Breeding Strategy: Selecting The Right Index

Navigating the vast landscape of genetic possibilities is a crucial endeavor when selecting bulls to shape the future of your herd. Genetic indices emerge as indispensable tools in this process, serving as the compass that guides breeders toward the creation of their next generation. The significance lies not just in using any index, but in choosing the one that mirrors the vision you have for the ideal cow within your herd.

Understanding that genetics operates on a cumulative basis underscores the importance of selecting bulls with a comprehensive view in mind. While we caution against the limitations of single-trait selection, leveraging a genetic index becomes the initial stepping stone in this intricate journey. It unveils a nuanced perspective, allowing breeders to explore bulls that might otherwise be concealed by an unimpressive score in an index that may not capture their true genetic potential.


£PLI (Profitable Lifetime Index):

£PLI is a comprehensive index designed to maximize the profitability of a cow over its lifetime. It considers a range of traits, including milk production, fertility, and health. This index is well-suited for breeders who prioritize long-term profitability and sustainability in their herds.

  • Focus: Overall profitability, with a focus on health traits and reducing overall size.
  • Components: Combines production, health, and fertility traits.
  • Application: Ideal for breeders seeking a comprehensive index that maximizes profitability over the lifetime of the cow.

£PLI is evaluated by AHDB, learn more about the index here.

SCI (Spring Calving Index) and ACI (Autumn Calving Index):

SCI and ACI are tailored for seasonal calving systems. They consider specific traits that align with the demands of spring or autumn calving, optimizing the genetic selection for cows in these distinct production systems.

  • Focus: Seasonal calving systems.
  • Components: Tailored to traits suitable for specific calving seasons.
  • Application: Relevant for breeders in systems with distinct calving seasons, helping to optimize traits for those specific times.

Both £SCI and £ACI are evaluated by AHDB, click the links to learn more.

GLOBAL Indices

TPI (Total Performance Index):

TPI is commonly used in the U.S. and places emphasis on overall performance. It considers a combination of production, conformation (body structure), and health traits. This index is valuable for breeders looking for a balanced approach that addresses both the cow's physical traits and its ability to produce efficiently.

  • Focus: Overall performance, promoting balance and production.
  • Components: Considers production, conformation, and health traits.
  • Application: Suited for breeders looking for a balanced approach that includes production, physical traits, and health.

TPI is a registered trademark of and produced by Holstein USA.

NM$ (Net Merit):

NM$ is a U.S. index focusing on net profit and takes into account factors such as milk production, health, and fertility. This index is suitable for breeders aiming to optimize both economic factors and the overall health and reproductive capabilities of their herd.

  • Focus: Emphasizing lifetime profitability.
  • Components: Prioritizes production, health, and fertility.
  • Application: Useful for breeders looking for an index that considers economic factors, health, and fertility.

Net Merit is evaluated by the CDCB, click here to learn more.

LPI (Lifetime Profit Index):

LPI is utilized in Canada and integrates production traits with durability factors. It's particularly beneficial for breeders who are interested in the long-term success of their herds, as it accounts for a cow's ability to maintain productivity over an extended period.

  • Focus: Combining production, conformation and durability.
  • Components: Integrates traits related to conformation, production and longevity.
  • Application: Useful for breeders interested in a long-term view, focusing on both production and the cow's ability to thrive over time.

LPI is evaluated by Lactanet in Canada, click here for more information.


EBI (Economic Breeding Index):

Economic Breeding Index (EBI) is a tool that aids Irish dairy farmers in selecting and breeding animals that contribute positively to the economic success and sustainability of their herds. It reflects the industry's emphasis on balanced breeding, considering both production and non-production traits for the long-term benefit of the farming operation.

  • Usage: Used in Ireland for evaluating the genetic merit of dairy cattle, particularly Holstein Friesian and Jersey breeds.
  • Traits: EBI incorporates a range of production, fertility, health, and conformation traits to provide a holistic evaluation of an animal's genetic potential. The key traits included in EBI are:
    • Production Traits: Milk production (kg), fat yield (kg), protein yield (kg).
    • Fertility Traits: Calving interval (days), survival (lifespan of the cow in the herd), and daughter fertility.
    • Health Traits: Somatic cell count (indicative of udder health and mastitis resistance).
    • Conformation Traits: Body conformation and udder traits, contributing to the overall structure and functionality of the cow.

Economic Breeding Index (EBI) is evaluated and published by ICBF in Ireland, click here to learn more.

BW (Breeding Worth):

Breeding Worth is a comprehensive breeding index used in New Zealand for evaluating the genetic merit of dairy cattle, particularly Holstein-Friesian and Jersey breeds.

  • Usage: Used in New Zealand for evaluating the genetic merit of dairy cattle.
  • Traits: Breeding Worth incorporates various traits, including production traits (milk, fat, protein), fertility traits (calving difficulty, daughter fertility), and health traits (mastitis and somatic cell count). It aims to estimate the overall genetic worth of an animal in terms of its contribution to farm profitability over its lifetime.
    • Production Traits: Milk production (kg), fat yield (kg), protein yield (kg).
    • Fertility Traits: Calving ease, calving interval (days), and daughter fertility.
    • Health Traits: Somatic cell count (indicative of udder health and mastitis resistance).
    • Conformation Traits: Body conformation and udder traits, contributing to the overall structure and functionality of the cow.
  • Importance: Breeding Worth is a comprehensive index that helps New Zealand dairy farmers select animals that not only excel in milk production but also contribute positively to fertility, health, and overall farm economics.

Breeding Worth (BW) is evaluated and published by DairyNZ, click here to learn more.

Cogent has an extensive range of genetics specialising in grazing with our partnerships with LIC, Eurogene and Dovea. Take a look at our line up, here. If BW is more your style, you may wish to explore LIC UK's line up of market-leading genetics.


When choosing an index, it's essential to align it with your breeding goals and priorities. Consult with a genetic consultant or industry expert to tailor your strategy based on the specific needs and objectives of your herd. Additionally, staying informed about the latest developments and updates in genetic indices can help you make informed decisions for the long-term success of your breeding program.

In essence, genetic indices provide a strategic entry point into the intricate world of breeding. They offer breeders a systematic approach to align their selection with the broader goals of their herd. By recognizing the cumulative nature of genetics and the multidimensional qualities that contribute to a cow's excellence, breeders can embark on a journey of continuous improvement, ensuring that each generation builds upon the genetic successes of the past. The wise use of genetic indices acts as a beacon, guiding breeders toward the realization of their vision for an ideal and thriving herd.

You can explore the Cogent Difference, regardless of your breeding priorities. Our diverse range of genetic solutions is tailored to meet your unique needs. To delve deeper into our offerings, connect with your local Genetic Consultant. Alternatively, feel free to reach us through FREEPHONE at 0800 783 7258 or drop us an email at

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