Selecting Performance Targets for Feeder Cattle

 

Accurate input parameters are essential for generating reliable ration recommendations in COWBYTES. One field that often causes confusion is the “Slaughter/Mature Weight” entry, especially when formulating backgrounding rations. Understanding what this field represents—and its impact on calculated energy requirements—is important for setting realistic performance targets.
 
Understanding Slaughter Weight vs. Mature Weight
  • Slaughter Weight:
    The expected market weight at which cattle achieve the desired carcass grade (A, AA, AAA).
  • Mature Weight:
    The weight of the animal at 5 years of age at a body condition score (BCS) of 3 (Canadian scale).
COWBYTES compares this slaughter/mature weight to a reference animal, assuming cattle with similar degrees of maturity share similar body composition.
The reference animal is the NRC medium‑frame steer, which provides expected weights associated with specific marbling grades.
 
How COWBYTES Uses This Information
COWBYTES uses:
  • Starting weight
  • Slaughter/Mature weight
  • Expected marbling score
to calculate an Equivalent Body Weight, which is then used to determine:
  • Net energy for gain (NEg)
  • Expected average daily gain (ADG)
Example
Two feeder steers both start at 704 lb, but have different slaughter weights:
Feeder
Slaughter Wt (lb)
Equivalent Body Wt (lb)
NEg
Expected ADG
A
1320
562
5 Mcal/day
~3.0 lb/day
B
1056
702
5 Mcal/day
~2.6 lb/day
Takeaway:
A lower slaughter weight results in a higher equivalent body weight, reducing expected gain at the same energy intake.
For more detail, see the COWBYTES Help Screen or NRC (1996), Chapter 3.
 
Performance Targets for Feeder Cattle
Source: Dr. J. McKinnon, University of Saskatchewan
Target Rates of Gain & Feeder Weights
Frame Size
Purchase Weight (lb)
Backgrounding Gain (lb/day)
Target Feeder Weight (lb)
Destination
Small
300–400
1.50–1.75
650–700
To grass
Medium
400–500
1.50–2.00
700–800
To feedlot
Large
500–600
—
750–900*
Feedlot (steers/heifers)
*Upper weight depends on sex (steers typically heavier).
 
Expected Slaughter Weights
Steers
Frame Size
Canadian Market (lb)
American Market (lb)
Small
1000–1050
1100–1150
Medium
1100–1175
1200–1300+
Large
1150–1300
1300–1400+
Heifers
Frame Size
Canadian Market (lb)
American Market (lb)
Small
850
900+
Medium
900–1000
1000–1050
Large
1000–1100
1100+
 
Key Takeaways
  • Accurate slaughter/mature weight inputs are essential for correct COWBYTES calculations.
  • Equivalent body weight greatly influences predicted NEg and ADG.
  • Frame size, market destination, and sex all impact feasible growth targets.
  • Use published benchmarks to set realistic performance goals for backgrounding and finishing cattle.