Research update: Breeding and weaning update from the maternal herd at Grange
Colin Byrne, Animal and Bioscience Research Department, Teagasc Grange, Dunsany, Co. Meath, reports on the breeding performance of the maternal herd and weaning update.
Breeding took place for 10 weeks beginning on May 2 until July 11. Two rounds of sexed female semen were used on all animals followed by one round of conventional semen if needed. The bulls used are described in the June Future Beef newsletter.
For conventional semen, the AM/PM rule was applied for AI. For sexed semen, the recommended AI time is 16- 22 hours after first observed in standing heat, with the later the better in this timeframe applied. For sexed semen at Grange, animals were inseminated 22-24 hours after the start of standing heat.
The final pregnancy scan took place on August 25, 2023. Overall, the pregnancy rate is 76%. While low, this is in line with the 85% typical pregnancy rate achieved in the herd over the past number of years.
Pre-weaning performance and build-up to weaning
2023 has seen excellent pre-weaning performance in calves. On September 13, calves averaged 278kg, growing at 1.21kg/day since birth. Males were castrated on August 30, and all calves received bovine respiratory disease and infectious bovine rhinotracheitis booster vaccines on September 13. Calves have been creep grazed since July.
Weaning will begin in mid-October. Weaning will start with the heaviest 30% of calves. The dams of these calves will be removed and housed to dry off, five days later the next heaviest 30% will have their dams removed, and the same for the remainder another five days after. It is important that paddocks are secure and ideally are a reasonable distance from the cows.
Ongoing methane research
During the production cycles of 2022 and 2023, methane was measured at grass and during the dry period, with dry matter intake estimated at the same time points from first cross dairy cows or beef x beef cows and beef x beef cows of average or high genetic merit. This will allow us to outline how breeding strategy can be used as a tool to reduce on-farm methane emissions. The analysis of these data is ongoing and will allow the characterisation of methane output from suckler cows with the aim of providing accurate information for Ireland’s national greenhouse gas (GHG) inventories.
This article first appeared in the Teagasc Beef Advisory newsletter for October. Access the publication here.