The Genetic Evaluation Board (GEB) held its regular semi-annual meeting on Wednesday, March 5, 2014 at the Best Western Plus Hotel Universel in Drummondville, Québec, which was preceded the day before by its regular Open Industry Session.
The following is a summary of the discussions and recommendations from the GEB, which will be considered by the Canadian Dairy Network (CDN) Board of Directors at its next meeting scheduled for May 7-8, 2014.
- Art Pruim from Plum Blossom Dairy in Osler, Saskatchewan, was elected as Chairman of the Genetic Evaluation Board for 2014.
To be implemented for the April 2014 release, the GEB recommended that CDN apply an adjustment to traditional progeny proofs for production and major type traits for Holstein sires that have more than 30% of their milk-recorded daughters resulting from embryo transfer (ET). This adjustment, aimed at accounting for the preferred treatment of daughters, will reduce proofs by 55, 3.8 and 1.8 kg for milk, fat and protein, respectively, and by .5 for each of Conformation, Mammary System, Feet & Legs, Dairy Strength and Rump for every 10% ET above 30%. While relatively few sires will be affected by this adjustment, the accuracy of genomic evaluations for all animals is expected to be improved.
Based on a proposal received from CDN, the GEB supported the exclusion of insemination data collected by DHI agencies from the calculation of Semen Fertility ratings for bulls that have any reported breedings using sexed semen during each of the 12-month periods included in the analysis. This additional process for data editing will be implemented by the monthly analysis released in June 2014 at the latest and results provided to the A.I. member organizations. Unless properly reported, the inclusion of inseminations using sexed semen systematically biases the bull’s rating for Semen Fertility downwards, leading to an inaccurate evaluation. Going forward, DHI agencies are working to improve the completeness of recording breedings
with sexed semen at the farm level and more A.I. organizations may submit insemination data directly to CDN.
In an effort to maximize the accuracy of cow evaluations, the GEB recommended the
implementation of a proposed methodology for adjusting the degree of deviation that an evaluation can have from the cow’s pedigree index based on the proof for their sire and maternal grandsire. This adjustment, which will apply to the production and type traits as well as Somatic Cell Score, has a more significant impact on high ranking cows that are not genotyped compared to those with a genomic evaluation. Implementation by CDN will apply to breeds with genomic evaluations, namely Holstein, Ayrshire, Jersey and Brown Swiss, and is targeted for the August 2014 release.
As part of the final stages prior to the implementation of official Mastitis Resistance evaluations for the Holstein, Ayrshire and Jersey breeds in August 2014, the GEB recommended that (1) the Mastitis Resistance index combine Clinical Mastitis in first lactation, Clinical Mastitis in later lactations and Somatic Cell Score with equal weights on each, (2) official genomic evaluations be computed for the Holstein breed, and (3) the minimum criteria for an official progeny proof 2 be the same as those applied for Daughter Fertility based on the number of daughters and herds with data for Clinical Mastitis in first lactation and the corresponding Reliability. A table
outlining the minimum criteria for an official traditional progeny proof for each trait within breed is available on the CDN web site. In accordance with the August 2014 genetic evaluation release, CDN will launch a new page providing details associated with evaluations for “Health” traits that will be linked to the Genetic Evaluation Summary page for each progeny proven sire.
The GEB continued the discussions that ensued during the previous day’s Open Industry Session following up on the CDN Strategic Planning Session and meeting of the Board of Directors. Of particular interest was the mandate for CDN to explore the development of a second national profitability index aiming to maximize herd profitability for commercial dairy producers, alongside the LPI. Through consultation with the various breed associations, A.I. organizations and producer groups, CDN will provide a report on this mandate at the next Open Industry Session in October 2014. No changes to the LPI formula will be implemented prior to April 2015, which is also the target date for introduction of any second profitability index that may arise from this effort.
In terms of eventual changes to the LPI formula, the GEB supported the inclusion of Mastitis Resistance in the Health and Fertility component for the Holstein, Ayrshire and Jersey breeds, instead of the current udder health traits, namely Somatic Cell Score, Udder Depth and Milking Speed. The GEB recommended that the calculation of LPI for genomic young sires also include an adjustment to credit bulls with an outcross pedigree, as reflected by having a publishable Relationship Value (R-Value) that is lower than average. The GEB also encouraged CDN to continue the ongoing analysis showing the existing association between LPI for each breed and realized profit at the herd level, including the publication of extension articles on this important topic.
One of the key priority areas for CDN identified by the GEB is the improvement of procedures for processing MACE evaluations received from Interbull and the subsequent calculation of genomic evaluations. Specifically, traits where improvement is expected include female fertility, longevity, calving performance, the five major type traits as well as fat and protein deviation. CDN will report on the impact of improvements at the Open Industry Session in October 2014 with implementation planned by the December 2014 release.
Given that Canada will officially participate in the Genomic MACE services provided by Interbull on an ongoing basis starting with the April 2014 release, the GEB recommended that CDN conduct an analysis of the ranking of young genomic sires marketed in Canada on the scales of other major countries based on their resulting Genomic MACE evaluations.
As follow-up to the project funded by Zoetis Canada that led to the 50K genotyping of over 550 Ayrshire cows born before 2008, CDN presented results showing the gain in accuracy of prediction with genomics achieved by their inclusion in the reference population. As a consequence, the GEB recommended that CDN work towards the inclusion of genotyped cows with an official LPI in the reference population for Ayrshire, Jersey and Brown Swiss genomic evaluations starting December 2014. An impact analysis including the gain in accuracy achieved will be presented at the Open Industry Session in October 2014.
In conjunction with the genomic validation analyses conducted by CDN, the GEB recommended that a similar analysis be carried out to quantify the degree to which high LPI genomic heifers may be over-estimated compared to their evaluation as a cow. It was agreed that any level of bias in genomic evaluations for young sires and heifers should ideally be removed by improving the accuracy of traditional evaluations for their sires and dams.
The GEB supported the continued effort of CDN aimed at developing extension tools for producers to better understand the risk of change in a genomic evaluation depending of the level of Reliability. It was recommended that CDN publish tables including the average 3Reliability of genomic evaluations on a trait by trait basis for various groups of A.I. sires as well as the associated confidence ranges that quantify the risk of change.
The GEB received a technical update on research at CDN examining methods for
approximating Reliability of Direct Genomic Values (DGVs) with the aim of increasing the frequency of genomic evaluation updates in the future. It was agreed that CDN could introduce simplified procedures that achieve this goal for monthly services provided to A.I. member organizations.
The next Open Industry Session will be held on Tuesday, October 21, 2014 at the Holiday Inn in Guelph, Ontario with the Genetic Evaluation Board meeting the following day.
If there are any questions, concerns or comments regarding the recommendations of the Genetic Evaluation Board, as outlined in this summary, please feel free to contact committee members listed at http://www.cdn.ca/committees-geb.php or by contacting Brian Van Doormaal directly at Canadian Dairy Network.