By: Chuck Sattler, vice president of genetic programs, Select Sires Inc.
While selection for improved production has always been a part of Select Sires’ sire development, we’ve had an explicit focus on feed efficiency since 2008. That’s when the FeedPRO® designation was introduced to highlight sires that excel in transmitting the combination of traits that maximize income over feed costs.
The initial version of FeedPRO focused on production and body size as indicators of feed intake. The designation identified bulls that transmitted high production and moderate body size while maintaining fertility and body condition.
Today, thanks to investments by USDA, the Foundation for Food and Agriculture Research and the Council on Dairy Cattle Breeding (CDCB), we have a new tool to add to sire selection that helps us do better. Recently, CDCB has begun publishing genetic evaluations for residual feed intake (RFI) that provide additional insight into how efficiently cows convert feed into milk.
These evaluations are based on data gathered at a handful of research herds in the U.S. and Canada that have taken detailed feed intake records on genomically tested cows. These efforts have produced a genomic evaluation reference population that includes more than 7,700 cows and grows each year. Thanks to the power of genomic selection technology, the genetic insights from this intensively studied reference population can be extended to all genomic-tested animals.
Decoding rfi evaluations
Genetic evaluations for RFI are expressed as predicted transmitting abilities (PTA) like other CDCB evaluations. PTA RFI are expressed in pounds of feed per lactation. Values for currently available bulls range from -250 to +250. Even though the reference population is small, RFI measurements have a moderate heritability of 19%. Based on these two factors, CDCB published evaluations for RFI have a low but meaningful reliability. Genomic young sires have evaluation reliability of 20-25% while some older sires have reliability values over 50%.
RFI is the difference between a cow’s actual feed intake and what she was expected to eat based on how much milk she produces, how much she weighs and whether she’s gaining or losing weight. RFI is basically how much feed is used for things other than body maintenance or producing milk. For this reason, lower values for RFI are preferred. Cows with low RFI will turn a higher percentage of their feed into milk and less of their feed into heat and manure.
PTA values for RFI are a tool we can use along with production and body size traits to breed for cows that produce more income over feed costs. It is now routinely available on Select Sires’ website and included in tools like the FeedPRO designation, Herd Health Profit Dollars™ (HHP$™), Net Merit $ and TPI® indexes.
With rising prices, managing income over feed costs has never been more important for improving farm profitability. Residual feed intake values provide an additional tool in breeding a herd of cows that more effectively convert feed into milk.
CDCB changes to evaluation system (December 2021) | Council on Dairy Cattle Breeding (uscdcb.com)