That’s what a new study at the University of Wisconsin – Madison concluded. The study evaluated the factors influencing pregnancy loss for cows diagnosed with twin or single pregnancies. Losses were assessed at two separate exams, one taking place 25 – 40 days after A.I. and the second 48 – 82 days after A.I. In the group, 518 cows were diagnosed with one pregnancy and 98 with twins at the first pregnancy exam. Results were published in the June 2009 issue of Theriogenology.
After the second pregnancy exam:
- 3.7 percent of cows with a single pregnancy were diagnosed with a nonviable embryo at the first exam and 4.6 percent with a viable embryo underwent pregnancy loss by the second exam.
- 11.2 percent of cows with twins experienced a single embryo reduction at the second exam, while 13.3 percent lost both embryos.
- The total proportion of cows with pregnancy loss or embryo reduction was greater for cows with twin than single pregnancies.
- 91.9 percent of cows with a single pregnancy experienced embryo survival compared to 75.5 percent in cows diagnosed with twin pregnancies.
Researchers also found that the risk of twinning and double ovulation increased with days in milk, and the risk of double ovulation was greater in cows diagnosed with ovarian cysts and lacking a CL at the onset of OvsynchTM.
To access the study, click here.