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SELECTIONS - Fall 2002
Fertility Measures and Perspective


With the challenge of getting cows pregnant these days, added attention is being given to bull fertility in the sire-selection process. While it’s always good to consider sire fertility, it’s important to keep that in perspective.

Variation in fertility by sire usually is a function of variation in the quality of semen produced. However, unlike the herd bull running with the cows, every ejaculate taken from an A.I. sire in a major stud must pass stringent quality standards before being released into inventory. Any collections that fail to meet these high standards are discarded immediately. As a result, what many people don’t realize is that 90 percent of all active-A.I. dairy sires are within ±3 percent of the breed average, according to Estimated Relative Conception Rates (ERCRs) calculated by Dairy Records Manage-ment Systems (DRMS), Raleigh, N.C. The spread of fertility from the very best to the very worst A.I. sire seldom is more than about 10 percent.

Figure 1


In contrast, because of varying environmental and management factors, A.I. representatives routinely see the same batch of semen from the same bull achieve a 60 percent conception rate in one herd and 25 percent in the next. If the 25 percent herd wants to stack the odds in his favor by selecting for higher fertility sires, it’s not such a bad idea. But the reality is that selection for sire fertility only can move that average to 28 or 29 percent at best. To become a 60 percent herd like his neighbor, it’s going to take some changes that are more challenging than mere sire selection. It’s difficult, but we need to stop thinking in terms of high- and low-fertility bulls, and start thinking about above- and below-average. Because of intense quality control at major studs, all A.I. bulls are high-fertility bulls. However, by definition, when you calculate an average, there are above- and below-average groups.

A good comparison is the Cincinnati Bengals, which consistently has fielded a well below-average football team recently. But, they could beat the socks off of most any amateur group of players. They’re simply below average in a highly selected population of professionals.

Just as selecting for high-fertility sires is not going to cure a herd’s breeding problems, using a bull that is a few percentage points below the industry average is not going to send the farm into foreclosure. If he’s got the genetics you want, don’t be afraid to use him; he’s still a safe bet to get cows pregnant. Keep the value of genetics and fertility in perspective, or you may be throwing out the baby with the bath water.

Fertility Values for Select Sires Lineup 

	                       ERCR	Rel	TPI/JPI
* 7HO5192 WAHOO*TV #		+3	95%	+1276
* 7HO5491 MOZER*TV		+3	97%	+1506
* 7HO5650 ALLOY*TV #		+3	81%	+1476
  7HO6247 ELATION*TV #		+3	96%	+1571
* 7HO5206 CLARK*TV		+2	98%	+1234
* 7HO5211 BLACKBART*TV		+2	96%	+1162
* 7HO5484 BOONE*TV		+2	88%	+1474
* 7HO5687 FORBIDDEN*TV		+2	94%	+1608
* 7HO5760 LINK*TV		+2	61%	+1536
* 7HO6250 EMERSON*BL, TV #	+2	99%	+1571
* 7HO8419 APPROVAL*TV #		+2	98%	+1305
* 9HO2393 SHAWNEE*CV #		+2	77%	+1249
* 7HO4951 MEADOWLANE*TV		+1	94%	+1414
* 7HO5112 BRETON*TV		+1	98%	+1331-M
  7HO5157 DURHAM*CV #		+1	99%	+1590
  7HO5255 KENNETH*TV		+1	98%	+1320
* 7HO5386 CHIL*CV		+1	97%	+1292
* 7HO5408 CURTIS*CV		+1	95%	+1459
* 7HO5412 SOVEREIGN-RED*TV	+1	81%	+1076
* 7HO5708 BLITZ*TV		+1	94%	+1425
* 7HO5710 DANE*TV		+1	92%	+1639-M
* 7HO5724 TALISMAN*TV		+1	52%	+1376
* 9HO1878 WINDSOR*TV		+1	98%	+1313-M
* 7JE0290 BARBER		+2	93%	+148
  7JE0386 DECLO #		+2	95%	+188
* 7JE0488 BARKLY #		+2	71%	+212
* 7JE0424 FREEDOM #		+1	96%	+191
* 9JE0153 FLYER			+1	85%	+232
* 9JE0172 KLASSIC		+1	58%	+230


#SUPERIOR SETTLERs offer the optimum in fertility, based 
 on high-tech laboratory evaluations and monitored field trials.

*Semen available for export to Canada.




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