15 February 2025
Genotyping gains
Stuart Childs, Teagasc Dairy Specialist, tells us how genotyping is enhancing the reliability and accuracy of the main dairy breeding indexes.
In 2023 the Minister for Agriculture, Food and the Marine, Charlie McConologue, launched the National Genotyping Programme. Since then, the share of the national dairy herd that is genotyped has increased from 6.5% to 35%. By the end of November last year, 700,000 calves had been genotyped and registered through Phase 2 of the programme. This represents 35% of all calves born in Ireland in 2024. The proportion will increase further in 2025 as an additional 4,000 herds have joined the programme bringing the total number of participating herds (dairy and beef) to 14,600.
The benefits of genotyping include increased accuracy and reliability of the Economic Breeding Index (EBI), Dairy Beef Index (DBI) and the Commercial Beef Value (CBV) of calves. The strengthening of the numbers behind these indexes gives greater confidence to both breeders and buyers about what stock to breed from, or in the case of the CBV, what calf to buy. Four fifths of the just less than 11% of samples submitted with no sire identified had a sire identified based on the genotype. Early identification of carriers of lethal genetic conditions is another plus. Over time this will minimise, or potentially eliminate, these conditions. Enhanced traceability is a further benefit from a genotyping programme at this scale.
New technology
A bonus from genotyping of the herd is the opportunity to avail of a new technology that will be on the market in 2025: ‘Genocells’. Genocells is an innovative, genomic technology that was developed in Belgium at the University of Liege.
It will now be available to Irish dairy farmers who have genotyped their herds through ICBF, and the milk recording organisations, Munster Bovine and Progressive Genetics.
How it works
1. Genotyping an animal identifies its individual DNA.
2. Milk cells contain DNA.
3. Genotyping a milk sample then allows for the calculation of the contribution of each cow to the SCC of the sample.
Validation
The milk recording organisations and ICBF undertook a comprehensive validation process in July/ August of 2024. A total of 85 herds submitted three samples each over a number of weeks to verify accuracy, administration and logistics management around the sample turnaround time and subsequent reporting.
Validation results
The accuracy was found to be 90-98%. Including non-genotyped Milk recording yields together with the Genocell bulk tank SCC result are used to create Genocell SCC bands. This means that GenoCell results can be colour coded. animals and incorrectly identifying cows who contributed to the tank on the day of sampling were found to be the main factors which reduced accuracy.
It took just seven days to complete the whole process from sampling on farm to results received.
Colour-coded reports
Milk recording yields together with the GenoCell bulk tank SCC result are used to create Genocell SCC bands. This means that GenoCell results can be colour coded. Farmers who are already milk recording will be familiar with the colour coded reporting for SCC. This format is also being utilised in GenoCell sample reporting.
The benefits
Better management of SCC delivers better overall milk quality, reduces the usage of antibiotics and lowers costs associated with mastitis in dairy herds. Combining Genocells sampling with your milk recording allows you to manage your herd’s SCC more effectively throughout the lactation.
Samples can easily be taken between milk recordings. This means you can take action to manage SCC more quickly than waiting to complete a milk recording. Farmers that have high SCC will be able to use the report to identify the ‘culprits’ and take action. In herds where SCC is good but a spike or issue comes out of the blue, Genocells will allow for rapid identification of the main offender(s). Swift action to address the source of the issue can follow.
Selective dry cow therapy
Genocells will also have a role to play in selective dry cow therapy (SDCT). Sampling allows you to identify cows not suitable for SDCT, for example in cases where cows are being milked for more than the four weeks following the last recording before drying off. Milk recording will still be necessary for fat and protein percentage analysis and to establish individual cow yields.
Milk recording yields, in conjunction with the Genocells sample results, will indicate the percentage contribution from individual cows. This is a key element in determining each cow’s impact on the bulk milk SCC.
‘You get a lot of information for minimal effort’
Conor O’Brien, who is farming with his father Vincent and mother Mary at Kilmurry, Tynagh, near Loughrea, Co. Galway participated in the validation trial.
“The biggest benefit of the Genocells is the report you can get for what really is very minimal effort,” says Conor
“It only takes two minutes to take the sample, drop it in the post and you get the report back in no time.
“The report contains results for 10% of the herd with a minimum of 10 Cows and a maximum of 20 cows being displayed on the report. I like that it also gives you confirmation that the low SCC cows are genuinely low.”
Conor, who has just completed his ninth season of sub-00 average SCC milk supply to his co-op, Arrabawn, says he foresees himself doing a number of Genocells samples early in the season to maintain a low SCC. He will use it again later in the season as he approaches drying off to facilitate his selective dry cow therapy programme.
“This will be done along with the usual four or five milk recordings we do during the year,” adds Conor.
Access to new technologies
“Acknowledging that herds will need to be fully genotyped in order to avail of the service. I would strongly encourage people to join the National Genotyping Programme (NGP) if they get the opportunity,” says Conor.
“It opens the door to new and innovative technologies. Genocells is just one example.”
Genocells technology will be available to dairy farmers who have their herds genotyped in 2025. For more information contact your milk recording provider.
Rosarii O’Connor (Munster Bovine) and Matthew Thompson (ICBF) assisted in the research and writing of this article.
This article was first published in Today’s Farm