WestVic Dairy News - January 2011 Edition
Summer heifer care
Jo Crosby, DPI Warrnambool
Well grown heifers produce more milk, are easier to get in calf and last longer in the milking herd than heifers that suffer growth checks during early life. But what is the definition of a well grown heifer and how do we produce them?
What is a well grown heifer?
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Well grown heifers will weight at least 85 percent of the weight of your mature cows at the time of their first calving. So, if the average weight of mature animals in your herd is 600 kg, your heifers should weigh at least 510 kg at first calving. If you have a jersey herd with average mature weight of 440 kg, then first calvers should weigh at least 374kg.
Another key target is weight at joining. Well grown heifers will weigh at least 55 percent of their mature weight at joining, at around 15 months of age.
It is important to remember that the youngest heifer in the group must reach the same target weight at joining as the oldest, so these animals must grow at a more rapid rate. See Table 1 for a comprehensive list of target weights.
So, you do need to have an idea of the average liveweight of your herd to know what your targets are for the heifers. If you have never weighed any of the mature cows, the weight of culls will give you some indication.
Table 1: Recommended minimum heifer weights by age*
| Age (months) |
440 kg mature Jersey |
600 kg mature Holstein – Friesian or crossbred |
700 kg mature Holstein – Friesian or crossbred |
|---|---|---|---|
| 3 | 80 | 100 | 100 |
| 4 | 95 | 120 | 124 |
| 5 | 110 | 140 | 148 |
| 6 | 125 | 160 | 172 |
| 7 | 140 | 180 | 196 |
| 8 | 155 | 200 | 220 |
| 9 | 170 | 220 | 244 |
| 10 | 185 | 240 | 268 |
| 11 | 200 | 260 | 292 |
| 12 | 215 | 280 | 316 |
| 13 | 230 | 300 | 340 |
| 14 | 245 | 320 | 364 |
| 15 | 260 | 340 | 388 |
| 24 | 375 | 510 | 595 |
*Incalf – Heifers:Big girls XL
While weighing the calves every three months is to check that these targets are being met, many farmers do not have the facilities to do this. Girth tapes are useful while calves are small, but become less accurate once they reach 200 kg liveweight.
Wither height is an alternative measurement and it is a relatively simple exercise to mark target heights on a plank of wood and fix this in the drenching race or crush. Calves can then be measured whenever they are in for drenching, vaccination or other procedures. See Table 2 for wither height targets.
Table 2: Wither heights*^
| Wither height (cm) | ||
|---|---|---|
| Age (months) | Holstein-Friesian | Jersey |
| 6 | 100 | 90 |
| 7 | 105 | 95 |
| 8 | 108 | 100 |
| 9 | 112 | 103 |
| 10 | 115 | 106 |
| 11 | 117 | 108 |
| 12 | 118 | 110 |
| 13 | 120 | 111 |
| 14 | 123 | 112 |
| 15 | 125 | 114 |
| 16 | 126 | 115 |
| 17 | 127 | 117 |
| 18 | 128 | 118 |
* Ref InCalf.
^ the highest part of a calf's back, lying at the base of the neck above the shoulders
How do we produce well grown heifers?
The key to growing out heifers well is nutrition, and their first summer is a critical period.
For heifers to reach their target live weights for mating, they need to grow at a steady rate of 0.6 to 0.8 kg per day and this can only be achieved when they are fed a diet high in both energy and protein. See table 3 for details of heifer requirements.
Table 3: Energy and protein requirements for heifers growing at 0.7 kg / day
| Liveweight | Energy required (MJ/day) |
Crude protein required (%) |
|---|---|---|
| 100 | 40 | 17 |
| 200 | 61 | 16 |
| 300 | 82 | 15 |
| 400 | 97 | 13 |
| 500 | 105 | 13 |
Summer pasture is low in energy and protein and can not fully supply the needs of young growing animals. Supplements will be required. High protein supplements include legume based hays and silages such as lucerne, vetch and clover, or concentrates such as lupins, peas and oilseed meals.
A high protein heifer rearing pellet or meal is a convenient method of supplying the nutrients required, but make sure the heifers also have access to sufficient roughage in the form of pasture, silage or hay.
Dairy farming has become more complex and demanding and heifer rearing is a task that often becomes lower on the priority list once the calves are weaned. If you lack the time to give your heifers the attention they need, perhaps consider sending them to a specialist heifer rearer.
A heifer must reach her second lactation before she pays off her rearing cost. Well grown heifers are more likely to survive in the herd beyond their second lactation and start paying a dividend on your investment.
If you would like further information on heifer rearing contact Jo Crosby on (03) 5561 9911 (Warrnambool DPI) or Ann Mc Dowell on (03) 5557 5805 (Camperdown DPI).
