d. h. “denny” crews, jr. colorado state university bif subcommittee chair
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D. H. “Denny” Crews, Jr. Colorado State UniversityBIF SubCommittee Chair
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
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
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
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
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
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
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
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
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
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
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
Denny.Crews@ColoState.eduG-Carstens@tamu.eduRodHill@UIdaho.eduJohn.Basarab@gov.ab.ca
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