Interpreting Norwegian Proofs

Time to read: ca 5 min

The Total Merit Index (TMI) in the Norwegian EBVs is influenced by and determined by the key genetic traits that will stimulate dairy cattle's profitability. What should you expect when the index for the trait is above 100?

The Total Merit Index will show a high score for bulls that excel in production, fertility, health, and udder conformation. It also underlines excellent results in functional traits such as calving ease, livability, and claw health.

The score also suggests excellent genetics that helps improve farmers' profitability with good health and low use of antibiotics. The medium-sized cow also offers excellent feed efficiency. 

Table 1. Trait averages and standard deviations for purebred Norwegian Reds in units converted from breed average of 100 and standard deviation (SD)* of 12.
Trait Definition Average proof in units (kg, %, etc.) Expected difference from average when Norwegian proof is +1 SD (or +12 index points) above 100
Milk yield Average milk per lactation for lactations 1-3 (kg) 8,144 274
Protein yield Average protein per lactation for lactations 1-3 (kg) 285 8.9
Fat yield Average fat per lactation for lactations 1-3 (kg) 339 10.7
Protein percent Average % protein per lactation for lactations 1-3 (%) 3.52 0.05
Fat percent Average % fat per lactation for lactations 1-3 (%) 4.18 0.09
Stature Rump height in lactation 1 (cm) 136.8 1.13
Temperament Lact 1 daughters classified with good temperament (%) 91.4 2.3
No. of inseminations, heifers Number of inseminations in heifers until pregnant 1.45 -0.05
No. of inseminations, cows Number of inseminations in cows until pregnant 1.59 -0.05
Calving to first insemination (CFI) Days from calving to first insemination for lact 1-4 (days) 76.3 -2.2
Calving ease, direct No calving problems when bred to 1st lact heifers (%) 88.0 3.5
Clinical mastitis Lact 1-3 daughters not treated for clinical mastitis (%) 89.3 1.9
Somatic cell count (SCC) SCC for lactation 1-3 daughters (cells/ml) 70,645 -7,948
Feed$aved™ Daily dry matter intake compared to 700 kg cow (kg) -0.65 -0.18
Body weight Average mature (live) body weight (kg) 610 12.1
*68% of the population is within ±1 SD (±12 points) of the average, 95% within ±2 SD (±24 points) of the average, etc.

Example Milk yield

The average kg of milk for lactations 1-3 is 8,144kg (17,955 lbs.). For Milk yield=112  expect +274kg (604 lbs.) for total milk yield of 8,418kg (18,559 lbs.) per lactation.

Example Calving ease, direct

88.0% of calvings of 1st lactation heifers, attributed to sire of calf, have no difficulty. For a bull with direct calving ease=112 expect 3.5% better or 91.5% of calvings of 1st lactation heifers with no calving difficulty due to sire of calf.

Example Stature

Average 1st lactation cows have rump height of 136.8 cm (53.9”). For a bull with Stature=112 expect an average daughter to be 1.13 cm (0.44”) taller. For Stature=88 an average daughter would be 1.13 cm (0.44”) shorter.