animal health
A regular column from Rochester Vet Practice
Understand your herd’s calving pattern What happens next will affect the next joining. Many of you will be just starting your spring calving or about to. Your upcoming calving pattern will have a big impact on the next joining. Cows and heifers that calve early have a significantly higher chance to get in calf early compared to their later calving counterparts. Later calving cows will also be at greater risk of being empty at the end of joining. Table one demonstrates this. These figures are taken from the InCalf study. Now is a good time to sit down and look at what your likely calving pattern will be this spring. This can be worked out by looking at your joining information and pregnancy testing results. The accuracy will be dependent on how good your records are and the stage and methods that you used for pregnancy testing. These won’t include your rising two-year-olds normally. Many of the software packages available can produce this for you but it is not too difficult to produce manually. From this list your calving can be split into four three-week blocks. This will give you an impression of what impact your calving pattern will have on your next joining. Table two shows how calving patterns were for the farms in the InCalf study. Changing your calving pattern can be difficult to do immediately but there are ways you can have a positive impact. If you normally induce your later calving cows, plan to do it early in batches so that you can push as many cows into the first and second batch of three weeks rather than the third and fourth batch of three weeks. Otherwise it is likely these cows will be late or empty again next year. All of this should be done in consultation with your vet to minimise the risks and to maximise the benefits. Now is the time to act rather than late September/early October. If you plan to buy-in cows make sure that they are early calving. Look at selling late calving cows especially if they are poor producers and you have too many cows. Another tactic is to join your maiden heifers before the milking herd. This gives more time for them to break in to the milking routine and the herd’s pecking order. Two-year-olds take 10 to 14 days longer to start cycling after calving so calving them earlier helps overcome this. If your two-year-olds are slow to calve you should check that they are well-grown and meet target weights. Bulls may also be the reason for not calving early. By Mitch Crawford, Rochester Vet Practice 12
August 2013
Picture: Jayme Lowndes
Table one Calving to Mating Start Date Six-week in-calf rate
Not in-calf rate
More than 12 weeks
76%
5%
9 – 12 weeks
71%
6%
6 – 9 weeks
61%
9%
3 – 6 weeks
51%
13%
Less than 3 weeks
22%
23%
Average farms achieve
Top farms achieve
Calved by week 3
51%
61%
Calved by week 6
77%
94%
Calved by week 9
94%
100%
Table two