Increases in input costs and the price of milk are reflected in the latest updates to AHDB’s dairy genetic indexes.
The formulas for profitable lifetime index (PLI), spring calving index (SCI) and autumn calving index (ACI) have been modified to reflect changing economic conditions, notably in feed, labour and replacement costs, as well as in the value of cull cows.
Marco Winters, AHDB’s head of animal genetics, said there was more volatility in the market for inputs than when previous updates to the indexes had been made.
“However, we don’t know how sustained current prices will be, so we have to base our decisions on longer-term projections. We will continue to carry out regular reviews and may have to make adjustment if circumstances dictate.”
To address the rising significance of feed cost, feed advantage (FAdv) – which combines maintenance index with a genomic prediction of feed efficiency – has been added to PLI for Holsteins.
Maintenance will continue to be used for other dairy breeds and for the across-breed indexes ACI and SCI.
Genetic evaluation for digital dermatitis (DD) has been added to the three main indexes and across all breeds.
This follows ongoing work at the University of Liverpool, which showed the AHDB genomic evaluation for DD was very effective in predicting the odds of a cow having DD.
DD will now be included alongside lameness advantage (LAdv). By using LAdv and DD indexes together, more rapid genetic benefits can be achieved to help tackle lameness.
For the SCI only, bulls whose daughters are heavier will now be penalised more severely for spring block calving, grazing-based systems.
This is because many farmers running grazing systems place a higher value – over and above the additional maintenance feed cost – on the lack of soil damage and ease of management smaller cows can bring, according to AHDB.
The changes to the genetic evaluations will lead to a slight shift in the running order in the next AHDB bull rankings, out on 5 April.
What are the main genetic valuation indexes?
- Profitable lifetime index is tailored for year-round calving herds and is a within-breed index
- Autumn calving index is an across-breed index, designed for autumn block-calving herds producing much of their milk during the winter months
- Spring calving index is for herds with a heavy reliance on grazed grass that calve in a tight block in spring, and can also compare animals across breeds
About two-thirds of the value of each index is placed on health and efficiency and one-third on production.