Gordon E. Dickerson
Date of this Version
Data from an embryo transfer project were used to study the effect of twinning on both dams and calves in terms of meat and milk production and post-partum fertility. and to evaluate the changes in energy requirements during gestation. lactation and postweaning periods.
Pregnancy rate at first palpation was 70% (45% twin pregnacy and 25% single pregnancy) and calving rate was 65% (39% twins and 26% singles). Losses from abortion were 2.7%. Calf mortality was 2% higher for twin-calving dams. Dystocia was affected (P<.05) more by parity than by twinning (30% in heifers and 10% in cows) but retained placenta was the opposite (8.5% in single-calving and 32% in twincalving dams).
Twin-calving dams gained 22% slower during gestation but 5% faster during lactation and the 9% of advantage in weight at the beginning of gestation compared with single-calving dams was reduced to about 3.2% at calving and 2.8% at weaning.
Twin-calving dams produced 28% more total lactation milk and 23% more daily milk at peak lactation. They also reached peak lactation later. but were 2% higher in persistency.
Twin-calving dams were 23% later in days to first ovulation. 13% later in days open and 4% later in calving interval although twinning effect on calving interval was not significant.
Twin-pregnancy was at least 3 days shorter (P<.01) and produced 13% lighter calves at birth. Twins gained 19% slower (P<.01). were 17% lighter at weaning (P<.01) and had 4% lower relative preweaning relative growth rate than singles. Twins were similar in postweaning daily gain and 14% higher in relative growth rate (P<.01) but were still 10% lighter than singles (P<.01) at slaughter.
Daily fetal ME requirements during last third of gestation for twin-pregancy was 67% higher than for single-pregnancy but daily gain in empty body weight was 22% less (P<.01). Daily ME for maintenance and intake were not affected by parity and twinning.
Dams nursing twins required 44% more of ME daily for milk yield and ingested 11% more of daily ME than dams nursing singles during 180-d lactation. Daily ME for maintenance was similar for all types of dams.
During postweaning growth to market age. twins consumed 6% less feed daily. required 4% less feed/gain. 12% less net nergy/gain. 11% less net energy/kg metabolic size and 3% less metabolizable energy for gain or maintenance.
A commercial beef industry using twinning could expect an an increase in output relative to the total input in the range of 20 to 25% at slaughter time.