Comparison of birth weight and growth characteristics of bovine calves produced by nuclear transfer (cloning), embryo transfer and natural mating

Data presented in this study compare weight (kg) at birth, and at 205 (weaning) and 365 (yearling) days of age for bovine calves produced from nuclear transfer (CLONE), embryo transfer (ET), and artificial insemination/natural mating (AI/NM). Birth weight data, for three consecutive years, include 418 CLONE, 4687 ET and 8925 AI/NM calves. Additionally, data for (219 CLONE, 2515 ET and 3895 AI/NM) weaning and (66 CLONE, 1250 ET and 1630 AI/NM) yearling weights were analyzed. Calves produced by CLONE were grown and maintained with calves produced by ET and AI/NM. CLONE calves were approximately 20% larger at birth than calves produced by ET or AI/NM when all data were compared and when data were adjusted for sire or for sire and dam. Moreover, the variability in birth weight for CLONE calves was four- to 12-fold greater than for ET or AI/NM calves. The accelerated growth and variability did not continue beyond birth. The 205 day and 365 day weights of CLONE calves were less variable than their birth weight and were similar to those for ET and AI/NM calves. Differences between weight for CLONE, ET and AI/NM calves when measured as a percent of body weight declined from approximately 24% at birth to < 5% at 365 days.