Check on bull power before it’s too late

07-12-2009 | Not Specified

Buying or leasing fewer bulls than required to run with the cows once artificial breeding has finished will not save money in the long run, says FarmWise's Bridget Ray.

The farm consultant says that with many farmers opting to do less artificial breeding (AB) this season it is important they calculate how many bulls they really need.

"The shorter the AB period, the fewer the number of cows in calf so the greater the number of bulls required."

Ray says the first thing farmers need to do is calculate how many open cows (cows not in calf) there are in the herd. If a farmer has done AB for three weeks they need to do the following calculation: Number of cows in herd multiplied by the three-week submission rate multiplied by the conception rate.

The submission rate can be ascertained by either running the submission rate report off the MINDA herd service software programme or asking the AB technician.

Ray says the conception rate is not so easy. If a farmer has captured all mating data from the previous season and entered it into MINDA they can run the fertility focus report. This will provide them with last season's conception rate. Otherwise they will need to take an educated guess; top farmers are achieving a 60% conception rate so unless the farmer is exceptional he or she should not use a higher figure than this.

Ray says using the above calculation for a 400-cow herd with a three-week submission rate of 80% and a perceived CR of 60% shows: 400 x 80% x60% = 192 in-calf cows.

Therefore 208 cows are not pregnant (400 cows-192 in calf =208).

In the situation where four weeks of AB is being done either run the submission rate report to determine the four-week submission rate or simply apply the following: Of the 208 cows not pregnant, a third of 80% will come on heat and of these, 60%will hold to that AB mating.

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