The main focus over the next 12 weeks must be on getting cows back in calf and maximising the number of cows in calf to AI.

This takes up enormous energy on the part of the farmer but the rewards are massive in terms of compact calving and the extra milk generated as a result of that.

Compact calving, lots of replacements and more surplus stock are some of the benefits. The target is to have 75% to 80% of the cows pregnant after the first six weeks of breeding, so when you include the heifers next spring, over 90% of the herd will calve in six weeks.

Timing

There’s a hot debate raging at the moment over the best time to start the breeding season. Despite very favourable weather conditions this spring, there is a cohort of farmers who feel that they are probably calving a bit too early and so have decided to push back mating start date by a few days.

As many herds have now reduced their breeding season to nine or ten weeks, the mean calving date occurs very quickly after the start of calving.

With so many cows calved early, there is a huge demand on grass very early in the season. Where this demand cannot be met, then a lot of extra supplement such as meal and silage has to be fed, which adds to costs.

Grass growth and soil types also play a big part in the decision around calving start date, so these are all considerations when it comes to deciding the right day to start breeding.

With good weather this week, many farmers who may have been planning to start AI later in the week have decided to bring it forward as a lot of cows are coming in heat these days.

Heat detection

Many might be of the view that there are only two or three signs of heat, but in fact there are ten.

Of these, there are probably only three sure signs of heat, but a good stockperson will spot the other signals and use these to build up the case as to whether the cow is “on” or not.

1) The most definite sign is when a cow is standing to be mounted by other cows.

2) Tail paint is removed.

3) Heat mount detector (kamar or scratch card is triggered).

4) The cow attempts to mount other cows.

5) Tail paint is rubbed but not removed.

6) The cow is restless or bellowing or acting out of character such as running on the farm roadway.

7) The cow has poor milk let-down.

8) You see clear mucus around the vulva.

9) You see mud marks on the flanks.

10) The heat mount detector is lost.

Heat detection aids such as tail paint or other devices such as scratch cards or kamars or vasectomised bulls are essential for good results.

Many farmers have invested in automatic heat detection aids over recent years which reduces a lot of the labour associated with heat detection.

One thing to watch for though with some of these devices is that most are designed for twice a day AI, rather than once a day AI.

For most devices a cow must be bulling for seven or eight hours before the system will select her for AI.

This can create a bit of confusion at times because a cow that came into heat at say 2am, could be bulling strong at 8am but the system won’t draft her for AI that morning.

If twice a day AI is practised she will be drafted in the evening, which is perfect timing for AI. But if only once a day AI is practised, then it could be a bit late to be inseminating her the morning after.