07 August 2015
The recently released Priority list of endemic diseases for the red meat industries report by MLA found dystocia was the number three animal health condition impacting the Australian sheep industry. Here, we take a closer look at sheep dystocia.
The impact
Dystocia (or difficulty in lambing) costs the Australian sheep industry $219.6 million annually and also contributes towards the number one sheep health challenge of peri-natal mortality (costing $540.4 million annually).
The causes
Size: A disproportion in the pelvic size of the ewe and the size of the lamb, often caused when a sire of a large breed is used on a small framed ewe or in maiden ewes, or excess feed leading to high lamb birth weight. Over fat ewes also can have difficulties lambing. Malpresentations: The lamb may not be positioned correctly for birthing. Commonly seen are head back, one front leg back, breech or head only positioning. Multiple births: There is an increased risk of dystocia in ewes carrying more than one lamb.Prevention
Lambing ease has a major impact on the profitability of a flock. Here are some of the factors producers can consider.
Genetics: ASBVs can assist in eliminating lamb birthing difficulties and increasing the output of lamb/ha. They will also help to reduce ewe losses, a significant long-term profit driver of lamb production. As lambing ease decreases, ewe and lamb mortality increases, which also increases labour requirements and veterinary expenses. Though many large studies have consistently shown birth weight to be the most important genetic factor influencing lambing ease, there are also other aspects that need to be considered, such as lamb shape and pelvic area. When looking at birth weight ASBVs, avoid low and high birth weights. There is a 25% difference in lambing ease between the best and worst terminal sires, highlighting the large amount of genetic variation. Use tools such as the Sheep Genetics program. Measure to manage: Using tools such as scanning all joined ewes to identify empties, singles and multiple carrying ewes can be used to allocate feed most efficiently and help with monitoring lamb and ewe loss at weaning to identify losses. Ewe condition: Target condition score (CS) 3 for ewes at joining and maintain ewes at that CS. Once CS 4 is reached, the risk of dystocia occurring increases significantly. Learn about condition scoring in the Making More From Sheep ‘Wean More Lambs’ module. Keeping check: Monitor ewes close to lambing and learn how to safely and correctly intervene during delivery.
