Colostrum quality is key to lamb survival and is quantified by the amount of gamma globulin present –these are the large molecules of protein that provide antibody protection. But they will only be absorbed if colostrum is the first protein feed. Feeding sufficient energy and protein to the ewe increases the production level of colostrum.
Maximising forage intake is key to any cost-effective winter ration. Simple things like making sure there is enough space at ring feeders and barriers and breaking up hard-centres of silage bales will help to ensure all ewes get their share.
Even with high quality silage there can still be a protein deficit in sheep rations at lambing. The protein requirements of a ewe in the last 3 weeks pre-lambing are different, and at this stage even best quality forage, together with conventional compound feeds, cannot meet the needs of the ewe.
In the weeks prior to lambing there are increased demands for protein for lamb birth weight, colostrum for disease protection and to grow the birth coat to give the lamb protection from hypothermia at birth.
Rumen degradable (microbial) protein supply from forage or conventional compound feeds is just not enough for the ewe at this stage. As a result of this protein deficit the ewe temporarily loses her immunity, worms becoming active and the ewe is open to disease challenge. Immunity loss caused by protein deficits is one of the reasons for higher death rates in ewe flocks in the weeks immediately prior to lambing
To combat the protein deficit prior to lambing, it is advised to include a source of Digestible Undegradable Protein (DUP) in the ewe ration prior to lambing. This can be in the form of soya, fed daily to multiple bearing ewes at the rate of 100g/day per lamb carried, for the last 3 weeks of pregnancy. It can be put on top of the silage.
For fit ewes, replace compound feed with soya, while for thin ewes feed it in addition to the compound. But all this adds to complications and hard pressed stockpersons prefer the convenience of compound feeds. These are now available with 15% soya inclusion.
It is important to split ewes according to their condition score and their scanning results, then feed accordingly. For silage with an ME of 10.5 or over, feed at a flat rate of 0.4 to 0.6kg/day of concentrate to twin bearing ewes for the last month. By lambing time, thin ewes and gimmers can be given at up to 0.7kg/day, split into two feeds. Managing condition score to avoid prolapse and give an easy lambing, together with correcting protein deficiency, are likely to result in high colostrum production resulting in more live lambs.
Low immunoglobulin levels found in triplet pedigree lambs that died, despite a well managed farm with good hygiene, show the importance of colostrum quality. The farmer was supplementing lambs with a powdered colostrum substitute as necessary. The triplets had been given a full feed of supplement and put back with the ewe. As with all infants after a full feed a good sleep follows. So the lambs may not have sucked for several hours by which time the mechanism that allows large immunoglobulin proteins through the gut wall had closed down. Even expensive colostrum substitutes are no comparison with the real thing when it comes to Immunoglobulin content. They are sold as a food resource only, not as a source of passive antibody protection despite what hints may be made.
To maximise colostrum quality some block and bucket manufactures add mannan oligosaccharides to their products which in SAC trials have been shown to increase the gammaglobulin content of colostrum to a worthwhile and significant degree.
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