Whole herd genotyping by farmers for management purposes becomes more and more popular. The basic principle for dairy farmers is to analyse the DNA of the female animals born on their farms . Then this data is used to improve the selection process.
The benefit of whole herd genotyping for dairy farmers management is demonstrated by the prediction power of young stock for differences in later phenotypic performance. The genomic informations presents new opportunities for the herd management. vit offers the customers to make use of the genomic information for boosting the farm efficiency.
Under the roof of German Holstein Association (DHV) and genetic evaluation center vit the german Holstein herdbook organizations introduced the project KuhVision in June 2016 to achieve a reference population of 120.000 cows from whole herd genotyping within 3 years until June 2019. The goal of 550 participating herds with average 200 milking cows was reached already at the beginning of 2017. Meanwhile over 50,000 cows are in milk and provide phenotypes.
Comparison of 1st lactation milk yield (kg, 305 d) for classes of gEBV milk kg (n total = 26,877). The difference in gEBV milk yield between the two extreme quantiles is 1,349 kg. This corresponds to 1,495 kg difference in milk production 1st lactation (305d) or 8,340 versus 9835 kg compared to the average production of 9,093 kg for all cows. There is variation within the groups but the overall expectation that within bigger groups of cows in same management conditions gEBV differences reflect differences in phenotypic performance is fulfilled.
The figure gives the differences in somatic cell count (SCC) from the average of first 3 test days in 1st lactation for the 4 classes of gRZS (relative breeding value SCS, low SCS = higher RZS). A difference of 22 relative points for gRZS (1.85 genetic standard deviations) between the upper and lower quantile results in 97,000 cells/ml milk phenotypic difference or 111,000 versus 208,000 cells (average of 42,617 cows: 153,000 cells/ml).
Even for a low heritable fertility trait like non-return-rate-56days (NR56) phenotypic differences between classes of gEBV NR56 were big. 20.9 points of gEBV correspond to almost 11% of phenotypic difference NR56 in first lactation cows (47% versus 58% NR56).
For farmers conformation gEBV – besides animal selection – have a special importance in mating strategy. The use of mating programs including the definition of cow individual needs is widespread in German Holsteins. Most cow individual needs are defined for conformation traits. But for non-genotyped heifers there is no classification result or EBV based on own performance. Therefore gEBVs offer the first time a good information base to define heifer needs for individual mating. A good prediction of differences in phenotype is important to convince farmers for the benefit of whole herd genotyping.