FETAL AGING AND FETAL SEXING Fetal Aging
Crown/rump length
Head length
Head diameter
Jill Colloton, DVM Bovine Services, LLC Edgar, Wisconsin [email protected] www.bovineultrasound.net
Fetal length in mm + 18 = fetal age in days (works until about day 50)
45 days
All measurements in millimeters
Fetal Development (Sandra Curran) Characteristic Earliest Mean Range Embryo proper 20.3 19-24 Heartbeat 20.9 19-24 Allantois 23.2 22-25 Spinal cord 29.1 26-33 Forelimb buds 29.1 28-31 Amnion 29.5 28-33 Eye orbit 30.2 29-33 Hindlimb buds 31.2 30-33 Placentomes 35.2 33-38 Split hooves 44.6 42-49 Fetal movement 44.8 42-50 Ribs 52.8 51-55
1 2 REASONS FOR FETAL SEXING
• Increase sale value of pregnant females
FETAL SEXING • Early negotiation of bull contracts
• Dystocia monitoring for heifers
• Assist in culling decisions
• Replacement planning
EQUIPMENT NEEDS WHAT • The genital tubercle will become the penis • Good quality in the male and the clitoris in the female image • The GT appears as a bright white bi‐lobed • 5MHz linear rectal structure in both the male and female probe • The GT may appear tri‐lobed in older fetuses • Proper settings • Scrotum and teats may be visualized, but the genital tubercle is the only “cardinal sign” of fetal sex
3 WHEN • Prior to day 55 the genital tubercle may not be fully migrated • 55‐90 days in dairy cattle, 55‐110 in beef cattle • 60‐80 days is ideal
• In later gestation WHERE The GT in the the fetus is out of The GT in the male female appears reach or too large appears directly behind under the tail in the to orient properly the umbilical cord perineal area
• In later gestation the genital tubercle becomes less echogenic
Photo courtesy of Brad Stroud, DVM Photo courtesy of Brad Stroud, DVM
4 Photo courtesy of Photo courtesy of Brad Stroud, DVM Brad Stroud, DVM
ACCURACY HOW Position the fetus as close to the face of the probe • 99% or more accurate as possible • Difficulties include: Larger fetuses Remember that Uncooperative cows everything will look Female fetuses exactly as expected for a • Keep records B/W picture through the structures
Orient with landmarks Ribcage
Umbilicus
5 Head Fetal stomach
When something doesn’t look right it probably isn’t
Dead fetus Fetal Anasarca
6 Schistosomous Reflexus Fetal Monster
Fetal Sexing DVD Bovine Fetal Sexing Unedited By Brad Stroud, DVM
Numbered fetal sexing test with 52 real‐ time scans.
Available through Bovine Services
7 BOVINE FETAL AGING TABLES (all measurements in mm)
TRUNK DAYS BRAINCASE DAYS CROWN/RUMP DAYS HEAD DAYS DIAMETER DIAMETER LENGTH LENGTH 15 54 7 50 4 20 25 62 20 65 11 55 6 25 30 70 25 73 15 62 9 28 35 76 30 80 20 69 10 35 40 82 35 86 23 75 15 37 45 86 40 91 25 79 20 40 50 90 45 95 28 85 25 42 55 94 50 99 30 87 30 45 60 98 55 103 31 90 35 48 70 104 60 106 35 94 40 50 80 109 70 112 40 100 45 52 90 114 80 117 45 105 50 54 100 118 90 121 50 110 60 57 110 122 100 125 60 118 70 60 120 126 110 128 70 125 80 62 130 129 120 132 80 131 140 132
Adapted from White 39 and Kahn 14 Ultrasonic Detection of Fetal Structures Adapted from Curran et al, 1986
Characteristic Earliest Mean Range
Embryo proper 20.3 19-24 Heartbeat 20.9 19-24 Allantois 23.2 22-25 Spinal cord 29.1 26-33 Forelimb buds 29.1 28-31 Amnion 29.5 28-33 Eye orbit 30.2 29-33 Hindlimb buds 31.2 30-33 Placentomes 35.2 33-38 Split hooves 44.6 42-49 Fetal movement 44.8 42-50 Ribs 52.8 51-55