Interpretation of breeding values
Interpretation of breeding values for milk, fat and protein
Braunvieh Schweiz use the following genetic base definition within the framework of breeding value estimation: the average breeding value of all cows aged 6 to 8 years equals to zero. This so-called rolling base is reviewed every year in April and is valid for one year. The current genetic base (BS21) was obtained by considering Brown Swiss cows born between 2013 and 2015. Within a population, breeding values therefore allow to compare the genetic potential of an animal with adult cows directly. To this purpose, the table “Interpretation of breeding values” can provide useful information. The specified BV ranges are to be considered as rough indications that, thanks to the rolling base, can remain unchanged over several years.
Functional traits
The expression of breeding values for functional traits – somatic cell score, persistency, longevity, female fertility, calving ease and milk flow are published on a 100 base and with a genetic standard deviation equal to 12.
Traits for which low phenotypic values are desirable (somatic cell score, waiting period) are also expressed in a way that always allows to aim for high breeding values. This simplifies interpretation significantly: two thirds of all BVs for these traits are between 90 and 110 index points. Breeding values over 110 are rated as good, those over 120 as very good. Breeding values over 130 or below 70 are rare.
Interpretation of breeding values for conformation traits
All first lactation cows on farms involved in the programs Bruna Data and Bruna Classic are linearly described and classified. Estimated breeding values for conformation traits are published as indices, where the average BV of cows aged six to eight years equals to 100 and 12 units of the index corresponds to one genetic standard deviation for each trait. To interpret the bar charts on BrunaNet, please note that not for all conformation traits high positive values are most desirable.
Interpretation of OB breeding values
The breeding values of Original Braunvieh cattle are expressed on a separate genetic base (OB21). To compare OB breeding values t with breeding values on a BS base, it is necessary to apply the base constants specified in the table “Interpretation of breeding values” (OB breeding values = BS breeding values + OB constant).
Interpretation of breeding values
| Evaluation (% of all BVs) | satisfactory (c. 68 %) | good (c. 14 %) | very good (c. 2 %) | OB constant |
|---|---|---|---|---|
| Milkkg | -400 to +400 | +401 to +800 | > +800 | 629 |
| Fat kg | -17 to +17 | +18 to +35 | > +35 | 28 |
| Fat % | -0.15 to +0.15 | +0.16 to +0.30 | > 0.30 | 0.04 |
| Protein kg | -12 to +12 | +13 to +25 | > 25 | 21 |
| Protein % | -0.10 to +0.10 | +0.11 to +0.20 | > 0.20 | -0.02 |
| Milk value | 90 to 110 | 111 to 120 | > 120 | 18 |
| Persistency | 90 to 110 | 111 to 120 | > 120 | -4 |
| Somatic cell score | 90 to 110 | 111 to 120 | > 120 | -7 |
| Mastitis resistance | 90 to 110 | 111 to 120 | > 120 | -8 |
| Conformation | 90 to 110 | 111 to 120 | > 120 | 4 |
| Longevity | 90 to 110 | 111 to 120 | > 120 | -9 |
| Milking speed | 90 to 110 | 111 to 120 | > 120 | -5 |
| Temperament | 90 to 110 | 111 to 120 | > 120 | -1 |
| Fertility index | 90 to 110 | 111 to 120 | > 120 | -6 |
| Calving ease, direct | 90 to 110 | 111 to 120 | > 120 | 18 |
| Calving ease, maternal | 90 to 110 | 111 to 120 | > 120 | 4 |
| Calf survival, direct | 90 to 110 | 111 to 120 | > 120 | -5 |
| Calf survival, maternal | 90 to 110 | 111 to 120 | > 120 | -5 |
| Rearing losses | 90 to 110 | 111 to 120 | > 120 | -5 |
| TMI | 900 to 1100 | 1101 to 1200 | > 1200 | * |
| Fitness value | 90 to 110 | 111 to 120 | > 120 | -15 |
| TMI grazing | 90 to 110 | 111 to 120 | > 120 | * |
* Due to different weighting of the characteristics, TMI and TMI grazing cannot be directly compared for BS and OB.
Total merit indices
The total merit index (TMI) is a modern tool available to Brown Cattle breeders in Switzerland. It combines fitness and performance traits in an ideal way. Besides TMI, two partial merit indices, i.e. the milk value index and the fitness value index, as well as a total merit index for grazing are calculated.
For TMI, milk value index, fitness value index and TMI grazing a rolling genetic base is used. During the evaluation run in April, these indices are standardized so that the mean genetic base of the animals is equal to 0 (production traits) and 100 (fitness traits).
The base adjustment for milk value index, fitness value index and TMI grazing is done automatically with the base adjustment of the single traits. For TMI, the base value is 1000 and a genetic standard deviation of 120 index points is used. For milk value index, fitness value index and TMI grazing the base value is 100 and the genetic standard deviation is 12 index points.
Publication dates
Tuesday, April 6, 2021
Tuesday, August 10, 2021
Tuesday, December 7, 2021
