Improve lamb survival

Improve lamb survival

On average 20% of lambs born will die, with 90% of deaths occurring during or within seven days of birth. This represents a large income loss for producers, and may be perceived as a welfare issue. The major cause of death for lambs varies between properties and seasons, but starvation, mismothering, exposure and difficult births are generally the largest causes.

So which lambs are most at risk? Lambs born as multiples (twins 30% mortality) compared to singles (10% mortality), merino rather than crossbred lambs, and lambs born to maiden ewes – maidens have 10% lower survival rates than mature ewes. 

“Ewe nutrition is the most important factor influencing lamb survival,” Dr Susan Robertson said. “Optimum nutrition minimises difficulties during birth, improves maternal behaviour, allows ewes to provide sufficient colostrum and milk, and allows ewes to stay on the birth site longer to bond with the lamb, reducing mismothering.”

Ewes gain weight and maintain condition during late pregnancy with adequate nutrition. Avoid having fat ewes (condition score 4) at lambing as this increases the risk of pregnancy toxaemia and ambing difficulty. “The month of lambing effects both the likelihood of adequate pasture being available for the ewe and the risk of poor weather causing either heat or cold stress to new-born lambs. The month of lambing also influences the number of ewes able to be carried by the association between feed supply and demand, and hence the potential number of lambs born,” said Dr Robertson.

“Shelter that reduces wind speed can increase lamb survival in cold, windy weather, but will be ineffective in mild weather.” “Consider the cost of creating shelter against the value of potential increased production. Where possible use natural, existing shelter,” Dr Robertson said. Lambing twin-bearing ewes in separate paddocks to singles does not appear to increase lamb survival. But separation may improve survival if it allows preferential management, as twin bearing ewes can be placed in more sheltered paddocks or where better feed is available.

Dr Robertson advises against lambing mature and maiden ewes in the same paddock, as research suggests this can reduce the survival of lambs from maiden ewes by 10%. “Genetics also plays an important role. Avoid buying rams with high birthweight Australian Sheep Breeding Values or blocky shoulders as this can result in increased lambing difficultiesManaging your ewes correctly in the last 8 weeks prior to lambing is one of the most critical stages in the sheep calendar. If things go wrong at this stage then lamb birth weight could be low, lamb losses high, colostrum supplies and quality poor and that’s mean lamb growth below target.

Body Condition: ideal BC at lambing will be 2.5-3, it’s preferable for ewes to reach these condition 8 weeks before lambing and to maintain them right through to lambing.

Nutrition: Good quality grass (11-12 MjME/kgDM) is capable of suppling the majority of nutrients needed by a ewe until lambing, if you have several types of paddocks available, and then always save the best quality for close to lambing.

Minerals: An annual mineral test of your pasture will give you a good idea of mineral content in the grass, make sure the ewes cover their minerals requirements, particularly selenium and iodine, they are important in mobilising brown fat in the newborn.  If brown fat reserves are low (no correctly feed ewes prelambing) or can’t be mobilising efficiently then hypothermia is a very high risk.

Remember:

70% of foetal growth occurs in the last third of a ewe’s pregnancy. That means that ewe’s requirements for energy increase rapidly in the last 6 weeks of gestation.

- 50% of total lamb losses occur in the first 48 hours, with a further 11% occurring 2-14 days post-lambing. The reasons for this are low colostrum intake

CALOSTRUM (the fuel for life): It is the first feed for the new-born lamb and the key to survival. A newborn lamb should receive colostrum from its mother within 6-12 hours of birth. Colostrum is the first source of immunity; new-born lamb has a very permeable gut lining that can allow any ingested bacteria and toxins into the blood. They have limited energy reserves (brown fat) and new-born lambs have a large surface area to body weight ratio which makes them susceptible to heat loss.

NUTRIMIX SPECIAL PRELAMBING MOLASSES BLOCK: help to decrease incidence of bearing, improve immune system, and increase colostrum quality (more lamb survival). Price: $60/30 l plastic bin. Content organic minerals, mycotoxin binders and bypass protein. Can be customised for your farm.