D. H. “Denny” Crews, Jr. Colorado State University BIF SubCommittee Chair

1. D. H. “Denny” Crews, Jr. Colorado State University BIF SubCommittee Chair

2. Guidelines draft and editing • Dr. G. E. Carstens, Texas A&M University • Dr. R. A. Hill, University of Idaho • Dr. J. A. Basarab, Alberta Agriculture and Food • Academic reviewers and discussions • Dr. D. Strohbehn, Iowa State University • Dr. R. M. Enns, Colorado State University • Dr. M. Nielsen, University of Nebraska • Industry representatives • Dr. S. Northcutt, American Angus Association • Dr. L. Hyde, North American Limousin Foundation • Dr. R. Williams, American International Charolais Association

3. General minimum guidelines • Individual feed intake data recording • Reporting of intake and efficiency data • Animal classes • Growing bulls • Steer and heifer progeny • Guidelines document • Posting to the web • Incorporation into BIF guidelines, 9th edition • Guidelines updates

4. Breed • 3-generation pedigree • Age of dam • Birth date • Birth weight • Weaning date • Weaning weight • Information required for defining feeding contemporary group • Reference to breed association rules

5. Start of test date • Back-calculate age on test using birth date • This is pre-warmup start date • Age limits should be defined • Weaning is approximately 205 d, with range 175 to 235 d • Minimum age on test should be older than weaning • Animals within a feeding contemporary group • Maximum age range 90-100 d • Pen of feeding will also define CG for intake traits • Dependent on weaning CG size • Target > 5 animals per feeding CG

6. Adjustment period is typically 21 days • Acclimation to facility and equipment • Diet warmup – transition to final test diet • End of transitional period / start of test will be recorded • Used to define start of intake recording • Longer warmup periods are okay, but probably unnecessary • This will likely be a decision by test managers • Transitional diets for market progeny • Step-up from growing to finishing ration is common • The transition period data can’t generally be used • The goal is to get intake on a constant diet • Research is unclear regarding grow/finish choice with progeny tests but finishing diet is most common

7. Minimum 70 d after warmup is required • This makes a 91-d minimum total test period • Intake requires less time, but growth requires about 70 d • Animals don’t specifically have to have intake records for all (growth) test days if intake recording equipment usage is an issue • Ad libitum intake is required • Sickness • Days/dates absent from the pen are usually recorded for all animals • Full consumption (ad libitum) should return before recording resumes • Removal of animal(s) from pens • Absence leads to a “non-test-day” and data is set to missing • Working days (weights, RTU) are removed • Equipment failures are also “non-test-day” criteria

8. No assumptions or restrictions about diet ingredients • These are specific to test location and conditions • Ingredient composition should be recorded • Proximate analysis is also recommended • All animals within a test receive the same diet • Energy density should be sufficient for expression of animal differences • Dry matter content of the diet must be tested • Intake is expressed on a dry-matter basis • Increases comparability with other tests/studies • Minimize measurement variation

9. Dry matter intake per day is the key measure • Electronic equipment • Follow hardware specifications for animal density • GrowSafe: ~7 (8 ?) young bulls or ~9 steer/heifer progeny per node • Calan: 1 animal per gate • Beginning/end of data recording period • Avoid animals with large missing blocks • Minimum days with intake data • Most studies show 45-50 days or more is sufficient • Some missing data is to be expected, especially with some hardware • Data auditing will remove some data from test days

10. Recommend > 6 live weights during the test period • Enables the regression of live weight on test day to get ADG • Minimization of measurement error • R2 should be at least 0.90 for these animal regressions, else ADG missing • 2 on / 2 off is less desirable • Easier to collect, but data quality is lower • Serial weights • 14-d intervals are common, but not required • Some test utilize 21- or 28-d weight intervals • Equal spacing seems to be important

11. Measuring body composition is important • Intake is related to fat / muscle deposition = energy sink • Ultrasound measures of FAT and REA are desirable • Start/end is desirable • If only one ultrasound measure is taken, measure at end of test • Utilize BIF guidelines for ultrasound data collection • Consult and follow breed association specific rules • Data could also support carcass evaluation • Serial ultrasound • Can estimate deposition “curves” for body composition similar to ADG • Multiple measurements on a commercial test will be more expensive

12. End of test date • Computation of ages and length of test • Test should be completed by 450 d of age • Ensure intake data recording equipment is known • Intake data “audit” • Increases test data integrity • Allows for across-test comparisons • Audits for outliers and potentially biased data • Intake and growth correlations • Within animal variability • Residual feed intake calculations • Equipment failures • Extent is somewhat equipment specific

13. Denny.Crews@ColoState.edu G-Carstens@tamu.edu RodHill@UIdaho.edu John.Basarab@gov.ab.ca