Date of Award


Degree Type


Degree Name

Master of Science - Agriculture



First Advisor

Erin. G. Brown

Second Advisor

Gordon E. Carstens

Third Advisor

John Michael P. Mehaffey

Fourth Advisor

Joey L. Bray


Two trials were conducted with Santa Gertrudis steers, trial 1 (n = 115) and trial 2 (n = 118), were fed a roughage-based diet during the growing phase and high-grain diet during the finishing phase. Steers were weighed at 14-d intervals and dry matter intake (DMI) measured for 70 d during both phases. Residual feed intake (RFI) is the difference between actual DMI and DMI predicted from linear regression of DMI on mid-test metabolic body weight. Ultrasound carcass measurements were measured on day 0 and 70 of the growing phase. Steers were harvested after finishing phase and carcass cooler traits were obtained. Low RFI steers consumed less than high RFI steers, but did not differ in average daily gain (ADG). Low RFI steers had less backfat compared to high RFI steers. Residual feed intake was independent of growth rate and mature body size, but highly correlated with DMI. Moreover, adjusting RFI for ultrasound carcass traits could improve feed efficiency independent of growth, body size, and carcass composition. Furthermore, residual gain (RG) could have an effect on marbling and quality grade.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.



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