What exactly does CRV measure to calculate the feed efficiency breeding value?

CRV measures:

• milk production
• feed intake
• body weight
• water intake
• health traits

Breeding for feed efficiency has no effect on conformation traits or health.

Which factors affect feed efficiency?

• Body weight of the cows. The heavier the cow, the more maintenance feed required
• Quality of the feed
• Cows with higher milk production generally have better feed efficiency
• The genetic preposition of the cow partly determines how efficiently it converts feed
• Lactation stage of the cow. Newly calved cows often have a higher feed efficiency that can be affected by a positive or negative energy balance
• Age of the cow. Older cows generally have a slightly higher feed efficiency. Heifers in particular often need a little extra feed for growth while they are young
  
  

What is the difference between CRV’s feed efficiency breeding value and that of the competitors?

• Saved Feed Index (Viking)
• Ecofeed (Cogent)
• EcoFeed index (ST Genetics)
  

CRV has the largest reference population with actual feed intake data of dairy cows (7008 cows). Viking does not yet use actual feed intake data when calculating feed efficiency, whereas ST Genetics/Cogent uses feed intake data from young stock (4000 cows). They convert the feed intake for growth into the feed intake for milk production. Literature suggests there is a correlation between this data, but it is clearly less strong than the feed intake measured in lactating animals.

Which factors affect the feed intake?

• Palatability of the feed
• How often fresh rations of feed are offered
• Feed composition. Coarse structured feed with lots of stalks is often consumed less
• Temperature (too high) can play an important role
• Is there enough space at the feed fence to allow young heifers to eat?
• Is plenty of clean and fresh drinking water available?
• The dry matter % of the ration
• Lactation stage of the cow
• Age of the cow