Farm Ireland

Sunday 22 April 2018

Scan cows to plan for 2011 calving

Dr Dan Ryan

The breeding season should be finished now. However, stock bulls are still running on many farms. Cows bred now will calve next June, resulting in a short, non-profitable lactation in a grass-based system.

It is now time to find out how you got on with this year's breeding programme, to plan for next year's calving season and subsequent breeding seasons.

Scanning is an excellent tool to give you a picture of the reproductive status in the herd. However, the information from scanning is dependent on the operator using the equipment.

Aim to have your cows scanned no later than four months from the start of the breeding season. This will give you the most accurate information. Pregnancies can be identified from 21 days after breeding.

It is considered a safe pregnancy from 35 days of gestation. The ageing of pregnancies can be accurate to within five days of the true age of the foetus, up to 120 days of gestation.

Cows identified as non-pregnant should be assessed for suitability to go into an autumn-calving programme or for next spring's breeding programme. It is difficult to manage empty (dry) cows which are recycled to the following spring. Scanning will tell you if these empty cows are prospective candidates for subsequent breeding.

The sex of the pregnancy can be identified accurately between 51 and 120 days of pregnancy. Some farmers use this information to cull cows which are carrying Friesian or Jersey bull calves and are not suitable for breeding next year because of health problems. Many farmers get maiden heifers scanned to identify the sex of the calves. Subsequently, they plan the sale of in-calf heifers. Knowing the sex of the dairy cows now will enable you:

  • To know if you have enough potential replacements in advance;
  • To buy extra dairy calves if needed.

Scanning will identify cows carrying twins up to 120 days of pregnancy. However, many cows which start with twins will lose one or both pregnancies. The incidence of embryonic mortality is higher in cows carrying twins. This continues to occur at a higher frequency in the second and third month of pregnancy. Cows carrying twins need better management from the fourth month of pregnancy.

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In the past few years, empty cows were moved off the farm from this time of year onwards. More profitable milk production and a greater supply of grass for grazing will, in my opinion, result in empty cows being retained in milk on the farm until December.

Plan now to ensure that your pregnant cows are fit at drying off. First-lactation cows and cows with poor body condition scores -- because of lameness or old age -- need a dry period up to 12 weeks. An eight-week dry period will work if the cows have a body condition score (BCS) of 3.0 at drying off.

However, the focus on grass-based milk production has resulted in a high proportion of cows in an unacceptable condition score at this time of year.

Concentrate supplementation now may not be economically justified on the basis of milk alone. But getting cows fit with a BCS of 3.0 at drying off has to be the primary focus in the next three months. Remember that next year's breeding programme begins with BCS management now.

Maiden in-calf heifers should not be forgotten at this time of year. We are currently identifying between five and 10pc of empty heifers. The reasons for empty heifers include:

  • Under-size heifers, which did not cycle or began cycles too late in the season;
  • Freemartin condition;
  • Embryonic mortality.

Many in-calf heifers are not reaching the target weights. The quality and quantity of grass made available decreases at this time of year. Identify lighter heifers now. Supplement with a good quality growing ration until the heifers are seven months pregnant. This will pay dividends next year when the heifers calve and need to resume normal ovarian activity to go back in calf.

Finally, getting your cows scanned now will enable you to get accurate information to the ICBF before their deadline in a few weeks' time. They will supply you with a useful pocket notebook, which will help you plan for next year's calving and breeding season.

  • Dr Dan Ryan is a reproductive management consultant. He can be contacted via the website,

Irish Independent