Breeding values level the playing field

The production of a dairy cow is influenced by factors such as age, calving season, lactation number and stage, pregnancy status, length of her previous intercalving period (ICP), nutrition, temperature, and management.

- By Dr Bernice Mostert, geneticist, SA Stud Book

Underlying all these is the genetic potential she inherited from her parents, and which plays a decisive role in her production performance. These influences vary among cows that are milked together.

Emma's average 305-day production is, for example, 5 655kg (based on her most recent milk recording figures), with a milk breeding value (EBV) of +54kg. Blommie, milked in the same group, averages only 4 920kg, but her milk EBV is +419kg.

Emma was born in September 2012 and has already completed nine lactations. She calved for the first time at 30 months and has thus far recorded a lifetime production of 49 636kg. This equates to 12,64kg of milk per day of life. She also has a daughter currently in her third lactation.

Blommie was born in July 2020 and is in her second lactation. She calved for the first time at just 20 months and has so far produced 8 128kg (6,57kg per day of life). At the time of evaluation, she had no daughters in milk yet. Since cows typically reach peak production in their fourth and fifth lactations, Blommie’s future potential is still to be realised.

Genetic lines