5 Reasons to Genomic Test Your Ayrshires – Cowsmo

5 Reasons to Genomic Test Your Ayrshires

Genomic selection in the Canadian Ayrshire breed has been a reality for almost 10 years now. Today, essentially  every  bull  with  semen  available  to  Ayrshire  breeders  was  pre‐selected  by  the  A.I.  organization based on genomic testing and has an official genomic evaluation published by Lactanet. In this way, there has been full adoption of genomic testing among Ayrshire bulls and every Ayrshire herd is benefiting from some benefits of genomic selection.

Sire selection is only one side of the rate of genetic progress achieved in a herd – with female selection also being an important opportunity. Unfortunately, the vast majority of Canadian Ayrshire breeders have not yet taken advantage of benefits associated with the genomic testing of their heifers and cows. In fact, during the past four years from 2018 to 2021, only 24 to 37 Canadian Ayrshire breeders have genotyped at least five females in their herd and the average number of genotyped Canadian‐born females has been less than 600. This translates to an 11‐12% adoption rate of heifer genotyping in Canadian Ayrshires. Let’s review the 5 reasons why Canadian Ayrshire breeders need to change their mindset and start genomic testing their heifers and cows.

#1 – Herdbook Integrity
The first outcome of genotyping any animal is a guaranteed confirmation of any recorded parentage for  any  parent  that  has  also  been  genotyped.    In  the  event  that  a  parentage  conflict  is  identified,  Lactanet’s processes are able to discover each animal’s correct sire. Given the high frequency of bull genotyping, this essentially gives 100% certainty of each heifer’s sire. In herds that routinely genotype their females, then when they become dams of future genotyped heifers the full parentage will be confirmed or discovered with certainty. Herdbook integrity is important for Ayrshire Canada but it is also important for your herd and the accuracy of genetic information used for management decisions.

#2 – Managing Genetic Abnormalities
There are multiple genetic abnormalities known to exist in the Canadian Ayrshire population. The most recent example was the discovery of the AM gene associated with the Curly Calf Syndrome, which has an estimated frequency near 20%. The process of genomic testing identifies those animals that are expected to be a carrier of any known genetic abnormality. For Ayrshire breeders, genomic testing of your  females  will  clarify  those  that  are  carriers,  which  is  important  for  making  optimal  sire  mating  decisions to eliminate the impact of any genetic abnormality in your herd.

#3 – More Accurate Selection and Mating Decisions
The average Reliability level for an Ayrshire heifer’s Parent Average for LPI and Pro$ is 32%, which reflects its accuracy. Once a heifer is genotyped this Reliability increases, on average, by 12 percentage points to become 44%. This accuracy level is almost as high as the 45% level that a milk‐recorded, classified  cow  obtains  in  first  lactation.    In  other  words,  Ayrshire  breeders  that  genomic  test  their  heifers can make genetic selection and mating decisions that are nearly as accurate as if those heifers already had their first lactation performance data available. An added bonus with genomic testing of heifers  at a young  age is  that  the  contribution of  their  DNA  to  increase  the  accuracy of  its  genetic  evaluations will also continue into adulthood as a producing cow.

#4 – Faster Rates of Breed Improvement
The  Canadian  Ayrshire  breed  continues  to  make  genetic  progress  for  key  traits  of  importance,  as  reflected by the LPI and Pro$ trends in Figure 1. These trends clearly show the faster rates of genetic gains achieved since the start of Figure 1: Realized Genetic Trend for LPI and Pro$ in Canadian Ayrshires genomic selection in 2014. In fact, the rate of genetic progress for LPI and Pro$ has been 1.24 times faster during the past five years  compared  to  rates  achieved before genomics. The increased  use  of  genomic  testing of heifers and cows by Canadian Ayrshire breeders will augment  this  rate  of  breed  improvement even further.

Figure 1: Realized Genetic Trend for LPI and Pro$ in Canadian Ayrshires

#5 – Boost Future Reliability Gains with Genomics
Canadian Ayrshire breeders can have a significant influence  on  how  much  gain  in  accuracy  (i.e.:  Reliability) can be achieved with genomics in the future. Increased Reliability gains translate to even more breed improvement for traits of importance. Table 1 shows the Reliability gain of 12 percentage points  currently  achieved  for  LPI  and  Pro$  in  the  Ayrshire breed. This gain is directly related to the size  of  the  reference  population  of  genotyped  proven sires and cows used as the basis for genomic evaluation predictions.

Table 1: Reliability Gain vs Reference Population Size

For Ayrshires, the reference population size is estimated at approximately 2,000 bull equivalents. As shown by the relationship between the reference population size and Reliability gains achieved for other breeds in Canada (Table 1), Canadian Ayrshire breeders can see the opportunity available in the future. By doubling the current rate of genomic testing from an average of 600 females per year to 1,200, say in 2022, this would be the same as adding roughly 200 genotyped progeny proven sires to the  reference  population  in  2025.  Genomic testing another 1,200  females  next  year  would  add  another 200 bull equivalents in 2026, etc.

Summary
The  benefits  of  genomic  selection  have  been  highly  realized  through the sire  side of  the  genetic  pathway. Five important reasons why Ayrshire breeders should embrace and adopt genomic selection of their heifers and cows have been outlined. Some of these are most relevant at the herd level while others  represent  major  opportunities for more  accurate and  faster  rates  of  improvement  for  the  Canadian Ayrshire breed.

Author: Brian Van Doormaal, Chief Services Officer, Lactanet Canada

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