I got a call from a farmer during the week who said that his AI technician was worn out from work. We are now at peak AI time and everyone is busy, but the farmer said the AI man was being overworked by doing two calls to farmers in the one day, and he was wondering if this was necessary.

Were the farmers right to be asking him back in the evenings? There are plenty of studies to show that there are no significant differences between once-a-day and twice-a-day AI. Twice-a-day AI involves following the am/pm rule, whereby cows that are seen bulling in the morning are served that evening and vice-versa. The optimum time for AI is 12 hours after the onset of heat. But if you are only watching cows for signs of heat twice a day, then you won’t know exactly when the heat commenced. Older research, which involved a lot more observations than used now, showed more of a benefit to twice-a-day AI.

However, with fewer observations now, and more reliance on heat detection aids, there is no real benefit of once- versus twice-a-day AI.

Farmers who do DIY AI may still prefer to AI twice a day, because it spreads out the workload, but for farmers relying on a technician, there is no reason to call him or her back twice in the day. Serve whatever cows are bulling in the morning, and if a cow is bulling again in the evening, serve her a second time the following morning.

A small percentage may be served twice.

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