Scientists Find Twinning Technology in Dairy Cattle Succesful
The cow (Bos Taurus for European breeds and Bos indicus for indian Breeds), belonging to the family Bovidae, is characterized as a uniparous large ruminant- an animal capable of producing only a single offspring per birth.
The low prolificacy of cattle coupled with the small population used in breeding have contributed to the dwindling cattle production in the country. This problem may just have found solution in the first successful induced twinning in dairy cattle spearheaded by Dr. Antonio A. Rayos, veterinarian and assistant professor at the Dairy Training and Research Institute (DTRI) UP los Banos.
In a series of laboratory tests, two healthy calves (male and female) each weighing 18kg were successfully conceived after 254 days of gestation with the female co-twin having a normal reproductive tract on examination.
Scientists used two pure Holstein Friesians as donor and recipient cows in this study. Both cows were injected with dinoprost tromethamine to synchronize estrus period. Three days after the injection both cows were in estrus and were artificially inseminated with frozen thawed semen from two superior bulls with the Holstein-Sahiwal bull for the donor and the Holstein Friesians for the recipeient cow. Having reached its intitial stage of development after one week the embryo was flushed out of the donor cows and was transferred nonsurgically using an embryo transfer gun to the uterine horn of the recipient cow previously bred by artificial insemination (AI). Forty five days after the embryo transfer, the left and right uterin horns of the recipient cow were confirmed pregnant.
Fifty days after birth, the male calf weighed 45 kg while the female calf weighed 54 kg indicating normal growth.
Induced twinning in dairy cattle was adopted from the Japanese Practice of multiplying the wagyu or Japanese Black cattle, the source of very expensive and famous KOBE and Matsusaka beef. Dairy cows were used in this study to prove whether induced twinning can overcome the problem of Freemartinism an inhibition of the development of the female co-twin’s reproductive organs caused by some chemical substance secreted by the developing male co-twin embryo through the blood vessels of the placenta. This phenomenon occurs usually in twin that developed in the same uterine horn. Further to determine if this technology can solve the problem of “freemartinism” scientists placed the embryos in separate uterine horns. Although initial examination one week after birth showed a normal vagina of the female calf, the cervix, uterus and ovaries were found under-developed after the animal was slaughtered at 18 months of age.
Aside from AI and embryo transfer, here are two other methods to induce twinning in cattle. These are: 1) transfer of two embryos into the uterine horn/horns of the surrogate cow.
2) ovulation of two ova by administration of low dosage of follicle stimulating hormone or pregnant mare serum gonadotropin.
Source: BAR Today Jan mar 2001 issue, mary Charlotte O. Fresco