Reducing the incidence of lamb deaths is the aim of every sheep producer.
With prime lamb prices at record levels and demand for all types of sheep nearly inexhaustible, reducing lamb deaths by even 10 per cent will have a significant impact on the bottom line for individual sheep producers, not to mention the gross returns to the industry as a whole.
In the interests of showing lamb producers common causes of lamb deaths, Riverina Local Land Services (LLS) vet Sophie Hemley conducted post mortem examinations at a workshop at Morundah hosted by Elders, Narrandera.
"If we decrease lamb mortality by 10pc we will be 50 million sheep better off," Ms Hemley told her audience.
"With lamb mortality we are talking about the perinatal times, from the time the ewe goes into labour until seven days of age ... that is when 90pc of lamb deaths occur, and 80pc of lamb deaths occur within 48 hours."
By far the most common cause of lamb death in those periods is the lack of sufficient nutrients ingested and Riverina LLS information described three main causes of that occurring; low birth weight, difficult birth and inappropriate behaviour by either ewe or lamb.
These factors are interrelated and the nutrition of the ewe has far reaching effects on lamb survival.
"The lamb's ability to utilize colostrum declines rapidly, and 12 hours is the limit of the benefit of colostrum," Ms Hemley said.
The lamb's ability to utilize colostrum declines rapidly, and 12 hours is the limit of the benefit of colostrum
- Sophie Hemley, Riverina Local Land Services vet
"Birthing trauma can be maternal or foetal in origin ... maternal in origin occurs when ewes are in low condition and they don't have enough energy or they suffer from hypocalcaemia and can't deliver the lamb."
During the birth, a nerve paralysis can occur through the pelvis which will cause birthing stress, and a further cause of lamb death is when the lambs are too big to birth easily.
"Large lambs occur when you have fed the ewes really well through the last trimester because you didn't want the ewes to get 'preg-tox' and the pelvis is not big enough," Ms Hemley said.
She also noted in utero lamb death can occur due to a viral infection, or similar issues. If the lamb does not actively engage into the cervix (i.e. the lamb is not pushing) it therefore does not stimulate the maternal hormones to encourage a proper birth.
"The birthing process should take about an hour or less, so if the birthing time increases, that will give the lamb more stress," she said.
"As the lambing time increases, the incidence of mortality increases."
When the ewe lambs naturally without any pressure from predators, she will normally stand on the place where she gave birth for the first four to six hours of the lamb's life. It is important the ewe licks the lamb.
Healthy ewes equals healthy lambs
The behaviour of the ewe at lambing is critical for lamb survival, Riverina Local Lands Service vet Sophie Hemley said at the lamb death workshop at Morundah.
"The initial maternal offspring bonding is done through nasal and eye sight sensors, and lambs once they are born, within a few minutes, should be sitting up on their brisket, within half an hour they should be standing up, and within two hours they should be drinking," she said.
The age and breed of the ewe, litter size and nutrition of the ewe all have a bearing on whether or not the ewe will have that maternal bond.
"If the lamb has been in-utero for too long and is slow and not actively seeking the udder, that is when you will have failure for the actual bond to occur," she said.
