Scanning Season: What Tracking Data Tells You That the Scanner Cannot

Scanning is the most informative morning of the sheep year. In a couple of hours you find out your conception rate, your multiples, your barrens, and therefore most of what next spring is going to look like and cost.

What it does not tell you is why. The scanner reports a state, not a cause, and the causes happened weeks ago out in the fields. That is the gap tracking data can close, and the useful thing is that the data has already been collected by the time you need it.

The barren ewes are the question worth asking

A barren rate within your normal range is not worth investigating. One that is up on previous years is, and the standard approach is to work backwards through the usual suspects: ram working or not, ewe condition at tupping, nutrition, disease, weather.

The problem is that those explanations are usually applied to the whole flock, when the barrens are frequently not spread evenly across it. If you can look at where each barren ewe actually was during tupping, the pattern often declares itself without much interpretation.

• Whether the barrens cluster in one group, one field, or one part of a large block.
• Whether they were in the part of the ground the ram was not using. On a big hill or a rough block, rams do not cover the whole area evenly, and ewes that settle at the far end may simply not have been served.
• Whether they were the ewes ranging furthest — walking more, lying up less — which generally points at the grazing rather than the ram.
• Whether they overlap with the wet ground you were already thinking about, which is a different conversation and one for your vet.

The first two of those are the ones that come up most, and they are both fixable for next year by changing ram numbers or how the ground is used, rather than by changing anything about the ewes.

Ram coverage is the one most farms underestimate

This is worth drawing out, because it is the explanation people reach for last and it is often the right one.

A ram turned out on a large or broken block will establish a working area, and it will not be the whole block. Ewes that have settled in a corner he does not visit can go through the whole cycle unserved while the paperwork says they were tupped. A ratio that looks fine on a spreadsheet can be quite wrong in practice once the ground is big enough or the terrain divides it.

Location history over the tupping period shows you both halves of that: where the ewes concentrated, and whether the ram was in the same places. Where they do not overlap, you have your answer, and it is a management fix rather than a veterinary one.

Grouping the in-lamb ewes by more than their scan result

The immediate practical job after scanning is splitting the flock — singles, twins, triples, barrens — so feeding can match requirement. That is the right first cut and it is not the only useful one.

Two ewes both scanned with twins are not necessarily the same management problem. One has held condition on good ground close in; the other has been walking a long way on a poor block and is carrying the same load with less behind her. The scan cannot distinguish them. Activity and location over the autumn can, and it is the sort of thing that decides which animals want the better field and earlier supplementary feed.

It also tells you which ewes to keep an eye on rather than treating the whole twin group identically. The ones that ranged hardest through a wet autumn carrying multiples are the ones most likely to need attention first, and knowing that in December is worth considerably more than noticing it at lambing.

Deciding where the groups go

Once the groups are drawn, they have to be put somewhere, and that is a ground-condition decision as much as a grazing one. The fields that carried sustained use through the autumn are the ones least able to take a group of in-lamb ewes through midwinter, and the records from the last few months tell you which those are.

This runs straight into the turn-in question we have been through separately in deciding when to bring them in — the same information serves both, which is the argument for keeping it rather than only looking at it when something goes wrong.

What to write down

1. The barren list, with where each of those ewes spent tupping. This is the one that earns its keep.
2. Which fields and which parts of them the tupping groups actually used, against where the rams were.
3. Scan result per ewe alongside how hard she worked through the autumn, so the twin and triple groups can be split by more than the scan.
4. Which ground is tired, so the in-lamb groups go somewhere that will carry them.

Kept for two or three seasons, that becomes something better than a single year's scan percentage: it tells you which of your ground reliably produces a result and which does not, and whether your ram numbers suit the way your fields are actually shaped.

Worth stating plainly: this is management information, not veterinary diagnosis. Where a barren rate is genuinely out of line, or where there is any suggestion of abortion or disease, that is a conversation with your vet and a sampling job, and no amount of location data substitutes for it. What tracking does is tell you which animals and which ground to point them at.