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ARTICLES >> Livestock Articles

Disappointing lamb marking raises more questions than answers

Posted by Bestprac on Jan 23 2012

By Allie Jones, Livestock Extension Officer (Sheep and Wool)
NSW Department of Trade and Investment, Regional Infrastructure and Services
 

Sheep producers from Western NSW and surrounds have reported poor lambing and marking results from their traditional spring/autumn joining. Scanning contractors showed reasonable joining. Marking % has been poor from these same producers, indicating either loss during late pregnancy, which is very unusual in sheep, or lamb losses after birth. Producers are asking me why?

There have been a number of unusual differences this last year that could affect sheep reproduction:

high summer rainfall:
the better feed should have improved lambings
attack by mosquitoes and other biting insects:
insects can carry viruses and other infections that could affect unborn lambs, directly or through increased body temperatures
these biting insects can carry viruses and other infections that could affect unborn lambs, directly or through increased body temperatures
the combination of heat and humidity can cause heat stress which can produce small lambs with lower chance of survival at birth
the good seasons have increased fox, pig and dingo numbers, increasing the chance of lambs being killed
worms have been a major problem, reducing body condition, making sheep sick and sometimes killing them
sheep spending extended periods in water or water logged pastures leading to foot and skin infection
It is really odd that producers have had significantly high scanning rates however the lambs have not hit the ground. The scanning to marking % has been very disappointing and frustrating for producers to comprehend.

Is the issue related to fertility and joining or lamb loss?

Producers who have scanned their ewes have been able to identify this issue occurring from mid pregnancy to lambing. As the producers have received promising scanning results and a bumper season they were expecting a good lambing. Unfortunately for some producers this did not prevail. For example, one property in the Western division scanned 120% foetuses per ewe joined, however only marked 30%. This is a result you would expect in a dry year. There are a number of producers who have had poor marking % who do not utilise scanning. I have not been able to identify the issue as being related to fertility and joining or lamb loss at lambing.
This season has highlighted the benefits of scanning to producers.

Pregnancy scanning- A valuable management tool

The information generated from pregnancy scanning allows for active management of the flock to increase the survival of new born lambs.

Ultrasound scanning is the only practical and reliable method of determining the number of foetuses carried by commercial ewes.

Scanning information allows farmers to:

identify non-pregnant ewes – decide weather to rejoin or cull
compare scanning percentage with expected percentage (based on ewe live weight at mating)
quantify lamb losses between scanning and birth or marking
identify single and twin bearing ewes
plan lambing paddocks for single and multiple-bearing ewes — e.g., allocating areas with better shelter and more pasture cover to multiple-bearing ewes if few suitable paddocks are available
Scanning results give farmers a measure of their potential lambing percentage and losses between scanning and marking.

An important benefit from scanning is separation of ewes with multiples from those with singles for preferential feeding and lambing management.

Lamb losses, at or shortly after birth, can be significantly reduced if the birth weight of new born single and twin lambs is managed by targeted nutrition of the ewe after scanning.

Economics of scanning

Scanning contractors charge approximately $0.40 per head. At present producers are securing $80 per head for cull ewes through the saleyards. 1 dry ewe out of 200 scanned in lamb ewes will pay for the cost of a contractor. It costs $80 to scan 200 ewes.

The current optimistic sheep prices and the demand for replacement ewes should be incentive enough to adopt at least some of these simple management steps to lift lamb and embryo survival and contribute to the back pocket.

Allie is currently organising a webinar on reproduction and ewe management that will be held early to mid December. The aim of the presentation is to encourage producers to talk about the challenging lambing they have seen this season. Greg Curran, the Department veterinarian placed at Broken Hill, will be the facilitator of the presentation and will be on hand to discuss evidence producers have witnessed in regard to their challenging lambings. Further information and details can be obtained from the Bourke office.

Allie Jones | Livestock Extension Officer (Sheep and Wool)
NSW Department of Trade and Investment, Regional Infrastructure and Services
Bourke NSW 2840
T: 02 68300001 E: allie.jones@industry.nsw.gov.au 
W: www.industry.nsw.gov.au

 

Last changed: Jan 23 2012

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