Familiar names amongst the bulls suited for use in spring block calving were published in AHDB Dairy index throughout the year for the increasing numbers of herds which choose the block calving option.

Grazing based herds include the Jersey, Danish VJ Tester, who retains his number one position amongst proven sires of all dairy breeds, with a Spring Calving Index (SCI) of £462.

The number two sire is the first in a run of Holsteins, in the shape of Progenesis Unicorn. Also taking second place in the previous (December 2020) run, he now has an SCI of £447.

Third place is taken by the newcomer, VH Balisto Brixton, whose low maintenance feed costs and low daughter cell counts contribute to his SCI of £439.

Westcoast Guarantee ranked fourth is a familiar feature of these across-breed rankings, and moves up this time, thanks to an SCI of £436.

Stowey Magician rises into the top five for the first time, with an SCI of £433.

Autumn Calving Index (£ACI)

For those looking ahead, it is little surprise that many of the same high efficiency sires feature in the £ACI rankings, with Westcoast Guarantee (ACI £640) taking the lead and Stowey Magician (ACI £612) falling in behind.

Two newly proven bulls tie with Magician in second position, one being the high milk bull, Hurtgenlea Richard Charl, who also leads on £PLI, and level pegging is ABS Crimson, a top fat transmitter.

De-Su 14222 Kenobi, also newly daughter proven, rounds off the top five with an ACI of £609.

“Producers who are block calving have a wide choice of sire types from which to select,” said Marco Winters, head of animal genetics for AHDB Dairy.

“They may also have a particular interest in the new Gestation Length Index (GL) which is published for the first time this April. This is more of a management tool than a breeding aid, and can contribute to bringing later breeders in block calving herds back on track.”