On average, Friesians have the highest milkfat breeding value.

Milkfat breeding values are estimated from information derived from herd testing. The production information which is collected for a cow during her first 6 lactations is run through a test day model. The test day model compares each animal to the other animals in her contemporary group (all animals with the same age group (2, 3, 4, 5 and mature), season of calving, test day and test year). Other main adjustments including removing the impact of permanent environmental effect (e.g. effect of rearing to two years of age), days in milk at test, hybrid vigour and induced calving.

The method to estimate breeding values also includes the genetic relationship between individuals in his or her pedigree who may have left better or worse than average progeny for milkfat, protein or volume performance.

More detail? Description of Genetic Evaluation System View PDF (43 kb)

On average, Friesians have the highest liveweight breeding value.

Liveweight breeding values are estimated from information derived from weigh scales and Traits Other than Production (TOP) 2 year old weight scores. This is information is then run through a single trait model, where each animal is compared relative to her contemporary group (all animals with the same age (e.g. lactation 1, 2, 3, 4-6 or >6), year, season of calving) with other main adjustments including permanent environmental effect (eg. effect of rearing to two years of age), age and hybrid vigour.

The method to estimate breeding values also includes the genetic relationship between individuals in his or her pedigree who may have left equal, smaller or larger than average progeny for liveweight.

On average, Jerseys have the highest fertility breeding value.

Fertility breeding values (% calving within 42 days of the start of calving) are calculated from information derived from herd recording software such as MINDA and MISTRO, herd testing and Traits Other Than Production (TOP) assessments. Eight individual predictor traits are currently used to estimate the fertility breeding value:

• Presented for mating within 21 days of the planned start of mating (PM21) in lactation 1, 2 and 3
• Calving rate in the first 42 days after the planned start of calving (CR42) in lactation 2, 3 and 4
• Volume in a cows' first lactation
• Body condition score (BCS) in a cows' first lactation at 60 days in milk.

All these traits are included as they are correlated (negatively or positively) with overall fertility. For instance, cows with genetically higher BCS have improved fertility, cows with genetically higher milk volumes have poorer fertility, and cows that are presented for mating within 21 days of the planned start of mating have improved fertility. Information from all these predictor traits are then run through a multi trait model, where each animal is compared relative to her contemporary group (all animals with the same age (e.g. lactation 1, 2, 3, 4-6 or >6), year and season of calving) with other main adjustments including permanent environmental effect (e.g. effect of rearing to 2 years of age), age and hybrid vigour. Again, the method to estimate breeding values also includes the genetic relationship between individuals in his or her pedigree who may have left better or worse than average progeny for fertility performance.

More detail? Description of Genetic Evaluation System View PDF (55 kb)

Historically genetic gain in this trait has been minimal, but this is predicted to increase following the inclusion of the BCS in Breeding Worth (Feb, 2016).

The body condition score breeding value is calculated using records collected on two year old heifers. These records are collected in early lactation, and the majority of them come from CRV and LIC progeny test herds.

Raw scores are converted into a day 60 lactation equivalent, and then enter the AE model. 

As a result of a recent review (see below) a ‘breed neutral’ adjustment has been applied to this breeding value. This means that the breed average for this trait is 0 across all breeds.

• BCS Breeding Value: 2014 Review

  NZAEL have completed a thorough review of the methods that are used to estimate a cows breeding value for body condition score. The review had three key focus points:

  1. To investigate whether BCS data collected on two year old heifers provided enough information to predict an animal’s lifetime genetic merit i.e. were genetically thin heifers also genetically thin older cows.
  2. To look at the correlation of early and late lactation BCS data, and determine whether data collected earlier in the season can be used to accurately predict late lactation body condition.
  3. To look into the breed differences which were apparent in the BCS breeding value, and determine if they were correctly representing the genetic differences in BCS between breeds.

  This review showed that the existing approach used to predict genetic merit for BCS was generally sound, and there was a strong genetic relationship between young and old cow BCS and early and late lactation BCS, particularly within breeds. However, it was found that when looking at breed averages, the differences in the BV were not consistent with actual observations in late lactation. As a result of these findings, and because the economic value for this trait is largely based on late lactation BCS, NZAEL began investigating ways in which this breed effect could be removed from the breeding value.

  Following industry consultation and a Technical review, the Standing Advisory Committee and the NZAEL board approved a method of removing these breed differences, which involves applying a ‘breed neutral’ adjustment. This process will strengthen the BCS breeding value, making it a more accurate prediction of an animal’s genetic merit for this trait.