Progressive lamb production.








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I use a lot of data to manage my flock.  The following data is collected and analyzed:

  • Prolificacy is measured by the number of lambs weaned per ewe dry-lotted after breeding. 

  • Ewe longevity is measured by the ewe's age.

  • Growth is measured by taking 3 weights of the lambs.  Generally, these are at weaning, around 100 days and right before slaughter.  The weights are then standardized to 60, 120 and 180 day values by curve fitting the 3 measurements to the Gompertz growth function.  The Gompertz growth function is a mathematical model for growth.  It accounts for the fact that a lamb's growth rate continuously varies with time.  This is particularly important because growth starts to decline as they 'finish' or put on fat.  This method is more accurate and far less optimistic than the linear methods used by virtually everyone else.

  • Ewe feed cost is computed from the ewe's mature weight and weaning rate.  Ewes are weighed once a year and adjusted to Body Condition Score  3.

  • Feed efficiency is computed from the 60, 120 and 180 day weights using a relationship between body weight and feed intake. 

  • Labor.  Prior to 2012, labor costs evenly across the ewe flock. Starting in 2012, an estimate of individual annual labor requirements is assigned to each ewe.  The principle differentiator is the number of assisted births.  The goal of the labor tracking is to make sure that production levels are optimized with labor requirements. Labor requirements have been used in determining ewe lamb selections starting with the 2013 crop.

This data is used to rank ewes by their financial performance, using a 4-year average.  This ranking, along with constraints to limit prolificacy and lambing problems is used to select breeding stock and identify culls. 

I began using this data-driven approach in Spring 2008.  For the first two years, I did not have a scale, so the growth data was estimated.  Starting In 2010, precise growth data was added. 

In 2014, I began limiting proflicacy in order to reduce labor requirements.  Specifically, ewes were no longer allowed to wean quads, very problematic ewes were culled and lambing ease became a selection criteria.  While progress is not a straight line, progress in reducing the number of assisted births is being made.  From 2013 to 2019, the trendline reduction in assisted birth is 13%.

Production results for ewes born on my farm are presented below.  The finish weights are standardized to 180-day weights.

Production has remained mostly flat, increasing 0.5% from 2013 to 2019.  This is despite removing the ultra-prolific ewes from my flock.  The goal is maximum profit, not maximum production.

The effect on the ewe lambs is more pronounced.  Trendline production dropped 4% from 2013 to 2019.  The decline was largely driven by a challenging 2019 season.  The trend from 2016-2017 is encouraging.