THE proven Holstein sire rankings, published by AHDB Dairy, present a picture of stability, with little re-ranking amongst the front-runners and the gradual appearance of a few young sires which were formerly in the genomic rankings.
The number one sire remains unchanged, with Mocon retaining his lead with a Profitable Lifetime Index (£PLI) of £738. Transmitting excellent feed savings for maintenance, (Maintenance -20) while being a high milk volume bull (Predicted Transmitting Ability (PTA) 857kg milk), he demonstrates how smaller cows can make efficient milk producers. His daughters are also long living (+0.7 Lifespan).
In second position is S-S-I Shamrock Mystic (PLI £719), an exceptional daughter fertility improver (Fertility Index +19.4) who is level pegging with Larcrest Commend, a bull with the best milk solids package of the top 10, at +0.29% fat and +0.19% protein.
Climbing into the top 10 are fourth placed Cookiecutter Harper (PLI £708), another bull transmitting high weights of fat and protein, and Weigeline Jacey Tabasco (PLI £704), one of the highest milk yield bulls in the top 20 (+1039kg).
New in the proven bull listings is S-S-I Headway Alltime (PLI £701), who transmits excellent resistance to mastitis (Mastitis Index -4).
The final four places in the top 10 are all occupied by previous top 10 sires – View-Home Littlerock (PLI £699), De-Su 11236 Balisto (PLI £679), who has the best TB Advantage of the top PLI sires (+3.3), Co-op Robust Cabriolet (also £679), the best fat transmitter in the top 10 at 39.6kg, and Gen-I-Beq Lavaman (PLI £675), who rates the best for Lameness Advantage (+5.3).
“As with all genetic ranking indexes, the £PLI is regularly reviewed to make sure it keeps pace with industry changes and cattle genetic developments,” says Marco Winters, head of animal genetics with AHDB Dairy. “This month, the new Calf Survival and Lameness Advantage have been added to its formula, as well as Body Condition Score.
“Minor changes to the production component of the index have also been built in, and while the index continues to reward bulls which transmit high weights of fat and protein, those transmitting a higher weight of milk will be less severely penalised than in the £PLI’s previous formula.”
As a result of this particular change, bulls such as Weigeline Jacey Tabasco and Seagull-Bay Supersire have now moved into the top 20 proven sire list for the first time.