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Compact calving is key for optimum performance

As a discussion group facilitator, I often get the participants of a group to benchmark their performance. This gives individuals a great sense of how their own farms are doing this year compared to their contemporaries.

It involves a number of parameters which focus both on pasture performance, including average pasture cover and pre-grazing yield, and on cow performance indicators such as litres per cow and heat detection.

At this time of year a spring calving herd will be very close to peak milk production and either have started mating or are on the verge of doing so. For a grass-based system, a production of around 28l/cow/day is a common figure at peak and in a number of cases this year it is currently being done without any meal. However, production levels of 24l also very common and occasionally figures as low as 20l may be presented.

I never look solely at the litres produced in isolation. I also consider butterfat and protein concentrations to generate production per cow in terms of milk solids. The calculation is as follows: Milk solids/cow/day = daily litres/cow x 1.025 x (butterfat + protein/100)

This ranges from a massive 2.2kgMS/cow to 1.6kgMS/cow. Any herd near 2kgMS/cow/day would be considered to be doing very well, and from 1.8-1.9kgMS/cow/day would be very respectable. Where once-a-day (OAD) is being used because of quota limitation this maybe as low as 1.5-1.2kgMS/cow but don't be too disheartened as the difference between OAD and twice (TAD) will decrease as the season progresses.

On seeing these figures it's only natural to question your own performance and whether it's good or whether it should be better and an area that needs improvement. So how do you hit the 2.0kgMS/cow? The farmers I see reaching this level of production are always good operators, doing all the right things at the right time, but also have spent years breeding good quality cows with high fertility, and have set up the farm to provide good quality pasture throughout the year. Supplementary feed would be used as and when needed relative to pasture supply.


However, a key link between the pasture and cow to achieve such a high level of performance is compact calving, which determines days in milk of the herd. Good operators are diligent and actively manage the herd to result in compact calving spread. This needs measurement, targets and triggers. Targets are areas to strive for and triggers are prompts to investigate a problem and act on it.

The first key to compact calving is the maiden heifers. At this stage, regardless of whether they are small or on target, these should have been mated at the same time or even a week earlier than the main herd.

When focusing on the herd, pregnancy and a good six-week in-calf rate is reliant on two important drivers: submission rate and conception rate. Obviously pregnancy will not occur unless a cow is presented for AI or the bull and she conceives to that service.

Therefor, it's very important that we record AI and bull inseminations accurately and use these to determine your three-week submission rate. The calculation is as follows:

Number of cows inseminated in first 21 days / number of cows at start of mating x 100.

Please note that it is the number of cows not the number of inseminations, as some cows may have had two services in this 21-day period.

Top farmers target and often achieve a three-week submission rate of about 90pc. If it is less than 80pc, seek advice and consider your heat detection management, and management options for cows that have not been detected in heat.

The submission rate target can also be considered on a daily basis. For example, if you had 100 cows and were targeting 90pc at 21 days (90 cows), then you would hope for an average of around 4-5 cows per day for AI to be reaching your 90pc submission rate target (90cows/21days).

A key element to a good submission rate is good heat detection. If you have new or young staff helping you this year, remember to talk about the signs to look out for and don't just assume that these are already known. In simple terms, a cow is most likely to be on heat if:

  • She is standing to be mounted by other cows;
  • Tail paint is removed or heat mount detector is triggered.

However, a cow may be on heat if:

  • She attempts to mount other cows;
  • Tail paint is rubbed but not removed, or heat mount detector is lost;
  • She is restless or bellowing;
  • She has poor milk letdown;
  • You see mucus around the vulva;
  • You see mud marks on the flanks, or rubbing on pins and tail head.

Mary Kinston is a farm consultant based in Kerry. Email:

Indo Farming