Residual Feed Intake (RFI)

Residual feed intake (RFI) is an efficiency measurement that partitions feed intake into requirements for maintenance and growth, and is calculated by subtracting actual feed intake from expected feed intake. Therefore, more efficient animals have a negative RFI value and consume less than expected, while less efficient animals have a positive RFI value and eat more than expected. Heritability of RFI has been shown to be moderate at approximately 0.36 (36%). Research has also shown that selecting for RFI may result in as much as a 9-10% reduction in cow herd maintenance costs, a 10-12% reduction in feed intake, a 25-30% decrease in methane emissions and a 15-20% decrease in manure production.

The CGA office will be organizing a testing period at Olds College (dependent upon participation). The testing period will be approximately 50 days plus a minimum 14 day warm-up. In addition to having the GrowSafe feed bunks, Olds College has installed the GrowSafe Beef watering systems. These waterers measure a partial weight every time the animal stands on the system, and through calculations can predict a whole-body weight with high accuracy. This system has allowed the test period to be shortened significantly compared to the original 76-day period. Performance data generated includes daily feed intake, average daily gain, feed conversion, ultrasound and RFI. In addition, each animal will have a 50K DNA test completed to allow for genomically enhanced RFI EPDs.

GrowSafe Beef watering system
RFI feed bunks
The CGA office will provide reports on the following information:
  • Weights
  • ADG
  • Feed to Gain
  • Ultrasound results
  • RFI data

If you are interested in participating in an RFI test or have any questions please contact the office.

Ultrasound

Scanning should be completed by a certified technician and within the acceptable age range. The range for Canadian Gelbviehs is 320 to 410 days of age. Barn sheets will be required by the lab. You may contact the office to receive a generated barnsheet.


Yearling Bulls

Weights – should be taken within 7 days of the scan date and preferably before morning feeding.

Gain - The best measure of a bull's propensity for marbling and muscle expression is when the bull is being fed to gain at least three pounds per day. Additionally, these tendencies will best be expressed at the end or near the end, of a post-weaning gain test.

Contemporary group – contemporaries must be from the same weaning contemporary group.

Replacement Heifers

Weights - should be taken within 7 days of the scan date and preferably before morning feeding.

Contemporary group – contemporaries must be from the same weaning contemporary group.

Feedlot Steers and Heifers

Scans - Feedlot animals should be scanned when the contemporary group averages 0.3 - 0.4 inches of external fat or just prior to slaughter.

Weights - should be taken within 7 days of the scan date and preferably before morning feeding.

Contemporary group – contemporaries must be from the same weaning contemporary group.

All animals within a contemporary group should be scanned on the same day or no more than three consecutive days.

Beef ultrasound measurements collected for each animal include:
  • Rump fat thickness
  • 12-13th rib fat thickness
  • Ribeye area
  • Percentage intramuscular fat (marbling)

EPDs

Maternal Traits

Calving ease direct (CED): Percent of unassisted births of a bull’s calves when he is used on heifers. A higher number is favorable, meaning better calving ease. This EPD can be vital to a rancher looking to decrease the amount of calves pulled in his herd.

Milk (Milk): The genetic ability of a sire’s daughters to produce milk expressed in pounds of weaning weight.

Calving ease maternal (CEM): Represented as percent of unassisted births in a sire’s first-calving daughters. A higher number represents more favorable calving ease. This EPD is important to a rancher’s bottom line because it predicts which animals produce daughters with a genetic pre-disposition to calve unassisted as heifers.

Heifer pregnancy (HP): Predicts the probability that a bull’s daughters will become pregnant as first-calf heifers in a regular breeding season, expressed as a percent. A higher value of this EPD is favorable, meaning that a higher percentage of a sire’s daughters get pregnant as first calf heifers compared to other sires in his contemporary group.

30-month pregnancy (Pg30): Predicts the probability that a bull’s daughters will become pregnant and calve at three years of age, given that they calved as first-calf heifers. This EPD is expressed as a percent, again, with a higher number being more favorable meaning a higher percentage of a sire’s daughters will calve at three years of age, given they calved as first-calf heifers.

Stayability (ST): Predicts the genetic difference, in terms of percent probability, that a bull’s daughters will stay productive within a herd to at least six year of age. The stayability EPD is one of the best measures currently available to compare a bull’s ability to produce females with reproductive longevity.

Growth Traits

Birth weight (BW): Predicts the difference, in pounds, for birth weight of the calf.

