Yearling
Yearling weight measurements should be taken between 320-410 days of age. Time between weaning and yearling weight measurement should be no less than 70 days. It is important to not take the yearling weight measurement too closely to the weaning weight to allow for more post-weaning growth and a more accurate measure of the yearling weight trait.
As with weaning weight proper measurement procedures are also important. Yearling weight should be collected on a high quality digital or mechanical individual animal scale and it should be recorded in pounds. Weights should be taken on the same day for an entire contemporary group. Especially for large contemporary groups, water should be provided to calves penned-up prior to weighing so that there is no effect due to differences in dehydration between the first and last calves weighed.
Yearling contemporary groups are always subsets of the weaning contemporary group.
Other measurements to take at this time include Temperament, Hip Height, Scrotal Measurements, Pelvic Measurements, and reporting status code.
It is important to identify calves that were on your weaning report but were culled from the herd before yearling weights were taken with an appropriate calf disposal code.
For adjusted 365 day hip height the AWA suggested age range for collecting measurements on calves is 320 to 410 days of age.
Use the same scoring and methods for Yearling Temperament as with Weaning Temperament.
Yearling Temperament scores should be collected at approximately the same time as yearling weights are collected.
Scrotal circumference is measured due to its positive relationship with the potential number of sperm cells that the bull can produce. It has been shown bulls with larger scrotal circumference reached puberty and produced higher quality sperm at a younger age and that their daughters also reached puberty at a younger age. Furthermore, larger scrotal circumference has been associated with an increased percentage of progressively motile sperm and less abnormal sperm production. (BIF)
Scrotal circumference for yearling bulls is collected between 320 and 410 days of age. Scrotal circumference is measured using a scrotal tape around the widest part of the scrotum when the testicles are fully extended. The tape should be pulled firmly around the scrotum. It is recommended to record the measure a few times to ensure accurate results. The circumference of the scrotum is recorded in centimeters.
Pelvic area is an indicator of maternal calving ease. Selection of sires with high calving ease direct (CED) expected progeny differences (EPDs) mated to heifers that are screened for pelvic area will decrease the incidence and (or) severity of calving problems and minimize calf losses from dystocia. Pelvic measurements should be used in addition to, rather than in place of, selection for size, weight, and above all fertility. Producers should be aware that selection for pelvic area will likely not result in increased pelvic dimensions alone, but may result in increased size of the entire skeleton and animal. These correlated responses can be modulated in a multiple-trait selection program with emphases on moderate mature size and increased direct calving ease. Pelvic measurements can also be successfully used to identify abnormally small or misshaped pelvises. These situations, left unidentified, are often associated with extreme dystocia, resulting in caesarean delivery and even death of the calf or dam.
While pelvic area can be used as a possible indicator trait for maternal calving ease, it may be most helpful for predicting earlier maturing heifers. Bullock and Patterson (1995) reported that puberty exerts a positive influence on pelvic width and area in yearling heifers; however, the differences observed among heifers as yearlings were not preserved when calving as two-year-olds. The data suggest that puberty plays a role in pelvic size as yearlings, but once heifers reach puberty the effects may no longer be present.
Pelvimetry is a useful culling tool to aid in the management of dystocia. Pelvic measurements can be obtained with a Rice Pelvimeter (Lane Manufacturing, Denver, CO), the Krautman-Litton Bovine Pelvic Meter (Jorgensen Laboratories, Inc. Loveland, CO), or the Equibov Bovine Pelvimeter (Ontario, Canada). The Rice pelvimeter is the preferred instrument to obtain pelvic measurements in cattle due to its ease of use, good repeatability, ability to read to at least 20 cm, and low cost compared to other pelvimeters. Pelvic area measured by the Rice pelvimeter is accurate and repeatable between and within veterinarians.
It is important that the person doing the measuring have a thorough understanding of the birth canal, pelvic structure, and reproductive tract. Practice and experience are necessary before accurate measurements can be obtained. The vertical measurement is the vertical diameter between the symphysis pubis on the floor of the pelvis and the sacral vertebrae. The horizontal measurement is obtained by determining the horizontal diameter at its widest point between the left and right ileal shafts. These measurements are read in centimeters and multiplied together to obtain the total pelvic area in square centimeters. (BIF)
Ultrasound
The AWA Board of Directors has approved guidelines for the standardized collection of ultrasound data on Wagyu cattle. These guidelines should be adhered to when collecting ultrasound data on yearling seedstock. AWA ultrasound guidelines specify the use of ultrasound technicians fulfilling the certification requirements of the Ultrasound Guidelines Council (UGC).
Ultrasound data should be collected on all calves in the yearling contemporary group and cattle should be between 320–410 days of age. All cattle must also have a weaning and yearling weight taken at appropriate times and reported to AWA, furthermore a weight should be taken at the time of ultrasound data collection (this weight will work as the yearling weight). Calves should be reported to the AWA prior to scanning so that ultrasound reporting forms (Barnsheets) are available for the scanning technician prior to scanning.
When collecting ultrasound data it is very important that proper procedures are followed. It is the responsibility of the breeder to supply a squeeze chute with side panel doors to properly restrain cattle and provide access to the region of scanning. Technicians have several thousand dollars invested in equipment that must be protected and the quality of the images will be improved as well if cattle are properly restrained. Cattle must also be dry and clean in the regions to be scanned and out of direct sunlight to allow for seeing the images on the monitor. It is also necessary in most cases that cattle are clipped in the scanning region with no more than 1/2 inch of hair. By following these guidelines and by working with the technician you can improve the quality of ultrasound data that will be collected. If you have any questions about preparing cattle for scanning you should visit with the technician ahead of time or call the AWA office.
It is the responsibility of each producer to contact technicians to make arrangements to scan their cattle. If you are planning to collect ultrasound measurements on your cattle you should contact the AWA office well in advance for a copy of the ultrasound reporting forms (Barnsheet). For a list of qualified technicians contact the AWA office or the UGC office at ultrasoundguidelinescouncil.org.
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