accurate Sire Selection through Isa’s unique data set
We are excited to share with you the Isa Index, or $Isa! $Isa quantifies a bull’s individual performance and his genetic potential. It takes in 24 data points we believe are critical to balanced cattle selection using the Six Essentials and synthesizes them into a single number. We have used what we called “The Score” for many years to evaluate the bulls and put them in sale order. Previously we did not publish this number, but it has become apparent as we have added more and
Residual Feed Intake (RFI): Measures feed efficiency. RFI is the difference between an animal’s actual intake and expected intake based on size and growth on a feed test. Rib Eye Area (REA): Sires with relatively higher REA EPDs are expected to produce better muscled and higher percentage yielding progeny at the same age than will sires with lower EPDs. Intramuscular Fat Percent (MARB): Intramuscular fat percent (IMF%) or marbling of beef. Terminal Index ($T): Expressed in dollars and designed for retained-ownership cattlemen interested in fast-growing, high-performing steers that will be graded on carcass merit by packers. Maternal Index ($M): Expressed in dollars and designed for ranchers focused on maternal criteria. It accounts for growth, milk production and fertility and considers cow maintenance issues. Feed Efficiency Index ($FE): Expressed in dollars, it blends feed efficiency (from RFI EPD) and post-weaning growth, which is the growth from weaning to yearling. REA%: the area of the ribeye expressed in square inches, which is an indicator of muscling. Ratioed within peer group. IMF%: Percentage of intramuscular fat. Ranks the peer group for potential for marbling. Grass ADG%: Gain on grass between weaning and test. Ratioed within peer group. ADG%: Average daily gain ratio of feed test. Ratioed within peer group. WDA%: Weight per day of age. The off-test weight divided by the bull’s age in days. Ratioed within peer group. more data points (over 50 in this catalog) that we need a way to distill this ocean of performance data into a single, useful index to help speed up the evaluation process. $Isa uses a proprietary weighted formula to achieve what we believe is the optimum balance of growth, production efficiency, fertility and carcass value. We think you’ll find that as you evaluate the bulls using your usual system, $Isa will align nicely with your analysis.
EPD and Performance category descriptions Calving Ease Direct (CE): Higher calving ease direct scores represent more unassisted births and are therefore considered superior.
Birth Weight (BW): The lower the birth weight EPD of a sire the lighter is the expected birth weight of his progeny. 205-day (Weaning) Weight (WW): Indicates likely genetic differences between sires in the growth of their progeny to weaning. 365-day (Yearling) Weight (YW): The 365-day weight EPDs indicate likely genetic differences between sires in progeny growth potential through to market age. Milk: Sires with above average 205-day Milk EPDs are therefore expected to sire daughters with above average milking potential. Calving Ease Maternal (MCE): the percent unassisted births a daughter will have over the population average. Again, a higher number represents fewer unassisted births. Scrotal Size (SC): Increased scrotal size is associated with increased fertility in male progeny and with earlier age at puberty of male and female progeny. Stayability (STAY): the probability a female would be reported as calving in the herd at age 5 or greater. A higher number is more favorable. Age at First Calf (AFC): The difference between a cow’s birthdate and the birthdate of her first calf. A lower number is more favorable, indicating a female that will calve at a younger age.
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