National Dairy Conference Questions Answered: 6-week calving rate
On the day at the Virtual Dairy Conference Teagasc Specialists were not in a position to answer all of the questions asked due to the sheer volume of questions. Instead over the coming days they will attempt to answer some of those questions on the Dairy Daily. The 6-week calving rate is first up
Jim White, a dairy farmer from Mullinahone, Co. Tipperary was one of the speakers on Tuesday 23rd November. Two questions came in from an attendee relating to Jim’s herd and about whether 6-week in-calf rate or 6-week calving rate was the better measure of fertility in a dairy herd.
Is Jim's calving rate improvement being driven by the new heifers coming into the herd in the post quota years? And as the herds mature, the calving rate is decreasing as less heifers are coming into the herd? Would 6 week in-calf rate be a better KPI?
Careful management of heifers to compactly calve them close to the start of the calving season can skew the fertility metric, 6-week calving rate, in herds where a large percentage (>30%) of the herd is first calving heifers. In stable herds (replacement rate 18-22%), the 6-week calving rate of the cows has a much greater influence on the herd average. Jim quoted that at this stage, group members’ herds are maturing and averaging 22% and that good mating management practices and a high fertility sub index were both contributing to the 85% 6-week calving rate that the group was achieving.
6-week calving rate - more robust metric
Teagasc believes that 6-week calving rate rather than 6-week in-calf rate is the more robust metric to use for most herds. To achieve an accurate 6-week in-calf rate, all breeding events need to be recorded throughout the season. Typically at farm level, after a number of weeks of AI, stock bulls are typically released to ‘mop up’. Scanning results, recorded merely as in calf or empty, without all of the breeding event data recorded accurately, will result in an overestimation of 6-week in-calf rate.
See more on the Virtual Dairy Conference 2021 here.