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Calving Beef heifers at 2 Years Old

06 July 2020
Type Media Article

Find out the reasons for calving your beef heifers at 2 years old; why farmers are reluctant to try it and get some key statistics to help make the decision.

Why do it?

  • More output from the heifer over her lifetime (more calves produced)
  • Reduced stocking rate compared with calving heifers at old ages
  • Potential to reduce the number of stock groups
  • Quicker genetic progress
  • Reduces Costs – Grange work shows that for a 50 cow herd with a 20% replacement rate each additional month that calving is delayed cost of €490 or €50/heifer/month.

Why are farmers reluctant to try it? 
(Only 22% of heifers calve at 22-26 months)

  • Heifers aren’t sufficiently well grown at 15months to be bred
  • Believe that it will stunt the heifers growth if they are bulled too early
  • They are too difficult to calve
  • They won’t go back in calve again to calve as 2nd calvers
  • Not that saleable if things go wrong at calving.

Dispelling some of the Myths

Comparison of national statistics on the performance of 131,077 beef heifers, calved for the first time, between 23 and 40 months of age (supplied by ICBF).

Age at 1st calving (months)

Average subsequent calving interval (days)

% Calving for a second time

Average calving difficulty of bulls used Average calving difficulty of bulls used Average calving difficulty of bulls used
23-26 383 days 82% 4.7% 50% 3.2%
27-30 394 days 83% 5.1% 53% 2.8%
31-35 392 days 87% 5.2% 58% 2.6%
36-40 386 days 86% 5.2% 57% 2.0%

We often put up many reasons as to why not to calve heifers at 24 months such as if they calve at 2 years they will not calve again at 3 years. The table above clearly shows that this is not the case.

 For example:

  • Heifers that calved at 23-26 months of age had as good a subsequent calving interval and calved down again as a second calvers, just as early as their contemporaries calving down in the older age categories.
  • Another reason often suggested is that they are harder to calf at a younger age. The figures do show that younger heifers do have slightly higher calf mortality. On the same token heifers irrespective of age will be more difficult to calve and as the figures show will need a higher level of assistance at calving irrespective of age.
  • Correct sire selection is key if you want to consistently calve heifers at 24 months. As the table shows even younger calving heifers are being mated with sires with an average calving difficulty of 4.7% on the old scale which you could argue is high. We now have the new beef heifer calving difficulty figures available. Ideally select a high reliability bull with a beef heifer calving difficulty figure of less than 7.5%.
  • Heifers that calved for the 1st time at 23-26 month had greater survivability. Heifers that undergo puberty early generally have a shorter interval between calving and onset of first heat after calving.

Key Weight Targets

Mature Cow WeightWeaning Wt.Bulling Wt.Calving Wt.
Target % of Mature Wt.   60% 80%
600kg 260-280kg 360kg 480kg
700kg 300-320kg 420kg 560kg

Key points

 Heifers that are to calf down at two years of age will;

  • Come from the best cows in the herd and be sired by bulls with strong maternal traits.
  • Be born early in the calving season to allow them to be heavier at bulling
  • Need to achieve a daily liveweight gain of 1.1-1.3kg/day up to weaning as research shows they will typically undergo puberty and be eligible for breeding much earlier than poorer performing contemporaries
  • Have to be fed to achieve 60-80kg liveweight over the first winter so they will need good quality silage plus 1-2kg of concentrates.
  • Have reached 60% of their mature weight by bulling
  • Be turned out early in spring to grass to achieve good weight gain in the run up to bulling
  • Be bred to a high reliability easy calving sire (Ideally < 7.5% Beef heifer calving difficulty)
  • Have achieved 80% of their mature weight at calving.

Need preferential treatment if remaining indoors for a month or more after calving down. (Good silage plus 2-3kg Meal)