Farm Ireland

Tuesday 12 December 2017

Benchmark against best when tackling deficient herd fertility

Aim for calving interval and spread targets

Liam Fitzgerald

THE BASIC conditions required for good herd fertility are healthy cows in good body condition and a fertile bull or, where AI is used, top-rate heat detection. To know the fertility performance of your herd you need to know what are the achievable targets and to record the reproductive performance of your herd for comparison.


The key fertility targets have received a lot of attention but achievement is still well below what is possible or satisfactory on many suckler farms. Targets being achieved by top performing herds are as follows:

  • An average calving interval of 365 days;
  • 0.95 calves born per cow put to the bull;
  • 60pc of cows calved in the first month of the calving season;
  • All cows calve within 12 weeks;
  • Calf mortality of 2pc at birth to 3pc at 28 days.

These are exacting targets and achieving them depends on a high level of herd management. Hitting the targets on calving interval and calving spread will go most of the way in rectifying deficiencies in herd fertility.

Data from the Irish Cattle Breeding Federation (ICBF) shows that, for the beef herds on their database (which are most likely to be above average in performance), the top 15pc have a calving interval of 364 days, whereas for the bottom 15pc it is 434 days. The national average is 399 days.

It is estimated that the average number of calves born per cow per year is about 0.83 or 83 calves per 100 cows bred. Again, the best performing herds are achieving 0.95 calves per cow per year from a combination of short calving interval (365 days), tight calving spread (four months or less) and low calf mortality (4pc or less).

The table (see below) shows an estimate of the improvement in output per cow in going from average performance to the top 15pc for cow productivity.

An increase of €65 in output per cow can be obtained by improving calving interval and reducing mortality.

Also Read

Further improvements can be made by compact calving which should push the difference to about €100/cow.


The first step in an improvement plan is to benchmark your herd against the top performers. This can be done by keeping accurate records of service dates, calving date, calf mortality, etc.

However, the most convenient way is to join HerdPlus with ICBF. This system will provide a range of reports on herd performance at a modest fee.

The Beef Calving Report provides statistics which include the herd calving interval, calf mortality and calves per cow per year. It also benchmarks each herd performance relative to all beef herds on the database.

The Suckler Cow Report provides individual animal details on breed composition, ancestry, €uro-Star indexes, calving and fertility performance and the performance of the progeny of each cow if slaughtered in Ireland.

The section on calving and fertility shows the history of each cow in relation to calving ability, calving interval and number of calves produced. You can sign up to HerdPlus by contacting ICBF on 1850 600 900 or by downloading the form directly from the ICBF website

Improving fertility

The principal areas for attention in order to maximise herd fertility will revolve around cow body condition, bull fertility (if using natural service), heat detection (if using AI), herd health and the avoidance of difficult calvings.

Cow condition

With a gestation length of up to 290 days for continental breeds, it only leaves 75 days to get cows back in calf if the 365-day calving interval is to be achieved. Most suckler cows do not show heat until about 50 days after calving, so this leaves a very tight timeframe in which to stay within the yearly calving interval.

Cow condition at calving, and the extent of weight loss after calving, are two major factors that influence how soon cows come back in heat. Cows should be at condition score 2.5 at calving. They can be allowed lose a small amount of body condition after calving but should be approaching condition score 2.5 at mating. This year, where fodder and grass is scarce, cows will need meal supplementation to avoid excessive body weight loss.


It is estimated that up to 5pc of bulls are completely infertile and a further 15-20pc will be partially or periodically infertile. Keep a close lookout for repeats, especially at the start of the season. Allow young bulls to mate three to four cows before running with the full herd. The conception rate should be about 60pc and is often higher whether a bull or AI is used for cows that are calved 50 days or more. To achieve compact calving, it is best to confine young bulls to about 20 cows and older bulls to less than 40 cows. Bulls need to be in good physical condition, but not over fat.

Good heat detection is crucial for successful AI. The best method of heat detection is to use a vasectomised bull, preferably with a chin ball marker. In the absence of devices to aid heat detection, about five thorough observations a day are necessary, with early morning and late evening the best times to observe cows in heat.

Herd health

The introduction of diseases such as BVD and leptospirosis into clean herds can have a devastating effect on fertility. Get veterinary advice at the first signs of a problem. A herd health plan that includes bio-security, vaccinations and the culling of carrier animals, drawn up in consultation with your vet, is the best way to address disease problems.

Calving difficulty

Conception rates are reduced following difficult calvings and Caesareans. Following cases of serious calving difficulty, conception rates can be reduced by 50pc compared to normal, unassisted calvings. To avoid excessive calving difficulty, choose sires that suit your cows and keep cows in fit body condition (body condition score of about 2.5) at calving.

Irish Independent