New Sire Selection Indexes Highlight Top Bulls for Autumn and Spring Calving

United Kingdom (UK) 15.08.2024

Source: DairyNews.today

Producers focused on autumn calving with an emphasis on genetic improvement are being encouraged to base their sire selection on the Autumn Calving Index (£ACI). This index, which is tailored to the specific needs of autumn calving herds, offers a more accurate reflection of the economic factors that affect these systems, particularly the winter milk price and associated feed costs.

New Sire Selection Indexes Highlight Top Bulls for Autumn and Spring Calving

The £ACI, similar in principle to the widely used Profitable Lifetime Index (£PLI), places a greater emphasis on daughter fertility and the costs related to producing a higher proportion of winter milk. This refined focus has led to the emergence of a distinct ranking of bulls, topped by Winstar Mendel P, whose ACI of £719 underscores his strong Predicted Transmitting Ability (PTA) for fat weight and a solid Maintenance Index.

Winstar Graziano, ranking second with an ACI of £713, is noted for his high milk solids and lower somatic cell count transmission. Peak Mauney follows closely in third place with an ACI of £705, driven by his excellent ratings for both lifespan and daughter fertility.

Progenesis Wimbledon, ranked fourth, boasts the best daughter fertility in the top 20, with an ACI of £699. Meanwhile, Aardema Pistolero and Denovo Invictus round out the top five, with ACIs of £693 and £692 respectively. Notably, Denovo Invictus excels in daughter fertility and has a high reliability, with 2,430 UK milking daughters.

The Spring Calving Index (£SCI) also presents a competitive ranking, with Progenesis Wimbledon leading the way with an SCI of £601, largely due to his exceptional daughter fertility. Close contenders include Winstar Mendel P and Denovo Invictus, with SCIs of £599 and £598 respectively.

Marco Winters, Head of Animal Genetics at the Agriculture and Horticulture Development Board (AHDB), advises producers calving in a tight block of up to 12 weeks to prioritize these indexes. He emphasizes that both £SCI and £ACI are designed as across-breed indexes, facilitating direct comparisons between breeds when using these specific rankings.

However, Winters cautions against comparing these indexes with each other or with £PLI, as each index is calculated on its own genetic base and should be compared only within its relevant group.

These rankings are instrumental for producers seeking to optimize their breeding strategies, particularly for those navigating the nuances of seasonal calving in either autumn or spring.