Starting in April 2017, the CDCB will include Cow livability into the Net Merit $ formula.
Cow livability (LIV) was introduced as a new trait in August 2016. It measures a cow’s ability to stay alive on the farm, and has a high (0.70) correlation with Productive Life (PL). The difference between LIV and PL is that PL measures a cow’s ability to be productive on the farm. It does not distinguish between death and culling as the reason for leaving the herd.
Cows that die on the farm are a great expense. In fact, based on cull prices, farmers could earn $1,200 less profit for each cow that dies on farm and cannot be sold for beef.
LIV is also correlated to DPR by 0.45 and to SCS by -0.25.
Net Merit changes
Net Merit (NM$) is an estimate of a cow’s lifetime profit to the farm. CDCB updated the formula for April 2017 proofs. It now includes new traits and revisions of traits using current incomes and expenses.
New changes include:
- LIV is now part of the NM$ formula
- Economic values are updated and current
- Body weight composite (BWC) will replace Body size composite (BSC)
Relative values for most other traits included in the formula decreased slightly. The 2017 NM$ formula correlates by 0.989 to the previous NM$ from 2014. The table below shows the differences in the relative value of trait weights between the NM$ formula in 2014 and 2017.
|TRAIT||2014 NM$ TRAIT WEIGHT||2017 NM$ TRAIT WEIGHT|
|Somatic cell score||-7||-6.5|
|Daughter pregnancy rate||7||6.7|
|Calving ability $||5||4.8|
|Cow conception rate||1||1.6|
|Heifer conception rate||2||1.4|
|Feet & legs||3||2.7|
|Body size composite||-5||–|
|Body weight composite||–||-5.9|
The relative value of weight on PL decreases now that LIV is part of the NM$ formula. This adjustment will not hinder genetic progress for PL. Instead, it will increase the progress for LIV.
Body weight replaces body size
Since BWC is more closely related to the actual body weight of the cow than BSC, this change results in less selection against stature, body depth, and dairy form.
Finally, to account for updated milk component prices, the new NM$ formula increases emphasis on fat while decreasing emphasis on protein slightly.