Introduction of MSPD
August marks the culmination of years of research by the Council on Dairy Cattle Breeding (CDCB), USDA’s Animal Genomics and Improvement Laboratory, Dairy Records Management Systems, Holstein Association USA, National Dairy Herd Information Association (DHIA), and National Association of Animal Breeders (NAAB) into objectively measuring cow milking speed, standardizing complex data, and developing a new genetic selection tool. The result of this work is the new milking speed (MSPD) trait for Holsteins that will become available to the industry in August.
While milking speed is already measured in other countries and by CDCB in other breeds, MSPD is one of the only such traits that uses objective measurements to calculate the PTAs. In-line sensors in milking equipment make this possible. This technology records milk weights in combination with milking time to measure an animal’s true production per minute. CDCB then applies standardization factors to the data depending on the equipment manufacturer so that the data can be compared appropriately in the evaluations. MSPD will first be available for Holsteins due to data availability. PTAs for the trait will estimate the average pounds of milk an animal’s offspring will produce per minute in a conventional milking system as a standardized value.
Parlor turns per hour are a big factor of farm and labor efficiency, and because MSPD is so heritable (42%), it offers a real option for farmers to breed a more consistent and efficient herd.
Base change for calving traits
Another significant update coming in the August evaluations is the routine five-year base change for the four calving traits: sire calving ease (SCE), daughter calving ease (DCE), sire stillbirth (SSB), and daughter stillbirth (DSB). CDCB calculates all four traits for Holsteins and SCE and DCE for Brown Swiss.
When the base is changed, the starting line from which we measure genetic progress (through PTAs) is reset so that values are more representative of contemporary animals and environments. While other PTAs are measured using a cow base year, calving traits are aligned with the male population. For SCE and SSB, beginning in August, the genetic base is adjusted to bulls born in 2020. DCE and DSB require looking one generation prior to maternal grandsires, so the base birth year for this trait pair is bulls born in 2015.
While all other traits experienced the base change in April, the calving trait group’s base change was delayed due to unanticipated results at that point. A full investigation confirmed the results were correct, albeit unexpected, and primarily linked to the continued decline in difficult calvings in Holsteins that has constrained the spread of PTA values.
The 2025 base change is the first time calving traits have undergone this routine process since updates to the model were implemented in August 2020. Unlike other selection tools that rely solely on a genetic base population, calving traits incorporate both a genetic base and a phenotypic base. This phenotypic reference allows the traits to incorporate environmental differences, male and female calf data, consideration for the categorical nature of the traits, and more while being expressed on a real-world scale.
Interpret calving trait PTAs as the likelihood of a difficult calving or a stillbirth from a certain mating. For example, mating a cow to a bull with a SCE PTA of 1.87% is expected to result in a difficult calving just under 2% of the time. A difficult calving is defined as a score of 4 or 5 on the five-point calving ease scale, which is used to report calving data.
Comparing PTAs from April and those expected in August highlights variation in the traits over the past five years. Holsteins are having fewer difficult calvings and Brown Swiss are having slightly more difficult calvings, as reported by SCE. This means Holstein SCE PTAs will be a little lower and Brown Swiss SCE PTAs will be a little higher in August due to the new base population. Since calving traits are included in Lifetime Net Merit (NM$) as the Calving Ability $ subindex, some variation in NM$ linked to this base change is expected.
For both breeds – and any other breeds interested in adding these traits in the future – the need for routine data collection remains imperative. Genetic evaluations calculated by CDCB for calving traits and all others require contemporary data regularly flowing from farms across the country into the National Cooperator Database. Now is a great time to review standard operating procedures for calving data collection on-farm and to confirm data flow into the national database through the collaborative industry network supported by CDCB.
More information about the calving traits investigation, what to expect in August, and MSPD for Holsteins is available at www.uscdcb.com.
