm programme.

Data from over 3,000 mating records collected in the lowland flocks were examined to quantify the effects of ewe condition at joining on subsequent litter size. The results are summarised in Table 1. Using this information, we can determine that an increase in condition score by one unit will result in an increase in litter size by on average of 0.13 extra lambs born and an increase of over 0.1 lambs reared per ewe joined. This would equate to an increase in output of approximately €9 per ewe put to the ram.

Aside from the direct effects on ewe output, there are additional benefits to ewe health and, ultimately, ewe survival in the flock by having them in the correct condition during this stage of the season.

One of the problems encountered at farm level is the fact that a proportion of ewes in poor condition often go unnoticed within a flock.

Even in well managed flocks, there will be a proportion of ewes that are in poor condition (eg 2.5) post-weaning for various reasons. Flushing ewes for a two- to three-week period before joining will, in the majority of cases, not be sufficient to get them into the target body condition of 3.5. For an 80kg ewe, a one-unit change in condition is equivalent to that ewe putting on 10kg to 12kg in liveweight.

With good management, ewes can gain 1kg to 1.5kg per week depending on grass quality. Therefore, the key message is to start preparing the ewe flock in time. A guide to some of the key dates is summarised in Table 2.

To highlight this problem and how it can be addressed, we have used the data from one of the farms where ewe condition, and indeed output, was an issue at the start of the BETTER farm programme. We examined the data collected in the first two years to see the extent of the issue. Rather than focusing on individual condition scores, we have broken the flock into three groups – poor ewe condition (around 2.5) acceptable ewe condition (around 3) and target ewe condition (3.5 and greater).

This is summarised in Table 3. At joining in the first year, the flocks had an average condition score of 3.1. However, only 33% of the ewes in the flock could be categorised as being in ideal condition for breeding, with 26% of the ewes in the flock in ‘‘poor condition’’.

This cohort of ewes limited flock output through reduced litter size, lower pregnancy rate and were more likely to present with issues during late pregnancy by virtue of their poor condition score at the time of mating.

A plan was put in place with this farmer during the second year to address the problem. At joining in the second year, the flock had an average condition score of 3.7. Notably, 85% of ewes in the flock were categorised as ‘‘in target condition’’ and only 1% in poor condition. This, along with a number of other changes, led to an increase in output and a more trouble-free flock. The turnaround in just one year happened as a result of the farmer making a number of simple changes to his management that are directly applicable to any flock.

The key message from this farm and, indeed, other farms we have worked with is the earlier the preparation for the breeding season starts, the easier it is to achieve the target condition.