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Evaluating the Impact of Cow Size on Calf Weaning Weights

Applied Research

Selena Davila
Extension Educator
University of Idaho
Shoshone

Abstract

Cow size has increased over time due to selection for larger beef carcasses, raising questions about its impact on calf weaning weights and production efficiency. This study, conducted at the University of Idaho’s Nancy M. Cummings Research, Extension, and Education Center (REEC) from 2015 to 2024, evaluated the relationship between cow size and calf weaning performance. Data from 484 cows and their calves were analyzed, including cow weight at weaning, average calf weaning weight, adjusted weaning weight (205 days), and the percentage of cow body weight weaned. Linear regression analysis revealed a weak but significant positive relationship between cow weight and adjusted weaning weight (R² = 0.1138), while average weaning weight showed little correlation with cow weight (R² = 0.07). A strong negative relationship was found between cow weight and the percentage of body weight weaned (R² = 0.644), suggesting that larger cows may be less efficient at converting their size into calf growth. Cows were categorized into weight groups (<1100, 1101-1200, etc.), and an ANOVA test indicated that calves from lighter cows (<1100 and 1101-1200 lbs) had significantly lower adjusted weaning weights, while no significant differences were observed among heavier cow groups. These findings suggest that while larger cows may produce slightly heavier calves, the relationship is weak, and cow efficiency should be considered alongside size when making management decisions. Selecting for increased cow size alone may not maximize weaning weight efficiency, highlighting the importance of balancing size and productivity in beef operations.

Poster has NOT been presented at any previous NACAA AM/PIC

This poster is being submitted for judging. It will be displayed at the AM/PIC if not selected as a State winner. The abstract will be published in the proceedings.

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Authors: Selena Davila, Alynn Harder, Jim Sprinkle, John B. Hall
  1. Davila, S. Extension Educator, University of Idaho, Idaho, 83352
  2. Harder, A. Research Specialist, University of Idaho, Idaho, 83462
  3. Sprinkle, J. Professor & Extension Specialist, University of Idaho, Idaho, 83462
  4. Hall, J. Professor & Extension Specialist, University of Idaho, Idaho, 83462