Throughout the BETTER Farm NI programme, the participating farmers have repeatedly shown the benefits of calving homebred replacements at 24 months of age.

Along with the financial savings, calving heifers at 24 months simplifies herd management through reduced stocking groups and also increases farm output.

However, successfully calving heifers at 24 months does not happen by chance. Along with a high standard of management, there is forward planning and careful selection around genetics required.

With spring-calving herds, how animals are managed during the first winter period is crucial to getting heifers heavy enough for breeding at 15 months of age.

Weight gain

More often than not, maiden heifers do not get priority feeding or weighed regularly to monitor performance.

By the time these heifers go back to grass, they have not gained sufficient weight during the housing period and face an uphill struggle to hit target breeding weights.

On the programme farms, heifers are weighed regularly during the housing period.

If animals are below target, the farmers have time to amend winter diets and get animals back on track.

Drawbacks

Having heifers too light when going to the bull creates a multitude of problems, which inevitably puts most farmers off calving at 24 months.

While the majority of farmers can manage to get heifers settled in-calf at 15 to 16 months of age, the big problems usually arise at calving time or shortly after.

For example, under-developed heifers are less equipped to cope with the physical demands of lactation and can easily become stunted.

Under-developed heifers are also much harder to get back in-calf again, which increases the number of animals that have to be culled annually.

Management

Where farmers are giving serious consideration to calving at 24 months, now is the time to put a plan in action to have animals ready for breeding.

Outlined are a series of steps to follow, which have been successfully implemented on the programme farms in recent years.

1 Select and separate replacement heifers now

Spring-born weanling heifers destined for breeding next summer should be identified now and grouped separately from the other calves. This allows these animals to get priority management over winter. There is no point leaving it until next May to select replacements, as by that stage, options could be limited if too many heifers are not heavy enough for breeding.

If there are heifers with breeding potential still on the cow, these animals should be weaned sooner rather than later, so that they can be placed on a planned feeding programme.

2 Minimum weight targets

With heifers, the heavier the animals are at breeding time, the better. As a rule of thumb, heifers should weigh at least 60% of mature cow weight at the start of the breeding period.

This means for a herd with an average cow weight of 700kg, heifers should weigh at least 420kg at the outset of the breeding period, not half way, or two-thirds of the way through the breeding period. If cows are more typically 750kg, then heifers need to weigh at least 450kg.

The next target weight to meet is to have heifers weighing at least 90% of mature cow weight by the time they calve down. If cows averaged 700kg, heifers need to weigh at least 630kg on the point of calving.

3 Daily weight gains

Take the example of a group of March-born heifers weighing 280kg when weaned and housed by 1 November.

Assuming a minimum target breeding weight of 420kg by 1 June, the animal has to gain 140kg over 212 days, which is a daily gain of 0.66kg/day.

From 1 June to calving on 1 March, the heifers need to average 0.7kg/day in order to hit the 630kg target weight at calving time. If heifers fall short of the target breeding weight, do not let the physical appearance of the animal sway you to chance it, as under-developed heifers will most likely cause problems at a later date.

4 Parasite control

Given the level of weight gain required over winter, make sure heifers are free of worms, fluke, lice and have no setbacks from respiratory problems.

5 Diet

At the outlined target weight gain during winter, there is no place for feeding average, or below average-quality silage to replacement heifers.

Animals need to be offered good-quality silage of at least 70% D-Value, plus 2kg/day of concentrates when housed. If heifers are starting to get fat, reduce concentrates to 1kg/day.

Gaining close to 0.7kg/day during the housing period will be a challenge, so do not underestimate the role of silage quality in the winter diet.

6 Weighing

Weighing heifers every six to eight weeks will give a good handle on whether animals are on track to hit breeding target weights. The heifers weighing 280kg on 1 November should weigh around 310kg to 320kg by the end of the year, assuming a daily gain of 0.6kg/day. With a target turn out date of 20 March, heifers should weigh close to 360kg when going out to grass. This gives approximately 70 days to get heifers to meet the target breeding weight of 420kg by 1 June.

7 Early turnout

Replacement heifers should get first priority for going out to grass in spring, even if this delays other cattle being turned out for a couple of weeks. When heifers go out to grass without carrying excessive flesh, they usually experience a short period of compensatory growth, when daily liveweight gains can exceed 1.5kg/day.

This helps to get heifers to meet their target breeding weights before going to the bull. If managed properly, an early turnout usually results in heifers comfortably exceeding target breeding weights.