Thursday, July 30, 2015

Sheep Statistics

OK, fine, I am a BIG NERD when it comes to data. There are a lot of calculations behind this graph to normalize output, take into consideration lamb age at time of weight, etc. But basically, this is the chart I use to help determine who my good mamas and bad mamas are. Of course, there are also behavioral considerations, like lamb abandonment and temperament that sometimes outweight the data. Three strikes and you are out, so it might be one still born, the next season you abandon AND you like to head butt small children? DONE. So I've been looking at a lot of data over the years - average number of lambs born, average lamb weight, normalized weight based on lamb age, etc. etc. I finally put it all together, and using Shirley as our gage stick, this is what I have. Bear with me. First of all, Shirley is a superstar, and no one compares to her. Secondly, she's the oldest, has the most data and has been the best performer. Therefore she is our gage stick. This chart shows 3 things, the RED bars show the actual output of the ewes we have. This is how much lamb weight by averages, they have given out over their life. Now, comparing their age to Shirley's age, using their average output via # of lambs and weight of those lambs, the blue bars show me the POTENTIAL they have left in them, by the time they get to Shirley's age. SO, lambs showing all blue are young ewes that have no yet lambed. The yellow line is Shirley's gage stick. If their actual output PLUS their potential future output can come close to that, they are keepers. We have one who has surpassed, but I suspect another lambing's worth of data, and she'll drop down. Sharon had triplets her first time out, so her average lamb output looks like 3, when it's unlikely she'll do that every time. She also happens to be Shirley's daughter, and so is Peppermint Patty. So is Persephone. Clearly, you can see who my obvious next 2 culls will be. Clarice, ironically, is Shirley's granddaughter, Peppermint Patty's daughter. She has skipped several seasons and I'm wondering about her fertility. She might go, as I can't afford to feed a ewe who doesn't produce anything for me. Judy is relatively new, although, she is almost 4 years old and has only lambed once. It doesn't fare well for her, either. Gertrude, who isn't the worst performer, is all around a grumpypuss, she likes to head butt the dogs, and just has more attitude than sense, and doesn't perform great, either. Those might be our next three mutton potentials. Which is fine, as we may be bringing in some more Katahdin blood from a friend's farm. Getting rid of my poor performers gives me room for new genetics, and hopefully build a more fruitful flock.