Autumn Calving Index (£ACI)

The Autumn Calving Index (£ACI) is suitable for autumn block-calving herds and reflects the costs of feeding for winter milk production and the higher milk price per litre received at that time of year.

It favours a greater weight of milk than £SCI but has less emphasis on fat health and protein percentages. £ACI has a slightly greater emphasis on female fertility than £PLI, which is for year-round-calving herds.

£ACI is an across-breed index, which means you can use it to compare bulls of different breeds.

The £ACI:

  • Promotes milk quality, with more weight on volume than the £SCI
  • Places strong emphasis on fertility
  • Selects for reduced maintenance cost
  • Improves udder and leg health
  • Places strong emphasis on longevity
  • Promotes easier calving
  • Improves functional type
  • Feet and Legs and Udders

The £ACI value represents the additional profit a high £ACI bull is expected to return from each of its milking daughters over her lifetime compared with an average bull of zero £ACI.

The pie chart below shows the breakdown of the individual weightings of traits in the £ACI.

Weightings of the Autumn Calving Index

The Spring Calving Index (£SCI)

The Spring Calving Index (£SCI) is an across-breed genetic ranking index developed to breed cows that produce lower volumes of milk of a higher quality. It’s specifically for spring block-calving herds, which rely heavily on grazed grass and calve in a tight (12 weeks or less) block.

This index is expressed as a financial value and represents the additional profit a high £SCI bull is expected to return from each of its milking daughters over her lifetime compared with an average bull of zero £SCI.

Both the £SCI and £ACI Indexes emphasise important genetic areas are maintained or improved, e.g. fertility (calving interval and non-return rate), somatic cell count (SCC) and milk solids. While increased emphasis on the maintenance cost by reducing cow liveweight will give the daughters of high £SCI bulls improved efficiency suited to a spring-calving, grazing-based system.

As an across-breed index, you can use it to compare bulls of different breeds.

The Spring Calving Index (£SCI):

  • Promotes milk quality rather than volume
  • Places strong emphasis on fertility
  • Selects for reduced maintenance cost
  • Improves udder and leg health
  • Places strong emphasis on longevity
  • Promotes easier calving
  • Protects functional type
  • Feet and Legs and Udders

The pie chart below shows the breakdown of the individual weightings of traits in the £SCI.

Weightings of the Spring Calving Index