The Nebraska Maintenance Efficiency Genomics Effort
A reduction of up to 10% in maintenance requirements appears to be possible in some populations of beef cattle, Marlyn Nielson said Thursday, July 11. The University of Nebraska-Lincoln (UNL) animal scientist was addressing attendees of the Emerging Technologies Committee breakout session at the 34th annual Beef Improvement Federation (BIF) Research Symposium and Meeting in Omaha, Neb.
Animals consume food for energy, Nielson explained. After it’s consumed, that energy is metabolized. The metabolized energy is used in two ways — maintenance for the animal, which is lost as heat; and in production for growth, lactation, etc.
UN L researchers are working on a study measuring heat loss, instead of feed intake, to compare what individual animals require for maintenance. Using 9- to 11-week-old male mice, Nielson said, the study compares genetic lines selected for high heat loss (MH) and low heat loss (ML) to that of a control group (MC). 
So far, Nielson said, the study has shown the MH group to be leaner than the ML group, even though the MH group eats up to 81% more. The MH group was also twice as active as the ML group. Nielson said they can explain up to 35% of feed intake by differences in activity levels.
Nielson said he thinks the study may be a unique resource for QTL searches. They are working on three large searches and have found five QTL for heat loss, 10 QTL for body weight and five QTL for liver weight.
In his summary, Nielson said that desirable genetic relationships do exist. He said he believes that a reduction of up to 10% in maintenance seems possible for some populations of beef cattle, but the last increments of the study are slower to accomplish because of the possible correlations with other traits. 
— by Stephanie Veldman