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Nutrition
and body condition score

Scanning
Lambing
Weaning
Sheep

Nutrition and body condition score

Ewes are capable of conceiving, carrying, delivering and feeding twin lambs. However, on many properties the marking percentage of twin lambs is very low due to the extra nutritional burden of twins. It is essential that if ewes are managed for maximum fecundity (i.e. high number of multiple births) at joining then the correct management decisions are carried through at scanning, lambing and weaning to ensure that losses are kept to a minimum.

The single most important determinant of reproductive rate is ewe nutrition. Ewes in higher condition score conceive more lambs. Hence, monitoring ewe condition during each phase of the reproductive cycle is critical in the lifetime performance of any sheep enterprise.

Maintaining BCS targets will have positive implications for:

Conception success 

Reproductive rate

Udder development and colostrum production
Lamb growth including wool follicle development 

Ewe milk production

Management of ewes strongly depends upon management of nutritional inputs to match the energy requirements through the different stages of the reproductive cycle. Ewes that do not meet condition score targets at key times during the reproductive cycle are costly to the sheep enterprise, leading to reduced lamb and ewe survival and decreased fleece quality.  Figure 1 shows the effect of ewe body condition score on success of joining and fecundancy (Source Lifetime Wool).  Figure 2 is a study of 4 farms which shows a strong correlation between ewe body condition and the number of lambs born (Source Lifetime Wool).  

The effect of ewe condition at joining on the proportion of dry, single and twin bearers

Graph 1

The effect of ewe condition at joining on the reproductive rate for four flocks

Graph 2

Figure 1 & 2.  Lifetimewool LTEM 2.1 www.lifetimewool.com.au

Body Condition Score (BCS)

Body condition scoring is a simple yet effective tool for measuring ewe's nutritional status.  Condition scoring assesses the amount of soft tissue over the short ribs and backbone, on a scale of 1-5 (refer to Lifetime scale below).

Correct method of assessing sheep body condition score

WA Department of Primary Industries & Regional Development

Sourced from WA Department of Primary Industries & Regional Development

BCS is a personal perception of the feel of the soft tissue along the short ribs. In Picture 1 it can be seen the correct location to examine to determine the BCS. There are training programs through government and industries. Time and practice is required to become competent in BCS. It is best to start assessing BCS immediately and continue at every opportunity.

Condition Score 1

Condition Score 1

Backbone

The bones form a sharp narrow ridge. Each vertebrae can be easily felt as a bone under the skin. There is only a very small eye muscle. The sheep is quite thin (virtually unsaleable).

Short Ribs

The ends of the short ribs are very obvious. It is easy to feel the squarish shape of the ends. Using fingers spread 1cm apart, it feels like the fingernail under the skin with practically no covering.

Condition Score 2

Condition Score 2

Backbone

The bones form a narrow ridge but the points are rounded with muscle. It is easy to press between each bone. There is a reasonable eye muscle. Store condition - ideal for wethers and lean meat.

Short Ribs

The ends of the short ribs are rounded but it is easy to press between them. Using fingers spread 0.5cm apart, the ends feel rounded like finger ends. They are covered with flesh but it is easy to press under and between them.

Condition Score 3

Condition Score 3

Backbone

The verebrae are only slightly elevated above a full eye muscle. It is possible to feel each rounded bone but not to press between them. (Forward store condition ideal for most lamb markets now. No excess fat).

Short Ribs

The ends of short ribs are well rounded and filled in with muscle. Using 4 fingers pressed tightly together, it is possible to feel the rounded ends but not between them. They are well covered and filled in with muscle.

Condition Score 4

Condition Score 4

Backbone

It is possible to feel most verebrae with pressure. The back bone is a smooth slightly raised ridge above full eye muscles and the skin floats over it.

Short Ribs

It is only possible to feel or sense one or two short ribs and only possible to press under them with difficulty. It feels like the side of the palm, where maybe one end can just be sensed.

Condition Score 5

Condition Score 5

Backbone

The spine may only be felt (if at all) by pressing down firmly between the fat covered eye muscles. A bustle of fat may appear over the tail (wasteful and uneconomic).

Short Ribs

It is virtually impossible to feel under the ends as the triangle formed by the long ribs and hip bone is filled with meat and fat. The short rib ends cannot be felt.

Fecundity

This relates to multiple ovulations and the chance of having twins or triplets. The number of ova released from the ovary is highly-dependent on the ewe’s long-term nutrition and is increased by a rising plane of nutrition at joining.

As seen in Figure 3 from lifetime ewe, there is a strong correlation between BCS and successful fertility and fecundity.

The relationship between ewe condition score and the number of lambs conceived

Relationship between ewe condition score and the number of lambs conceived

Figure 3. Condition score of ewes and the number of lambs conceived from 5 properties (Source: Lifetimewool and LTEM).

Ewe monitoring

Having ewes in the optimum condition at the right time is important as it contributes to:

Improved reproduction 

Increased lamb survival

Increased progeny fleece weight and lower fibre diameter

Improved ewe health and survival

It is more profitable to feed ewes to maintain weight during pregnancy than to allow the animals to lose weight from joining through to lambing. Hence it makes sense to invest in larger stores of grain/ supplements to be able to feed ewes to meet their target profiles.

Figure 4 shows the trend and correction of BCS through the pregnancy year.

Optimum condition score profile

(for Merino ewes, late winter-spring lambing)

Optimum condition score profile

Figure 4: Optimal body condition score (BCS) for ewes (Source Lifetime Wool ewe management handbook)

Weaning

Live weight at weaning and the growth path following weaning will have a high impact on weaner survival. For example, in tough years it is likely that weaners will have low live-weights as a result of poor lactation and/or weaning early. In these years, lower condition scoring animals should be given access to the best available pasture, to ensure a low cost/high benefit management strategy. 


An additional management practice is to imprint feed (or ‘creep feed’) lambs, prior to weaning, whilst still on their mothers (i.e. ewes and their lambs should be fed the supplement they will be likely eating over their first summer). This makes for a faster transition due to early exposure and development of appetite and enhances rumen development.

Further Reading

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