“We have worked hard on improving our feed management and ewe body condition, plus have stabilised what was genetically a very variable flock,” station manager Kim Robinson said.
“But bearings have continued to bug us and it is especially gutting when you know the ewes you lose are carrying multiple lambs.”
Lochiel has recently introduced electronic identification into a proportion of its ewe flock.
Having this resource available made it easier to set up a study on bearings, where large numbers of animals are required to get any meaningful information.
A previous survey led by Hawke’s Bay vet Richard Hilson highlighted ewe body condition gain in early pregnancy as being an important driver of bearings.
The current study captured body condition information and also investigated a preventive role of salt application to pasture, plus the impact of various pasture minerals and nutritional components as possible bearing triggers.
The study found that good body condition score (BSC) was not a risk factor for bearings. In fact, ewes that were in light condition (<BCS 2.5) at both scanning and tupping were more at risk from bearings. No relationship between bearings and body condition change was seen in this investigation.
There was no link between bearing incidence and pasture components. This includes aspects such as protein, energy, fibre and pasture minerals including calcium, phosphorus, sodium, chloride and potassium. This is in line with other work Totally Vets has done showing variations in pasture components could not be linked to ewe deaths.
Salt application to pastures did not reduce the incidence of bearings.
The results of this study do need to be interpreted with caution because a severe autumn drought nearly halved the number of twinning ewes available, meaning the analyses were performed on about 2500 ewes instead of the planned 4500. Also, because the study was located on one property the results might not be applicable across New Zealand.
Repeating the study over more seasons and more ewes would improve the quality of the information presented here. In the meantime, farmers are encouraged to apply industry recommendations to reduce the risk of bearings:
- Avoid sudden changes in feed type-level through the main risk period
- Avoid salt supplements and feeding of swedes close to lambing (shown to be risk factors in the Hilson survey)
- Avoid a marked increase in liveweight over the first half of pregnancy
- Shear pre-mating or in the latter half of pregnancy
- Ewes that sit down for extended periods during the immediate pre-lamb period are more at risk (there may be practical ways to reduce this on some farms), and
- Oestrogenic pasture components (eg: in some types of red clover, and feeds infected with Fusaria fungi) might exacerbate the risk and should be avoided.
A full copy of the report will be available soon from B+LNZ.
- Ginny Dodunski is a senior veterinarian with Totally Vets.
