Twin producing cattle have the potential to increase productivity while reducing emissions and water use.*


  • Selection for cows with high ovulation rates was carried out over 30 years at  Meat Animal Research Center (MARC) in Nebraska. The cows originated from a large cross breeding and selection program which has resulted in a herd comprising about 12 breeds.
  • The actual genes involved in twinning have not yet been fully identified but it seems clear that several genes are involved. It is thought that Chromosome 5 influences ovulation rate however there are several genes that influence the twinning inheritence that have not yet been pinpointed.
  • Evaluations of growth and carcass compositions after backgrounding and finishing have shown that the MARC single born females were 24kg heavier at 5 months and 18kg heavier at 22 months. Twin born steers were only slightly lighter than their single born mates, but had higher grading scores.
  • Where the twins are male and female, more than 95% of the females will be freemartins. This is due to the male developing faster than the female in the uterus, and, since calves share placentas, male hormones passing into the female calf prevent proper growth of the reproductive tract. It is important to identify freemartins which can then be treated like steers and sold accordingly. Freemartins have higher marbling scores than other females.
  • Freemartin heifers are good meat animals because they have very satisfactory marbling and carcase traits.
  • Freemartinism does NOT reduce the number of heifers available for breeding compared to a herd of single bearing cows.

* For academic and mainstream articles supporting these statements, see news.