Scanning Ewes and Pregnancy Testing Cows
Scanning and pregnancy testing allows feed to be saved, or fed to animals with higher potential production, and should be considered in the drought recovery period.
The advantages of scanning or pregnancy testing is to identify opportunities for:
- Feed saving.
- Feed allocation.
- Extra spring feed.
- Optimum tupping times.
Pregnancy test or scan all mated cows at eight weeks after the bull has been taken out, and cull all dry cows immediately. If yearling heifers are mated, separate the in-calf heifers from the dry heifers and run them on separate blocks so the in-calf heifers can have preferential feeding.
Ewes are best scanned at 90-110 days after mating. At that time, cull all dry ewes, and separate the single and twin bearing ewes. Multiple bearing ewes need better feeding over the winter. Recent research work has shown the potential of the placenta to transfer nutrients to the lambs is determined in the early part of pregnancy. Limiting the feed in early pregnancy means good feeding before lambing is of little advantage to the lamb.
The feed saved by scanning and selling dry ewes, and differential feeding over the winter, is best fed to the twin bearing ewes so that ideally the weight of the twin lamb is the same as a single lamb. Losses to exposure are greatest in multiple lambs.
Differential feeding will reduce ewe dystocia because single-bearing ewes can be held back. Twin-bearing ewes are not usually as much of a problem. Sheep health is usually better if the mobs are run separately, but if the scanner makes an error so that a single-bearing ewe is in the twins, then there may be a problem.
If hoggets are mated, run the in-lamb hoggets separately from the dry hoggets. Aim to feed the in-lamb hoggets as well as possible until about 6 weeks before lambing, then keep them on maintenance until lambing. Dry hoggets can be wintered normally.
Another advantage of scanning is the identification of twin-bearing ewes, which should be retained for future years. Some farmers are permanently identifying ewes that are scanned with twin lambs so that they can be mated to rams of a higher genetic merit.
Note-For more information on feeding levels for twin- and single-bearing ewes, refer to graph titled "Ewe demand before and after lambing" under section on Maintenance Feed Requirements.
Ken Muscroft-Taylor
Agricultural Consultant
Agriculture New Zealand
Darfield
Contact for Enquiries
Manager
North Island Regions
Sector Performance Policy
MAF Policy
Hamilton
NEW ZEALAND
Phone: +64 7 957 8313
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