The calving season is approaching for many grazing-based producers and the new ranking for Spring Calving Index (£SCI), is where they’re advised to look for service sires.

New at the top of this across-breed ranking is the high health and fertility Jersey sire, VJ Groenbjerg Lobo Lobster which has 94 UK daughters contributing to his good milk solids figures and earns an SCI of £583. He also has the highest daughter lifespan of the top 20 sires and high daughter fertility.

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Equally notable on daughter fertility is the Holstein sire, Progenesis Wimbledon (SCI £582), which ranks second. A higher kg milk transmitter than the No 1 placed Jersey, Wimbledon also rates well for udder health.

Holstein sire, Denovo Invictus, stands third and is on a par with Wimbledon for daughter fertility. Just tipping Wimbledon for SCC improvement, he earns an SCI of £571.

In fourth place is the next Jersey sire, VJ Hoeholt Jern James, which transmits a favourable low maintenance feed index, good milk components (both fat and protein) and earns an SCI of £559.

Westcoast Guarantee comes in fifth (SCI £544), with good udder health ratings and the best index for Calf Survival in the top 20.

High fat and daughter fertility are amongst the qualities of the sixth ranking, Holstein-bred Denovo 7921 Atrium, which now has 3718 UK milking daughters contributing to his SCI, which stands at £539.

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In seventh, VJ Haugstedgaard Choko Chief (SCI £533), rates well amongst his Jersey peers for kg fat, but the New Zealand-bred Jersey, Shelby Integ Labyrinth, has the highest milk quality figures of the top 20 sires (fat and protein percent). A favourable mastitis rating helped earn him eighth place and an SCI of £530.

The final two sires in the £SCI top 10 are the Holsteins, FB Kenobi Targaryen (SCI £528), and Aardema Pistolero (SCI £526), Targaryen transmitting the highest production of the top 20 leading sires.

£ACI Producers calving in a block in autumn can refer to the Autumn Calving Index (£ACI) to shortlist their sires, where, retaining Progenesis Wimledon (ACI £678) retains his lead position. This Holstein bull also has the highest combination of fat and protein percentages of the top 20 and leads for Lameness Advantage across the group.

Westcoast River climbs a few places to reach second (ACI £677), and stands out for his good udder health traits and daughter fertility.

A new entry in third, FB Kenobi Targaryen (ACI £664), becomes the highest protein transmitter of the group.

Fourth, Westcoast Guarantee also transmits good udder health as well as calf survival and has an ACI of £660.

Calving ease sire, Aardema Pistolero now ranks fifth (ACI £657), and is followed by the favourable low maintenance feed index sire, Denovo Invictus (ACI £651), which also transmits good daughter fertility.

Seventh ranking Denovo 14744 Ginetta offers good fat and protein production and an ACI of £646 while the No. 1 proven £PLI sire, Genosource Captain, ranks in eighth (ACI £644).

Also, a long-term feature of the £PLI rankings is Pine-Tree CW Legacy, which led the young genomic sires five years ago and now ranks ninth for ACI at £635. Legacy transmits the best lifespan of the top-ranking sires, as well as all-around strong ratings for health and fertility. He stands ahead of high daughter fertility bull, Peak Mauney, that, at £626, rounds off the £ACI top 10.

“These block-calving indexes have been formulated specifically to meet the needs of producers calving in tight blocks in either spring or autumn respectively,” says Marco Winters, head of animal genetics with AHDB. “Some of these herds – particularly those calving in spring – will be using more than one breed, all of which can be compared on these seasonal calving rankings.

“For spring calvers, bulls can be found which tend to transmit less stature, higher milk quality and better fertility, with a strong emphasis on efficiency, durability and ease of management,” he says.

Mr Winters added that £ACI is formulated around the higher production generally required of an autumn block-calving herd and takes account of the cost of winter feed. For this reason, it is recommended producers choose the index to suit their farming system to maximise profitability.