Recent trials of new sex-sorted semen had resulted in comparable conception rates to conventional semen, a seminar was told last week.
And these improvements in fertility have been labelled a potential “game changer” by a Western Victorian dairy vet.
US business Sexing Technologies research and development director Dr Vish Vishwanath told about 150 people at Noorat last week that the first demonstrated fertility improvement in sex-sorted semen for a decade was the first trial of the new product called, SexedULTRA, in 2013.
But as recently as September last year, German trials that increased the dose rate of sperm in each straw of the new, improved SexedULTRA frozen semen proved that sex-sorted semen could achieve the equivalent fertility of conventional semen.
Previously, researchers didn’t believe increasing the sperm dose rate in sex-sorted semen would increase fertility. But changes to the process of sex sorting, including changes to the physiology of the sperm and time it takes to complete the sorting process, had helped it lift fertility with a bigger dose rate.
“For the first time ever, and this was all done with heifers, (monitoring) the 56-day non-return-rate we found that highest dose rate, four million (sperm in a straw), we could get almost the equivalent conception rates to that of conventional (semen),” he said.
“It’s a significant change.
“It was the first time we could demonstrate sex-sorted semen, at that concentration, could actually get equivalent conception rates to that of conventional semen.”
This trial included about 8000 inseminations with sex-sorted semen and about 50,000 inseminations with conventional semen.
Dr Vishwanath said the next dose rate research would look to improve the fertility of the lower dose straw, 2.1 million sperm, and lift it to the fertility levels of conventional semen.
This work is being done in New Zealand with fresh sex-sorted semen.
A 2013 trial of SexedULTRA saw an overall improvement in pregnancy rate of 7.4 per cent in favour of the SexedULTRA semen when compared with conventional semen.
Overall SexedULTRA had a 54.7 per cent pregnancy rate. The biggest difference was in the Holstein breed where the difference was a 10.9 per cent increase in favour of the new product. Following this research another trial including 40 herds and 7000 inseminations showed a 4.5 per cent increase in pregnancy with the new SexedULTRA semen compared with the conventional product.
Dr Vishwanath said researchers then returned to the laboratory and “tweaked” a few things across six months.
They developed a new SexedULTRA and research in the US and Canada, across a total of 6000 inseminations, proved the new SexedULTRA was about 2.5 per cent more fertile than the old.
Total Livestock Genetics, based in Western Victoria, hosted the seminar and operates four sex semen sorting machines.
Warrnambool Vet Clinic director Jon Kelly said the improvements in the fertility of sexed semen could be a “game changer” for the local industry.
He has recorded pregnancies and data from clients using sex sorted semen (both fresh and frozen) as well as the new SexedULTRA, which had produced much more consistent results. Further data would better compare the products.
By: Simone Smith
Source: The Weekly Times (Australia)