Your yearling heifers have just completed their first winter and are coming up on one-year-old, which means that farmers may be thinking of turning them out to grass in the coming weeks.
After feeding costs, heifer rearing is the second largest expense in the dairy system, accounting for 20% of total costs, but if it is done efficiently and successfully, it is certainly a great investment.
Last year proved to be a tough year for rearing heifers with many heifers across the country underweight and behind target due to poor grazing conditions, slow grass growth and poor quality silage being fed to heifers over the winter.
With only over three months until your heifers are set for the breeding season, farmers need to prioritise good quality pasture for heifers behind target.
Grazing
Getting heifers out early to graze for at least six weeks before the mating start date (MSD) can really help push them them towards their target weight at mating this April or May.
In general, higher weight gains are achieved from pasture than from winter diets as studies have shown that weight gains of 1kg/day are achievable when heifers are out at early spring pasture.
In the scenario where there is poor grass growth or grass supply is tight and therefore will not meet the demand of all the heifers, turn-out date might be delayed, but if there are lighter heifers in the group, they should be selected and turned out before the main group.
Ideally, all your heifers are a uniform group, but as we know, this is not always the case as most farmers will have one or two animals which are little behind the rest – concentrates along with early grass should be allocated if necessary.
Studies from Teagasc Moorepark show that although heifer growth rates are lower when grass supply is limited, they still tend to better than those achieved on overwinter diets.
Yearling heifers
Research has shown that maiden heifers which achieve their target body weight by the start of the breeding season will have higher levels of production during at least their first three lactations.
If heifers are not at the correct weight currently, supplementation should be added to their diet, as it would be too late to address the issue when it is time for breeding.
A well worthwhile investment for a farm is a weighing scales as it will allow you to get the average weight of your herd which will allow you to set heifer targets throughout the 24 months.
The end of May / early June is an ideal time to weigh the fully grown (3rd lactation +) cows in the herd.
These should be the cows that have been reared to achieve their potential weight and which represent the future size of the herd.
Once a farmer has the mature bodyweight of their herd, the target weight through the 24-month rearing process can be calculated for the heifers.
Investing in a weighing scales allows you to keep track of these heifers every couple of months which leads to timely intervention of heifers that are underweight and not meeting targets.
The bodyweight targets for heifers throughout the 24 months by breed/crossbreed, according to Animal Health Ireland (AHI) are as follows:
Mature BW 6 months 12 months 15 months Calving % Mature BW 30% 50% 60% 90% Hols-Fries (HF) 580 175 290 350 525 NZ/Br Fries 550 165 275 330 495 Nor Red x HF 580 175 290 350 525 Jersey x HF 500 150 250 300 450 Jersey 450 135 240 270 405
The mature bodyweights from the breeds above are only a guideline and an average for the particular breed, as there are many Holstein-Friesian herds out there, for instance, with an average herd bodyweight of 650-700kg.
At this moment in time, if your heifers were born in early February last year, they should be weighing in at 50% of their mature bodyweight.
It is important that you continue to check the group and ensure that animals are continuing to achieve their targets and in this situation, a group average is irrelevant – as each animal needs to be looked at on an individual basis.
If heifers can’t get out to graze early, feeding a 67% dry matter digestibility (DMD) silage will require an extra kg of concentrates, compared to a 72% DMD silage.
Feed space is also an important consideration – for yearling heifers, 0.3m should be sufficient and if space is tight, there may be a reduced performance from your heifers during the housed period.
It is important to weigh your heifers now and pick out the ones that are underperforming in order to give them priority grazing or priority feeding in the shed.