Replacement heifer rearing is an important component of suckler farm management.
These animals are the future of the herd, and good heifer rearing provides a sound basis for a profitable business, whereas failing to rear them appropriately may lead to economic losses.
These losses occur during the rearing period or after the animals join the herd, through mortality, increased disease, forced culls, and reduced productivity.
A good heifer-rearing strategy sets defined targets and ensures that these are achieved through regular monitoring of the animals throughout the rearing period.
The ultimate objective is to raise, at least cost, an animal that, once calved, is capable of maximising her genetic potential for production.
Central to the cost of production is the chosen age for calving.
For sucklers, the accepted optimal target is generally 22-24 months.
Below this age, there will be an increased incidence of calving difficulties, and reduced productivity after calving.
Heifers that calve late may become over-fat before calving, and rearing costs are increased.
However, if a farm is unable to achieve target weight gains required to calve at 24 months, it is better to calve later and accept increased rearing costs than to calve small, unproductive animals.
Heifers on the farm at present
At this time of year, there are generally three types of heifers on most suckler farms — those suckling their mothers, those for finishing off grass or indoors, and those in calf for next season.
Heifer rearing is expensive, with up to 60% of the costs being incurred in the first nine months while with their mothers.
The temptation is often to try to find feeding and management systems that reduce rearing costs.
However, it is no good saving feed costs for a calf if it later results in increased mortality, increased time to service and smaller heifers at calving. Ensuring that target growth rate is met during this period is important, to maximise the future fertility and productivity of the animal.
The target growth rate for heifers varies according to age, and is influenced by the planned age and weight at calving and also by their breed.
The aim should ultimately be to achieve a well grown heifer at calving. Obviously, the bigger the heifer at calving, the less growing she needs to do in her first and second lactation, and the more milk she will produce for rearing her calf.
There is a fine line between achieving target weights at calving and falling short.
For example, if your target is to have a heifer at 600kg for calving at 24 months, with a birth weight of 40kg, she must gain an average of 0.77kg/day over the 730 days (two years) of her life.
Achieving an average of only 0.7kg/day will leave a 551 kg heifer at first calving.
Getting the right type of growth
Growth in heifers should be directed towards lean tissue and not fat deposition.
This can be most influenced by providing suitable levels of protein, and avoiding diets with high starch and low protein content.
Digestible fibre and protein are the essential nutrients required for efficient frame growth.
High starch diets in heifers will result in excessive fat deposition in the udder, reducing mammary tissue development, and subsequently reducing milk production.
Given the requirements for growth, it is critical that there are no prolonged periods of very low growth in replacement heifers.
Heifers that have been inseminated to calve next spring need to be provided with sufficient good quality grass to maintain good growth.
If these heifers are on poor quality grass or are tight on grass, they will be supplemented with concentrates.
If suckler cows with calves at foot are on restricted pasture quantity or quality, then creep feeding should be introduced to keep calves growing.
Many suckler herdowners will look to buy in replacements rather than breed their own.
It is important to know what you want in a heifer before you go out buying.
One thing that is worth remembering is “aim for milk in the cow and meat in the bull”.
Obviously, for those in the BDGP scheme, the focus is now firmly on having the required number of four and five star females on the farm in 2018, and finally in 2020.
This will be achieved by either producing homebred heifers which have the stars, or outsourcing appropriate heifers.
With trends in the industry perhaps requiring lighter carcasses into the future, many are now looking at Angus and Hereford cross heifers out of the dairy herd as suckler cows.
Obviously, these crosses will have milk, but will they have good conformation to get the grades from their progeny?
It is still important that you produce a good quality weanling which may be suitable for export or further finishing, so that you have options at sale time.
These cows may also have lower maintenance requirements, which may help to control costs.
Most however will continue to source progeny from a suckler unit, or continental heifers from the dairy herd.
Whatever you choose, it is important that the heifers suit your production system, your facilities, your land and you.
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