An Australian-first study showing fresh sexed semen is better for dairy reproduction could revolutionise how farmers use it to improve their herds.
The study conducted by the Warrnambool Veterinary Clinic has found that when fresh sexed semen is used, the results are better for farmers than frozen sexed semen.
Dr Jon Kelly, director and senior dairy veterinarian with the Warrnambool Veterinary Clinic, says the results could be a “game changer” for Australian dairy farmers.
“More reliable results mean more people will start using sexed semen,” Dr Kelly said.
“We have used it in heifers in a FTAI (fixed time artificial insemination) program and in cows, and it is better,” he said.
Fresh sexed semen gives consistently higher conception rates then frozen sexed because the semen is not damaged by the freeze/thaw process.
The Warrnambool Veterinary Clinic has released the results of fresh sexed semen conception rates and the improvement seen when compare to frozen sexed semen.
Dr Kelly says frozen sexed semen is a compromised product that yields variable conception rate results.
“Fresh sexed semen is now available, which theoretically should be better than frozen,” he says.
“Sexed semen has been around for a number of years with the obvious benefits of more heifers being born, but many dairyfarmers choose not to take full advantage of its potential to increase heifer numbers and maximise its potential.
“We believe the information we have gathered will help dairyfarmers make better decisions.”
Dr Kelly says farmers need to ensure sexed semen insemination is done correctly to increase chances of getting more animals pregnant.
“Due to the decrease in fertility of sexed semen, it is vitally important that animal selection and management, and semen handling and insemination are the best it can be,” he says.
Individual conception rates for fresh sexed semen in Warrnambool Veterinary Clinic dairy heifers in 2014 show that conception rates of up to 70 per cent are achievable, but 55 per cent was the overall average. This compares to a 40 per cent conception rate with frozen sexed semen.
He said the biggest factor in the success of a sexed semen pregnancy in a heifer was achieving critical mating weight of between 55-60 per cent of adult weight.
“A bigger heifer is more likely to have reached puberty and be more sexually mature, so underlying fertility is maximised,” he says.
Dr Kelly says synchrony programs can be used to help minimise management interventions, and for FTAI programs, can alleviate the heat detection accuracy risk.
An important factor that determines the success of FTAI programs is that the correct hormone, dose, route of injection and timing is adhered to.
Prostaglandin (PG) programs make a heifer show heat can give good conception results to sexed semen. Accurate heat detection and consistent timing of AI are essential for a PG program, he says.
Dr Kelly says cows are generally less fertile than heifers when using sexed semen.
“Because early calving cows are the key to a herd’s fertility the next season, I believe a synchrony program is essential when using sexed semen in cows, other than when individual cow are being selected,” he says.
Selecting only the most fertile cows for joining with sexed semen is critical.
Despite the relative success of fresh sexed semen, Dr Kelly said “there are disadvantages with fresh semen, which include the logistics and sire selection, so the holy grail remains a frozen sexed semen product that behaves the same in cows and heifers as frozen conventional semen.”
Source: farmonline.com.au