The single most important factor determining the reproductive performance in ewes is nutrition. Ewes in optimal body condition score (≥3) carry more lambs, have higher lamb survival, and produce bigger lambs at weaning. Hence, monitoring ewe condition during each phase of the reproductive cycle is critical for the performance of any sheep flock.
Maintaining BCS targets will have positive impacts on:
Lamb growth rate.
Lamb weaning weight.
Body Condition Scoring
Body condition scoring is a simple yet effective tool for measuring a ewe’s body reserves and response to feeding levels. Condition scoring assesses the amount of soft tissue over the short ribs and backbone, to examine the degree of sharpness or roundness on a scale of 1-5.
The spinous processes are prominent and sharp. The transverse processes are also sharp, with fingers passing easily under the end of this process. The eye muscle areas are shallow with little to no fat cover.
The spinous processes are smooth but still prominent. The individual processes can still be felt but only as fine corrugations. The transverse processes are smooth and rounded. However, it is still possible to pass the fingers under the ends of the processes with some pressure. The eye muscle areas are of moderate depth, but have sparse fat cover.
The spinous processes are smooth and rounded, and individual bones can only be felt with some pressure applied. The transverse processes are also smooth and are well covered. Firm pressure is required to feel over the ends. Eye muscle area is full and covered by a moderate degree of fat.
With pressure applied, the spinous processes can just be detected, although the ends of the transverse processes cannot. Eye muscle areas are full with a thick covering of fat.
Even with firm pressure applied, the spinous processes cannot be detected. Due to a high level of fat adjacent to the spinous process, a depression directly above where the spinous processes would normally be felt may be present. It is not possible to detect the transverse processes. The eye muscle areas are very full with very thick fat cover. It is possible to have significant deposits of fat cover over the rump and tail.
Optimal BCS by production period1
At breeding, a ewe should have a BCS in the range of 2.5–3.5. BCS should be maintained in early pregnancy.
In mid- to late pregnancy, ewes will likely lose body condition due to the demands of pregnancy. However, ewes can lose 0.5 to 1.0 units of BCS, depending on their starting point, with minimal impacts on productivity.
Ideally, ewes would be of BCS 2.5–3.0 at lambing, with an absolute minimum of 2.0. This minimum is important, because of the likely further loss of body condition during lactation.
At weaning, ewes should not have a BCS below 2.0 and should not have lost more than 1.0 unit of BCS in lactation.
Post-weaning, ewes need to be managed appropriately to ensure that the target breeding BCS is met.
For highly fecund ewes, BCS at the various stages of production should probably be at the upper end of the recommended target range.
Kenyon, P. R., et al. (2014). "Review of sheep body condition score in relation to production characteristics." New Zealand Journal of Agricultural Research57(1): 38-64.