Lamb mortality can be unacceptably high in the first two weeks of life, with the majority of deaths occurring in the first 48 hours. A target for you should be to keep mortality, including still births, to below 8pc.
There can sometimes be an acceptance that lamb mortality is a part of sheep farming, but these should be minimised. While we may not like to admit it, the shepherd is the biggest factor influencing lamb mortality in the Irish context.
If a lot of small lambs are born, it points to inadequate energy nutrition of the ewe. If large lambs are born but the ewes have no colostrum it points to inadequate protein nutrition.
A lamb birth weight of 5-6kg should be the target, although an allowance up to 7kg for singles is ok where there is good supervision available.
With triplets it is relatively easy to achieve an average lamb birth weight of at least 4.5kg.
2.Hypothermia and starvation
The biggest killers of newborn lambs are hypothermia, starvation and disease. Obviously, lambing conditions will also have an effect.
Hypothermia will be a higher risk factor in an outdoor environment. Disease will most likely present more of a challenge indoors, and starvation can occur across the board.
Starvation and hypothermia will kill the lamb long before disease will get the opportunity to do so. When the lamb is born it has very limited energy reserves.
In order to utilise these energy reserves to generate heat, the ewe must receive adequate selenium supplementation during pregnancy. If selenium levels are inadequate the newborn lamb will have a reduced ability to keep itself warm, increasing the chances of hypothermia.
Recent work from New Zealand points to the importance of this issue in outdoor lambing. This is due to the fact that grass contains high levels of polyunsaturated fatty acids which increase the selenium requirement.
Hungry lambs are easy to identify but can cause a major headache at lambing time. In most instances, the newborn lamb is enthusiastic in searching for the teat. If this is unsuccessful the lamb quickly becomes weak and is incapable of making much effort to suckle.
These lambs will become gaunt, hollow and stand with a hunched appearance. It will take two to three days for these lambs to die. This means that there should be ample opportunity to detect and treat at risk lambs.
However, the window of opportunity to remedy this situation is shortened in cold, draughty or wet conditions. A quick post-mortem examination will confirm any suspicions you may have that a lamb died from hunger.
The key are the kidneys. If these are not surrounded by fat it is most likely death due to starvation. Hunger is therefore often combined with hypothermia.
Between 37-39C we refer to the lamb as being moderately hypothermic, and this is quite easy to correct at this stage. Below 37C, the lamb is said to be severely hypothermic and is more difficult to treat. So it goes without saying that the earlier you can act, the better the outcome.
Treatment of the moderately hypothermic lamb includes drying the lamb if it is wet, feeding colostrum by stomach tube and moving the ewe plus lamb(s) to a sheltered environment.
The use of artificial heat and separation of the lamb from its mother is usually unnecessary. In fact, if the latter happens it may well upset the bond between the ewe and lamb.
The lamb also becomes deficient in glucose if it becomes severely hypothermic after the first five hours of its life. Research suggests that death from cerebral hypoglycaemia (glucose deficiency in the brain) is still likely even if the lamb is warmed up from this state.
The glucose deficiency needs to be corrected by the administration of an intraperitoneal glucose injection. This involves the injection of a 20pc warm glucose solution into the abdomen of the lamb at a rate of 10ml/kg lamb birth weight.
The injection site should be approximately 1 cm to the side of the navel and 2 cm behind the line of the navel. When holding the lamb by the front legs the injection should be administered at a 45 degree angle, almost aiming for the tail head of the lamb.
A 19 gauge one inch needle is used. Then you can warm the lamb, which requires the use of artificial heat. A red lamp is often the best option as it can allow the lamb to remain with the ewe and preserve the bond.
Lambs which are hungry are also more likely to suffer from disease. Colostrum is also required to prevent disease in early life. It contains special proteins known as antibodies which help the lamb to fight off disease.
If the lamb receives adequate colostrum then he should be immune to all the infectious diseases that the ewe was exposed to, with the exception of orf.
Ensuring adequate colostrum supply is the best way to ensure the lamb receives immunity. A lamb will require approximately 1 litre of colostrum in the first 24 hours of life. For a twin-bearing ewe she must produce two litres over 24 hours.
She should also have approximately half a litre available at birth. The earlier lambs consume colostrum the less likely they are to suffer disease.
E coli (watery mouth/rattle belly) and joint ill are associated with less than optimum hygiene around lambing time or inappropriate handling of the lamb.
Both can be largely countered by ensuring a clean environment at lambing and adequate colostrum supply. The E coli challenge can build up as lambing progresses, especially where bedding becomes wet. Newborn lambs will inevitably ingest some E coli but adequate colostrum allows them to fight off this challenge.
If E coli is a problem on your farm, stomach tubing the lamb with 30ml of natural yoghurt at 24 hours of age can help to prevent scour.
Research in Britain shows the yoghurt helps to acidify the stomach contents and reduces the risk of scour. If you don't have an E coli problem this is unnecessary.
Any pen where a lamb has developed, or died from, E coli must be cleaned and disinfected before reuse.
For many years we had a severe joint ill problem at Lyons. Recently we have addressed and greatly reduced this problem. The single biggest change we made is to reduce the handling of the lamb when it's wet.
This has made our research more difficult but reduced the opportunity of transferring disease to the lamb. The savings are certainly worth it.
Hygiene has also been improved. Disposable gloves are worn at all times when assisting birth and handling newborn lambs.
Gloves are changed between ewes and anybody handling newborn lambs is required to wear a disposable apron and change this between lambs.