Genetic gain in dairy cows has increased rapidly in recent years, report shows
Following the introduction of the Gene Ireland Programme and genomic selection, milk and fertility sub-indices have increased significantly.
The rate of genetic gain in the Economic Breeding Index (EBI) has accelerated rapidly over the last number of years.
According to the latest report from the Irish Cattle Breeding Federation (ICBF), the current annual trend in the EBI is €11.65 per year.
When making comparisons on an annual basis, ICBF compares genetic indices based on the number of dairy cows in dairy herds at the start of July and is calculated for the September evaluation.
The overall countrywide increase in genetic gain has notably increased profit per lactation. Every €1 increase in EBI translates to a €2 increase in farm profit.
Over the last 20 years, following the introduction of the Gene Ireland programme and genomic selection in 2005 and 2009 respectively, the milk and fertility sub-indices have improved significantly and simultaneously and at an equal rate.
Before this, milk production was increasing, but fertility was declining. This year, the average EBI of dairy cows is €188 higher than it was 20 years ago, which ICBF says translates to an additional €376 per lactation for cows calved this year compared to those in 2002. The genetic progress has allowed farmers to breed more efficient and sustainable animals.
The calving sub index, which is critical for improving calving ease and reducing mortality rates, guides farmers to make sire choices and identify bulls which can produce offspring with fewer calving difficulties.
The calving sub-index has consistently improved year after year and has increased linearly. With these improvements, gestation periods leading to earlier calving seasons and better herd management have improved.
A spokesperson for ICBF commented regarding the latest report: “Breeding is a long-term investment — it takes several years for genetic improvements to fully filter through the herd. That’s why bull selection is so important every year.
"The latest genetic trends show that dairy farmers continue to place strong emphasis on EBI when choosing sires. It’s also important to remember that genetics is both cumulative and permanent. Each year’s improvement builds on the last and remains within the herd.”
ICBF has reported a slight increase in the maintenance sub-index; however, in the last three to four years, the trend has begun to decline. It appears the size of cows has begun to increase again in recent years, which has been indicated via genetic data.
The beef sub-index has also seen a continued decline, but the rate of decline has slowed in recent years.
Management and health sub-indices have remained relatively stable. The health sub-index experienced an initial increase but has declined slightly in recent years. Similarly, the management sub-index has seen some improvement, but overall gains have been minimal in the last five years.
TB breeding values were first published as a standalone trait in 2019 and were included in the EBI in November 2022 as part of an update. Since then, ICBF has reported a stabilising trend to the sub-index.
ICBF has advised farmers that to improve TB resistance, herds should aim to use bulls with a TB breeding value of less than 8.5%. If farmers want to see a more rapid improvement, bulls with values below 6.5% are recommended. Each animal’s breeding value is expressed as the expected prevalence of the infection in its progeny.
In conclusion of the report, ICBF said the national breeding programme and genomic selection have both contributed to the increased rate of genetic gain in the national herd.
