The perinatal lamb mortality rate is high in many sheep flocks; as a consequence of such deaths triplet lambs are fostered on to those ewes which have lost a lamb.
In addition, lambs are also fostered onto those ewes which produce a single lamb. No large scale surveys have been undertaken to determine the number of attempted "fosterings" in lowground flocks but it could be more than 10 to 15 per cent of all ewes. This procedure is not as simple as would first appear and the long-term acceptance rate by the ewe is likely to be less than 60 per cent.
Orphan lambs are either triplet lambs or twin lambsremoved because of poor dam milk yield. The majority of these lambs have failed to ingest sufficient colostrum and are therefore prone to a wide range of bacterial diseases during the neonatal period including polyarthritis, enteric infections, and respiratory disease. Older lambs may have been hungry for a number of days before removal from the dam.
It is recommended that "surplus" lambs are removed from the ewe as early as possible because these lambs learn to suck much more quickly from the milk bar than if left with their dam for two or three days. It could be reasoned that the smallest triplet of every litter should be removed within hours of birth, fed colostrum, and either fostered immediately or reared artificially. The ewe and two remaining lambs could then be turned out to pasture the following day.
Rubbing an orphan lamb in the foetal fluids of the newborn single lamb before the ewe licks her own lamb is the most successful fostering method where good acceptance rates are achieved when the foster lamb is as young as possible, and preferably newborn. A variation on the fostering method described above is to place both lambs in a hessian sack which is then tied at the neck and placed in the pen with the ewe for one hour. This practice facilitates mixing of odours and increases the foster lamb acceptance rate when the lambs are introduced to the anxious ewe. Disparity in size of the new "pair" of lambs typically results (6-7 kg singleton and 3.5 kg triplet).
Fostering lambs with the aid of the dead lamb's skin generally has good success although confinement in a small pen for a few days may be necessary.
There are many designs of foster crates. It is essential that clean water and good quality roughage are always available and that concentrates were fed at least twice daily where the ewe can reach them. Inadequate ewe nutrition leads to poor milk production and poor long-term acceptance rates.
The use of rope halter provides limited freedom and improved comfort for the ewe provided the halter does not tighten across the bridge of the ewe's nose and the ewe can lie down. Halters should be made of soft rope and not a single strand of polypropylene baler twine. Occasionally, the rope is tied around the ewe's horns which is unacceptable.
The ewe and lambs must be carefully supervised to detect early rejection such as not letting the foster lamb suck, pushing the lamb away, to vigorous head butting. Head butting lambs can often be detected by the presence of marker fluid used to identify lambs on the ewe's forehead.
Orphans lambs can be reared very successfully on artificial rearing systems achieving excellent growths rates and a low incidence of digestive disturbances such as abomasal bloat and/or volvulus. Haphazard feeding of lambs from a bucket and teat system does not work and at weaning such lambs are small, poorly-fleshed and pot-bellied, and remain so for many months.
The Codes of recommendations for the welfare of livestock - sheep
Tail docking and castration cause both acute and chronic pain in lambs and there are doubts whether both (either) procedures are necessary in fattening lambs sold before December (8-9 month-old) when pregnancy is not a major concern. Recent developments in pain management at castration involves a device ("Numnuts") which delivers a local anaesthetic at the same time as the elastrator ring is applied. Operator acceptance is likely to be the major factor in adoption of this instrument but the process could be driven by farm assurance schemes. Previous devices, such as the modified Burdizzo clamp, proved unpopular due to increased handling time and failure to effectively castrate some lambs.
There is a lot of very useful advice contained within the Codes of recommendations for the welfare of livestock - sheep available at http://www.awtraining.com/pdf/pdffiles/sheep.pdf
Welfare code recommendation 62: Farmers and shepherds should consider carefully whether tail docking within a particular flock is necessary. Tail docking may be carried out only if failure to do so would lead to subsequent welfare problems because of dirty tails and potential fly strike.
Blowfly strike is prevented by controlling faecal contamination of the perineum by correct parasite control, dagging when appropriate, and use of insect growth regulators such as dicyclanil as necessary.
Government regulatory authorities are actively promoting schemes to reduce tail docking and castration of lambs; some of these schemes offer financial incentives. In these schemes farmers are encouraged to limit use of such procedures to specific instances where their veterinary practitioner considers that not undertaking them would compromise animal welfare.
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