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Fall Sire Selection Decisions
Dairy Pipeline: September 1997
by
Bennet Cassell
Extension Dairy Scientist, Genetics and Management
Virginia Tech
It's time to stock the semen tank for fall breeding season. The August 1997 sire summaries are out and many producers have had their first look at information from the different studs. It helps to know the overall picture like what Net Merit rating it takes to be in the top 20% of each breed (the 80th percentile) or what average PTA milk is for an AI bull. Those figures are in the table below. Farmers should be choosing bulls well above the average values in the table. A good goal would be to buy semen on bulls that are above the 80th percentile for Net Merit. Bulls in the top 20% for Net Merit could then be screened for superiority in traits other than Net Merit without jeopardizing overall progress for this most useful index. Finally, use the semen purchased for this fall's matings. Try to make matings within six months of the selection process.
Table 1. Average PTA's for AI bulls in the August 1997 USDA animal model.
| Breed | Number of AI bulls | Average PTA milk | Average PTA protein | Average PTA fat | Net Merit rating for 80th percentile |
| Ayrshire | 16 | 1074 | 32 | 35 | 141 |
| Guernsey | 29 | 1158 | 43 | 40 | 127 |
| Holstein | 587 | 1442 | 47 | 48 | 172 |
| Jersey | 84 | 1337 | 44 | 47 | 156 |
| Brown Swiss | 47 | 973 | 42 | 34 | 141 |