Keeping and Maintaining Ewe Condition
9 December 2024Managing a ewe’s body condition score (BCS) is an essential tool to ensure performance and productivity of the ewe. This allows to assess the level of fat along the ewes spinous and transverse processes to allow for an understanding of the nutritional status of the ewe.
There are industry targets for condition scoring, shown in table 1 below. These targets show a large difference from weaning to tupping of one condition score. One condition score is equivalent to 10-13% of body weight, which for a 70kg ewe is 7-9kg of bodyweight. If a BCS score decreases, the weight takes time to regain. On good quality pasture one condition score takes around 8 weeks to gain.
Table 1: Current industry targets for BCS throughout production
| Lowland | Upland | Hill | |
|---|---|---|---|
| Tupping | 3.5 | 3.0 | 2.5 |
| Scanning | 3.0 | 2.5 | 2.0 |
| Lambing | 3.0 | 2.54 | 2.0 |
| Weaning | 2.5 | 2.0 | 2.0 |
*CS 1 is very lean, CS 5 is very fat
These traditional targets allow the ewes condition to drop with seasonal grazing quality and quantity. In the targets, ewes are shown to decrease 0.5 condition score between tupping and scanning (mid pregnancy). However, work carried out by AHDB has shown that ewes who maintained their condition from tupping to scanning achieved better scanning results than those who lost condition in this period. This allowed the ewe to carry more condition over the winter, and then lose her condition slightly between lambing and weaning. This resulted in lambs being heavier at both 8 weeks and weaning.
The production cycle
Research has shown that ewes who are tupped at optimum condition (up to CS 4) have higher ovulation rates to leaner ewes. The term ovulation refers to the release of the eggs from the ovary, which typically happens the day after oestrous or tupping. The eggs enter the fallopian tubes, which is where the egg and sperm meet, once the egg is fertilised it becomes an embryo. Gradually over 3-4 days the embryos enter the uterus, where they remain during pregnancy, with the lamb developing in one of the two uterus horns. The placenta develops and grows to fill the uterus. Through the cotyledons of the placenta nutrients will transfer to the lambs, through a connection of the foetus and the mother.
Ewe nutrition and her body condition throughout tupping and pregnancy is essential to the survivability of these embryos. However, the relationship starts well in advance of tupping, with her nutrition having an influence on her ovulation rate, for up to six months prior to tupping. Given the time that is required to raise a condition score, and the effect of nutrition and body condition on ovulation rate, ewe condition must be managed throughout the production year to minimise changes in body condition.
During pregnancy the lamb gains it nutrients from the placenta, this can grow to ~1kg of weight during mid pregnancy, with the key stage for placental development from day 50 – 90 after conception. If the development of the placenta is compromised, through poor condition or nutrition of the mother, then it can result in poor growth of the foetus, low lamb birth weights and low survivability of lambs. In mid pregnancy the foetus only grows ~20% of its final birth weight, while the placenta grows considerably at this stage.
Figure 1: Products of conception as a % of total weight at lambing time over development
With the processes of fertilising the egg, and placental development all occurring during mid pregnancy this demonstrates how keeping the plane of nutrition stable is essential to enhance productivity through viable lambs being born.
In the last 6 weeks of pregnancy, the foetus grows quickly (around 75% of its birth weight), while the ewes udder is developing. Meaning late pregnancy nutrition has a huge effect on the vigour and survivability of the lambs, as well as preventing the ewes from metabolic disorders. Late pregnancy nutrition is vitally important, as this can also affect the lifetime performance of the lamb.
Ewes in poor condition pre lambing have shown to have low milk yields, less fat reserves on lambs, low birth weight of lambs, low vigour, lower mothering ability, etc.
Once ewes are pregnant, body condition score can be difficult to manage, given the relationship between condition and nutrition, along with lamb survival. To allow for maximum lamb survival, managing condition in a year-round cycle is essential.
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Energy requirements
A breeding ewe requires more energy to gain one body condition score than she does to lose one condition score.
It is important to manage body condition changes gradually to minimise any production losses in ewes, with fertility closely linked to body condition. Ideally ewe condition is managed and maintained throughout the year.
Lean ewes have a higher appetite and therefore, higher dry matter intake from ewes who are in the correct condition. Gaining condition can be costly to a system and a difficult balance to strike when ensuring there is forage available for tupping.
Table 2: energy and dry matter intake requirements for a ewe to maintain, gain and lose body condition
| Energy (MJ/day) | Dry Matter Intake | |
| Maintenance | 10.0 MJ/day | 1.0kg DM/day |
| Gain 1 BCS | 14.2 MJ/day | 1.42 DM/day |
| Lose 1 BCS | 6.5 MJ/day | 0.65 DM/day |
*based on BCS being 12% of liveweight over a 90 day period.
It is important that minimum requirements for protein are also met during this time with a dry ewe requiring a diet with a protein around 12% crude protein on a dry matter basis.
Year round management is essential
Gaining a condition score takes time. this usually takes in the region of 8 weeks. The key handling times for sheep tend to allow this 8-week period between handlings (see example in Table 3 below).
Table 3: Time to next handling from key production stages
| Approx. Time to next handling… | |
|---|---|
| Tupping | 12 weeks to scanning |
| Scanning | 9 weeks to lambing |
| Lambing | 8 weeks to 8-week weights |
| 8-week weights | 4-8 weeks to weaning |
| Weaning | ~15 weeks to tupping |
Meaning for those ewes who are lean at tupping, there is not a great deal of time to regain condition while mating and dealing with the extremes of the winter weather. The condition score of a sheep, doesn’t just impact her at her current stage of production, it also impacts the productivity of the ewe for the whole year. e.g. a ewe at CS 2.0 at tupping will have fewer lambs, poorer placenta, and lower lamb vigour at birth. She will also have less milk and the lambs will be lighter at birth and weaning. The ewe will be leaner at weaning and the cycle will continue. Meaning the poor condition at one stage, will impact her production for the next year.
How does it look?
It is very difficult to condition score by eye, given sheep have a fleece which can mask her condition by eye. To condition score you use your fingers and feel the transverse processes of the ewe (short ribs and spine). If you can feel easily between the short ribs, and they feel like the ends of your fingers, the ewe is too thin. As the ewe gets fitter, the ends of the transverse processes get covered in fat tissue feeling more like the joints on your hand, as described below in Table 4.
Table 4: Guide to conditioning scoring using your hand as an indicator
| Thin | Fit | Fit/Fat | Fat | |
|---|---|---|---|---|
| Condition score | 3 | 4 | ||
| Description | Finger ends | Finger knuckles | Fist knuckles | Wrist joint |
The series of photos below, show condition scores 1, 2 and 3 in Scottish Blackface ewes from SRUC Kirkton Farm. It is very difficult to tell these sheep apart from the photos in terms of condition due to the fleece. Demonstrating the importance of handling the sheep by hand.
There are numerous resources available through FAS on condition scoring of ewes, which discuss how to condition score and how to adjust management of ewes on condition score:
Condition Scoring for sheep | Helping farmers in Scotland | Farm Advisory Service
Kirsten Williams, SAC Consulting
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