A new sexed semen product, with double the amount of cells per straw of its predecessor, is a success for a Yorkshire family. They have been using 4M Sexed Semen to breed replacements from their best cows, taking full advantage of its improved conception rate.
Having double the amount of cells in every sexed semen straw means the Pratt family now has the confidence to use 4M on cows and heifers, safe in the knowledge conception rates will not be compromised. Traditionally, the Pratt family would have only used sexed semen on heifers, following concerns conception rates would drop off in less fertile cows on a more inconsistent diet.
However, that was at a time when they were reliant on using straws containing the usual two million sexed semen cells per straw. Since then, they have swapped to SexedULTRA 4M, in which every straw contains 4million sex-sorted sperm cells (see Q&A panel). As a result, conception rates have become more consistent, as James Pratt explains. “Until recently, we had mixed success with sexed semen,” he says. “We would have a run of nine in-calf heifers when we served 10, then five in-calf out of 10.
It was just a bit inconsistent. It did not seem as consistent as it does now.” James farms with his parents Alan and Edith and brother Richard at Studdah Farm, Bellerby, Leyburn. They run the Studdah herd of 130 pedigree Holsteins, yielding 9,811kg a cow a year at 4.31% fat and 3.19% protein. Cows calve year-round, with all replacements reared on farm.
Recently, the family decided to focus on producing more beef from the dairy herd in response to low milk and heifer prices. As a result, they were keen to breed replacements from their best animals and put the lower end to beef. To do so, they wanted to produce females from their top-end cows, as well as their heifers.
This was where 4M came in. James says: “There were trials to show SexedULTRA 4M had similar conception rates to rival conventional semen. So, if conception rates are similar, you have more chance to get heifers off your top cows and put beef on the bottom.” Now, about 50 cows are served to 4M and the remaining go to a three-sire British Blue semen straw; 50% of heifers are also served to 4M with the rest put to Aberdeen-Angus or used as embryo recipients. The best cows are selected based on classification data and the family’s knowledge, opting to breed for balanced type, quality udders, feet and legs, and positive milk, fat and protein.
In October, the business began genetically testing heifers with the view to using this knowledge to make more informed decisions on which heifers to breed replacements from, and to make faster genetic progress. This will help select embryo recipients when flushing cows to sexed semen.
The business is now achieving similar conception rates with sexed semen as they were with conventional. Cows are currently achieving 55% conception rate to first service with a 100-day in-calf rate of 68%. This figure includes beef semen and some overlap with using sexed semen straws with 2M cells. Of 10 heifers recently served to 4M, they achieved conception rates to first service of 80%.
The business also saw no effect on conception rates in cows during summer grazing. James says good conception rates from using the combination of 4M and the three-sire beef straw on cows has helped reduce calving interval from 395 days to 376 days between 2016 and 2017.
At the same time, the business is receiving a strong income from beef calves, with eight-weekold Angus calves averaging £300 and Blue calves averaging £380 at Leyburn market. James says there is a wide selection of quality bulls available in 4M, with the farm currently using three genomic sires. This includes Rubi-Agronaut, the top £PLI bull in the country; Aladdin Red, one of the highest red £PLI and type bulls; and Kingstar, a well-balanced sire.
Cogent is the first UK-based breeding company to introduce sexed semen straws with double the usual dose rate. Sarah Felstead, Cogent vet and production and supply chain manager, answers some key questions on the benefits.
What is SexedULTRA 4M? SexedULTRA 4M includes four million sex-sorted sperm cells per straw, compared to the usual 2m. This is the biggest number available on the UK market.
Lower conception rates are often seen when using sexed semen. Does 4M help with this, and if so, why? Sexing semen is an expensive process, which is why most sexed semen straws have traditionally included 2m sperm cells per straw. The fact sexed semen straws include less semen means lower conception rates are often seen, and farmers tend to prioritise using sexed semen on heifers which have higher fertility than cows. Conception rates to artificial insemination – whether using sexed or conventional – are influenced by a number of factors, the number of sperm cells being one of them. By doubling the number of cells from 2m to 4m, you are getting closer to the optimum level of fertility across more bulls. At the same time, the unique medium used in SexedULTRA 4M supports sperm cells and their longevity within the uterus. All this means farmers can expect to see similar conception rates to conventional semen when using SexedULTRA 4M. An independent German study compared sexed semen straws with 2m, 3m, 4m dose rates against conventional semen. They found 4m achieved comparable conception rates to conventional semen. This was the first time a dose response effect had been demonstrated with sexed semen.
How many bulls will be available as SexedULTRA 4M? The key thing is we are not just going to be picking certain bulls to be sexed; 4M will be available on all our bulls. We are aiming for all of our dairy bulls to be available in sexed ULTRA 4M at the next bull proof run in April/May.
What are the potential benefits of using 4M? The higher level of sperm cells mean you can now start using 4M on your cows with confidence. It also means there is the potential for less wastage from your herd by having fewer dairy bull calves. Combining the use of 4M with genomic testing of females can offer more accurate and selective breeding of replacements.
How do you ensure you maximise conception rates with SexedULTRA 4M? You still have to adhere to the basics when it comes to AI. To optimise results, use 4M on first and second lactation animals, cows which have had no prior fertility damaging events and an observed pre-cycle heat. Choose first services on cows displaying strong heats.