The Cow Own Worth or COW rank is a performance ranking designed to rank dairy females on their expected profit potential for their remaining lifetime. This rank is very much in the pilot stage. Below is an explanation and some of the latest developments on COW.
COW represents more closely the actual performance of dairy females in the herd due to the combination of not only genetic effects (i.e. the EBI), but also includes environmental factors (e.g. calving date, age of cow, individual effects such as an injury to a cow’s teats) that highly influence the performance of cows within a Spring-calving system.
COW aims to identify under performing cows to help farmers make informed decisions on dairy females for culling and retention in the herd to improve herd profitability and efficiency. The COW rank can only be generated for females.
COW considers the FULL genetic merit (EBV) of the dairy female, her crossbreeding effects, her environmental influences, her calving date and age at the time of ranking.
EBI identifies the most profitable bulls and cows for breeding dairy replacements. The EBI considers HALF the genetic merit (PTA) of each parent as only 50% of the genes from each parent can be passed on to the offspring.
DO NOT USE COW FOR BREEDING YOUR REPLACEMENTS
– This will reduce the genetic gain of your herd.
EBI is for selecting your best animals for BREEDING. COW is for CULLING females.
– The genetics of any animal will remain the same throughout its lifetime – therefore the EBI does not need to know the age of the cow, her calving date or any environmental factors affecting her.
– But the performance of a cow in your herd is highly influenced by other factors other than genetic merit. For example, a high EBI heifer will be considered for culling if she is empty after the breeding season, where your 10th lactation cow might be kept in the herd for another season if she is due to calve next year in February and has good milk solids and low SCC. Similarly, a second lactation cow is worth more than a fifth lactation cow even though the two might have the same EBI figure.
– Individual environmental effects can only be collected from milk recorded herds.
How does COW rank my cows?
The COW rank considers the expected lifetime profit from each cow from 3 sources;
- Current lactation profit
- Future lactations profit
- Net culling costs.
Does the COW ranking work?
The COW ranking was tested using national data from 2011 and compared to the actual performance of these cows in 2012. The results showed that that dairy females ranking higher on COW yield more milk and milk solids in their lactation, and calve earlier in a seasonal calving production system than their lower ranking contemporaries. Using the A+B-C milk pricing system, the difference in expected profit between the top 25% of cows on COW and the bottom 25% of cows on COW would be worth €360/cow/lactation – which is €9000 in a 100 cow herd.
Where COW is currently at?
A pilot system has been put in place this summer where a group of herds have been contacted and their cows ranked on the COW. These herds are from all over the country and are all spring calving herds that are currently milk recording. The purpose of this group is to get feedback from these herd owners on the accuracy of the COW rank in both high and low input systems with varying optimal calving dates.
- COW ranks dairy cows on expected profitability – it is a management tool
- COW is complimentary to EBI (the breeding tool)
- COW can only be calculated for milk recorded herds
- COW includes the genetic merit, crossbreeding effects, and individual (environmental) effects of traits of economic importance, as well as the age of the cow and her actual calving date to rank within the herd on expected profitability.
- Pregnancy diagnosis has a huge impact on a cow’s rank in the herd
- There is potential to include new traits of importance
- Genomics will improve the accuracy of COW
To view the full slideshow presented by Margaret Kelleher at a recent Dairy Industry meeting please click on the PDF icon below.