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
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
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
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.