"The key reasons I chose sexed semen was for faster genetic gain, easier calving and early replacements".
“We wanted high quality Friesian calves from our Friesian yearling heifers, as opposed to mating them to Jersey,” he says. “In the past, if we had calving difficulty with a heifer, 90% of the time she would have a bull calf. So, we took bull calves out of the equation by going to sexed semen.
“Our younger animals also have the best genetics, so breeding heifers using high quality sires helps us continue to fast track these gains.”
Heifers were mated for 7 days as they came on heat. The balance had a PG (prostaglandin) shot on day 7 and were then mated based on observed heats. 95% of them were mated in 12 days. Friesians were mated to sexed Friesian semen and crossbreeds to unsexed Jersey. Pregnancy testing six weeks after AI showed there was no difference in conception rates. Ian mates his heifers two weeks earlier than the milking herd to give them longer to get back in calf again.
“Our average conception rate was between 58 and 65% with the unsexed jersey semen depending on the bull. So, despite being told I would see a reduction in conception rate using sexed, 63% for sexed semen was a great result!” he says.
“Using sexed semen on heifers will help us achieve good quality early replacements as well as fast tracking our genetic gain. If you’re investing in a sexed straw, you’re better to use it on a heifer rather than a high producing cow with a lower chance of conceiving.”
Ian says using sexed semen also allowed him to get enough replacements early and mate a larger percentage of his milking herd with short gestation Belgian Blue to help condense his calving. The milking herds are mated to CRV unsexed Friesian straws for 4 weeks and the Belgian Blue for 5 weeks. Ian says they really are easy calving and the calf rearers love them.
“Using Belgian Blue gives us markets for calves and a better price than bobbies. We used Belgian Blue last year and on average our cows calved three days earlier than the dairy sires.”
CRV sexed semen customers can select their bulls. There was one CRV Friesian sire in particular that caught Ian’s eye.
“We used CRV’s highest BW bull, Lennan. One of our farms supplies Synlait, so it was important he was also A2A2. He was easy calving and had good udder conformation, which I really value.”