This winter has proven to be a variable mixed bag for sheep farmers in the run up to lambing.
Some regions, including King Country and Manawatū, are reporting good feed levels, while areas like inland Canterbury and Marlborough have had little growth and are coming off the back of a tough autumn.
Zoetis consulting veterinarian Dr Clive Bingham has seen first-hand the impact this variability is having in the run up to lambing.
It has some farmers grappling with near record low feed levels and the real prospect of compromised ewe and lamb health as a result.
He also has some valuable insights on the best tactical moves for farmers scrambling in the face of a tough winter, and references the “four pillars” of a successful lambing – good nutrition, good body condition, disease prevention and parasite management.
“Ultimately setting your targets for feed levels and ewe condition goes right back to autumn. Winter is generally the most consistent season in terms of its pasture growth rates so predicting what your feed covers are likely to be at lambing based on your autumn covers is generally quite accurate. If you are not close to where you want to be in autumn then it can be tough, if not impossible to make it up through winter, as we have seen in some areas.”
For many South Island farmers who winter ewes on crop, transitioning ewes back onto pasture prior to lambing can be difficult when pasture levels are too low.
“Typically, you want to allow about 25 days ex crop for the rumen bacteria to modify for pasture digestion, ideally moving to good levels of high quality pasture. When ewes transition onto pasture that is too short or if it is done too close to lambing there is a higher risk of metabolic disease resulting in higher ewe and lamb loss.”
Ideally target pasture covers at set stocking should be 1400kgDM per hectare for twin ewes, allowing for ewes to eat this down no lower than 1200kgDm/ha.
Body condition score at lambing wants to be between 2.5-3.5. When ewes get too light, not only is performance compromised but there is a higher ewe and lamb mortality rate, particularly in the twins.
Where feed levels and body condition are compromised the flock is more vulnerable to single extreme weather events, which quickly reveals that level of vulnerability through high stock losses.
The third pillar, disease prevention, will help avoid losses from infectious diseases. Vaccination for campylobacter, the primary cause of flock abortions in late pregnancy, and Toxoplasmosis (a parasitic disease transmitted by cats) can reduce the wastage from scanning to docking.
“Vaccinating ewes against clostridial disease such as tetanus, pulpy kidney, black disease, blackleg and malignant oedema in the last few weeks of pregnancy will not only protect the ewe but will make sure they have good colostrum antibody levels to pass onto their lambs once they start suckling. It’s really a no brainer and even in these tougher times, not something you want to compromise on.”
Typically, ewe boosters would be administered as a single shot two to four weeks prior to lambing, and lambs will receive their first vaccination dose at docking followed by the booster 4-6 weeks later or at the next time you have them in.
Alongside disease prevention comes the increasingly critical and complex task of parasite management. In an environment where triple drench resistance is much more common, Bingham emphasises farmers are no longer able to just drench their way out of parasite problems. They need to consider all aspects of parasite management such as reducing or avoiding pasture contamination with L3 larvae and adjusting their drench practices to allow for refugia.
“There is little prospect of any new actives on the horizon, and the supply of novel actives is pretty tight right now.”
Pre-spring, he recommends faecal egg counts (FEC)s be conducted on ewe flocks approaching lambing to give an early warning indication of potential parasite issues before it’s too late to do anything.
“This year particularly, store lamb prices have been lower so farmers have held onto lambs longer, with a risk those lambs are contaminating pastures the ewes are now on. It could well be a pre-lamb drench will be necessary, but you can also be smart about how you go about that.”
He also recommends identifying the most vulnerable ewes, including thinner ones that may be carrying multiple lambs.
“Pre-lamb drenching really is the last lever you have to pull before lambing to help ewes out if their nutrition has been compromised through winter or if they are lambing on contaminated paddocks.”
Bingham is heartened to see more farmers taking notice of these recommendations around resistance avoidance, and the realisation there is not a chemical solution on the way any time soon.
Mixing up stock classes, avoiding intensive, prolonged grazing patterns with young stock, monitoring FECs and being selective in drench programmes are all strategies on hand.
“It’s about trying not to be too complicated. We have the tools, we just need to use them.”
This article was made possible by Zoetis.
