By Grace Thomas, M.Agr.Sc. P.A.S.
Heifers are the future herd. Despite this, they are often the group of animals that are overlooked by producers until it is time for breeding.
Any mismanagement before breeding can result in delayed breeding and lower the heifer’s future yield.
The cost of heifer rearing is the second largest cost on a dairy farm, and it takes on average one and a half lactations before a heifer returns a profit. Consequently, lowering age at first calving to 22-24 months of age can help producers start making a return on their investment earlier.
In order to achieve an age of first calving below two years of age, every stage of the heifer’s life needs to be well managed. You must monitor her growth and animal nutrition closely to avoid any setbacks.
HOW CAN EARLY CALVING BE ACHIEVED?
The point at which a heifer reaches puberty is determined by her weight and stature, not her age. The target weight for each stage of life is based on the percentages of the mature bodyweight of the animal.
Table 1 lists the target percentage of the mature body weight versus the age of the heifer. As the heifer growth rate correlates closely to the frame size, you can determine heifer weight by measuring the heifer’s height at the withers.
Table 2, lists the recommend ranges of body weight and wither height for a Holstein heifer.
This table can be a guide to ensure heifers reach each milestone weight for their age.
If any heifers fall behind or get overfit, you should separate them out and give them the correct nutrition to help them get back on track.
It is vital to remember these numbers are target weights, not averages. It is crucial that heifers receive the best nutrition at every stage of their life. Table 3 outlines a brief overview of the requirements and targets for each age group.
For a calving age of 24 months, the heifer needs to reach puberty by 12 months of age. To help maximize fertility, it is better to allow the heifer to have two or three cycles before breeding.
Condition for breeding is important, with animals that are overfit tending to have poor fertility. A heifer that has received more than four artificial insemination services is also more likely to not complete its first lactation. Therefore, it may be cost-effective to stop serving heifers after two cycles.
ADVANTAGES OF EARLY CALVING
There is a strong correlation between heifer age at first calving, lifetime yield and longevity. Heifers that calve at 22-24 months produce more milk in their lifetime than heifers that calve at an older age. This, of course, translates to greater income.
The younger calving animals also tend to have greater longevity. Increasing the longevity of the animals in a herd can lead to a cost-saving, with less animals needed for replacements. In addition, any surplus replacements can be sold to generate extra income.
With the average cost of rearing a heifer estimated at between $1,800- $2,500 (£1,800, €1,400), it makes sense to lower age at first calving, as it can reduce feed and management costs for rearing.
Also, the earlier a heifer can join a herd, the earlier she can start paying back the cost of rearing. Table 4 shows the rearing cost for every month after 24 months of age.
AGRI-KING CAN HELP WITH HEIFER REARING
In recent years, the age at first calving has been decreasing in most countries, though improvement is still possible.
The USA is currently averaging 25 months. In the UK, spring calving animals averaged at 30 months, and autumn calving at 26 months. In Ireland, 69% of heifers had an age of first calving between 22-26 months.
Agri-King can help lower this age at first calving in a herd. Using Agri-King’s unique ration programme, combined with our vitamin trace mineral packs and enzyme technology, Agri-King can work with a producer to help heifers achieve their target weights and attain an earlier calving age.
Agri-King Products available for heifers in the US include Heifer Pre-mix with Monensin, Heifer Fortifier, Tri-Lution®, Super Calf Tone®. For Agri-King LTD market, Tri-Lution® is available for the pre-weaned calf. Super Micro, VT Max and Ru-Max are options for the weaned animal. AK