Weaning weight (WW): Predicts the difference, in pounds, for weaning weight (adjusted to age of dam and a standard 205 days of age). This is an indicator of growth from birth to weaning.

Yearling weight (YW): Predicts the expected difference, in pounds, for yearling weight (adjusted to a standard 365 days of age). This is an indicator of growth from birth to yearling.

Mature weight EPD (MW): Predicts the average difference in pounds of mature weight of a sire’s progeny compared to their contemporaries.

Carcass Traits

Yield grade (YG): Differences in yield grade score, which is a predictor of percent retail product. Smaller values suggest that progeny will have a better lean to fat ratio.

Carcass weight (CW): Differences in pounds of hot carcass weight, adjusted to an industry standard age endpoint.

Ribeye area (REA): Differences in ribeye area in inches between the 12th and 13th rib. Greater ribeye areas are preferable.

Marbling (MB): Predicts the differences in the degree of marbling within the ribeye as expressed in marbling score units. Greater marbling numbers are preferable and are an indicator of higher carcass quality grades.

Fat (FT): Differences for fat thickness, in inches, for a carcass over the 12th rib, smaller numbers of fat thickness are preferable as excess fat can be detrimental to yield grade.

Efficiency Traits

Dry matter intake (DMI): Represents the average daily dry matter intake per day consumed in pounds. A negative, or lesser value, is more favorable. For example, Bull A has a DMI EPD of .15 and Bull B has a DMI EPD of -.20, so the progeny of Bull B consume, on average, .35 pound less dry matter per day than progeny from Bull A.

Average daily gain (ADG): Difference in average daily gain in pounds based on an animal’s performance during a feed intake test period.

Residual feed intake (RFI): Defined as the difference between an animal’s actual daily feed intake and its predicted daily intake based on growth rate and body size. Animals with a positive RFI value are deemed more inefficient because they consume more than expected while animals with a negative RFI value are considered more efficient because they consume less than expected.

Indexes

Indexes are tools that allow producers to select for several EPDs at once, making selections more efficient than selecting on one trait at a time. Indexes weigh traits based on their importance to a producer’s bottom line by using a trait’s economic and genetic value. Indexes are a good way to put selection emphasis on traits that are economically relevant.

Total maternal (TM): An index that combines growth and milk information as a prediction of the weaning weight performance of calves from a sire’s daughters. As an index, this value is not reported with an accompanying accuracy. A greater TM value means a mother that returns comparatively higher weaning weights on her calves. TM Index = MK EPD + ½ WW EPD.

$Cow: Represents the genetic value in dollars of profit of an animal when retained as a replacement female relative to other animals in the herd. A higher number represents more profitable genetics for maternal productivity. $Cow will serve producers in selecting bulls that will sire daughters with stayability and reproductive efficiency as well as other traits that lead to profitability in a production system, such as milk, calving ease, moderate mature weight and the ability of calves to gain. A female’s genetics also influence the performance of her calves in the feedlot and at slaughter, so traits such as feed efficiency and carcass value are also included in $Cow.

Efficiency profit index (EPI): An economic selection index developed to aid producers in selecting for more feed efficient cattle that still have acceptable amounts of gain. The EPI provides slight negative pressure on intake, while keeping gain at a constant value. By selecting on this index, producers will be able to find those animals that gain the same amount as their contemporaries while eating less.

FPI™ which stands for feeder profit index: An economic selection index designed to aid producers in selecting sires whose progeny will perform in the feedlot and are sold on a grade and yield standpoint. Well ranking sires for FPI have higher marbling and carcass weight than their contemporaries. As a terminal index, little emphasis is put on maternal traits such as stayability and calving ease.

Sourced from the American Gelbvieh Association

DNA Testing

Please ensure that you have reviewed the CGA DNA regulations and that all of your animals comply with the DNA requirements.

DNA Regulations

Pulling Hair

When pulling hair, make sure you are taking it from the tail switch. Ensure that the hair is clean and dry. The follicle at the base of the hair must be intact for testing to be possible. Contaminated hair or hair missing the follicle will be unfit for testing and an additional sample will have to be provided.

Request Form

Submitting DNA samples

A completed DNA request form must be submitted to the CGA office before mailing your samples to the lab. All DNA tests have a 21 day turnaround time. Delays in results may occur if you have not submitted your form before the samples arrive to the lab.

Samples must be submitted via hair card, blood card, or tissue sampling unit (TSU). You can order these supplies directly from Neogen Canada by contacting Michelle Miller at MMiller@neogen.com. You will be billed directly from Neogen Canada for these supplies.