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Breed frame size may influence twins

Multiple births are common among sheep and goats, but what about beef cattle?

Twins in beef cattle have always intrigued me. Then a Speckle Park producer from New Zealand combined two of my favourite things into triplet heifers — splashy colour and multiple births. Statistically, the odds of bovine triplets are 105,000 to one, with the odds of having same-sex triplets around 700,000 to one. Our experience with small ruminants raised the question of “Would it be true that dam lines in cattle that are inclined to multiple births are more productive overall?”

A project at the University of Wisconsin-Madison is furthering the research on this topic. Researchers identified a single gene with a large effect on ovulation rate in cattle (an increase from the typical single egg to two to three eggs ovulated per cycle). This gene for high ovulation rate was planned to be used as a tool to examine genetic variation in uterine function and reproductive success by creating a genetically diverse herd with one exception — all cows in the experimental herd would have one copy of the high-ovulation rate allele (gene frequency).

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These females are being evaluated for multiple reproductive and productive traits and genotyped for purposes of mapping genes contributing to these traits. This project is still continuing, so the results are not available yet, but it is still exciting to see. The results to date confirm that these females tend to be more productive overall. They are using Angus crossed with Jersey for this experiment.

Why not cows?

The sheer logic of the size of calves in relation to a cow’s body has made us wonder if that isn’t why cows are not as inclined to multiple births as sheep and goats. A story in the U.K. Farmers Weekly says Dr. Stanley Janyk, a senior researcher in reproduction physiology at the Agricultural Research Council (ARC) in South Africa, ascribed this reproductive efficiency to several factors — genetic composition, constitution, good nutrition and maintenance, and proper management He said twins were acceptable in beef breeds because they could handle twin pregnancies without negative effects on reproduction and general health.

However, with dairy cattle, every gestation resulting in twins had a negative effect on the following conception and lactation, in addition to the physical condition of a high-lactating cow.

For those trying to improve fertility in a grass-based herd pushing twinning genetics needs some deep thought. The Farmers Weekly story says Janyk’s theory is that frame size plays an important role in twinning in cattle. Higher twinning frequency is more predominant in the larger breeds with cow weights ranging from 665 kg to 800 kg.

A quick poll of our neighbours along with these scientific findings confirms our suspicions. Dam lines that have twins are the ones that they can count on having calves every year no matter what. They breed back faster, and usually are the first cows to calve every year and not calve till at least their 10th birthday. This is what we want in our cows.

For now, my order is in for a perfect calving/pasture season. Not too hot, not too cold. Not too dry and not too wet. All the cows have peaceful births and healthy calves and if a set or two of twins pops up then that would be fine too.

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