This may be a long shot but I’m looking for Bluetooth sensors I can put in livestock to I can pick up with lambs belong to witch ewes.(mothers).
The sensors on the ewes need to be a receiver and the sensors on the lambs need to be sender so after a 24 hour period of been on the ewe I can remove the tag and see with lamb hang around the ewe the longest
Here is the newspaper article about the farm that is trialling the technology
Shown in the article photograph is a rugged tablet computer with a cattle tag reading wand. Bluetooth is probably used for the link between the wand and the tablet, so the audience is already familiar with that use of Bluetooth.
Written about in the article is an animal tracker device, which uses actigraphy. Bluetooth would be able to read this device directly from the tablet.
The article doesn’t say where the device comes from, best would be to ask Beth Paganoni at the Department of Primary Industry and Regional Development; but there are many such devices now from China that have a sealed case, a battery, an accelerometer, a data logger, and are accessed over Bluetooth. Sort of like a simplified FitBit tracker.
I wrote about a children’s tracker on my blog. See end of the page for photographs.
https://quozl.linux.org.au//cforth-milo-champions-band/
While you could make something from components at Little Bird Electronics, your best bet will be to find a source in China of these trackers, especially rugged ones designed for rain and sheep droppings. 
So how to do it …
As lambing approaches, you’d charge each tracker at the farm house, and wipe the data.
At lambing begins, you’d power-up and tie a tracker to each ewe and lamb, especially noting if the ewe and lamb were seen together at birth.
Some time later, you’d remove the trackers, but not before you add a standard industry RFID tag or plain plastic tag, depending on your state and regulations. Somehow you’d have to link the tracker number to the permanent tag.
Then the data sets from each of the trackers would have to be processed to look for periods of simultaneous movement. For which you’ll need a good coder who understands signal processing maths. That would give you a list of likely pairings, and a probability of each pairing.
I’ve spoken with sheep farmers around where I live, and the pairings don’t always remain constant, so the analysis will be quite interesting.
A step up in cost is to add GPS receiver to the tracker. Adds bulk, reduces running time. But does have the advantage of removing ambiguity; a lamb and ewe that spend time together will show up in GPS data much more reliably than trying to correlate simultaneous movement.
Hope that helps!
My initial thoughts would be to use RFID in the lambs (lamb-ID). This would allow you to use a wand to identify the individual lambs.
But you want to the lamb-ewe relationship.
This would then require that the ewe has a device (ewe_ID) that includes an RFID reader that is within range of the lamb when it comes to feed. A ewe-ID on a collar might not suffice for this as the distance would be too great for RFID. If ewe-ID could be placed on a hind leg (but may be irritating to the ewe)or somewhere similar then the scan would be likely to be successful.
If each ewe had an RFID implant in the neck then ewe-ID would first scan this RFID in order to assitain ownership of ewe-ID. The RFID’s could also be used in stockyards and runs to identify each animal for vacination, drenching, crutching etc purposes (oh yes and shearing).
Ewe-ID could contain a bluetooth radio in order to collect information. Wifi could be used to collect information in bulk, as ewe-ID could automatically send records when connected to authorised wifi hotspot. This hotspot could be easily set up temperarally in a stockyard or wherever the heard is in an area that would be covered by the hot spot. Alternatly the devices themselves could act as a mesh network similar to the devices that are dropped in a fireprone area to provide realtime data of where the fire front is (the device stops reporting when burnt to a crisp)
Any RFID id that has multiple logs could be assumed to be offspring of the ewe.
I’m not sure ofthe iimplantability of any device that needs reasonable radio reception over a distance greater than that of RFID.
Hope this helps.
Sean
(yes the irony of my name and the topic has not easaped me)
I read your post a while back and at the time thought along the lines of RFID as Sean did. I’ve been thinking about it though and can see some benefits to Bluetooth.
I’m not sure what budget you would be aiming for per device. You could try something like these: https://learn.adafruit.com/adafruit-flora-bluefruit-le/overview
Flora Bluetooth board - https://www.adafruit.com/product/2487
Flora arduino board - https://www.adafruit.com/product/659
They’ll all be available from littlebird.
That probably ends up about $50 ea once you have a battery and case and way to attach it to the sheep. That might be ok for a proof of concept. I have suggested the Flora as they are nice and small and designed with battery operation in mind from the start.
I didn’t find any from a quick search that do what you want already. These guys (US based) have the right kind of device, they just haven’t made one for your specific application: https://www.bluemaestro.com/bluetooth-sensor-beacons-data-loggers/
And there’s the Alibaba version that is also close but not exactly what you need: https://wholesaler.alibaba.com/product-detail/NO-1-Sales-New-design-Proximity_60102230413.html
But they put you in the ballpark for what the tags could look like and cost when mass produced.